dmaengine: dw_dmac: move to generic DMA binding

The original device tree binding for this driver, from Viresh Kumar
unfortunately conflicted with the generic DMA binding, and did not allow
to completely seperate slave device configuration from the controller.

This is an attempt to replace it with an implementation of the generic
binding, but it is currently completely untested, because I do not have
any hardware with this particular controller.

The patch applies on top of the slave-dma tree, which contains both the base
support for the generic DMA binding, as well as the earlier attempt from
Viresh. Both of these are currently not merged upstream however.

This version incorporates feedback from Viresh Kumar, Andy Shevchenko
and Russell King.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Vinod Koul <vinod.koul@linux.intel.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Documentation/devicetree/bindings/dma/snps-dma.txt

@@ -3,59 +3,61 @@
 Required properties:
 - compatible: "snps,dma-spear1340"
 - reg: Address range of the DMAC registers
-- interrupt-parent: Should be the phandle for the interrupt controller
-  that services interrupts for this device
 - interrupt: Should contain the DMAC interrupt number
-- nr_channels: Number of channels supported by hardware
-- is_private: The device channels should be marked as private and not for by the
-  general purpose DMA channel allocator. False if not passed.
+- dma-channels: Number of channels supported by hardware
+- dma-requests: Number of DMA request lines supported, up to 16
+- dma-masters: Number of AHB masters supported by the controller
+- #dma-cells: must be <3>
 - chan_allocation_order: order of allocation of channel, 0 (default): ascending,
   1: descending
 - chan_priority: priority of channels. 0 (default): increase from chan 0->n, 1:
   increase from chan n->0
 - block_size: Maximum block size supported by the controller
-- nr_masters: Number of AHB masters supported by the controller
 - data_width: Maximum data width supported by hardware per AHB master
   (0 - 8bits, 1 - 16bits, ..., 5 - 256bits)
-- slave_info:
-	- bus_id: name of this device channel, not just a device name since
-	  devices may have more than one channel e.g. "foo_tx". For using the
-	  dw_generic_filter(), slave drivers must pass exactly this string as
-	  param to filter function.
-	- cfg_hi: Platform-specific initializer for the CFG_HI register
-	- cfg_lo: Platform-specific initializer for the CFG_LO register
-	- src_master: src master for transfers on allocated channel.
-	- dst_master: dest master for transfers on allocated channel.
+
+
+Optional properties:
+- interrupt-parent: Should be the phandle for the interrupt controller
+  that services interrupts for this device
+- is_private: The device channels should be marked as private and not for by the
+  general purpose DMA channel allocator. False if not passed.
 
 Example:
 
-	dma@fc000000 {
+	dmahost: dma@fc000000 {
 		compatible = "snps,dma-spear1340";
 		reg = <0xfc000000 0x1000>;
 		interrupt-parent = <&vic1>;
 		interrupts = <12>;
 
-		nr_channels = <8>;
+		dma-channels = <8>;
+		dma-requests = <16>;
+		dma-masters = <2>;
+		#dma-cells = <3>;
 		chan_allocation_order = <1>;
 		chan_priority = <1>;
 		block_size = <0xfff>;
-		nr_masters = <2>;
 		data_width = <3 3 0 0>;
-
-		slave_info {
-			uart0-tx {
-				bus_id = "uart0-tx";
-				cfg_hi = <0x4000>;	/* 0x8 << 11 */
-				cfg_lo = <0>;
-				src_master = <0>;
-				dst_master = <1>;
-			};
-			spi0-tx {
-				bus_id = "spi0-tx";
-				cfg_hi = <0x2000>;	/* 0x4 << 11 */
-				cfg_lo = <0>;
-				src_master = <0>;
-				dst_master = <0>;
-			};
 	};
+
+DMA clients connected to the Designware DMA controller must use the format
+described in the dma.txt file, using a four-cell specifier for each channel.
+The four cells in order are:
+
+1. A phandle pointing to the DMA controller
+2. The DMA request line number
+3. Source master for transfers on allocated channel
+4. Destination master for transfers on allocated channel
+
+Example:
+	
+	serial@e0000000 {
+		compatible = "arm,pl011", "arm,primecell";
+		reg = <0xe0000000 0x1000>;
+		interrupts = <0 35 0x4>;
+		status = "disabled";
+		dmas = <&dmahost 12 0 1>,
+			<&dmahost 13 0 1 0>;
+		dma-names = "rx", "rx";
 	};

drivers/dma/dw_dmac.c

@@ -19,6 +19,7 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/of.h>
+#include <linux/of_dma.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
@@ -170,7 +171,13 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
 	if (dwc->initialized == true)
 		return;
 
-	if (dws) {
+	if (dws && dws->cfg_hi == ~0 && dws->cfg_lo == ~0) {
+		/* autoconfigure based on request line from DT */
+		if (dwc->direction == DMA_MEM_TO_DEV)
+			cfghi = DWC_CFGH_DST_PER(dwc->request_line);
+		else if (dwc->direction == DMA_DEV_TO_MEM)
+			cfghi = DWC_CFGH_SRC_PER(dwc->request_line);
+	} else if (dws) {
 		/*
 		 * We need controller-specific data to set up slave
 		 * transfers.
@@ -1225,49 +1232,64 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
 	dev_vdbg(chan2dev(chan), "%s: done\n", __func__);
 }
 
-bool dw_dma_generic_filter(struct dma_chan *chan, void *param)
+struct dw_dma_filter_args {
+	struct dw_dma *dw;
+	unsigned int req;
+	unsigned int src;
+	unsigned int dst;
+};
+
+static bool dw_dma_generic_filter(struct dma_chan *chan, void *param)
 {
+	struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
 	struct dw_dma *dw = to_dw_dma(chan->device);
-	static struct dw_dma *last_dw;
-	static char *last_bus_id;
-	int i = -1;
+	struct dw_dma_filter_args *fargs = param;
+	struct dw_dma_slave *dws = &dwc->slave;
 
-	/*
-	 * dmaengine framework calls this routine for all channels of all dma
-	 * controller, until true is returned. If 'param' bus_id is not
-	 * registered with a dma controller (dw), then there is no need of
-	 * running below function for all channels of dw.
-	 *
-	 * This block of code does this by saving the parameters of last
-	 * failure. If dw and param are same, i.e. trying on same dw with
-	 * different channel, return false.
-	 */
-	if ((last_dw == dw) && (last_bus_id == param))
+	/* ensure the device matches our channel */
+        if (chan->device != &fargs->dw->dma)
                 return false;
-	/*
-	 * Return true:
-	 * - If dw_dma's platform data is not filled with slave info, then all
-	 *   dma controllers are fine for transfer.
-	 * - Or if param is NULL
-	 */
-	if (!dw->sd || !param)
-		return true;
 
-	while (++i < dw->sd_count) {
-		if (!strcmp(dw->sd[i].bus_id, param)) {
-			chan->private = &dw->sd[i];
-			last_dw = NULL;
-			last_bus_id = NULL;
+	dws->dma_dev	= dw->dma.dev;
+	dws->cfg_hi	= ~0;
+	dws->cfg_lo	= ~0;
+	dws->src_master	= fargs->src;
+	dws->dst_master	= fargs->dst;
+
+	dwc->request_line = fargs->req;
+
+	chan->private = dws;
 
 	return true;
-		}
-	}
+}
 
-	last_dw = dw;
-	last_bus_id = param;
-	return false;
+static struct dma_chan *dw_dma_xlate(struct of_phandle_args *dma_spec,
+					 struct of_dma *ofdma)
+{
+	struct dw_dma *dw = ofdma->of_dma_data;
+	struct dw_dma_filter_args fargs = {
+		.dw = dw,
+	};
+	dma_cap_mask_t cap;
+
+	if (dma_spec->args_count != 3)
+		return NULL;
+
+	fargs.req = be32_to_cpup(dma_spec->args+0);
+	fargs.src = be32_to_cpup(dma_spec->args+1);
+	fargs.dst = be32_to_cpup(dma_spec->args+2);
+
+	if (WARN_ON(fargs.req >= DW_DMA_MAX_NR_REQUESTS ||
+		    fargs.src >= dw->nr_masters ||
+		    fargs.dst >= dw->nr_masters))
+		return NULL;
+
+	dma_cap_zero(cap);
+	dma_cap_set(DMA_SLAVE, cap);
+
+	/* TODO: there should be a simpler way to do this */
+	return dma_request_channel(cap, dw_dma_generic_filter, &fargs);
 }
-EXPORT_SYMBOL(dw_dma_generic_filter);
 
 /* --------------------- Cyclic DMA API extensions -------------------- */
 
@@ -1553,9 +1575,8 @@ static void dw_dma_off(struct dw_dma *dw)
 static struct dw_dma_platform_data *
 dw_dma_parse_dt(struct platform_device *pdev)
 {
-	struct device_node *sn, *cn, *np = pdev->dev.of_node;
+	struct device_node *np = pdev->dev.of_node;
 	struct dw_dma_platform_data *pdata;
-	struct dw_dma_slave *sd;
 	u32 tmp, arr[4];
 
 	if (!np) {
@@ -1567,7 +1588,7 @@ dw_dma_parse_dt(struct platform_device *pdev)
 	if (!pdata)
 		return NULL;
 
-	if (of_property_read_u32(np, "nr_channels", &pdata->nr_channels))
+	if (of_property_read_u32(np, "dma-channels", &pdata->nr_channels))
 		return NULL;
 
 	if (of_property_read_bool(np, "is_private"))
@@ -1582,7 +1603,7 @@ dw_dma_parse_dt(struct platform_device *pdev)
 	if (!of_property_read_u32(np, "block_size", &tmp))
 		pdata->block_size = tmp;
 
-	if (!of_property_read_u32(np, "nr_masters", &tmp)) {
+	if (!of_property_read_u32(np, "dma-masters", &tmp)) {
 		if (tmp > 4)
 			return NULL;
 
@@ -1594,36 +1615,6 @@ dw_dma_parse_dt(struct platform_device *pdev)
 		for (tmp = 0; tmp < pdata->nr_masters; tmp++)
 			pdata->data_width[tmp] = arr[tmp];
 
-	/* parse slave data */
-	sn = of_find_node_by_name(np, "slave_info");
-	if (!sn)
-		return pdata;
-
-	/* calculate number of slaves */
-	tmp = of_get_child_count(sn);
-	if (!tmp)
-		return NULL;
-
-	sd = devm_kzalloc(&pdev->dev, sizeof(*sd) * tmp, GFP_KERNEL);
-	if (!sd)
-		return NULL;
-
-	pdata->sd = sd;
-	pdata->sd_count = tmp;
-
-	for_each_child_of_node(sn, cn) {
-		sd->dma_dev = &pdev->dev;
-		of_property_read_string(cn, "bus_id", &sd->bus_id);
-		of_property_read_u32(cn, "cfg_hi", &sd->cfg_hi);
-		of_property_read_u32(cn, "cfg_lo", &sd->cfg_lo);
-		if (!of_property_read_u32(cn, "src_master", &tmp))
-			sd->src_master = tmp;
-
-		if (!of_property_read_u32(cn, "dst_master", &tmp))
-			sd->dst_master = tmp;
-		sd++;
-	}
-
 	return pdata;
 }
 #else
@@ -1704,8 +1695,6 @@ static int dw_probe(struct platform_device *pdev)
 	clk_prepare_enable(dw->clk);
 
 	dw->regs = regs;
-	dw->sd = pdata->sd;
-	dw->sd_count = pdata->sd_count;
 
 	/* get hardware configuration parameters */
 	if (autocfg) {
@@ -1836,6 +1825,14 @@ static int dw_probe(struct platform_device *pdev)
 
 	dma_async_device_register(&dw->dma);
 
+	if (pdev->dev.of_node) {
+		err = of_dma_controller_register(pdev->dev.of_node,
+						 dw_dma_xlate, dw);
+		if (err && err != -ENODEV)
+			dev_err(&pdev->dev,
+				"could not register of_dma_controller\n");
+	}
+
 	return 0;
 }
 
@@ -1844,6 +1841,8 @@ static int __devexit dw_remove(struct platform_device *pdev)
 	struct dw_dma		*dw = platform_get_drvdata(pdev);
 	struct dw_dma_chan	*dwc, *_dwc;
 
+	if (pdev->dev.of_node)
+		of_dma_controller_free(pdev->dev.of_node);
 	dw_dma_off(dw);
 	dma_async_device_unregister(&dw->dma);
 

drivers/dma/dw_dmac_regs.h

@@ -13,6 +13,7 @@
 #include <linux/dw_dmac.h>
 
 #define DW_DMA_MAX_NR_CHANNELS	8
+#define DW_DMA_MAX_NR_REQUESTS	16
 
 /* flow controller */
 enum dw_dma_fc {
@@ -211,6 +212,8 @@ struct dw_dma_chan {
 	/* hardware configuration */
 	unsigned int		block_size;
 	bool			nollp;
+	unsigned int		request_line;
+	struct dw_dma_slave	slave;
 
 	/* configuration passed via DMA_SLAVE_CONFIG */
 	struct dma_slave_config dma_sconfig;
@@ -239,10 +242,6 @@ struct dw_dma {
 	struct tasklet_struct	tasklet;
 	struct clk		*clk;
 
-	/* slave information */
-	struct dw_dma_slave	*sd;
-	unsigned int		sd_count;
-
 	u8			all_chan_mask;
 
 	/* hardware configuration */

include/linux/dw_dmac.h

@@ -27,7 +27,6 @@
  */
 struct dw_dma_slave {
 	struct device		*dma_dev;
-	const char		*bus_id;
 	u32			cfg_hi;
 	u32			cfg_lo;
 	u8			src_master;
@@ -60,9 +59,6 @@ struct dw_dma_platform_data {
 	unsigned short	block_size;
 	unsigned char	nr_masters;
 	unsigned char	data_width[4];
-
-	struct dw_dma_slave *sd;
-	unsigned int sd_count;
 };
 
 /* bursts size */
@@ -114,6 +110,5 @@ void dw_dma_cyclic_stop(struct dma_chan *chan);
 dma_addr_t dw_dma_get_src_addr(struct dma_chan *chan);
 
 dma_addr_t dw_dma_get_dst_addr(struct dma_chan *chan);
-bool dw_dma_generic_filter(struct dma_chan *chan, void *param);
 
 #endif /* DW_DMAC_H */