mfd: Versatile Express system registers driver

This is a platform driver for Versatile Express' "system
register" block. It's a random collection of registers providing
the following functionality:

- low level platform functions like board ID access; in order to
  use those, the driver must be initialized early, either statically
  or based on the DT

- config bus bridge via "system control" interface; as the response
  from the controller does not generate interrupt (yet), the status
  register is periodically polled using a timer

- pseudo GPIO lines providing MMC card status and Flash WP#
  signal control

- LED interface for a set of 8 LEDs on the motherboard, with
  "heartbeat", "mmc0" and "cpu0" to "cpu5" as default triggers
Signed-off-by: Pawel Moll <pawel.moll@arm.com>

Documentation/devicetree/bindings/arm/vexpress-sysreg.txt

+ARM Versatile Express system registers
+--------------------------------------
+
+This is a system control registers block, providing multiple low level
+platform functions like board detection and identification, software
+interrupt generation, MMC and NOR Flash control etc.
+
+Required node properties:
+- compatible value : = "arm,vexpress,sysreg";
+- reg : physical base address and the size of the registers window
+- gpio-controller : specifies that the node is a GPIO controller
+- #gpio-cells : size of the GPIO specifier, should be 2:
+  - first cell is the pseudo-GPIO line number:
+    0 - MMC CARDIN
+    1 - MMC WPROT
+    2 - NOR FLASH WPn
+  - second cell can take standard GPIO flags (currently ignored).
+
+Example:
+	v2m_sysreg: sysreg@10000000 {
+ 		compatible = "arm,vexpress-sysreg";
+ 		reg = <0x10000000 0x1000>;
+		gpio-controller;
+		#gpio-cells = <2>;
+ 	};
+
+This block also can also act a bridge to the platform's configuration
+bus via "system control" interface, addressing devices with site number,
+position in the board stack, config controller, function and device
+numbers - see motherboard's TRM for more details.
+
+The node describing a config device must refer to the sysreg node via
+"arm,vexpress,config-bridge" phandle (can be also defined in the node's
+parent) and relies on the board topology properties - see main vexpress
+node documentation for more details. It must must also define the
+following property:
+- arm,vexpress-sysreg,func : must contain two cells:
+  - first cell defines function number (eg. 1 for clock generator,
+    2 for voltage regulators etc.)
+  - device number (eg. osc 0, osc 1 etc.)
+
+Example:
+	mcc {
+		arm,vexpress,config-bridge = <&v2m_sysreg>;
+
+		osc@0 {
+			compatible = "arm,vexpress-osc";
+			arm,vexpress-sysreg,func = <1 0>;
+		};
+	};

drivers/mfd/Makefile

@@ -138,4 +138,4 @@ obj-$(CONFIG_MFD_RC5T583)	+= rc5t583.o rc5t583-irq.o
 obj-$(CONFIG_MFD_SEC_CORE)	+= sec-core.o sec-irq.o
 obj-$(CONFIG_MFD_SYSCON)	+= syscon.o
 obj-$(CONFIG_MFD_LM3533)	+= lm3533-core.o lm3533-ctrlbank.o
-obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
+obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o vexpress-sysreg.o

include/linux/vexpress.h

@@ -24,6 +24,17 @@
 #define VEXPRESS_CONFIG_STATUS_DONE	0
 #define VEXPRESS_CONFIG_STATUS_WAIT	1
 
+#define VEXPRESS_GPIO_MMC_CARDIN	0
+#define VEXPRESS_GPIO_MMC_WPROT		1
+#define VEXPRESS_GPIO_FLASH_WPn		2
+
+#define VEXPRESS_RES_FUNC(_site, _func)	\
+{					\
+	.start = (_site),		\
+	.end = (_func),			\
+	.flags = IORESOURCE_BUS,	\
+}
+
 /* Config bridge API */
 
 /**
@@ -82,4 +93,18 @@ int vexpress_config_read(struct vexpress_config_func *func, int offset,
 int vexpress_config_write(struct vexpress_config_func *func, int offset,
 		u32 data);
 
+/* Platform control */
+
+u32 vexpress_get_procid(int site);
+u32 vexpress_get_hbi(int site);
+void *vexpress_get_24mhz_clock_base(void);
+void vexpress_flags_set(u32 data);
+
+#define vexpress_get_site_by_node(node) __vexpress_get_site(NULL, node)
+#define vexpress_get_site_by_dev(dev) __vexpress_get_site(dev, NULL)
+unsigned __vexpress_get_site(struct device *dev, struct device_node *node);
+
+void vexpress_sysreg_early_init(void __iomem *base);
+void vexpress_sysreg_of_early_init(void);
+
 #endif