sh: mach-sdk7786: Add support for fpga gpios.

The sdk7786 FPGA supports a number of user settable input switches that
are otherwise unused. This wires up a dummy gpio chip for the switch bank
to simply expose them to userspace.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/boards/Kconfig

@@ -155,6 +155,7 @@ config SH_SDK7786
 	depends on CPU_SUBTYPE_SH7786
 	select SYS_SUPPORTS_PCI
 	select NO_IOPORT if !PCI
+	select ARCH_WANT_OPTIONAL_GPIOLIB
 	help
 	  Select SDK7786 if configuring for a Renesas Technology Europe
 	  SH7786-65nm board.

arch/sh/boards/mach-sdk7786/Makefile

 obj-y	:= setup.o fpga.o irq.o
+
+obj-$(CONFIG_GENERIC_GPIO)	+= gpio.o

arch/sh/boards/mach-sdk7786/gpio.c

+/*
+ * SDK7786 FPGA USRGPIR Support.
+ *
+ * Copyright (C) 2010  Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/gpio.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/io.h>
+#include <mach/fpga.h>
+
+#define NR_FPGA_GPIOS	8
+
+static const char *usrgpir_gpio_names[NR_FPGA_GPIOS] = {
+	"in0", "in1", "in2", "in3", "in4", "in5", "in6", "in7",
+};
+
+static int usrgpir_gpio_direction_input(struct gpio_chip *chip, unsigned gpio)
+{
+	/* always in */
+	return 0;
+}
+
+static int usrgpir_gpio_get(struct gpio_chip *chip, unsigned gpio)
+{
+	return !!(fpga_read_reg(USRGPIR) & (1 << gpio));
+}
+
+static struct gpio_chip usrgpir_gpio_chip = {
+	.label			= "sdk7786-fpga",
+	.names			= usrgpir_gpio_names,
+	.direction_input	= usrgpir_gpio_direction_input,
+	.get			= usrgpir_gpio_get,
+	.base			= -1, /* don't care */
+	.ngpio			= NR_FPGA_GPIOS,
+};
+
+static int __init usrgpir_gpio_setup(void)
+{
+	return gpiochip_add(&usrgpir_gpio_chip);
+}
+device_initcall(usrgpir_gpio_setup);