Merge branch 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c updates from Wolfram Sang:
 "Most notable:

   - introducing the i2c_quirk infrastructure.  Now, flaws of I2C
     controllers can be described and the core will check if the flaws
     collide with the messages to be sent

   - wait_for_completion return type cleanup series

   - new drivers for Digicolor, Netlogic XLP, Ingenic JZ4780

   - updates to the I2C slave framework which include API changes.  Its
     only user was updated, too.  Documentation was finally added

   - changed dynamic bus numbering for the DT case.  This could change
     bus numbers for users.  However, it fixes a collision where dynamic
     and static busses request the same id.

   - driver bugfixes, cleanups"

* 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (52 commits)
  i2c: xlp9xx: Driver for Netlogic XLP9XX/5XX I2C controller
  of: Add vendor prefix 'netlogic'
  i2c: davinci: use ICPFUNC to toggle I2C as gpio for bus recovery
  i2c: davinci: use bus recovery infrastructure
  i2c: change input parameter to i2c_adapter for prepare/unprepare_recovery
  i2c: i2c-mux-gpio: remove error messages for probe deferrals
  i2c: jz4780: Add i2c bus controller driver for Ingenic JZ4780
  i2c: dln2: set the device tree node of the adapter
  i2c: davinci: fixup wait_for_completion_timeout handling
  i2c: mpc: Fix ISR return value
  i2c: slave-eeprom: add more info when to increase the pointer
  i2c: slave: add documentation for i2c-slave-eeprom
  Documentation: i2c: describe the new slave mode
  i2c: slave: rework the slave API
  i2c: add support for the Digicolor I2C controller
  i2c: busses with dynamic ids should start after fixed ids for DT
  of: base: add function to get highest id of an alias stem
  i2c: designware: Suppress error message if platform_get_irq() < 0
  i2c: mpc: assign the correct prescaler from SVR
  i2c: img-scb: fixup of wait_for_completion_timeout return handling
  ...

Documentation/devicetree/bindings/i2c/i2c-davinci.txt

@@ -10,6 +10,9 @@ Required properties:
 Recommended properties :
 - interrupts : standard interrupt property.
 - clock-frequency : desired I2C bus clock frequency in Hz.
+- ti,has-pfunc: boolean; if defined, it indicates that SoC supports PFUNC
+	registers. PFUNC registers allow to switch I2C pins to function as
+	GPIOs, so they can by toggled manually.
 
 Example (enbw_cmc board):
 	i2c@1c22000 {

Documentation/devicetree/bindings/i2c/i2c-digicolor.txt

+Conexant Digicolor I2C controller
+
+Required properties:
+ - compatible: must be "cnxt,cx92755-i2c"
+ - reg: physical address and length of the device registers
+ - interrupts: a single interrupt specifier
+ - clocks: clock for the device
+ - #address-cells: should be <1>
+ - #size-cells: should be <0>
+
+Optional properties:
+- clock-frequency: the desired I2C bus clock frequency in Hz; in
+  absence of this property the default value is used (100 kHz).
+
+Example:
+
+	i2c: i2c@f0000120 {
+		compatible = "cnxt,cx92755-i2c";
+		reg = <0xf0000120 0x10>;
+		interrupts = <28>;
+		clocks = <&main_clk>;
+		clock-frequency = <100000>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};

Documentation/devicetree/bindings/i2c/i2c-jz4780.txt

+* Ingenic JZ4780 I2C Bus controller
+
+Required properties:
+- compatible: should be "ingenic,jz4780-i2c"
+- reg: Should contain the address & size of the I2C controller registers.
+- interrupts: Should specify the interrupt provided by parent.
+- clocks: Should contain a single clock specifier for the JZ4780 I2C clock.
+- clock-frequency: desired I2C bus clock frequency in Hz.
+
+Recommended properties:
+- pinctrl-names: should be "default";
+- pinctrl-0: phandle to pinctrl function
+
+Optional properties:
+- interrupt-parent: Should be the phandle of the interrupt controller that
+  delivers interrupts to the I2C block.
+
+Example
+
+/ {
+	i2c4: i2c4@0x10054000 {
+		compatible = "ingenic,jz4780-i2c";
+		reg = <0x10054000 0x1000>;
+
+		interrupt-parent = <&intc>;
+		interrupts = <56>;
+
+		clocks = <&cgu JZ4780_CLK_SMB4>;
+		clock-frequency = <100000>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pins_i2c4_data>;
+
+	};
+};
+

Documentation/devicetree/bindings/i2c/i2c-xlp9xx.txt

+Device tree configuration for the I2C controller on the XLP9xx/5xx SoC
+
+Required properties:
+- compatible      : should be "netlogic,xlp980-i2c"
+- reg             : bus address start and address range size of device
+- interrupts      : interrupt number
+
+Optional properties:
+- clock-frequency : frequency of bus clock in Hz
+                    Defaults to 100 KHz when the property is not specified
+
+Example:
+
+i2c0: i2c@113100 {
+	compatible = "netlogic,xlp980-i2c";
+	#address-cells = <1>;
+	#size-cells = <0>;
+	reg = <0 0x113100 0x100>;
+	clock-frequency = <400000>;
+	interrupts = <30>;
+	interrupt-parent = <&pic>;
+};

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -125,6 +125,7 @@ mxicy	Macronix International Co., Ltd.
 national	National Semiconductor
 neonode		Neonode Inc.
 netgear	NETGEAR
+netlogic	Broadcom Corporation (formerly NetLogic Microsystems)
 newhaven	Newhaven Display International
 nintendo	Nintendo
 nokia	Nokia

Documentation/i2c/slave-eeprom-backend

+Linux I2C slave eeprom backend
+==============================
+
+by Wolfram Sang <wsa@sang-engineering.com> in 2014-15
+
+This is a proof-of-concept backend which acts like an EEPROM on the connected
+I2C bus. The memory contents can be modified from userspace via this file
+located in sysfs:
+
+	/sys/bus/i2c/devices/<device-direcory>/slave-eeprom
+
+As of 2015, Linux doesn't support poll on binary sysfs files, so there is no
+notfication when another master changed the content.
+

Documentation/i2c/slave-interface

+Linux I2C slave interface description
+=====================================
+
+by Wolfram Sang <wsa@sang-engineering.com> in 2014-15
+
+Linux can also be an I2C slave in case I2C controllers have slave support.
+Besides this HW requirement, one also needs a software backend providing the
+actual functionality. An example for this is the slave-eeprom driver, which
+acts as a dual memory driver. While another I2C master on the bus can access it
+like a regular EEPROM, the Linux I2C slave can access the content via sysfs and
+retrieve/provide information as needed. The software backend driver and the I2C
+bus driver communicate via events. Here is a small graph visualizing the data
+flow and the means by which data is transported. The dotted line marks only one
+example. The backend could also use e.g. a character device, be in-kernel
+only, or something completely different:
+
+
+              e.g. sysfs        I2C slave events        I/O registers
+  +-----------+   v    +---------+     v     +--------+  v  +------------+
+  | Userspace +........+ Backend +-----------+ Driver +-----+ Controller |
+  +-----------+        +---------+           +--------+     +------------+
+                                                                | |
+  ----------------------------------------------------------------+--  I2C
+  --------------------------------------------------------------+----  Bus
+
+Note: Technically, there is also the I2C core between the backend and the
+driver. However, at this time of writing, the layer is transparent.
+
+
+User manual
+===========
+
+I2C slave backends behave like standard I2C clients. So, you can instantiate
+them like described in the document 'instantiating-devices'. A quick example
+for instantiating the slave-eeprom driver from userspace:
+
+  # echo 0-0064 > /sys/bus/i2c/drivers/i2c-slave-eeprom/bind
+
+Each backend should come with separate documentation to describe its specific
+behaviour and setup.
+
+
+Developer manual
+================
+
+I2C slave events
+----------------
+
+The bus driver sends an event to the backend using the following function:
+
+	ret = i2c_slave_event(client, event, &val)
+
+'client' describes the i2c slave device. 'event' is one of the special event
+types described hereafter. 'val' holds an u8 value for the data byte to be
+read/written and is thus bidirectional. The pointer to val must always be
+provided even if val is not used for an event, i.e. don't use NULL here. 'ret'
+is the return value from the backend. Mandatory events must be provided by the
+bus drivers and must be checked for by backend drivers.
+
+Event types:
+
+* I2C_SLAVE_WRITE_REQUESTED (mandatory)
+
+'val': unused
+'ret': always 0
+
+Another I2C master wants to write data to us. This event should be sent once
+our own address and the write bit was detected. The data did not arrive yet, so
+there is nothing to process or return. Wakeup or initialization probably needs
+to be done, though.
+
+* I2C_SLAVE_READ_REQUESTED (mandatory)
+
+'val': backend returns first byte to be sent
+'ret': always 0
+
+Another I2C master wants to read data from us. This event should be sent once
+our own address and the read bit was detected. After returning, the bus driver
+should transmit the first byte.
+
+* I2C_SLAVE_WRITE_RECEIVED (mandatory)
+
+'val': bus driver delivers received byte
+'ret': 0 if the byte should be acked, some errno if the byte should be nacked
+
+Another I2C master has sent a byte to us which needs to be set in 'val'. If 'ret'
+is zero, the bus driver should ack this byte. If 'ret' is an errno, then the byte
+should be nacked.
+
+* I2C_SLAVE_READ_PROCESSED (mandatory)
+
+'val': backend returns next byte to be sent
+'ret': always 0
+
+The bus driver requests the next byte to be sent to another I2C master in
+'val'. Important: This does not mean that the previous byte has been acked, it
+only means that the previous byte is shifted out to the bus! To ensure seamless
+transmission, most hardware requests the next byte when the previous one is
+still shifted out. If the master sends NACK and stops reading after the byte
+currently shifted out, this byte requested here is never used. It very likely
+needs to be sent again on the next I2C_SLAVE_READ_REQUEST, depending a bit on
+your backend, though.
+
+* I2C_SLAVE_STOP (mandatory)
+
+'val': unused
+'ret': always 0
+
+A stop condition was received. This can happen anytime and the backend should
+reset its state machine for I2C transfers to be able to receive new requests.
+
+
+Software backends
+-----------------
+
+If you want to write a software backend:
+
+* use a standard i2c_driver and its matching mechanisms
+* write the slave_callback which handles the above slave events
+  (best using a state machine)
+* register this callback via i2c_slave_register()
+
+Check the i2c-slave-eeprom driver as an example.
+
+
+Bus driver support
+------------------
+
+If you want to add slave support to the bus driver:
+
+* implement calls to register/unregister the slave and add those to the
+  struct i2c_algorithm. When registering, you probably need to set the i2c
+  slave address and enable slave specific interrupts. If you use runtime pm, you
+  should use pm_runtime_forbid() because your device usually needs to be powered
+  on always to be able to detect its slave address. When unregistering, do the
+  inverse of the above.
+
+* Catch the slave interrupts and send appropriate i2c_slave_events to the backend.
+
+Check the i2c-rcar driver as an example.
+
+
+About ACK/NACK
+--------------
+
+It is good behaviour to always ACK the address phase, so the master knows if a
+device is basically present or if it mysteriously disappeared. Using NACK to
+state being busy is troublesome. SMBus demands to always ACK the address phase,
+while the I2C specification is more loose on that. Most I2C controllers also
+automatically ACK when detecting their slave addresses, so there is no option
+to NACK them. For those reasons, this API does not support NACK in the address
+phase.
+
+Currently, there is no slave event to report if the master did ACK or NACK a
+byte when it reads from us. We could make this an optional event if the need
+arises. However, cases should be extremely rare because the master is expected
+to send STOP after that and we have an event for that. Also, keep in mind not
+all I2C controllers have the possibility to report that event.
+
+
+About buffers
+-------------
+
+During development of this API, the question of using buffers instead of just
+bytes came up. Such an extension might be possible, usefulness is unclear at
+this time of writing. Some points to keep in mind when using buffers:
+
+* Buffers should be opt-in and slave drivers will always have to support
+  byte-based transactions as the ultimate fallback because this is how the
+  majority of HW works.
+
+* For backends simulating hardware registers, buffers are not helpful because
+  on writes an action should be immediately triggered. For reads, the data in
+  the buffer might get stale.
+
+* A master can send STOP at any time. For partially transferred buffers, this
+  means additional code to handle this exception. Such code tends to be
+  error-prone.
+

Documentation/i2c/summary

@@ -41,7 +41,3 @@ integrated than Algorithm and Adapter.
 
 For a given configuration, you will need a driver for your I2C bus, and
 drivers for your I2C devices (usually one driver for each device).
-
-At this time, Linux only operates I2C (or SMBus) in master mode; you can't
-use these APIs to make a Linux system behave as a slave/device, either to
-speak a custom protocol or to emulate some other device.

drivers/i2c/busses/Kconfig

@@ -485,6 +485,15 @@ config I2C_DESIGNWARE_BAYTRAIL
 	  the platform firmware controlling it. You should say Y if running on
 	  a BayTrail system using the AXP288.
 
+config I2C_DIGICOLOR
+	tristate "Conexant Digicolor I2C driver"
+	depends on ARCH_DIGICOLOR
+	help
+	  Support for Conexant Digicolor SoCs (CX92755) I2C controller driver.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-digicolor.
+
 config I2C_EFM32
 	tristate "EFM32 I2C controller"
 	depends on ARCH_EFM32 || COMPILE_TEST
@@ -574,6 +583,15 @@ config I2C_IOP3XX
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-iop3xx.
 
+config I2C_JZ4780
+	tristate "JZ4780 I2C controller interface support"
+	depends on MACH_JZ4780 || COMPILE_TEST
+	help
+	 If you say yes to this option, support will be included for the
+	 Ingenic JZ4780 I2C controller.
+
+	 If you don't know what to do here, say N.
+
 config I2C_KEMPLD
 	tristate "Kontron COM I2C Controller"
 	depends on MFD_KEMPLD
@@ -898,6 +916,16 @@ config I2C_XLR
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-xlr.
 
+config I2C_XLP9XX
+	tristate "XLP9XX I2C support"
+	depends on CPU_XLP || COMPILE_TEST
+	help
+	  This driver enables support for the on-chip I2C interface of
+	  the Broadcom XLP9xx/XLP5xx MIPS processors.
+
+	  This driver can also be built as a module.  If so, the module will
+	  be called i2c-xlp9xx.
+
 config I2C_RCAR
 	tristate "Renesas R-Car I2C Controller"
 	depends on ARCH_SHMOBILE || COMPILE_TEST

drivers/i2c/busses/Makefile

@@ -45,6 +45,7 @@ i2c-designware-platform-objs := i2c-designware-platdrv.o
 i2c-designware-platform-$(CONFIG_I2C_DESIGNWARE_BAYTRAIL) += i2c-designware-baytrail.o
 obj-$(CONFIG_I2C_DESIGNWARE_PCI)	+= i2c-designware-pci.o
 i2c-designware-pci-objs := i2c-designware-pcidrv.o
+obj-$(CONFIG_I2C_DIGICOLOR)	+= i2c-digicolor.o
 obj-$(CONFIG_I2C_EFM32)		+= i2c-efm32.o
 obj-$(CONFIG_I2C_EG20T)		+= i2c-eg20t.o
 obj-$(CONFIG_I2C_EXYNOS5)	+= i2c-exynos5.o
@@ -55,6 +56,7 @@ obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o
 obj-$(CONFIG_I2C_IMG)		+= i2c-img-scb.o
 obj-$(CONFIG_I2C_IMX)		+= i2c-imx.o
 obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
+obj-$(CONFIG_I2C_JZ4780)	+= i2c-jz4780.o
 obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o
 obj-$(CONFIG_I2C_MESON)		+= i2c-meson.o
 obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
@@ -87,6 +89,7 @@ obj-$(CONFIG_I2C_WMT)		+= i2c-wmt.o
 obj-$(CONFIG_I2C_OCTEON)	+= i2c-octeon.o
 obj-$(CONFIG_I2C_XILINX)	+= i2c-xiic.o
 obj-$(CONFIG_I2C_XLR)		+= i2c-xlr.o
+obj-$(CONFIG_I2C_XLP9XX)	+= i2c-xlp9xx.o
 obj-$(CONFIG_I2C_RCAR)		+= i2c-rcar.o
 
 # External I2C/SMBus adapter drivers

drivers/i2c/busses/i2c-at91.c

@@ -381,6 +381,7 @@ static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id)
 static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 {
 	int ret;
+	unsigned long time_left;
 	bool has_unre_flag = dev->pdata->has_unre_flag;
 
 	dev_dbg(dev->dev, "transfer: %s %d bytes.\n",
@@ -436,9 +437,9 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 		}
 	}
 
-	ret = wait_for_completion_timeout(&dev->cmd_complete,
-					     dev->adapter.timeout);
-	if (ret == 0) {
+	time_left = wait_for_completion_timeout(&dev->cmd_complete,
+					      dev->adapter.timeout);
+	if (time_left == 0) {
 		dev_err(dev->dev, "controller timed out\n");
 		at91_init_twi_bus(dev);
 		ret = -ETIMEDOUT;
@@ -487,30 +488,10 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
 	if (ret < 0)
 		goto out;
 
-	/*
-	 * The hardware can handle at most two messages concatenated by a
-	 * repeated start via it's internal address feature.
-	 */
-	if (num > 2) {
-		dev_err(dev->dev,
-			"cannot handle more than two concatenated messages.\n");
-		ret = 0;
-		goto out;
-	} else if (num == 2) {
+	if (num == 2) {
 		int internal_address = 0;
 		int i;
 
-		if (msg->flags & I2C_M_RD) {
-			dev_err(dev->dev, "first transfer must be write.\n");
-			ret = -EINVAL;
-			goto out;
-		}
-		if (msg->len > 3) {
-			dev_err(dev->dev, "first message size must be <= 3.\n");
-			ret = -EINVAL;
-			goto out;
-		}
-
 		/* 1st msg is put into the internal address, start with 2nd */
 		m_start = &msg[1];
 		for (i = 0; i < msg->len; ++i) {
@@ -540,6 +521,15 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
 	return ret;
 }
 
+/*
+ * The hardware can handle at most two messages concatenated by a
+ * repeated start via it's internal address feature.
+ */
+static struct i2c_adapter_quirks at91_twi_quirks = {
+	.flags = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | I2C_AQ_COMB_SAME_ADDR,
+	.max_comb_1st_msg_len = 3,
+};
+
 static u32 at91_twi_func(struct i2c_adapter *adapter)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
@@ -777,6 +767,7 @@ static int at91_twi_probe(struct platform_device *pdev)
 	dev->adapter.owner = THIS_MODULE;
 	dev->adapter.class = I2C_CLASS_DEPRECATED;
 	dev->adapter.algo = &at91_twi_algorithm;
+	dev->adapter.quirks = &at91_twi_quirks;
 	dev->adapter.dev.parent = dev->dev;
 	dev->adapter.nr = pdev->id;
 	dev->adapter.timeout = AT91_I2C_TIMEOUT;

drivers/i2c/busses/i2c-axxia.c

@@ -334,12 +334,7 @@ static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg)
 	u32 int_mask = MST_STATUS_ERR | MST_STATUS_SNS;
 	u32 rx_xfer, tx_xfer;
 	u32 addr_1, addr_2;
-	int ret;
-
-	if (msg->len > 255) {
-		dev_warn(idev->dev, "unsupported length %u\n", msg->len);
-		return -EINVAL;
-	}
+	unsigned long time_left;
 
 	idev->msg = msg;
 	idev->msg_xfrd = 0;
@@ -388,15 +383,15 @@ static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg)
 
 	i2c_int_enable(idev, int_mask);
 
-	ret = wait_for_completion_timeout(&idev->msg_complete,
-					  I2C_XFER_TIMEOUT);
+	time_left = wait_for_completion_timeout(&idev->msg_complete,
+					      I2C_XFER_TIMEOUT);
 
 	i2c_int_disable(idev, int_mask);
 
 	if (readl(idev->base + MST_COMMAND) & CMD_BUSY)
 		dev_warn(idev->dev, "busy after xfer\n");
 
-	if (ret == 0)
+	if (time_left == 0)
 		idev->msg_err = -ETIMEDOUT;
 
 	if (unlikely(idev->msg_err) && idev->msg_err != -ENXIO)
@@ -408,17 +403,17 @@ static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg)
 static int axxia_i2c_stop(struct axxia_i2c_dev *idev)
 {
 	u32 int_mask = MST_STATUS_ERR | MST_STATUS_SCC;
-	int ret;
+	unsigned long time_left;
 
 	reinit_completion(&idev->msg_complete);
 
 	/* Issue stop */
 	writel(0xb, idev->base + MST_COMMAND);
 	i2c_int_enable(idev, int_mask);
-	ret = wait_for_completion_timeout(&idev->msg_complete,
-					  I2C_STOP_TIMEOUT);
+	time_left = wait_for_completion_timeout(&idev->msg_complete,
+					      I2C_STOP_TIMEOUT);
 	i2c_int_disable(idev, int_mask);
-	if (ret == 0)
+	if (time_left == 0)
 		return -ETIMEDOUT;
 
 	if (readl(idev->base + MST_COMMAND) & CMD_BUSY)
@@ -454,6 +449,11 @@ static const struct i2c_algorithm axxia_i2c_algo = {
 	.functionality = axxia_i2c_func,
 };
 
+static struct i2c_adapter_quirks axxia_i2c_quirks = {
+	.max_read_len = 255,
+	.max_write_len = 255,
+};
+
 static int axxia_i2c_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
@@ -511,6 +511,7 @@ static int axxia_i2c_probe(struct platform_device *pdev)
 	strlcpy(idev->adapter.name, pdev->name, sizeof(idev->adapter.name));
 	idev->adapter.owner = THIS_MODULE;
 	idev->adapter.algo = &axxia_i2c_algo;
+	idev->adapter.quirks = &axxia_i2c_quirks;
 	idev->adapter.dev.parent = &pdev->dev;
 	idev->adapter.dev.of_node = pdev->dev.of_node;
 

drivers/i2c/busses/i2c-bcm-iproc.c

@@ -160,14 +160,6 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
 	u32 val;
 	unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT_MESC);
 
-	/* need to reserve one byte in the FIFO for the slave address */
-	if (msg->len > M_TX_RX_FIFO_SIZE - 1) {
-		dev_err(iproc_i2c->device,
-			"only support data length up to %u bytes\n",
-			M_TX_RX_FIFO_SIZE - 1);
-		return -EOPNOTSUPP;
-	}
-
 	/* check if bus is busy */
 	if (!!(readl(iproc_i2c->base + M_CMD_OFFSET) &
 	       BIT(M_CMD_START_BUSY_SHIFT))) {
@@ -287,6 +279,12 @@ static const struct i2c_algorithm bcm_iproc_algo = {
 	.functionality = bcm_iproc_i2c_functionality,
 };
 
+static struct i2c_adapter_quirks bcm_iproc_i2c_quirks = {
+	/* need to reserve one byte in the FIFO for the slave address */
+	.max_read_len = M_TX_RX_FIFO_SIZE - 1,
+	.max_write_len = M_TX_RX_FIFO_SIZE - 1,
+};
+
 static int bcm_iproc_i2c_cfg_speed(struct bcm_iproc_i2c_dev *iproc_i2c)
 {
 	unsigned int bus_speed;
@@ -413,6 +411,7 @@ static int bcm_iproc_i2c_probe(struct platform_device *pdev)
 	i2c_set_adapdata(adap, iproc_i2c);
 	strlcpy(adap->name, "Broadcom iProc I2C adapter", sizeof(adap->name));
 	adap->algo = &bcm_iproc_algo;
+	adap->quirks = &bcm_iproc_i2c_quirks;
 	adap->dev.parent = &pdev->dev;
 	adap->dev.of_node = pdev->dev.of_node;
 

drivers/i2c/busses/i2c-bcm2835.c

@@ -147,7 +147,7 @@ static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev,
 				struct i2c_msg *msg)
 {
 	u32 c;
-	int time_left;
+	unsigned long time_left;
 
 	i2c_dev->msg_buf = msg->buf;
 	i2c_dev->msg_buf_remaining = msg->len;

drivers/i2c/busses/i2c-cadence.c

@@ -475,7 +475,7 @@ static void cdns_i2c_master_reset(struct i2c_adapter *adap)
 static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
 		struct i2c_adapter *adap)
 {
-	int ret;
+	unsigned long time_left;
 	u32 reg;
 
 	id->p_msg = msg;
@@ -501,8 +501,8 @@ static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
 		cdns_i2c_msend(id);
 
 	/* Wait for the signal of completion */
-	ret = wait_for_completion_timeout(&id->xfer_done, adap->timeout);
-	if (!ret) {
+	time_left = wait_for_completion_timeout(&id->xfer_done, adap->timeout);
+	if (time_left == 0) {
 		cdns_i2c_master_reset(adap);
 		dev_err(id->adap.dev.parent,
 				"timeout waiting on completion\n");

drivers/i2c/busses/i2c-cpm.c

@@ -308,22 +308,12 @@ static int cpm_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 	struct i2c_reg __iomem *i2c_reg = cpm->i2c_reg;
 	struct i2c_ram __iomem *i2c_ram = cpm->i2c_ram;
 	struct i2c_msg *pmsg;
-	int ret, i;
+	int ret;
 	int tptr;
 	int rptr;
 	cbd_t __iomem *tbdf;
 	cbd_t __iomem *rbdf;
 
-	if (num > CPM_MAXBD)
-		return -EINVAL;
-
-	/* Check if we have any oversized READ requests */
-	for (i = 0; i < num; i++) {
-		pmsg = &msgs[i];
-		if (pmsg->len >= CPM_MAX_READ)
-			return -EINVAL;
-	}
-
 	/* Reset to use first buffer */
 	out_be16(&i2c_ram->rbptr, in_be16(&i2c_ram->rbase));
 	out_be16(&i2c_ram->tbptr, in_be16(&i2c_ram->tbase));
@@ -424,10 +414,18 @@ static const struct i2c_algorithm cpm_i2c_algo = {
 	.functionality = cpm_i2c_func,
 };
 
+/* CPM_MAX_READ is also limiting writes according to the code! */
+static struct i2c_adapter_quirks cpm_i2c_quirks = {
+	.max_num_msgs = CPM_MAXBD,
+	.max_read_len = CPM_MAX_READ,
+	.max_write_len = CPM_MAX_READ,
+};
+
 static const struct i2c_adapter cpm_ops = {
 	.owner		= THIS_MODULE,
 	.name		= "i2c-cpm",
 	.algo		= &cpm_i2c_algo,
+	.quirks		= &cpm_i2c_quirks,
 };
 
 static int cpm_i2c_setup(struct cpm_i2c *cpm)

drivers/i2c/busses/i2c-davinci.c

@@ -60,6 +60,12 @@
 #define DAVINCI_I2C_IVR_REG	0x28
 #define DAVINCI_I2C_EMDR_REG	0x2c
 #define DAVINCI_I2C_PSC_REG	0x30
+#define DAVINCI_I2C_FUNC_REG	0x48
+#define DAVINCI_I2C_DIR_REG	0x4c
+#define DAVINCI_I2C_DIN_REG	0x50
+#define DAVINCI_I2C_DOUT_REG	0x54
+#define DAVINCI_I2C_DSET_REG	0x58
+#define DAVINCI_I2C_DCLR_REG	0x5c
 
 #define DAVINCI_I2C_IVR_AAS	0x07
 #define DAVINCI_I2C_IVR_SCD	0x06
@@ -93,6 +99,29 @@
 #define DAVINCI_I2C_IMR_NACK	BIT(1)
 #define DAVINCI_I2C_IMR_AL	BIT(0)
 
+/* set SDA and SCL as GPIO */
+#define DAVINCI_I2C_FUNC_PFUNC0	BIT(0)
+
+/* set SCL as output when used as GPIO*/
+#define DAVINCI_I2C_DIR_PDIR0	BIT(0)
+/* set SDA as output when used as GPIO*/
+#define DAVINCI_I2C_DIR_PDIR1	BIT(1)
+
+/* read SCL GPIO level */
+#define DAVINCI_I2C_DIN_PDIN0 BIT(0)
+/* read SDA GPIO level */
+#define DAVINCI_I2C_DIN_PDIN1 BIT(1)
+
+/*set the SCL GPIO high */
+#define DAVINCI_I2C_DSET_PDSET0	BIT(0)
+/*set the SDA GPIO high */
+#define DAVINCI_I2C_DSET_PDSET1	BIT(1)
+
+/* set the SCL GPIO low */
+#define DAVINCI_I2C_DCLR_PDCLR0	BIT(0)
+/* set the SDA GPIO low */
+#define DAVINCI_I2C_DCLR_PDCLR1	BIT(1)
+
 struct davinci_i2c_dev {
 	struct device           *dev;
 	void __iomem		*base;
@@ -129,43 +158,6 @@ static inline u16 davinci_i2c_read_reg(struct davinci_i2c_dev *i2c_dev, int reg)
 	return readw_relaxed(i2c_dev->base + reg);
 }
 
-/* Generate a pulse on the i2c clock pin. */
-static void davinci_i2c_clock_pulse(unsigned int scl_pin)
-{
-	u16 i;
-
-	if (scl_pin) {
-		/* Send high and low on the SCL line */
-		for (i = 0; i < 9; i++) {
-			gpio_set_value(scl_pin, 0);
-			udelay(20);
-			gpio_set_value(scl_pin, 1);
-			udelay(20);
-		}
-	}
-}
-
-/* This routine does i2c bus recovery as specified in the
- * i2c protocol Rev. 03 section 3.16 titled "Bus clear"
- */
-static void davinci_i2c_recover_bus(struct davinci_i2c_dev *dev)
-{
-	u32 flag = 0;
-	struct davinci_i2c_platform_data *pdata = dev->pdata;
-
-	dev_err(dev->dev, "initiating i2c bus recovery\n");
-	/* Send NACK to the slave */
-	flag = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
-	flag |=  DAVINCI_I2C_MDR_NACK;
-	/* write the data into mode register */
-	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);
-	davinci_i2c_clock_pulse(pdata->scl_pin);
-	/* Send STOP */
-	flag = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
-	flag |= DAVINCI_I2C_MDR_STP;
-	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);
-}
-
 static inline void davinci_i2c_reset_ctrl(struct davinci_i2c_dev *i2c_dev,
 								int val)
 {
@@ -262,6 +254,99 @@ static int i2c_davinci_init(struct davinci_i2c_dev *dev)
 	return 0;
 }
 
+/*
+ * This routine does i2c bus recovery by using i2c_generic_gpio_recovery
+ * which is provided by I2C Bus recovery infrastructure.
+ */
+static void davinci_i2c_prepare_recovery(struct i2c_adapter *adap)
+{
+	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+
+	/* Disable interrupts */
+	davinci_i2c_write_reg(dev, DAVINCI_I2C_IMR_REG, 0);
+
+	/* put I2C into reset */
+	davinci_i2c_reset_ctrl(dev, 0);
+}
+
+static void davinci_i2c_unprepare_recovery(struct i2c_adapter *adap)
+{
+	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+
+	i2c_davinci_init(dev);
+}
+
+static struct i2c_bus_recovery_info davinci_i2c_gpio_recovery_info = {
+	.recover_bus = i2c_generic_gpio_recovery,
+	.prepare_recovery = davinci_i2c_prepare_recovery,
+	.unprepare_recovery = davinci_i2c_unprepare_recovery,
+};
+
+static void davinci_i2c_set_scl(struct i2c_adapter *adap, int val)
+{
+	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+
+	if (val)
+		davinci_i2c_write_reg(dev, DAVINCI_I2C_DSET_REG,
+				      DAVINCI_I2C_DSET_PDSET0);
+	else
+		davinci_i2c_write_reg(dev, DAVINCI_I2C_DCLR_REG,
+				      DAVINCI_I2C_DCLR_PDCLR0);
+}
+
+static int davinci_i2c_get_scl(struct i2c_adapter *adap)
+{
+	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+	int val;
+
+	/* read the state of SCL */
+	val = davinci_i2c_read_reg(dev, DAVINCI_I2C_DIN_REG);
+	return val & DAVINCI_I2C_DIN_PDIN0;
+}
+
+static int davinci_i2c_get_sda(struct i2c_adapter *adap)
+{
+	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+	int val;
+
+	/* read the state of SDA */
+	val = davinci_i2c_read_reg(dev, DAVINCI_I2C_DIN_REG);
+	return val & DAVINCI_I2C_DIN_PDIN1;
+}
+
+static void davinci_i2c_scl_prepare_recovery(struct i2c_adapter *adap)
+{
+	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+
+	davinci_i2c_prepare_recovery(adap);
+
+	/* SCL output, SDA input */
+	davinci_i2c_write_reg(dev, DAVINCI_I2C_DIR_REG, DAVINCI_I2C_DIR_PDIR0);
+
+	/* change to GPIO mode */
+	davinci_i2c_write_reg(dev, DAVINCI_I2C_FUNC_REG,
+			      DAVINCI_I2C_FUNC_PFUNC0);
+}
+
+static void davinci_i2c_scl_unprepare_recovery(struct i2c_adapter *adap)
+{
+	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+
+	/* change back to I2C mode */
+	davinci_i2c_write_reg(dev, DAVINCI_I2C_FUNC_REG, 0);
+
+	davinci_i2c_unprepare_recovery(adap);
+}
+
+static struct i2c_bus_recovery_info davinci_i2c_scl_recovery_info = {
+	.recover_bus = i2c_generic_scl_recovery,
+	.set_scl = davinci_i2c_set_scl,
+	.get_scl = davinci_i2c_get_scl,
+	.get_sda = davinci_i2c_get_sda,
+	.prepare_recovery = davinci_i2c_scl_prepare_recovery,
+	.unprepare_recovery = davinci_i2c_scl_unprepare_recovery,
+};
+
 /*
  * Waiting for bus not busy
  */
@@ -282,8 +367,7 @@ static int i2c_davinci_wait_bus_not_busy(struct davinci_i2c_dev *dev,
 				return -ETIMEDOUT;
 			} else {
 				to_cnt = 0;
-				davinci_i2c_recover_bus(dev);
-				i2c_davinci_init(dev);
+				i2c_recover_bus(&dev->adapter);
 			}
 		}
 		if (allow_sleep)
@@ -304,7 +388,7 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
 	struct davinci_i2c_platform_data *pdata = dev->pdata;
 	u32 flag;
 	u16 w;
-	int r;
+	unsigned long time_left;
 
 	/* Introduce a delay, required for some boards (e.g Davinci EVM) */
 	if (pdata->bus_delay)
@@ -368,11 +452,11 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
 		flag |= DAVINCI_I2C_MDR_STP;
 	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);
 
-	r = wait_for_completion_timeout(&dev->cmd_complete, dev->adapter.timeout);
-	if (r == 0) {
+	time_left = wait_for_completion_timeout(&dev->cmd_complete,
+						dev->adapter.timeout);
+	if (!time_left) {
 		dev_err(dev->dev, "controller timed out\n");
-		davinci_i2c_recover_bus(dev);
-		i2c_davinci_init(dev);
+		i2c_recover_bus(adap);
 		dev->buf_len = 0;
 		return -ETIMEDOUT;
 	}
@@ -380,17 +464,13 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
 		/* This should be 0 if all bytes were transferred
 		 * or dev->cmd_err denotes an error.
 		 */
-		if (r >= 0) {
-			dev_err(dev->dev, "abnormal termination buf_len=%i\n",
-				dev->buf_len);
-			r = -EREMOTEIO;
-		}
+		dev_err(dev->dev, "abnormal termination buf_len=%i\n",
+			dev->buf_len);
 		dev->terminate = 1;
 		wmb();
 		dev->buf_len = 0;
+		return -EREMOTEIO;
 	}
-	if (r < 0)
-		return r;
 
 	/* no error */
 	if (likely(!dev->cmd_err))
@@ -674,6 +754,10 @@ static int davinci_i2c_probe(struct platform_device *pdev)
 		if (!of_property_read_u32(pdev->dev.of_node, "clock-frequency",
 			&prop))
 			dev->pdata->bus_freq = prop / 1000;
+
+		dev->pdata->has_pfunc =
+			of_property_read_bool(pdev->dev.of_node,
+					      "ti,has-pfunc");
 	} else if (!dev->pdata) {
 		dev->pdata = &davinci_i2c_platform_data_default;
 	}
@@ -715,6 +799,14 @@ static int davinci_i2c_probe(struct platform_device *pdev)
 	adap->timeout = DAVINCI_I2C_TIMEOUT;
 	adap->dev.of_node = pdev->dev.of_node;
 
+	if (dev->pdata->has_pfunc)
+		adap->bus_recovery_info = &davinci_i2c_scl_recovery_info;
+	else if (dev->pdata->scl_pin) {
+		adap->bus_recovery_info = &davinci_i2c_gpio_recovery_info;
+		adap->bus_recovery_info->scl_gpio = dev->pdata->scl_pin;
+		adap->bus_recovery_info->sda_gpio = dev->pdata->sda_pin;
+	}
+
 	adap->nr = pdev->id;
 	r = i2c_add_numbered_adapter(adap);
 	if (r) {

drivers/i2c/busses/i2c-designware-core.c

@@ -656,8 +656,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	i2c_dw_xfer_init(dev);
 
 	/* wait for tx to complete */
-	ret = wait_for_completion_timeout(&dev->cmd_complete, HZ);
-	if (ret == 0) {
+	if (!wait_for_completion_timeout(&dev->cmd_complete, HZ)) {
 		dev_err(dev->dev, "controller timed out\n");
 		/* i2c_dw_init implicitly disables the adapter */
 		i2c_dw_init(dev);

drivers/i2c/busses/i2c-designware-platdrv.c

@@ -143,10 +143,8 @@ static int dw_i2c_probe(struct platform_device *pdev)
 	u32 clk_freq, ht = 0;
 
 	irq = platform_get_irq(pdev, 0);
-	if (irq < 0) {
-		dev_err(&pdev->dev, "no irq resource?\n");
-		return irq; /* -ENXIO */
-	}
+	if (irq < 0)
+		return irq;
 
 	dev = devm_kzalloc(&pdev->dev, sizeof(struct dw_i2c_dev), GFP_KERNEL);
 	if (!dev)

drivers/i2c/busses/i2c-digicolor.c

+/*
+ * I2C bus driver for Conexant Digicolor SoCs
+ *
+ * Author: Baruch Siach <baruch@tkos.co.il>
+ *
+ * Copyright (C) 2015 Paradox Innovation Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#define DEFAULT_FREQ		100000
+#define TIMEOUT_MS		100
+
+#define II_CONTROL		0x0
+#define II_CONTROL_LOCAL_RESET	BIT(0)
+
+#define II_CLOCKTIME		0x1
+
+#define II_COMMAND		0x2
+#define II_CMD_START		1
+#define II_CMD_RESTART		2
+#define II_CMD_SEND_ACK		3
+#define II_CMD_GET_ACK		6
+#define II_CMD_GET_NOACK	7
+#define II_CMD_STOP		10
+#define II_COMMAND_GO		BIT(7)
+#define II_COMMAND_COMPLETION_STATUS(r)	(((r) >> 5) & 3)
+#define II_CMD_STATUS_NORMAL	0
+#define II_CMD_STATUS_ACK_GOOD	1
+#define II_CMD_STATUS_ACK_BAD	2
+#define II_CMD_STATUS_ABORT	3
+
+#define II_DATA			0x3
+#define II_INTFLAG_CLEAR	0x8
+#define II_INTENABLE		0xa
+
+struct dc_i2c {
+	struct i2c_adapter	adap;
+	struct device		*dev;
+	void __iomem		*regs;
+	struct clk		*clk;
+	unsigned int		frequency;
+
+	struct i2c_msg		*msg;
+	unsigned int		msgbuf_ptr;
+	int			last;
+	spinlock_t		lock;
+	struct completion	done;
+	int			state;
+	int			error;
+};
+
+enum {
+	STATE_IDLE,
+	STATE_START,
+	STATE_ADDR,
+	STATE_WRITE,
+	STATE_READ,
+	STATE_STOP,
+};
+
+static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd)
+{
+	writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND);
+}
+
+static u8 dc_i2c_addr_cmd(struct i2c_msg *msg)
+{
+	u8 addr = (msg->addr & 0x7f) << 1;
+
+	if (msg->flags & I2C_M_RD)
+		addr |= 1;
+
+	return addr;
+}
+
+static void dc_i2c_data(struct dc_i2c *i2c, u8 data)
+{
+	writeb_relaxed(data, i2c->regs + II_DATA);
+}
+
+static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte)
+{
+	dc_i2c_data(i2c, byte);
+	dc_i2c_cmd(i2c, II_CMD_SEND_ACK);
+}
+
+static void dc_i2c_write_buf(struct dc_i2c *i2c)
+{
+	dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]);
+}
+
+static void dc_i2c_next_read(struct dc_i2c *i2c)
+{
+	bool last = (i2c->msgbuf_ptr + 1 == i2c->msg->len);
+
+	dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK);
+}
+
+static void dc_i2c_stop(struct dc_i2c *i2c)
+{
+	i2c->state = STATE_STOP;
+	if (i2c->last)
+		dc_i2c_cmd(i2c, II_CMD_STOP);
+	else
+		complete(&i2c->done);
+}
+
+static u8 dc_i2c_read_byte(struct dc_i2c *i2c)
+{
+	return readb_relaxed(i2c->regs + II_DATA);
+}
+
+static void dc_i2c_read_buf(struct dc_i2c *i2c)
+{
+	i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c);
+	dc_i2c_next_read(i2c);
+}
+
+static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable)
+{
+	if (enable)
+		writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
+	writeb_relaxed(!!enable, i2c->regs + II_INTENABLE);
+}
+
+static int dc_i2c_cmd_status(struct dc_i2c *i2c)
+{
+	u8 cmd = readb_relaxed(i2c->regs + II_COMMAND);
+
+	return II_COMMAND_COMPLETION_STATUS(cmd);
+}
+
+static void dc_i2c_start_msg(struct dc_i2c *i2c, int first)
+{
+	struct i2c_msg *msg = i2c->msg;
+
+	if (!(msg->flags & I2C_M_NOSTART)) {
+		i2c->state = STATE_START;
+		dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART);
+	} else if (msg->flags & I2C_M_RD) {
+		i2c->state = STATE_READ;
+		dc_i2c_next_read(i2c);
+	} else {
+		i2c->state = STATE_WRITE;
+		dc_i2c_write_buf(i2c);
+	}
+}
+
+static irqreturn_t dc_i2c_irq(int irq, void *dev_id)
+{
+	struct dc_i2c *i2c = dev_id;
+	int cmd_status = dc_i2c_cmd_status(i2c);
+	unsigned long flags;
+	u8 addr_cmd;
+
+	writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
+
+	spin_lock_irqsave(&i2c->lock, flags);
+
+	if (cmd_status == II_CMD_STATUS_ACK_BAD
+	    || cmd_status == II_CMD_STATUS_ABORT) {
+		i2c->error = -EIO;
+		complete(&i2c->done);
+		goto out;
+	}
+
+	switch (i2c->state) {
+	case STATE_START:
+		addr_cmd = dc_i2c_addr_cmd(i2c->msg);
+		dc_i2c_write_byte(i2c, addr_cmd);
+		i2c->state = STATE_ADDR;
+		break;
+	case STATE_ADDR:
+		if (i2c->msg->flags & I2C_M_RD) {
+			dc_i2c_next_read(i2c);
+			i2c->state = STATE_READ;
+			break;
+		}
+		i2c->state = STATE_WRITE;
+		/* fall through */
+	case STATE_WRITE:
+		if (i2c->msgbuf_ptr < i2c->msg->len)
+			dc_i2c_write_buf(i2c);
+		else
+			dc_i2c_stop(i2c);
+		break;
+	case STATE_READ:
+		if (i2c->msgbuf_ptr < i2c->msg->len)
+			dc_i2c_read_buf(i2c);
+		else
+			dc_i2c_stop(i2c);
+		break;
+	case STATE_STOP:
+		i2c->state = STATE_IDLE;
+		complete(&i2c->done);
+		break;
+	}
+
+out:
+	spin_unlock_irqrestore(&i2c->lock, flags);
+	return IRQ_HANDLED;
+}
+
+static int dc_i2c_xfer_msg(struct dc_i2c *i2c, struct i2c_msg *msg, int first,
+			   int last)
+{
+	unsigned long timeout = msecs_to_jiffies(TIMEOUT_MS);
+	unsigned long flags;
+
+	spin_lock_irqsave(&i2c->lock, flags);
+	i2c->msg = msg;
+	i2c->msgbuf_ptr = 0;
+	i2c->last = last;
+	i2c->error = 0;
+
+	reinit_completion(&i2c->done);
+	dc_i2c_set_irq(i2c, 1);
+	dc_i2c_start_msg(i2c, first);
+	spin_unlock_irqrestore(&i2c->lock, flags);
+
+	timeout = wait_for_completion_timeout(&i2c->done, timeout);
+	dc_i2c_set_irq(i2c, 0);
+	if (timeout == 0) {
+		i2c->state = STATE_IDLE;
+		return -ETIMEDOUT;
+	}
+
+	if (i2c->error)
+		return i2c->error;
+
+	return 0;
+}
+
+static int dc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct dc_i2c *i2c = adap->algo_data;
+	int i, ret;
+
+	for (i = 0; i < num; i++) {
+		ret = dc_i2c_xfer_msg(i2c, &msgs[i], i == 0, i == num - 1);
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static int dc_i2c_init_hw(struct dc_i2c *i2c)
+{
+	unsigned long clk_rate = clk_get_rate(i2c->clk);
+	unsigned int clocktime;
+
+	writeb_relaxed(II_CONTROL_LOCAL_RESET, i2c->regs + II_CONTROL);
+	udelay(100);
+	writeb_relaxed(0, i2c->regs + II_CONTROL);
+	udelay(100);
+
+	clocktime = DIV_ROUND_UP(clk_rate, 64 * i2c->frequency);
+	if (clocktime < 1 || clocktime > 0xff) {
+		dev_err(i2c->dev, "can't set bus speed of %u Hz\n",
+			i2c->frequency);
+		return -EINVAL;
+	}
+	writeb_relaxed(clocktime - 1, i2c->regs + II_CLOCKTIME);
+
+	return 0;
+}
+
+static u32 dc_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
+}
+
+static const struct i2c_algorithm dc_i2c_algorithm = {
+	.master_xfer	= dc_i2c_xfer,
+	.functionality	= dc_i2c_func,
+};
+
+static int dc_i2c_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct dc_i2c *i2c;
+	struct resource *r;
+	int ret = 0, irq;
+
+	i2c = devm_kzalloc(&pdev->dev, sizeof(struct dc_i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+				 &i2c->frequency))
+		i2c->frequency = DEFAULT_FREQ;
+
+	i2c->dev = &pdev->dev;
+	platform_set_drvdata(pdev, i2c);
+
+	spin_lock_init(&i2c->lock);
+	init_completion(&i2c->done);
+
+	i2c->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(i2c->clk))
+		return PTR_ERR(i2c->clk);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	i2c->regs = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(i2c->regs))
+		return PTR_ERR(i2c->regs);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	ret = devm_request_irq(&pdev->dev, irq, dc_i2c_irq, 0,
+			       dev_name(&pdev->dev), i2c);
+	if (ret < 0)
+		return ret;
+
+	strlcpy(i2c->adap.name, "Conexant Digicolor I2C adapter",
+		sizeof(i2c->adap.name));
+	i2c->adap.owner = THIS_MODULE;
+	i2c->adap.algo = &dc_i2c_algorithm;
+	i2c->adap.dev.parent = &pdev->dev;
+	i2c->adap.dev.of_node = np;
+	i2c->adap.algo_data = i2c;
+
+	ret = dc_i2c_init_hw(i2c);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(i2c->clk);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_add_adapter(&i2c->adap);
+	if (ret < 0) {
+		clk_unprepare(i2c->clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int dc_i2c_remove(struct platform_device *pdev)
+{
+	struct dc_i2c *i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&i2c->adap);
+	clk_disable_unprepare(i2c->clk);
+
+	return 0;
+}
+
+static const struct of_device_id dc_i2c_match[] = {
+	{ .compatible = "cnxt,cx92755-i2c" },
+	{ },
+};
+
+static struct platform_driver dc_i2c_driver = {
+	.probe   = dc_i2c_probe,
+	.remove  = dc_i2c_remove,
+	.driver  = {
+		.name  = "digicolor-i2c",
+		.of_match_table = dc_i2c_match,
+	},
+};
+module_platform_driver(dc_i2c_driver);
+
+MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
+MODULE_DESCRIPTION("Conexant Digicolor I2C master driver");
+MODULE_LICENSE("GPL v2");

drivers/i2c/busses/i2c-dln2.c

@@ -144,7 +144,6 @@ static int dln2_i2c_xfer(struct i2c_adapter *adapter,
 {
 	struct dln2_i2c *dln2 = i2c_get_adapdata(adapter);
 	struct i2c_msg *pmsg;
-	struct device *dev = &dln2->adapter.dev;
 	int i;
 
 	for (i = 0; i < num; i++) {
@@ -152,11 +151,6 @@ static int dln2_i2c_xfer(struct i2c_adapter *adapter,
 
 		pmsg = &msgs[i];
 
-		if (pmsg->len > DLN2_I2C_MAX_XFER_SIZE) {
-			dev_warn(dev, "maximum transfer size exceeded\n");
-			return -EOPNOTSUPP;
-		}
-
 		if (pmsg->flags & I2C_M_RD) {
 			ret = dln2_i2c_read(dln2, pmsg->addr, pmsg->buf,
 					    pmsg->len);
@@ -187,6 +181,11 @@ static const struct i2c_algorithm dln2_i2c_usb_algorithm = {
 	.functionality = dln2_i2c_func,
 };
 
+static struct i2c_adapter_quirks dln2_i2c_quirks = {
+	.max_read_len = DLN2_I2C_MAX_XFER_SIZE,
+	.max_write_len = DLN2_I2C_MAX_XFER_SIZE,
+};
+
 static int dln2_i2c_probe(struct platform_device *pdev)
 {
 	int ret;
@@ -209,7 +208,9 @@ static int dln2_i2c_probe(struct platform_device *pdev)
 	dln2->adapter.owner = THIS_MODULE;
 	dln2->adapter.class = I2C_CLASS_HWMON;
 	dln2->adapter.algo = &dln2_i2c_usb_algorithm;
+	dln2->adapter.quirks = &dln2_i2c_quirks;
 	dln2->adapter.dev.parent = dev;
+	dln2->adapter.dev.of_node = dev->of_node;
 	i2c_set_adapdata(&dln2->adapter, dln2);
 	snprintf(dln2->adapter.name, sizeof(dln2->adapter.name), "%s-%s-%d",
 		 "dln2-i2c", dev_name(pdev->dev.parent), dln2->port);

drivers/i2c/busses/i2c-i801.c

@@ -223,8 +223,6 @@ struct i801_priv {
 #endif
 };
 
-static struct pci_driver i801_driver;
-
 #define FEATURE_SMBUS_PEC	(1 << 0)
 #define FEATURE_BLOCK_BUFFER	(1 << 1)
 #define FEATURE_BLOCK_PROC	(1 << 2)
@@ -1140,7 +1138,7 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	int err, i;
 	struct i801_priv *priv;
 
-	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 
@@ -1182,34 +1180,35 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	}
 	priv->features &= ~disable_features;
 
-	err = pci_enable_device(dev);
+	err = pcim_enable_device(dev);
 	if (err) {
 		dev_err(&dev->dev, "Failed to enable SMBus PCI device (%d)\n",
 			err);
-		goto exit;
+		return err;
 	}
+	pcim_pin_device(dev);
 
 	/* Determine the address of the SMBus area */
 	priv->smba = pci_resource_start(dev, SMBBAR);
 	if (!priv->smba) {
-		dev_err(&dev->dev, "SMBus base address uninitialized, "
-			"upgrade BIOS\n");
-		err = -ENODEV;
-		goto exit;
+		dev_err(&dev->dev,
+			"SMBus base address uninitialized, upgrade BIOS\n");
+		return -ENODEV;
 	}
 
 	err = acpi_check_resource_conflict(&dev->resource[SMBBAR]);
 	if (err) {
-		err = -ENODEV;
-		goto exit;
+		return -ENODEV;
 	}
 
-	err = pci_request_region(dev, SMBBAR, i801_driver.name);
+	err = pcim_iomap_regions(dev, 1 << SMBBAR,
+				 dev_driver_string(&dev->dev));
 	if (err) {
-		dev_err(&dev->dev, "Failed to request SMBus region "
-			"0x%lx-0x%Lx\n", priv->smba,
+		dev_err(&dev->dev,
+			"Failed to request SMBus region 0x%lx-0x%Lx\n",
+			priv->smba,
 			(unsigned long long)pci_resource_end(dev, SMBBAR));
-		goto exit;
+		return err;
 	}
 
 	pci_read_config_byte(priv->pci_dev, SMBHSTCFG, &temp);
@@ -1254,8 +1253,9 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (priv->features & FEATURE_IRQ) {
 		init_waitqueue_head(&priv->waitq);
 
-		err = request_irq(dev->irq, i801_isr, IRQF_SHARED,
-				  i801_driver.name, priv);
+		err = devm_request_irq(&dev->dev, dev->irq, i801_isr,
+				       IRQF_SHARED,
+				       dev_driver_string(&dev->dev), priv);
 		if (err) {
 			dev_err(&dev->dev, "Failed to allocate irq %d: %d\n",
 				dev->irq, err);
@@ -1276,7 +1276,7 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	err = i2c_add_adapter(&priv->adapter);
 	if (err) {
 		dev_err(&dev->dev, "Failed to add SMBus adapter\n");
-		goto exit_free_irq;
+		return err;
 	}
 
 	i801_probe_optional_slaves(priv);
@@ -1286,14 +1286,6 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	pci_set_drvdata(dev, priv);
 
 	return 0;
-
-exit_free_irq:
-	if (priv->features & FEATURE_IRQ)
-		free_irq(dev->irq, priv);
-	pci_release_region(dev, SMBBAR);
-exit:
-	kfree(priv);
-	return err;
 }
 
 static void i801_remove(struct pci_dev *dev)
@@ -1304,11 +1296,6 @@ static void i801_remove(struct pci_dev *dev)
 	i2c_del_adapter(&priv->adapter);
 	pci_write_config_byte(dev, SMBHSTCFG, priv->original_hstcfg);
 
-	if (priv->features & FEATURE_IRQ)
-		free_irq(dev->irq, priv);
-	pci_release_region(dev, SMBBAR);
-
-	kfree(priv);
 	/*
 	 * do not call pci_disable_device(dev) since it can cause hard hangs on
 	 * some systems during power-off (eg. Fujitsu-Siemens Lifebook E8010)
@@ -1330,7 +1317,7 @@ static int i801_resume(struct pci_dev *dev)
 {
 	pci_set_power_state(dev, PCI_D0);
 	pci_restore_state(dev);
-	return pci_enable_device(dev);
+	return 0;
 }
 #else
 #define i801_suspend NULL

drivers/i2c/busses/i2c-img-scb.c

@@ -988,15 +988,16 @@ static irqreturn_t img_i2c_isr(int irq, void *dev_id)
 static int img_i2c_reset_bus(struct img_i2c *i2c)
 {
 	unsigned long flags;
-	int ret;
+	unsigned long time_left;
 
 	spin_lock_irqsave(&i2c->lock, flags);
 	reinit_completion(&i2c->msg_complete);
 	img_i2c_reset_start(i2c);
 	spin_unlock_irqrestore(&i2c->lock, flags);
 
-	ret = wait_for_completion_timeout(&i2c->msg_complete, IMG_I2C_TIMEOUT);
-	if (ret == 0)
+	time_left = wait_for_completion_timeout(&i2c->msg_complete,
+					      IMG_I2C_TIMEOUT);
+	if (time_left == 0)
 		return -ETIMEDOUT;
 	return 0;
 }
@@ -1007,6 +1008,7 @@ static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	struct img_i2c *i2c = i2c_get_adapdata(adap);
 	bool atomic = false;
 	int i, ret;
+	unsigned long time_left;
 
 	if (i2c->mode == MODE_SUSPEND) {
 		WARN(1, "refusing to service transaction in suspended state\n");
@@ -1068,11 +1070,11 @@ static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			img_i2c_write(i2c);
 		spin_unlock_irqrestore(&i2c->lock, flags);
 
-		ret = wait_for_completion_timeout(&i2c->msg_complete,
-						  IMG_I2C_TIMEOUT);
+		time_left = wait_for_completion_timeout(&i2c->msg_complete,
+						      IMG_I2C_TIMEOUT);
 		del_timer_sync(&i2c->check_timer);
 
-		if (ret == 0) {
+		if (time_left == 0) {
 			dev_err(adap->dev.parent, "i2c transfer timed out\n");
 			i2c->msg_status = -ETIMEDOUT;
 			break;

drivers/i2c/busses/i2c-imx.c

@@ -601,6 +601,7 @@ static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx,
 					struct i2c_msg *msgs)
 {
 	int result;
+	unsigned long time_left;
 	unsigned int temp = 0;
 	unsigned long orig_jiffies = jiffies;
 	struct imx_i2c_dma *dma = i2c_imx->dma;
@@ -624,10 +625,10 @@ static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx,
 	 */
 	imx_i2c_write_reg(msgs->addr << 1, i2c_imx, IMX_I2C_I2DR);
 	reinit_completion(&i2c_imx->dma->cmd_complete);
-	result = wait_for_completion_timeout(
+	time_left = wait_for_completion_timeout(
 				&i2c_imx->dma->cmd_complete,
 				msecs_to_jiffies(DMA_TIMEOUT));
-	if (result == 0) {
+	if (time_left == 0) {
 		dmaengine_terminate_all(dma->chan_using);
 		return -ETIMEDOUT;
 	}
@@ -663,6 +664,7 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
 			struct i2c_msg *msgs, bool is_lastmsg)
 {
 	int result;
+	unsigned long time_left;
 	unsigned int temp;
 	unsigned long orig_jiffies = jiffies;
 	struct imx_i2c_dma *dma = i2c_imx->dma;
@@ -682,10 +684,10 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
 		return result;
 
 	reinit_completion(&i2c_imx->dma->cmd_complete);
-	result = wait_for_completion_timeout(
+	time_left = wait_for_completion_timeout(
 				&i2c_imx->dma->cmd_complete,
 				msecs_to_jiffies(DMA_TIMEOUT));
-	if (result == 0) {
+	if (time_left == 0) {
 		dmaengine_terminate_all(dma->chan_using);
 		return -ETIMEDOUT;
 	}

drivers/i2c/busses/i2c-ismt.c

@@ -380,6 +380,7 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
 		       int size, union i2c_smbus_data *data)
 {
 	int ret;
+	unsigned long time_left;
 	dma_addr_t dma_addr = 0; /* address of the data buffer */
 	u8 dma_size = 0;
 	enum dma_data_direction dma_direction = 0;
@@ -578,13 +579,13 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
 	ismt_submit_desc(priv);
 
 	/* Now we wait for interrupt completion, 1s */
-	ret = wait_for_completion_timeout(&priv->cmp, HZ*1);
+	time_left = wait_for_completion_timeout(&priv->cmp, HZ*1);
 
 	/* unmap the data buffer */
 	if (dma_size != 0)
 		dma_unmap_single(&adap->dev, dma_addr, dma_size, dma_direction);
 
-	if (unlikely(!ret)) {
+	if (unlikely(!time_left)) {
 		dev_err(dev, "completion wait timed out\n");
 		ret = -ETIMEDOUT;
 		goto out;

drivers/i2c/busses/i2c-mpc.c

@@ -29,6 +29,7 @@
 #include <linux/delay.h>
 
 #include <asm/mpc52xx.h>
+#include <asm/mpc85xx.h>
 #include <sysdev/fsl_soc.h>
 
 #define DRV_NAME "mpc-i2c"
@@ -95,8 +96,9 @@ static irqreturn_t mpc_i2c_isr(int irq, void *dev_id)
 		i2c->interrupt = readb(i2c->base + MPC_I2C_SR);
 		writeb(0, i2c->base + MPC_I2C_SR);
 		wake_up(&i2c->queue);
+		return IRQ_HANDLED;
 	}
-	return IRQ_HANDLED;
+	return IRQ_NONE;
 }
 
 /* Sometimes 9th clock pulse isn't generated, and slave doesn't release
@@ -346,6 +348,33 @@ static u32 mpc_i2c_get_sec_cfg_8xxx(void)
 	return val;
 }
 
+static u32 mpc_i2c_get_prescaler_8xxx(void)
+{
+	/* mpc83xx and mpc82xx all have prescaler 1 */
+	u32 prescaler = 1;
+
+	/* mpc85xx */
+	if (pvr_version_is(PVR_VER_E500V1) || pvr_version_is(PVR_VER_E500V2)
+		|| pvr_version_is(PVR_VER_E500MC)
+		|| pvr_version_is(PVR_VER_E5500)
+		|| pvr_version_is(PVR_VER_E6500)) {
+		unsigned int svr = mfspr(SPRN_SVR);
+
+		if ((SVR_SOC_VER(svr) == SVR_8540)
+			|| (SVR_SOC_VER(svr) == SVR_8541)
+			|| (SVR_SOC_VER(svr) == SVR_8560)
+			|| (SVR_SOC_VER(svr) == SVR_8555)
+			|| (SVR_SOC_VER(svr) == SVR_8610))
+			/* the above 85xx SoCs have prescaler 1 */
+			prescaler = 1;
+		else
+			/* all the other 85xx have prescaler 2 */
+			prescaler = 2;
+	}
+
+	return prescaler;
+}
+
 static int mpc_i2c_get_fdr_8xxx(struct device_node *node, u32 clock,
 					  u32 prescaler, u32 *real_clk)
 {
@@ -363,7 +392,7 @@ static int mpc_i2c_get_fdr_8xxx(struct device_node *node, u32 clock,
 	if (of_device_is_compatible(node, "fsl,mpc8544-i2c"))
 		prescaler = mpc_i2c_get_sec_cfg_8xxx() ? 3 : 2;
 	if (!prescaler)
-		prescaler = 1;
+		prescaler = mpc_i2c_get_prescaler_8xxx();
 
 	divider = fsl_get_sys_freq() / clock / prescaler;
 

drivers/i2c/busses/i2c-mxs.c

@@ -568,6 +568,7 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 	int ret;
 	int flags;
 	int use_pio = 0;
+	unsigned long time_left;
 
 	flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
 
@@ -599,9 +600,9 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 		if (ret)
 			return ret;
 
-		ret = wait_for_completion_timeout(&i2c->cmd_complete,
+		time_left = wait_for_completion_timeout(&i2c->cmd_complete,
 						msecs_to_jiffies(1000));
-		if (ret == 0)
+		if (!time_left)
 			goto timeout;
 
 		ret = i2c->cmd_err;

drivers/i2c/busses/i2c-nomadik.c

@@ -446,9 +446,9 @@ static void setup_i2c_controller(struct nmk_i2c_dev *dev)
  */
 static int read_i2c(struct nmk_i2c_dev *dev, u16 flags)
 {
-	u32 status = 0;
+	int status = 0;
 	u32 mcr, irq_mask;
-	int timeout;
+	unsigned long timeout;
 
 	mcr = load_i2c_mcr_reg(dev, flags);
 	writel(mcr, dev->virtbase + I2C_MCR);
@@ -517,7 +517,7 @@ static int write_i2c(struct nmk_i2c_dev *dev, u16 flags)
 {
 	u32 status = 0;
 	u32 mcr, irq_mask;
-	int timeout;
+	unsigned long timeout;
 
 	mcr = load_i2c_mcr_reg(dev, flags);
 

drivers/i2c/busses/i2c-opal.c

@@ -104,18 +104,8 @@ static int i2c_opal_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 		req.buffer_ra = cpu_to_be64(__pa(msgs[0].buf));
 		break;
 	case 2:
-		/* For two messages, we basically support only simple
-		 * smbus transactions of a write plus a read. We might
-		 * want to allow also two writes but we'd have to bounce
-		 * the data into a single buffer.
-		 */
-		if ((msgs[0].flags & I2C_M_RD) || !(msgs[1].flags & I2C_M_RD))
-			return -EOPNOTSUPP;
-		if (msgs[0].len > 4)
-			return -EOPNOTSUPP;
-		if (msgs[0].addr != msgs[1].addr)
-			return -EOPNOTSUPP;
-		req.type = OPAL_I2C_SM_READ;
+		req.type = (msgs[1].flags & I2C_M_RD) ?
+			OPAL_I2C_SM_READ : OPAL_I2C_SM_WRITE;
 		req.addr = cpu_to_be16(msgs[0].addr);
 		req.subaddr_sz = msgs[0].len;
 		for (i = 0; i < msgs[0].len; i++)
@@ -210,6 +200,15 @@ static const struct i2c_algorithm i2c_opal_algo = {
 	.functionality	= i2c_opal_func,
 };
 
+/*
+ * For two messages, we basically support simple smbus transactions of a
+ * write-then-anything.
+ */
+static struct i2c_adapter_quirks i2c_opal_quirks = {
+	.flags = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | I2C_AQ_COMB_SAME_ADDR,
+	.max_comb_1st_msg_len = 4,
+};
+
 static int i2c_opal_probe(struct platform_device *pdev)
 {
 	struct i2c_adapter	*adapter;
@@ -232,6 +231,7 @@ static int i2c_opal_probe(struct platform_device *pdev)
 
 	adapter->algo = &i2c_opal_algo;
 	adapter->algo_data = (void *)(unsigned long)opal_id;
+	adapter->quirks = &i2c_opal_quirks;
 	adapter->dev.parent = &pdev->dev;
 	adapter->dev.of_node = of_node_get(pdev->dev.of_node);
 	pname = of_get_property(pdev->dev.of_node, "ibm,port-name", NULL);

drivers/i2c/busses/i2c-pmcmsp.c

@@ -456,14 +456,6 @@ static enum pmcmsptwi_xfer_result pmcmsptwi_xfer_cmd(
 		return -EINVAL;
 	}
 
-	if (cmd->read_len > MSP_MAX_BYTES_PER_RW ||
-	    cmd->write_len > MSP_MAX_BYTES_PER_RW) {
-		dev_err(&pmcmsptwi_adapter.dev,
-			"%s: Cannot transfer more than %d bytes\n",
-			__func__, MSP_MAX_BYTES_PER_RW);
-		return -EINVAL;
-	}
-
 	mutex_lock(&data->lock);
 	dev_dbg(&pmcmsptwi_adapter.dev,
 		"Setting address to 0x%04x\n", cmd->addr);
@@ -520,25 +512,14 @@ static int pmcmsptwi_master_xfer(struct i2c_adapter *adap,
 	struct pmcmsptwi_cfg oldcfg, newcfg;
 	int ret;
 
-	if (num > 2) {
-		dev_dbg(&adap->dev, "%d messages unsupported\n", num);
-		return -EINVAL;
-	} else if (num == 2) {
-		/* Check for a dual write-then-read command */
+	if (num == 2) {
 		struct i2c_msg *nextmsg = msg + 1;
-		if (!(msg->flags & I2C_M_RD) &&
-		    (nextmsg->flags & I2C_M_RD) &&
-		    msg->addr == nextmsg->addr) {
-			cmd.type = MSP_TWI_CMD_WRITE_READ;
-			cmd.write_len = msg->len;
-			cmd.write_data = msg->buf;
-			cmd.read_len = nextmsg->len;
-			cmd.read_data = nextmsg->buf;
-		} else {
-			dev_dbg(&adap->dev,
-				"Non write-read dual messages unsupported\n");
-			return -EINVAL;
-		}
+
+		cmd.type = MSP_TWI_CMD_WRITE_READ;
+		cmd.write_len = msg->len;
+		cmd.write_data = msg->buf;
+		cmd.read_len = nextmsg->len;
+		cmd.read_data = nextmsg->buf;
 	} else if (msg->flags & I2C_M_RD) {
 		cmd.type = MSP_TWI_CMD_READ;
 		cmd.read_len = msg->len;
@@ -598,6 +579,14 @@ static u32 pmcmsptwi_i2c_func(struct i2c_adapter *adapter)
 		I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_PROC_CALL;
 }
 
+static struct i2c_adapter_quirks pmcmsptwi_i2c_quirks = {
+	.flags = I2C_AQ_COMB_WRITE_THEN_READ,
+	.max_write_len = MSP_MAX_BYTES_PER_RW,
+	.max_read_len = MSP_MAX_BYTES_PER_RW,
+	.max_comb_1st_msg_len = MSP_MAX_BYTES_PER_RW,
+	.max_comb_2nd_msg_len = MSP_MAX_BYTES_PER_RW,
+};
+
 /* -- Initialization -- */
 
 static struct i2c_algorithm pmcmsptwi_algo = {
@@ -609,6 +598,7 @@ static struct i2c_adapter pmcmsptwi_adapter = {
 	.owner		= THIS_MODULE,
 	.class		= I2C_CLASS_HWMON | I2C_CLASS_SPD,
 	.algo		= &pmcmsptwi_algo,
+	.quirks		= &pmcmsptwi_i2c_quirks,
 	.name		= DRV_NAME,
 };
 

drivers/i2c/busses/i2c-powermac.c

@@ -153,12 +153,6 @@ static int i2c_powermac_master_xfer(	struct i2c_adapter *adap,
 	int			read;
 	int			addrdir;
 
-	if (num != 1) {
-		dev_err(&adap->dev,
-			"Multi-message I2C transactions not supported\n");
-		return -EOPNOTSUPP;
-	}
-
 	if (msgs->flags & I2C_M_TEN)
 		return -EINVAL;
 	read = (msgs->flags & I2C_M_RD) != 0;
@@ -205,6 +199,9 @@ static const struct i2c_algorithm i2c_powermac_algorithm = {
 	.functionality	= i2c_powermac_func,
 };
 
+static struct i2c_adapter_quirks i2c_powermac_quirks = {
+	.max_num_msgs = 1,
+};
 
 static int i2c_powermac_remove(struct platform_device *dev)
 {
@@ -434,6 +431,7 @@ static int i2c_powermac_probe(struct platform_device *dev)
 
 	platform_set_drvdata(dev, adapter);
 	adapter->algo = &i2c_powermac_algorithm;
+	adapter->quirks = &i2c_powermac_quirks;
 	i2c_set_adapdata(adapter, bus);
 	adapter->dev.parent = &dev->dev;
 

drivers/i2c/busses/i2c-qup.c

@@ -412,17 +412,6 @@ static int qup_i2c_read_one(struct qup_i2c_dev *qup, struct i2c_msg *msg)
 	unsigned long left;
 	int ret;
 
-	/*
-	 * The QUP block will issue a NACK and STOP on the bus when reaching
-	 * the end of the read, the length of the read is specified as one byte
-	 * which limits the possible read to 256 (QUP_READ_LIMIT) bytes.
-	 */
-	if (msg->len > QUP_READ_LIMIT) {
-		dev_err(qup->dev, "HW not capable of reads over %d bytes\n",
-			QUP_READ_LIMIT);
-		return -EINVAL;
-	}
-
 	qup->msg = msg;
 	qup->pos  = 0;
 
@@ -534,6 +523,15 @@ static const struct i2c_algorithm qup_i2c_algo = {
 	.functionality	= qup_i2c_func,
 };
 
+/*
+ * The QUP block will issue a NACK and STOP on the bus when reaching
+ * the end of the read, the length of the read is specified as one byte
+ * which limits the possible read to 256 (QUP_READ_LIMIT) bytes.
+ */
+static struct i2c_adapter_quirks qup_i2c_quirks = {
+	.max_read_len = QUP_READ_LIMIT,
+};
+
 static void qup_i2c_enable_clocks(struct qup_i2c_dev *qup)
 {
 	clk_prepare_enable(qup->clk);
@@ -670,6 +668,7 @@ static int qup_i2c_probe(struct platform_device *pdev)
 
 	i2c_set_adapdata(&qup->adap, qup);
 	qup->adap.algo = &qup_i2c_algo;
+	qup->adap.quirks = &qup_i2c_quirks;
 	qup->adap.dev.parent = qup->dev;
 	qup->adap.dev.of_node = pdev->dev.of_node;
 	strlcpy(qup->adap.name, "QUP I2C adapter", sizeof(qup->adap.name));

drivers/i2c/busses/i2c-rcar.c

@@ -382,11 +382,11 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
 	if (ssr_filtered & SAR) {
 		/* read or write request */
 		if (ssr_raw & STM) {
-			i2c_slave_event(priv->slave, I2C_SLAVE_REQ_READ_START, &value);
+			i2c_slave_event(priv->slave, I2C_SLAVE_READ_REQUESTED, &value);
 			rcar_i2c_write(priv, ICRXTX, value);
 			rcar_i2c_write(priv, ICSIER, SDE | SSR | SAR);
 		} else {
-			i2c_slave_event(priv->slave, I2C_SLAVE_REQ_WRITE_START, &value);
+			i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_REQUESTED, &value);
 			rcar_i2c_read(priv, ICRXTX);	/* dummy read */
 			rcar_i2c_write(priv, ICSIER, SDR | SSR | SAR);
 		}
@@ -406,17 +406,15 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
 		int ret;
 
 		value = rcar_i2c_read(priv, ICRXTX);
-		ret = i2c_slave_event(priv->slave, I2C_SLAVE_REQ_WRITE_END, &value);
+		ret = i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_RECEIVED, &value);
 		/* Send NACK in case of error */
 		rcar_i2c_write(priv, ICSCR, SIE | SDBS | (ret < 0 ? FNA : 0));
-		i2c_slave_event(priv->slave, I2C_SLAVE_REQ_WRITE_START, &value);
 		rcar_i2c_write(priv, ICSSR, ~SDR & 0xff);
 	}
 
 	/* master wants to read from us */
 	if (ssr_filtered & SDE) {
-		i2c_slave_event(priv->slave, I2C_SLAVE_REQ_READ_END, &value);
-		i2c_slave_event(priv->slave, I2C_SLAVE_REQ_READ_START, &value);
+		i2c_slave_event(priv->slave, I2C_SLAVE_READ_PROCESSED, &value);
 		rcar_i2c_write(priv, ICRXTX, value);
 		rcar_i2c_write(priv, ICSSR, ~SDE & 0xff);
 	}

drivers/i2c/busses/i2c-tegra.c

@@ -532,7 +532,7 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
 {
 	u32 packet_header;
 	u32 int_mask;
-	int ret;
+	unsigned long time_left;
 
 	tegra_i2c_flush_fifos(i2c_dev);
 
@@ -585,18 +585,20 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
 	dev_dbg(i2c_dev->dev, "unmasked irq: %02x\n",
 		i2c_readl(i2c_dev, I2C_INT_MASK));
 
-	ret = wait_for_completion_timeout(&i2c_dev->msg_complete, TEGRA_I2C_TIMEOUT);
+	time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
+						TEGRA_I2C_TIMEOUT);
 	tegra_i2c_mask_irq(i2c_dev, int_mask);
 
-	if (ret == 0) {
+	if (time_left == 0) {
 		dev_err(i2c_dev->dev, "i2c transfer timed out\n");
 
 		tegra_i2c_init(i2c_dev);
 		return -ETIMEDOUT;
 	}
 
-	dev_dbg(i2c_dev->dev, "transfer complete: %d %d %d\n",
-		ret, completion_done(&i2c_dev->msg_complete), i2c_dev->msg_err);
+	dev_dbg(i2c_dev->dev, "transfer complete: %lu %d %d\n",
+		time_left, completion_done(&i2c_dev->msg_complete),
+		i2c_dev->msg_err);
 
 	if (likely(i2c_dev->msg_err == I2C_ERR_NONE))
 		return 0;

drivers/i2c/busses/i2c-viperboard.c

@@ -288,10 +288,6 @@ static int vprbrd_i2c_xfer(struct i2c_adapter *i2c, struct i2c_msg *msgs,
 			i, pmsg->flags & I2C_M_RD ? "read" : "write",
 			pmsg->flags, pmsg->len, pmsg->addr);
 
-		/* msgs longer than 2048 bytes are not supported by adapter */
-		if (pmsg->len > 2048)
-			return -EINVAL;
-
 		mutex_lock(&vb->lock);
 		/* directly send the message */
 		if (pmsg->flags & I2C_M_RD) {
@@ -358,6 +354,11 @@ static const struct i2c_algorithm vprbrd_algorithm = {
 	.functionality	= vprbrd_i2c_func,
 };
 
+static struct i2c_adapter_quirks vprbrd_quirks = {
+	.max_read_len = 2048,
+	.max_write_len = 2048,
+};
+
 static int vprbrd_i2c_probe(struct platform_device *pdev)
 {
 	struct vprbrd *vb = dev_get_drvdata(pdev->dev.parent);
@@ -373,6 +374,7 @@ static int vprbrd_i2c_probe(struct platform_device *pdev)
 	vb_i2c->i2c.owner = THIS_MODULE;
 	vb_i2c->i2c.class = I2C_CLASS_HWMON;
 	vb_i2c->i2c.algo = &vprbrd_algorithm;
+	vb_i2c->i2c.quirks = &vprbrd_quirks;
 	vb_i2c->i2c.algo_data = vb;
 	/* save the param in usb capabable memory */
 	vb_i2c->bus_freq_param = i2c_bus_param;

drivers/i2c/busses/i2c-wmt.c

@@ -128,7 +128,8 @@ static int wmt_i2c_write(struct i2c_adapter *adap, struct i2c_msg *pmsg,
 {
 	struct wmt_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
 	u16 val, tcr_val;
-	int ret, wait_result;
+	int ret;
+	unsigned long wait_result;
 	int xfer_len = 0;
 
 	if (!(pmsg->flags & I2C_M_NOSTART)) {
@@ -177,7 +178,7 @@ static int wmt_i2c_write(struct i2c_adapter *adap, struct i2c_msg *pmsg,
 
 	while (xfer_len < pmsg->len) {
 		wait_result = wait_for_completion_timeout(&i2c_dev->complete,
-							  500 * HZ / 1000);
+							msecs_to_jiffies(500));
 
 		if (wait_result == 0)
 			return -ETIMEDOUT;
@@ -218,7 +219,8 @@ static int wmt_i2c_read(struct i2c_adapter *adap, struct i2c_msg *pmsg,
 {
 	struct wmt_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
 	u16 val, tcr_val;
-	int ret, wait_result;
+	int ret;
+	unsigned long wait_result;
 	u32 xfer_len = 0;
 
 	if (!(pmsg->flags & I2C_M_NOSTART)) {
@@ -266,7 +268,7 @@ static int wmt_i2c_read(struct i2c_adapter *adap, struct i2c_msg *pmsg,
 
 	while (xfer_len < pmsg->len) {
 		wait_result = wait_for_completion_timeout(&i2c_dev->complete,
-							  500 * HZ / 1000);
+							msecs_to_jiffies(500));
 
 		if (!wait_result)
 			return -ETIMEDOUT;

drivers/i2c/i2c-core.c

@@ -561,7 +561,7 @@ static int i2c_generic_recovery(struct i2c_adapter *adap)
 	int i = 0, val = 1, ret = 0;
 
 	if (bri->prepare_recovery)
-		bri->prepare_recovery(bri);
+		bri->prepare_recovery(adap);
 
 	/*
 	 * By this time SCL is high, as we need to give 9 falling-rising edges
@@ -586,7 +586,7 @@ static int i2c_generic_recovery(struct i2c_adapter *adap)
 	}
 
 	if (bri->unprepare_recovery)
-		bri->unprepare_recovery(bri);
+		bri->unprepare_recovery(adap);
 
 	return ret;
 }
@@ -1875,6 +1875,13 @@ static int __init i2c_init(void)
 {
 	int retval;
 
+	retval = of_alias_get_highest_id("i2c");
+
+	down_write(&__i2c_board_lock);
+	if (retval >= __i2c_first_dynamic_bus_num)
+		__i2c_first_dynamic_bus_num = retval + 1;
+	up_write(&__i2c_board_lock);
+
 	retval = bus_register(&i2c_bus_type);
 	if (retval)
 		return retval;
@@ -1926,6 +1933,65 @@ module_exit(i2c_exit);
  * ----------------------------------------------------
  */
 
+/* Check if val is exceeding the quirk IFF quirk is non 0 */
+#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
+
+static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
+{
+	dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
+			    err_msg, msg->addr, msg->len,
+			    msg->flags & I2C_M_RD ? "read" : "write");
+	return -EOPNOTSUPP;
+}
+
+static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	const struct i2c_adapter_quirks *q = adap->quirks;
+	int max_num = q->max_num_msgs, i;
+	bool do_len_check = true;
+
+	if (q->flags & I2C_AQ_COMB) {
+		max_num = 2;
+
+		/* special checks for combined messages */
+		if (num == 2) {
+			if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD)
+				return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write");
+
+			if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD))
+				return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read");
+
+			if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr)
+				return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr");
+
+			if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len))
+				return i2c_quirk_error(adap, &msgs[0], "msg too long");
+
+			if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len))
+				return i2c_quirk_error(adap, &msgs[1], "msg too long");
+
+			do_len_check = false;
+		}
+	}
+
+	if (i2c_quirk_exceeded(num, max_num))
+		return i2c_quirk_error(adap, &msgs[0], "too many messages");
+
+	for (i = 0; i < num; i++) {
+		u16 len = msgs[i].len;
+
+		if (msgs[i].flags & I2C_M_RD) {
+			if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
+				return i2c_quirk_error(adap, &msgs[i], "msg too long");
+		} else {
+			if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
+				return i2c_quirk_error(adap, &msgs[i], "msg too long");
+		}
+	}
+
+	return 0;
+}
+
 /**
  * __i2c_transfer - unlocked flavor of i2c_transfer
  * @adap: Handle to I2C bus
@@ -1943,6 +2009,9 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 	unsigned long orig_jiffies;
 	int ret, try;
 
+	if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
+		return -EOPNOTSUPP;
+
 	/* i2c_trace_msg gets enabled when tracepoint i2c_transfer gets
 	 * enabled.  This is an efficient way of keeping the for-loop from
 	 * being executed when not needed.

drivers/i2c/i2c-slave-eeprom.c

@@ -36,7 +36,7 @@ static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
 	struct eeprom_data *eeprom = i2c_get_clientdata(client);
 
 	switch (event) {
-	case I2C_SLAVE_REQ_WRITE_END:
+	case I2C_SLAVE_WRITE_RECEIVED:
 		if (eeprom->first_write) {
 			eeprom->buffer_idx = *val;
 			eeprom->first_write = false;
@@ -47,17 +47,23 @@ static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
 		}
 		break;
 
-	case I2C_SLAVE_REQ_READ_START:
+	case I2C_SLAVE_READ_PROCESSED:
+		/* The previous byte made it to the bus, get next one */
+		eeprom->buffer_idx++;
+		/* fallthrough */
+	case I2C_SLAVE_READ_REQUESTED:
 		spin_lock(&eeprom->buffer_lock);
 		*val = eeprom->buffer[eeprom->buffer_idx];
 		spin_unlock(&eeprom->buffer_lock);
-		break;
-
-	case I2C_SLAVE_REQ_READ_END:
-		eeprom->buffer_idx++;
+		/*
+		 * Do not increment buffer_idx here, because we don't know if
+		 * this byte will be actually used. Read Linux I2C slave docs
+		 * for details.
+		 */
 		break;
 
 	case I2C_SLAVE_STOP:
+	case I2C_SLAVE_WRITE_REQUESTED:
 		eeprom->first_write = true;
 		break;
 

drivers/i2c/muxes/i2c-mux-gpio.c

@@ -76,10 +76,9 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
 		return -ENODEV;
 	}
 	adapter = of_find_i2c_adapter_by_node(adapter_np);
-	if (!adapter) {
-		dev_err(&pdev->dev, "Cannot find parent bus\n");
+	if (!adapter)
 		return -EPROBE_DEFER;
-	}
+
 	mux->data.parent = i2c_adapter_id(adapter);
 	put_device(&adapter->dev);
 
@@ -177,11 +176,8 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
 	}
 
 	parent = i2c_get_adapter(mux->data.parent);
-	if (!parent) {
-		dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
-			mux->data.parent);
+	if (!parent)
 		return -EPROBE_DEFER;
-	}
 
 	mux->parent = parent;
 	mux->gpio_base = gpio_base;

drivers/i2c/muxes/i2c-mux-pca954x.c

@@ -204,9 +204,9 @@ static int pca954x_probe(struct i2c_client *client,
 	i2c_set_clientdata(client, data);
 
 	/* Get the mux out of reset if a reset GPIO is specified. */
-	gpio = devm_gpiod_get(&client->dev, "reset");
-	if (!IS_ERR(gpio))
-		gpiod_direction_output(gpio, 0);
+	gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
 
 	/* Write the mux register at addr to verify
 	 * that the mux is in fact present. This also

drivers/of/base.c

@@ -1960,6 +1960,32 @@ int of_alias_get_id(struct device_node *np, const char *stem)
 }
 EXPORT_SYMBOL_GPL(of_alias_get_id);
 
+/**
+ * of_alias_get_highest_id - Get highest alias id for the given stem
+ * @stem:	Alias stem to be examined
+ *
+ * The function travels the lookup table to get the highest alias id for the
+ * given alias stem.  It returns the alias id if found.
+ */
+int of_alias_get_highest_id(const char *stem)
+{
+	struct alias_prop *app;
+	int id = -ENODEV;
+
+	mutex_lock(&of_mutex);
+	list_for_each_entry(app, &aliases_lookup, link) {
+		if (strcmp(app->stem, stem) != 0)
+			continue;
+
+		if (app->id > id)
+			id = app->id;
+	}
+	mutex_unlock(&of_mutex);
+
+	return id;
+}
+EXPORT_SYMBOL_GPL(of_alias_get_highest_id);
+
 const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
 			       u32 *pu)
 {

include/linux/i2c.h

@@ -253,10 +253,10 @@ static inline void i2c_set_clientdata(struct i2c_client *dev, void *data)
 
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 enum i2c_slave_event {
-	I2C_SLAVE_REQ_READ_START,
-	I2C_SLAVE_REQ_READ_END,
-	I2C_SLAVE_REQ_WRITE_START,
-	I2C_SLAVE_REQ_WRITE_END,
+	I2C_SLAVE_READ_REQUESTED,
+	I2C_SLAVE_WRITE_REQUESTED,
+	I2C_SLAVE_READ_PROCESSED,
+	I2C_SLAVE_WRITE_RECEIVED,
 	I2C_SLAVE_STOP,
 };
 
@@ -435,8 +435,8 @@ struct i2c_bus_recovery_info {
 	void (*set_scl)(struct i2c_adapter *, int val);
 	int (*get_sda)(struct i2c_adapter *);
 
-	void (*prepare_recovery)(struct i2c_bus_recovery_info *bri);
-	void (*unprepare_recovery)(struct i2c_bus_recovery_info *bri);
+	void (*prepare_recovery)(struct i2c_adapter *);
+	void (*unprepare_recovery)(struct i2c_adapter *);
 
 	/* gpio recovery */
 	int scl_gpio;
@@ -449,6 +449,48 @@ int i2c_recover_bus(struct i2c_adapter *adap);
 int i2c_generic_gpio_recovery(struct i2c_adapter *adap);
 int i2c_generic_scl_recovery(struct i2c_adapter *adap);
 
+/**
+ * struct i2c_adapter_quirks - describe flaws of an i2c adapter
+ * @flags: see I2C_AQ_* for possible flags and read below
+ * @max_num_msgs: maximum number of messages per transfer
+ * @max_write_len: maximum length of a write message
+ * @max_read_len: maximum length of a read message
+ * @max_comb_1st_msg_len: maximum length of the first msg in a combined message
+ * @max_comb_2nd_msg_len: maximum length of the second msg in a combined message
+ *
+ * Note about combined messages: Some I2C controllers can only send one message
+ * per transfer, plus something called combined message or write-then-read.
+ * This is (usually) a small write message followed by a read message and
+ * barely enough to access register based devices like EEPROMs. There is a flag
+ * to support this mode. It implies max_num_msg = 2 and does the length checks
+ * with max_comb_*_len because combined message mode usually has its own
+ * limitations. Because of HW implementations, some controllers can actually do
+ * write-then-anything or other variants. To support that, write-then-read has
+ * been broken out into smaller bits like write-first and read-second which can
+ * be combined as needed.
+ */
+
+struct i2c_adapter_quirks {
+	u64 flags;
+	int max_num_msgs;
+	u16 max_write_len;
+	u16 max_read_len;
+	u16 max_comb_1st_msg_len;
+	u16 max_comb_2nd_msg_len;
+};
+
+/* enforce max_num_msgs = 2 and use max_comb_*_len for length checks */
+#define I2C_AQ_COMB			BIT(0)
+/* first combined message must be write */
+#define I2C_AQ_COMB_WRITE_FIRST		BIT(1)
+/* second combined message must be read */
+#define I2C_AQ_COMB_READ_SECOND		BIT(2)
+/* both combined messages must have the same target address */
+#define I2C_AQ_COMB_SAME_ADDR		BIT(3)
+/* convenience macro for typical write-then read case */
+#define I2C_AQ_COMB_WRITE_THEN_READ	(I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | \
+					 I2C_AQ_COMB_READ_SECOND | I2C_AQ_COMB_SAME_ADDR)
+
 /*
  * i2c_adapter is the structure used to identify a physical i2c bus along
  * with the access algorithms necessary to access it.
@@ -474,6 +516,7 @@ struct i2c_adapter {
 	struct list_head userspace_clients;
 
 	struct i2c_bus_recovery_info *bus_recovery_info;
+	const struct i2c_adapter_quirks *quirks;
 };
 #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
 

include/linux/of.h

@@ -332,6 +332,7 @@ extern int of_count_phandle_with_args(const struct device_node *np,
 
 extern void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align));
 extern int of_alias_get_id(struct device_node *np, const char *stem);
+extern int of_alias_get_highest_id(const char *stem);
 
 extern int of_machine_is_compatible(const char *compat);
 
@@ -594,6 +595,11 @@ static inline int of_alias_get_id(struct device_node *np, const char *stem)
 	return -ENOSYS;
 }
 
+static inline int of_alias_get_highest_id(const char *stem)
+{
+	return -ENOSYS;
+}
+
 static inline int of_machine_is_compatible(const char *compat)
 {
 	return 0;

include/linux/platform_data/i2c-davinci.h

@@ -18,6 +18,7 @@ struct davinci_i2c_platform_data {
 	unsigned int	bus_delay;	/* post-transaction delay (usec) */
 	unsigned int    sda_pin;        /* GPIO pin ID to use for SDA */
 	unsigned int    scl_pin;        /* GPIO pin ID to use for SCL */
+	bool		has_pfunc;	/*chip has a ICPFUNC register */
 };
 
 /* for board setup code */