pinctrl: exynos5440: add pinctrl driver for Samsung EXYNOS5440 SoC

Add a new pinctrl driver for Samsung EXYNOS5440 SoC. The pin controller
module in EXYNOS5440 is different from the pin controller found on other
Samsung SoC. Hence, the pin controller driver for EXYNOS5440 SoC is
independent of the Samsung pinctrl framework.

Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

3 files changed, 925 insertions, 0 deletions

diff --git a/drivers/pinctrl/Kconfig b/drivers/pinctrl/Kconfig
index d96caefd..dd08b49 100644
--- a/drivers/pinctrl/Kconfig
+++ b/drivers/pinctrl/Kconfig
@@ -188,6 +188,11 @@ config PINCTRL_EXYNOS4
 	depends on OF && GPIOLIB
 	select PINCTRL_SAMSUNG
 
+config PINCTRL_EXYNOS5440
+	bool "Samsung EXYNOS5440 SoC pinctrl driver"
+	select PINMUX
+	select PINCONF
+
 config PINCTRL_MVEBU
 	bool
 	depends on ARCH_MVEBU
diff --git a/drivers/pinctrl/Makefile b/drivers/pinctrl/Makefile
index f395ba5..476928b 100644
--- a/drivers/pinctrl/Makefile
+++ b/drivers/pinctrl/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_PINCTRL_U300)	+= pinctrl-u300.o
 obj-$(CONFIG_PINCTRL_COH901)	+= pinctrl-coh901.o
 obj-$(CONFIG_PINCTRL_SAMSUNG)	+= pinctrl-samsung.o
 obj-$(CONFIG_PINCTRL_EXYNOS4)	+= pinctrl-exynos.o
+obj-$(CONFIG_PINCTRL_EXYNOS5440)	+= pinctrl-exynos5440.o
 obj-$(CONFIG_PINCTRL_MVEBU)	+= pinctrl-mvebu.o
 obj-$(CONFIG_PINCTRL_DOVE)	+= pinctrl-dove.o
 obj-$(CONFIG_PINCTRL_KIRKWOOD)	+= pinctrl-kirkwood.o
diff --git a/drivers/pinctrl/pinctrl-exynos5440.c b/drivers/pinctrl/pinctrl-exynos5440.c
new file mode 100644
index 0000000..b8635f6
--- /dev/null
+++ b/drivers/pinctrl/pinctrl-exynos5440.c
@@ -0,0 +1,919 @@
+/*
+ * pin-controller/pin-mux/pin-config/gpio-driver for Samsung's EXYNOS5440 SoC.
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *		http://www.samsung.com
+ *
+ * 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/module.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/device.h>
+#include <linux/pinctrl/pinctrl.h>
+#include <linux/pinctrl/pinmux.h>
+#include <linux/pinctrl/pinconf.h>
+#include "core.h"
+
+/* EXYNOS5440 GPIO and Pinctrl register offsets */
+#define GPIO_MUX		0x00
+#define GPIO_IE			0x04
+#define GPIO_INT		0x08
+#define GPIO_TYPE		0x0C
+#define GPIO_VAL		0x10
+#define GPIO_OE			0x14
+#define GPIO_IN			0x18
+#define GPIO_PE			0x1C
+#define GPIO_PS			0x20
+#define GPIO_SR			0x24
+#define GPIO_DS0		0x28
+#define GPIO_DS1		0x2C
+
+#define EXYNOS5440_MAX_PINS		23
+#define PIN_NAME_LENGTH		10
+
+#define GROUP_SUFFIX		"-grp"
+#define GSUFFIX_LEN		sizeof(GROUP_SUFFIX)
+#define FUNCTION_SUFFIX		"-mux"
+#define FSUFFIX_LEN		sizeof(FUNCTION_SUFFIX)
+
+/*
+ * pin configuration type and its value are packed together into a 16-bits.
+ * The upper 8-bits represent the configuration type and the lower 8-bits
+ * hold the value of the configuration type.
+ */
+#define PINCFG_TYPE_MASK		0xFF
+#define PINCFG_VALUE_SHIFT		8
+#define PINCFG_VALUE_MASK		(0xFF << PINCFG_VALUE_SHIFT)
+#define PINCFG_PACK(type, value)	(((value) << PINCFG_VALUE_SHIFT) | type)
+#define PINCFG_UNPACK_TYPE(cfg)		((cfg) & PINCFG_TYPE_MASK)
+#define PINCFG_UNPACK_VALUE(cfg)	(((cfg) & PINCFG_VALUE_MASK) >> \
+						PINCFG_VALUE_SHIFT)
+
+/**
+ * enum pincfg_type - possible pin configuration types supported.
+ * @PINCFG_TYPE_PUD: Pull up/down configuration.
+ * @PINCFG_TYPE_DRV: Drive strength configuration.
+ * @PINCFG_TYPE_SKEW_RATE: Skew rate configuration.
+ * @PINCFG_TYPE_INPUT_TYPE: Pin input type configuration.
+ */
+enum pincfg_type {
+	PINCFG_TYPE_PUD,
+	PINCFG_TYPE_DRV,
+	PINCFG_TYPE_SKEW_RATE,
+	PINCFG_TYPE_INPUT_TYPE
+};
+
+/**
+ * struct exynos5440_pin_group: represent group of pins for pincfg setting.
+ * @name: name of the pin group, used to lookup the group.
+ * @pins: the pins included in this group.
+ * @num_pins: number of pins included in this group.
+ */
+struct exynos5440_pin_group {
+	const char		*name;
+	const unsigned int	*pins;
+	u8			num_pins;
+};
+
+/**
+ * struct exynos5440_pmx_func: represent a pin function.
+ * @name: name of the pin function, used to lookup the function.
+ * @groups: one or more names of pin groups that provide this function.
+ * @num_groups: number of groups included in @groups.
+ * @function: the function number to be programmed when selected.
+ */
+struct exynos5440_pmx_func {
+	const char		*name;
+	const char		**groups;
+	u8			num_groups;
+	unsigned long		function;
+};
+
+/**
+ * struct exynos5440_pinctrl_priv_data: driver's private runtime data.
+ * @reg_base: ioremapped based address of the register space.
+ * @gc: gpio chip registered with gpiolib.
+ * @pin_groups: list of pin groups parsed from device tree.
+ * @nr_groups: number of pin groups available.
+ * @pmx_functions: list of pin functions parsed from device tree.
+ * @nr_functions: number of pin functions available.
+ */
+struct exynos5440_pinctrl_priv_data {
+	void __iomem			*reg_base;
+	struct gpio_chip		*gc;
+
+	const struct exynos5440_pin_group	*pin_groups;
+	unsigned int			nr_groups;
+	const struct exynos5440_pmx_func	*pmx_functions;
+	unsigned int			nr_functions;
+};
+
+/* list of all possible config options supported */
+struct pin_config {
+	char		*prop_cfg;
+	unsigned int	cfg_type;
+} pcfgs[] = {
+	{ "samsung,exynos5440-pin-pud", PINCFG_TYPE_PUD },
+	{ "samsung,exynos5440-pin-drv", PINCFG_TYPE_DRV },
+	{ "samsung,exynos5440-pin-skew-rate", PINCFG_TYPE_SKEW_RATE },
+	{ "samsung,exynos5440-pin-input-type", PINCFG_TYPE_INPUT_TYPE },
+};
+
+/* check if the selector is a valid pin group selector */
+static int exynos5440_get_group_count(struct pinctrl_dev *pctldev)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	return priv->nr_groups;
+}
+
+/* return the name of the group selected by the group selector */
+static const char *exynos5440_get_group_name(struct pinctrl_dev *pctldev,
+						unsigned selector)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	return priv->pin_groups[selector].name;
+}
+
+/* return the pin numbers associated with the specified group */
+static int exynos5440_get_group_pins(struct pinctrl_dev *pctldev,
+		unsigned selector, const unsigned **pins, unsigned *num_pins)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	*pins = priv->pin_groups[selector].pins;
+	*num_pins = priv->pin_groups[selector].num_pins;
+	return 0;
+}
+
+/* create pinctrl_map entries by parsing device tree nodes */
+static int exynos5440_dt_node_to_map(struct pinctrl_dev *pctldev,
+			struct device_node *np, struct pinctrl_map **maps,
+			unsigned *nmaps)
+{
+	struct device *dev = pctldev->dev;
+	struct pinctrl_map *map;
+	unsigned long *cfg = NULL;
+	char *gname, *fname;
+	int cfg_cnt = 0, map_cnt = 0, idx = 0;
+
+	/* count the number of config options specfied in the node */
+	for (idx = 0; idx < ARRAY_SIZE(pcfgs); idx++)
+		if (of_find_property(np, pcfgs[idx].prop_cfg, NULL))
+			cfg_cnt++;
+
+	/*
+	 * Find out the number of map entries to create. All the config options
+	 * can be accomadated into a single config map entry.
+	 */
+	if (cfg_cnt)
+		map_cnt = 1;
+	if (of_find_property(np, "samsung,exynos5440-pin-function", NULL))
+		map_cnt++;
+	if (!map_cnt) {
+		dev_err(dev, "node %s does not have either config or function "
+				"configurations\n", np->name);
+		return -EINVAL;
+	}
+
+	/* Allocate memory for pin-map entries */
+	map = kzalloc(sizeof(*map) * map_cnt, GFP_KERNEL);
+	if (!map) {
+		dev_err(dev, "could not alloc memory for pin-maps\n");
+		return -ENOMEM;
+	}
+	*nmaps = 0;
+
+	/*
+	 * Allocate memory for pin group name. The pin group name is derived
+	 * from the node name from which these map entries are be created.
+	 */
+	gname = kzalloc(strlen(np->name) + GSUFFIX_LEN, GFP_KERNEL);
+	if (!gname) {
+		dev_err(dev, "failed to alloc memory for group name\n");
+		goto free_map;
+	}
+	sprintf(gname, "%s%s", np->name, GROUP_SUFFIX);
+
+	/*
+	 * don't have config options? then skip over to creating function
+	 * map entries.
+	 */
+	if (!cfg_cnt)
+		goto skip_cfgs;
+
+	/* Allocate memory for config entries */
+	cfg = kzalloc(sizeof(*cfg) * cfg_cnt, GFP_KERNEL);
+	if (!cfg) {
+		dev_err(dev, "failed to alloc memory for configs\n");
+		goto free_gname;
+	}
+
+	/* Prepare a list of config settings */
+	for (idx = 0, cfg_cnt = 0; idx < ARRAY_SIZE(pcfgs); idx++) {
+		u32 value;
+		if (!of_property_read_u32(np, pcfgs[idx].prop_cfg, &value))
+			cfg[cfg_cnt++] =
+				PINCFG_PACK(pcfgs[idx].cfg_type, value);
+	}
+
+	/* create the config map entry */
+	map[*nmaps].data.configs.group_or_pin = gname;
+	map[*nmaps].data.configs.configs = cfg;
+	map[*nmaps].data.configs.num_configs = cfg_cnt;
+	map[*nmaps].type = PIN_MAP_TYPE_CONFIGS_GROUP;
+	*nmaps += 1;
+
+skip_cfgs:
+	/* create the function map entry */
+	if (of_find_property(np, "samsung,exynos5440-pin-function", NULL)) {
+		fname = kzalloc(strlen(np->name) + FSUFFIX_LEN,	GFP_KERNEL);
+		if (!fname) {
+			dev_err(dev, "failed to alloc memory for func name\n");
+			goto free_cfg;
+		}
+		sprintf(fname, "%s%s", np->name, FUNCTION_SUFFIX);
+
+		map[*nmaps].data.mux.group = gname;
+		map[*nmaps].data.mux.function = fname;
+		map[*nmaps].type = PIN_MAP_TYPE_MUX_GROUP;
+		*nmaps += 1;
+	}
+
+	*maps = map;
+	return 0;
+
+free_cfg:
+	kfree(cfg);
+free_gname:
+	kfree(gname);
+free_map:
+	kfree(map);
+	return -ENOMEM;
+}
+
+/* free the memory allocated to hold the pin-map table */
+static void exynos5440_dt_free_map(struct pinctrl_dev *pctldev,
+			     struct pinctrl_map *map, unsigned num_maps)
+{
+	int idx;
+
+	for (idx = 0; idx < num_maps; idx++) {
+		if (map[idx].type == PIN_MAP_TYPE_MUX_GROUP) {
+			kfree(map[idx].data.mux.function);
+			if (!idx)
+				kfree(map[idx].data.mux.group);
+		} else if (map->type == PIN_MAP_TYPE_CONFIGS_GROUP) {
+			kfree(map[idx].data.configs.configs);
+			if (!idx)
+				kfree(map[idx].data.configs.group_or_pin);
+		}
+	};
+
+	kfree(map);
+}
+
+/* list of pinctrl callbacks for the pinctrl core */
+static struct pinctrl_ops exynos5440_pctrl_ops = {
+	.get_groups_count	= exynos5440_get_group_count,
+	.get_group_name		= exynos5440_get_group_name,
+	.get_group_pins		= exynos5440_get_group_pins,
+	.dt_node_to_map		= exynos5440_dt_node_to_map,
+	.dt_free_map		= exynos5440_dt_free_map,
+};
+
+/* check if the selector is a valid pin function selector */
+static int exynos5440_get_functions_count(struct pinctrl_dev *pctldev)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	return priv->nr_functions;
+}
+
+/* return the name of the pin function specified */
+static const char *exynos5440_pinmux_get_fname(struct pinctrl_dev *pctldev,
+						unsigned selector)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	return priv->pmx_functions[selector].name;
+}
+
+/* return the groups associated for the specified function selector */
+static int exynos5440_pinmux_get_groups(struct pinctrl_dev *pctldev,
+		unsigned selector, const char * const **groups,
+		unsigned * const num_groups)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	*groups = priv->pmx_functions[selector].groups;
+	*num_groups = priv->pmx_functions[selector].num_groups;
+	return 0;
+}
+
+/* enable or disable a pinmux function */
+static void exynos5440_pinmux_setup(struct pinctrl_dev *pctldev, unsigned selector,
+					unsigned group, bool enable)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+	void __iomem *base;
+	u32 function;
+	u32 data;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	base = priv->reg_base;
+	function = priv->pmx_functions[selector].function;
+
+	data = readl(base + GPIO_MUX);
+	if (enable)
+		data |= (1 << function);
+	else
+		data &= ~(1 << function);
+	writel(data, base + GPIO_MUX);
+}
+
+/* enable a specified pinmux by writing to registers */
+static int exynos5440_pinmux_enable(struct pinctrl_dev *pctldev, unsigned selector,
+					unsigned group)
+{
+	exynos5440_pinmux_setup(pctldev, selector, group, true);
+	return 0;
+}
+
+/* disable a specified pinmux by writing to registers */
+static void exynos5440_pinmux_disable(struct pinctrl_dev *pctldev,
+					unsigned selector, unsigned group)
+{
+	exynos5440_pinmux_setup(pctldev, selector, group, false);
+}
+
+/*
+ * The calls to gpio_direction_output() and gpio_direction_input()
+ * leads to this function call (via the pinctrl_gpio_direction_{input|output}()
+ * function called from the gpiolib interface).
+ */
+static int exynos5440_pinmux_gpio_set_direction(struct pinctrl_dev *pctldev,
+		struct pinctrl_gpio_range *range, unsigned offset, bool input)
+{
+	return 0;
+}
+
+/* list of pinmux callbacks for the pinmux vertical in pinctrl core */
+static struct pinmux_ops exynos5440_pinmux_ops = {
+	.get_functions_count	= exynos5440_get_functions_count,
+	.get_function_name	= exynos5440_pinmux_get_fname,
+	.get_function_groups	= exynos5440_pinmux_get_groups,
+	.enable			= exynos5440_pinmux_enable,
+	.disable		= exynos5440_pinmux_disable,
+	.gpio_set_direction	= exynos5440_pinmux_gpio_set_direction,
+};
+
+/* set the pin config settings for a specified pin */
+static int exynos5440_pinconf_set(struct pinctrl_dev *pctldev, unsigned int pin,
+				unsigned long config)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+	void __iomem *base;
+	enum pincfg_type cfg_type = PINCFG_UNPACK_TYPE(config);
+	u32 cfg_value = PINCFG_UNPACK_VALUE(config);
+	u32 data;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	base = priv->reg_base;
+
+	switch (cfg_type) {
+	case PINCFG_TYPE_PUD:
+		/* first set pull enable/disable bit */
+		data = readl(base + GPIO_PE);
+		data &= ~(1 << pin);
+		if (cfg_value)
+			data |= (1 << pin);
+		writel(data, base + GPIO_PE);
+
+		/* then set pull up/down bit */
+		data = readl(base + GPIO_PS);
+		data &= ~(1 << pin);
+		if (cfg_value == 2)
+			data |= (1 << pin);
+		writel(data, base + GPIO_PS);
+		break;
+
+	case PINCFG_TYPE_DRV:
+		/* set the first bit of the drive strength */
+		data = readl(base + GPIO_DS0);
+		data &= ~(1 << pin);
+		data |= ((cfg_value & 1) << pin);
+		writel(data, base + GPIO_DS0);
+		cfg_value >>= 1;
+
+		/* set the second bit of the driver strength */
+		data = readl(base + GPIO_DS1);
+		data &= ~(1 << pin);
+		data |= ((cfg_value & 1) << pin);
+		writel(data, base + GPIO_DS1);
+		break;
+	case PINCFG_TYPE_SKEW_RATE:
+		data = readl(base + GPIO_SR);
+		data &= ~(1 << pin);
+		data |= ((cfg_value & 1) << pin);
+		writel(data, base + GPIO_SR);
+		break;
+	case PINCFG_TYPE_INPUT_TYPE:
+		data = readl(base + GPIO_TYPE);
+		data &= ~(1 << pin);
+		data |= ((cfg_value & 1) << pin);
+		writel(data, base + GPIO_TYPE);
+		break;
+	default:
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* get the pin config settings for a specified pin */
+static int exynos5440_pinconf_get(struct pinctrl_dev *pctldev, unsigned int pin,
+					unsigned long *config)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+	void __iomem *base;
+	enum pincfg_type cfg_type = PINCFG_UNPACK_TYPE(*config);
+	u32 data;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	base = priv->reg_base;
+
+	switch (cfg_type) {
+	case PINCFG_TYPE_PUD:
+		data = readl(base + GPIO_PE);
+		data = (data >> pin) & 1;
+		if (!data)
+			*config = 0;
+		else
+			*config = ((readl(base + GPIO_PS) >> pin) & 1) + 1;
+		break;
+	case PINCFG_TYPE_DRV:
+		data = readl(base + GPIO_DS0);
+		data = (data >> pin) & 1;
+		*config = data;
+		data = readl(base + GPIO_DS1);
+		data = (data >> pin) & 1;
+		*config |= (data << 1);
+		break;
+	case PINCFG_TYPE_SKEW_RATE:
+		data = readl(base + GPIO_SR);
+		*config = (data >> pin) & 1;
+		break;
+	case PINCFG_TYPE_INPUT_TYPE:
+		data = readl(base + GPIO_TYPE);
+		*config = (data >> pin) & 1;
+		break;
+	default:
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* set the pin config settings for a specified pin group */
+static int exynos5440_pinconf_group_set(struct pinctrl_dev *pctldev,
+			unsigned group, unsigned long config)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+	const unsigned int *pins;
+	unsigned int cnt;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	pins = priv->pin_groups[group].pins;
+
+	for (cnt = 0; cnt < priv->pin_groups[group].num_pins; cnt++)
+		exynos5440_pinconf_set(pctldev, pins[cnt], config);
+
+	return 0;
+}
+
+/* get the pin config settings for a specified pin group */
+static int exynos5440_pinconf_group_get(struct pinctrl_dev *pctldev,
+				unsigned int group, unsigned long *config)
+{
+	struct exynos5440_pinctrl_priv_data *priv;
+	const unsigned int *pins;
+
+	priv = pinctrl_dev_get_drvdata(pctldev);
+	pins = priv->pin_groups[group].pins;
+	exynos5440_pinconf_get(pctldev, pins[0], config);
+	return 0;
+}
+
+/* list of pinconfig callbacks for pinconfig vertical in the pinctrl code */
+static struct pinconf_ops exynos5440_pinconf_ops = {
+	.pin_config_get		= exynos5440_pinconf_get,
+	.pin_config_set		= exynos5440_pinconf_set,
+	.pin_config_group_get	= exynos5440_pinconf_group_get,
+	.pin_config_group_set	= exynos5440_pinconf_group_set,
+};
+
+/* gpiolib gpio_set callback function */
+static void exynos5440_gpio_set(struct gpio_chip *gc, unsigned offset, int value)
+{
+	struct exynos5440_pinctrl_priv_data *priv = dev_get_drvdata(gc->dev);
+	void __iomem *base = priv->reg_base;
+	u32 data;
+
+	data = readl(base + GPIO_VAL);
+	data &= ~(1 << offset);
+	if (value)
+		data |= 1 << offset;
+	writel(data, base + GPIO_VAL);
+}
+
+/* gpiolib gpio_get callback function */
+static int exynos5440_gpio_get(struct gpio_chip *gc, unsigned offset)
+{
+	struct exynos5440_pinctrl_priv_data *priv = dev_get_drvdata(gc->dev);
+	void __iomem *base = priv->reg_base;
+	u32 data;
+
+	data = readl(base + GPIO_IN);
+	data >>= offset;
+	data &= 1;
+	return data;
+}
+
+/* gpiolib gpio_direction_input callback function */
+static int exynos5440_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
+{
+	struct exynos5440_pinctrl_priv_data *priv = dev_get_drvdata(gc->dev);
+	void __iomem *base = priv->reg_base;
+	u32 data;
+
+	/* first disable the data output enable on this pin */
+	data = readl(base + GPIO_OE);
+	data &= ~(1 << offset);
+	writel(data, base + GPIO_OE);
+
+	/* now enable input on this pin */
+	data =  readl(base + GPIO_IE);
+	data |= 1 << offset;
+	writel(data, base + GPIO_IE);
+	return 0;
+}
+
+/* gpiolib gpio_direction_output callback function */
+static int exynos5440_gpio_direction_output(struct gpio_chip *gc, unsigned offset,
+							int value)
+{
+	struct exynos5440_pinctrl_priv_data *priv = dev_get_drvdata(gc->dev);
+	void __iomem *base = priv->reg_base;
+	u32 data;
+
+	exynos5440_gpio_set(gc, offset, value);
+
+	/* first disable the data input enable on this pin */
+	data = readl(base + GPIO_IE);
+	data &= ~(1 << offset);
+	writel(data, base + GPIO_IE);
+
+	/* now enable output on this pin */
+	data =  readl(base + GPIO_OE);
+	data |= 1 << offset;
+	writel(data, base + GPIO_OE);
+	return 0;
+}
+
+/* parse the pin numbers listed in the 'samsung,exynos5440-pins' property */
+static int __init exynos5440_pinctrl_parse_dt_pins(struct platform_device *pdev,
+			struct device_node *cfg_np, unsigned int **pin_list,
+			unsigned int *npins)
+{
+	struct device *dev = &pdev->dev;
+	struct property *prop;
+
+	prop = of_find_property(cfg_np, "samsung,exynos5440-pins", NULL);
+	if (!prop)
+		return -ENOENT;
+
+	*npins = prop->length / sizeof(unsigned long);
+	if (!*npins) {
+		dev_err(dev, "invalid pin list in %s node", cfg_np->name);
+		return -EINVAL;
+	}
+
+	*pin_list = devm_kzalloc(dev, *npins * sizeof(**pin_list), GFP_KERNEL);
+	if (!*pin_list) {
+		dev_err(dev, "failed to allocate memory for pin list\n");
+		return -ENOMEM;
+	}
+
+	return of_property_read_u32_array(cfg_np, "samsung,exynos5440-pins",
+			*pin_list, *npins);
+}
+
+/*
+ * Parse the information about all the available pin groups and pin functions
+ * from device node of the pin-controller.
+ */
+static int __init exynos5440_pinctrl_parse_dt(struct platform_device *pdev,
+				struct exynos5440_pinctrl_priv_data *priv)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *dev_np = dev->of_node;
+	struct device_node *cfg_np;
+	struct exynos5440_pin_group *groups, *grp;
+	struct exynos5440_pmx_func *functions, *func;
+	unsigned *pin_list;
+	unsigned int npins, grp_cnt, func_idx = 0;
+	char *gname, *fname;
+	int ret;
+
+	grp_cnt = of_get_child_count(dev_np);
+	if (!grp_cnt)
+		return -EINVAL;
+
+	groups = devm_kzalloc(dev, grp_cnt * sizeof(*groups), GFP_KERNEL);
+	if (!groups) {
+		dev_err(dev, "failed allocate memory for ping group list\n");
+		return -EINVAL;
+	}
+	grp = groups;
+
+	functions = devm_kzalloc(dev, grp_cnt * sizeof(*functions), GFP_KERNEL);
+	if (!functions) {
+		dev_err(dev, "failed to allocate memory for function list\n");
+		return -EINVAL;
+	}
+	func = functions;
+
+	/*
+	 * Iterate over all the child nodes of the pin controller node
+	 * and create pin groups and pin function lists.
+	 */
+	for_each_child_of_node(dev_np, cfg_np) {
+		u32 function;
+
+		ret = exynos5440_pinctrl_parse_dt_pins(pdev, cfg_np,
+					&pin_list, &npins);
+		if (ret)
+			return ret;
+
+		/* derive pin group name from the node name */
+		gname = devm_kzalloc(dev, strlen(cfg_np->name) + GSUFFIX_LEN,
+					GFP_KERNEL);
+		if (!gname) {
+			dev_err(dev, "failed to alloc memory for group name\n");
+			return -ENOMEM;
+		}
+		sprintf(gname, "%s%s", cfg_np->name, GROUP_SUFFIX);
+
+		grp->name = gname;
+		grp->pins = pin_list;
+		grp->num_pins = npins;
+		grp++;
+
+		ret = of_property_read_u32(cfg_np, "samsung,exynos5440-pin-function",
+						&function);
+		if (ret)
+			continue;
+
+		/* derive function name from the node name */
+		fname = devm_kzalloc(dev, strlen(cfg_np->name) + FSUFFIX_LEN,
+					GFP_KERNEL);
+		if (!fname) {
+			dev_err(dev, "failed to alloc memory for func name\n");
+			return -ENOMEM;
+		}
+		sprintf(fname, "%s%s", cfg_np->name, FUNCTION_SUFFIX);
+
+		func->name = fname;
+		func->groups = devm_kzalloc(dev, sizeof(char *), GFP_KERNEL);
+		if (!func->groups) {
+			dev_err(dev, "failed to alloc memory for group list "
+					"in pin function");
+			return -ENOMEM;
+		}
+		func->groups[0] = gname;
+		func->num_groups = 1;
+		func->function = function;
+		func++;
+		func_idx++;
+	}
+
+	priv->pin_groups = groups;
+	priv->nr_groups = grp_cnt;
+	priv->pmx_functions = functions;
+	priv->nr_functions = func_idx;
+	return 0;
+}
+
+/* register the pinctrl interface with the pinctrl subsystem */
+static int __init exynos5440_pinctrl_register(struct platform_device *pdev,
+				struct exynos5440_pinctrl_priv_data *priv)
+{
+	struct device *dev = &pdev->dev;
+	struct pinctrl_desc *ctrldesc;
+	struct pinctrl_dev *pctl_dev;
+	struct pinctrl_pin_desc *pindesc, *pdesc;
+	struct pinctrl_gpio_range grange;
+	char *pin_names;
+	int pin, ret;
+
+	ctrldesc = devm_kzalloc(dev, sizeof(*ctrldesc), GFP_KERNEL);
+	if (!ctrldesc) {
+		dev_err(dev, "could not allocate memory for pinctrl desc\n");
+		return -ENOMEM;
+	}
+
+	ctrldesc->name = "exynos5440-pinctrl";
+	ctrldesc->owner = THIS_MODULE;
+	ctrldesc->pctlops = &exynos5440_pctrl_ops;
+	ctrldesc->pmxops = &exynos5440_pinmux_ops;
+	ctrldesc->confops = &exynos5440_pinconf_ops;
+
+	pindesc = devm_kzalloc(&pdev->dev, sizeof(*pindesc) *
+				EXYNOS5440_MAX_PINS, GFP_KERNEL);
+	if (!pindesc) {
+		dev_err(&pdev->dev, "mem alloc for pin descriptors failed\n");
+		return -ENOMEM;
+	}
+	ctrldesc->pins = pindesc;
+	ctrldesc->npins = EXYNOS5440_MAX_PINS;
+
+	/* dynamically populate the pin number and pin name for pindesc */
+	for (pin = 0, pdesc = pindesc; pin < ctrldesc->npins; pin++, pdesc++)
+		pdesc->number = pin;
+
+	/*
+	 * allocate space for storing the dynamically generated names for all
+	 * the pins which belong to this pin-controller.
+	 */
+	pin_names = devm_kzalloc(&pdev->dev, sizeof(char) * PIN_NAME_LENGTH *
+					ctrldesc->npins, GFP_KERNEL);
+	if (!pin_names) {
+		dev_err(&pdev->dev, "mem alloc for pin names failed\n");
+		return -ENOMEM;
+	}
+
+	/* for each pin, set the name of the pin */
+	for (pin = 0; pin < ctrldesc->npins; pin++) {
+		sprintf(pin_names, "gpio%02d", pin);
+		pdesc = pindesc + pin;
+		pdesc->name = pin_names;
+		pin_names += PIN_NAME_LENGTH;
+	}
+
+	ret = exynos5440_pinctrl_parse_dt(pdev, priv);
+	if (ret)
+		return ret;
+
+	pctl_dev = pinctrl_register(ctrldesc, &pdev->dev, priv);
+	if (!pctl_dev) {
+		dev_err(&pdev->dev, "could not register pinctrl driver\n");
+		return -EINVAL;
+	}
+
+	grange.name = "exynos5440-pctrl-gpio-range";
+	grange.id = 0;
+	grange.base = 0;
+	grange.npins = EXYNOS5440_MAX_PINS;
+	grange.gc = priv->gc;
+	pinctrl_add_gpio_range(pctl_dev, &grange);
+	return 0;
+}
+
+/* register the gpiolib interface with the gpiolib subsystem */
+static int __init exynos5440_gpiolib_register(struct platform_device *pdev,
+				struct exynos5440_pinctrl_priv_data *priv)
+{
+	struct gpio_chip *gc;
+	int ret;
+
+	gc = devm_kzalloc(&pdev->dev, sizeof(*gc), GFP_KERNEL);
+	if (!gc) {
+		dev_err(&pdev->dev, "mem alloc for gpio_chip failed\n");
+		return -ENOMEM;
+	}
+
+	priv->gc = gc;
+	gc->base = 0;
+	gc->ngpio = EXYNOS5440_MAX_PINS;
+	gc->dev = &pdev->dev;
+	gc->set = exynos5440_gpio_set;
+	gc->get = exynos5440_gpio_get;
+	gc->direction_input = exynos5440_gpio_direction_input;
+	gc->direction_output = exynos5440_gpio_direction_output;
+	gc->label = "gpiolib-exynos5440";
+	gc->owner = THIS_MODULE;
+	ret = gpiochip_add(gc);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register gpio_chip %s, error "
+					"code: %d\n", gc->label, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+/* unregister the gpiolib interface with the gpiolib subsystem */
+static int __init exynos5440_gpiolib_unregister(struct platform_device *pdev,
+				struct exynos5440_pinctrl_priv_data *priv)
+{
+	int ret = gpiochip_remove(priv->gc);
+	if (ret) {
+		dev_err(&pdev->dev, "gpio chip remove failed\n");
+		return ret;
+	}
+	return 0;
+}
+
+static int __devinit exynos5440_pinctrl_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct exynos5440_pinctrl_priv_data *priv;
+	struct resource *res;
+	int ret;
+
+	if (!dev->of_node) {
+		dev_err(dev, "device tree node not found\n");
+		return -ENODEV;
+	}
+
+	priv = devm_kzalloc(dev, sizeof(priv), GFP_KERNEL);
+	if (!priv) {
+		dev_err(dev, "could not allocate memory for private data\n");
+		return -ENOMEM;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "cannot find IO resource\n");
+		return -ENOENT;
+	}
+
+	priv->reg_base = devm_request_and_ioremap(&pdev->dev, res);
+	if (!priv->reg_base) {
+		dev_err(dev, "ioremap failed\n");
+		return -ENODEV;
+	}
+
+	ret = exynos5440_gpiolib_register(pdev, priv);
+	if (ret)
+		return ret;
+
+	ret = exynos5440_pinctrl_register(pdev, priv);
+	if (ret) {
+		exynos5440_gpiolib_unregister(pdev, priv);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, priv);
+	dev_info(dev, "EXYNOS5440 pinctrl driver registered\n");
+	return 0;
+}
+
+static const struct of_device_id exynos5440_pinctrl_dt_match[] = {
+	{ .compatible = "samsung,exynos5440-pinctrl" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, exynos5440_pinctrl_dt_match);
+
+static struct platform_driver exynos5440_pinctrl_driver = {
+	.probe		= exynos5440_pinctrl_probe,
+	.driver = {
+		.name	= "exynos5440-pinctrl",
+		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(exynos5440_pinctrl_dt_match),
+	},
+};
+
+static int __init exynos5440_pinctrl_drv_register(void)
+{
+	return platform_driver_register(&exynos5440_pinctrl_driver);
+}
+postcore_initcall(exynos5440_pinctrl_drv_register);
+
+static void __exit exynos5440_pinctrl_drv_unregister(void)
+{
+	platform_driver_unregister(&exynos5440_pinctrl_driver);
+}
+module_exit(exynos5440_pinctrl_drv_unregister);
+
+MODULE_AUTHOR("Thomas Abraham <thomas.ab@samsung.com>");
+MODULE_DESCRIPTION("Samsung EXYNOS5440 SoC pinctrl driver");
+MODULE_LICENSE("GPL v2");