gpio: Driver for SYSCON-based GPIOs

diff --git a/Documentation/devicetree/bindings/gpio/gpio-syscon.txt b/Documentation/devicetree/bindings/gpio/gpio-syscon.txt
new file mode 100644
index 0000000..d8ecfe2
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-syscon.txt
@@ -0,0 +1,22 @@ 
+* SYSCON-based GPIO driver
+
+Required properties:
+- compatible: Should be "gpio-syscon".
+- syscon: Phandle to syscon device node.
+- gpio-controller: Marks the device node as a gpio controller.
+- #gpio-cells: Should be two. The first cell is the pin number and
+  the second cell is used to specify the gpio polarity:
+    0 = Active high,
+    1 = Active low.
+- bit-offset: Offset to the first bit used by driver.
+- bit-count: Number of bits used.
+
+Example:
+	sysgpio: sysgpio {
+		compatible = "gpio-syscon";
+		syscon = <&syscon>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		bit-offset = <4>;
+		bit-count = <1>;
+	};
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 365ea61..5eee6e7 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -259,6 +259,12 @@  config GPIO_STA2X11
 	  Say yes here to support the STA2x11/ConneXt GPIO device.
 	  The GPIO module has 128 GPIO pins with alternate functions.
 
+config GPIO_SYSCON
+	tristate "GPIO based on SYSCON"
+	depends on MFD_SYSCON && OF
+	help
+	  Say yes here to support GPIO functionality though SYSCON driver.
+
 config GPIO_TS5500
 	tristate "TS-5500 DIO blocks and compatibles"
 	help
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 95d7359..130bc76 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -75,6 +75,7 @@  obj-$(CONFIG_GPIO_STA2X11)	+= gpio-sta2x11.o
 obj-$(CONFIG_GPIO_STMPE)	+= gpio-stmpe.o
 obj-$(CONFIG_GPIO_STP_XWAY)	+= gpio-stp-xway.o
 obj-$(CONFIG_GPIO_SX150X)	+= gpio-sx150x.o
+obj-$(CONFIG_GPIO_SYSCON)	+= gpio-syscon.o
 obj-$(CONFIG_GPIO_TB10X)	+= gpio-tb10x.o
 obj-$(CONFIG_GPIO_TC3589X)	+= gpio-tc3589x.o
 obj-$(CONFIG_ARCH_TEGRA)	+= gpio-tegra.o
diff --git a/drivers/gpio/gpio-syscon.c b/drivers/gpio/gpio-syscon.c
new file mode 100644
index 0000000..2d02cc1
--- /dev/null
+++ b/drivers/gpio/gpio-syscon.c
@@ -0,0 +1,159 @@ 
+/*
+ *  SYSCON GPIO driver
+ *
+ *  Copyright (C) 2013 Alexander Shiyan <shc_work@mail.ru>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+
+#define GPIO_SYSCON_INPUT	(1 << 0)
+#define GPIO_SYSCON_OUTPUT	(1 << 1)
+
+/* SYSCON driver is designed to use 32-bit wide registers */
+#define SYSCON_REG_SIZE		(4)
+#define SYSCON_REG_BITS		(SYSCON_REG_SIZE * 8)
+
+struct syscon_gpio_priv {
+	struct gpio_chip	chip;
+	struct regmap		*syscon;
+	unsigned int		bit_offset;
+};
+
+static inline struct syscon_gpio_priv *to_syscon_gpio(struct gpio_chip *chip)
+{
+	return container_of(chip, struct syscon_gpio_priv, chip);
+}
+
+static int syscon_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
+	unsigned int val, offs = priv->bit_offset + offset;
+	int ret;
+
+	ret = regmap_read(priv->syscon,
+			  (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE, &val);
+	if (ret < 0)
+		return ret;
+
+	return !!(val & (offs % SYSCON_REG_BITS));
+}
+
+static void syscon_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
+{
+	struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
+	unsigned int offs = priv->bit_offset + offset;
+
+	regmap_update_bits(priv->syscon,
+			   (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE,
+			   offs % SYSCON_REG_BITS,
+			   val ? (offs % SYSCON_REG_BITS) : 0);
+}
+
+static int syscon_gpio_dir_in(struct gpio_chip *chip, unsigned offset)
+{
+	return 0;
+}
+
+static int syscon_gpio_dir_out(struct gpio_chip *chip, unsigned offset, int val)
+{
+	syscon_gpio_set(chip, offset, val);
+
+	return 0;
+}
+
+static const struct of_device_id syscon_gpio_ids[] = {
+	{
+		.compatible	= "gpio-syscon-input",
+		.data		= (void *)GPIO_SYSCON_INPUT,
+	},
+	{
+		.compatible	= "gpio-syscon-output",
+		.data		= (void *)GPIO_SYSCON_OUTPUT,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, syscon_gpio_ids);
+
+static int syscon_gpio_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *of_id =
+		of_match_device(syscon_gpio_ids, &pdev->dev);
+	struct device_node *np = pdev->dev.of_node;
+	struct syscon_gpio_priv *priv;
+	unsigned int flags;
+	u32 ngpio;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->syscon = syscon_regmap_lookup_by_phandle(np, "syscon");
+	if (IS_ERR(priv->syscon))
+		return PTR_ERR(priv->syscon);
+
+	ret = of_property_read_u32(np, "bit-offset", &priv->bit_offset);
+	if (ret)
+		return ret;
+
+	ret = of_property_read_u32(np, "bit-count", &ngpio);
+	if (ret)
+		return ret;
+
+	/* Sanity check */
+	if (ngpio < 1 || ngpio > (u16)-1)
+		return -EINVAL;
+
+	flags = (unsigned int)of_id->data;
+
+	priv->chip.owner = THIS_MODULE;
+	priv->chip.label = dev_name(&pdev->dev);
+	priv->chip.base = -1;
+	priv->chip.ngpio = ngpio;
+	if (flags & GPIO_SYSCON_INPUT) {
+		priv->chip.get = syscon_gpio_get;
+		priv->chip.direction_input = syscon_gpio_dir_in;
+	}
+	if (flags & GPIO_SYSCON_OUTPUT) {
+		priv->chip.set = syscon_gpio_set;
+		priv->chip.direction_output = syscon_gpio_dir_out;
+	}
+
+	platform_set_drvdata(pdev, priv);
+
+	return gpiochip_add(&priv->chip);
+}
+
+static int syscon_gpio_remove(struct platform_device *pdev)
+{
+	struct syscon_gpio_priv *priv = platform_get_drvdata(pdev);
+
+	return gpiochip_remove(&priv->chip);
+}
+
+static struct platform_driver syscon_gpio_driver = {
+	.driver	= {
+		.name		= "gpio-syscon",
+		.owner		= THIS_MODULE,
+		.of_match_table	= syscon_gpio_ids,
+	},
+	.probe	= syscon_gpio_probe,
+	.remove	= syscon_gpio_remove,
+};
+module_platform_driver(syscon_gpio_driver);
+
+MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
+MODULE_DESCRIPTION("SYSCON GPIO driver");
+MODULE_LICENSE("GPL");