basic_mmio_gpio: split into a gpio library and platform device

Allow GPIO_BASIC_MMIO_CORE to be used to provide an accessor library
for implementing GPIO drivers whilst abstracting the register access
detail.  Based on a patch from Anton Vorontsov[1] and adapted to allow
bgpio_chip to be embedded in another structure.

Changes since v1:
	- Register the gpio_chip in the platform device probe

1. https://lkml.org/lkml/2011/4/19/401Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/gpio/Kconfig

@@ -70,8 +70,14 @@ config GPIO_MAX730X
 
 comment "Memory mapped GPIO drivers:"
 
+config GPIO_BASIC_MMIO_CORE
+	tristate
+	help
+	  Provides core functionality for basic memory-mapped GPIO controllers.
+
 config GPIO_BASIC_MMIO
 	tristate "Basic memory-mapped GPIO controllers support"
+	select GPIO_BASIC_MMIO_CORE
 	help
 	  Say yes here to support basic memory-mapped GPIO controllers.
 

drivers/gpio/Makefile

@@ -6,6 +6,7 @@ obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
 
 obj-$(CONFIG_GPIO_ADP5520)	+= adp5520-gpio.o
 obj-$(CONFIG_GPIO_ADP5588)	+= adp5588-gpio.o
+obj-$(CONFIG_GPIO_BASIC_MMIO_CORE)	+= basic_mmio_gpio.o
 obj-$(CONFIG_GPIO_BASIC_MMIO)	+= basic_mmio_gpio.o
 obj-$(CONFIG_GPIO_LANGWELL)	+= langwell_gpio.o
 obj-$(CONFIG_GPIO_MAX730X)	+= max730x.o

include/linux/basic_mmio_gpio.h

@@ -13,9 +13,64 @@
 #ifndef __BASIC_MMIO_GPIO_H
 #define __BASIC_MMIO_GPIO_H
 
+#include <linux/gpio.h>
+#include <linux/types.h>
+#include <linux/compiler.h>
+
 struct bgpio_pdata {
 	int base;
 	int ngpio;
 };
 
+struct device;
+
+struct bgpio_chip {
+	struct gpio_chip gc;
+
+	unsigned long (*read_reg)(void __iomem *reg);
+	void (*write_reg)(void __iomem *reg, unsigned long data);
+
+	void __iomem *reg_dat;
+	void __iomem *reg_set;
+	void __iomem *reg_clr;
+	void __iomem *reg_dir;
+
+	/* Number of bits (GPIOs): <register width> * 8. */
+	int bits;
+
+	/*
+	 * Some GPIO controllers work with the big-endian bits notation,
+	 * e.g. in a 8-bits register, GPIO7 is the least significant bit.
+	 */
+	unsigned long (*pin2mask)(struct bgpio_chip *bgc, unsigned int pin);
+
+	/*
+	 * Used to lock bgpio_chip->data. Also, this is needed to keep
+	 * shadowed and real data registers writes together.
+	 */
+	spinlock_t lock;
+
+	/* Shadowed data register to clear/set bits safely. */
+	unsigned long data;
+
+	/* Shadowed direction registers to clear/set direction safely. */
+	unsigned long dir;
+};
+
+static inline struct bgpio_chip *to_bgpio_chip(struct gpio_chip *gc)
+{
+	return container_of(gc, struct bgpio_chip, gc);
+}
+
+int __devexit bgpio_remove(struct bgpio_chip *bgc);
+int __devinit bgpio_init(struct bgpio_chip *bgc,
+			 struct device *dev,
+			 unsigned long sz,
+			 void __iomem *dat,
+			 void __iomem *set,
+			 void __iomem *clr,
+			 void __iomem *dirout,
+			 void __iomem *dirin,
+			 bool big_endian);
+
 #endif /* __BASIC_MMIO_GPIO_H */