pinctrl: nsp: add gpio-a driver support for Broadcom NSP SoC

This adds the initial support of the Broadcom NSP gpio-a driver.

Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yrdreddy@broadcom.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

3 files changed, 767 insertions, 0 deletions

diff --git a/drivers/pinctrl/bcm/Kconfig b/drivers/pinctrl/bcm/Kconfig
index cd11d4d9ad58..1a8c83720551 100644
--- a/drivers/pinctrl/bcm/Kconfig
+++ b/drivers/pinctrl/bcm/Kconfig
@@ -54,3 +54,20 @@ config PINCTRL_CYGNUS_MUX
 	  The Broadcom Cygnus IOMUX driver supports group based IOMUX
 	  configuration, with the exception that certain individual pins
 	  can be overrided to GPIO function
+
+config PINCTRL_NSP_GPIO
+	bool "Broadcom NSP GPIO (with PINCONF) driver"
+	depends on OF_GPIO && (ARCH_BCM_NSP || COMPILE_TEST)
+	select GPIOLIB_IRQCHIP
+	select PINCONF
+	select GENERIC_PINCONF
+	default ARCH_BCM_NSP
+	help
+	  Say yes here to enable the Broadcom NSP GPIO driver.
+
+	  The Broadcom Northstar Plus SoC ChipcommonA GPIO controller is
+	  supported by this driver.
+
+	  The ChipcommonA GPIO controller support basic PINCONF functions such
+	  as bias pull up, pull down, and drive strength configurations, when
+	  these pins are muxed to GPIO.
diff --git a/drivers/pinctrl/bcm/Makefile b/drivers/pinctrl/bcm/Makefile
index 2b2f70ee804c..2fb1ed85b737 100644
--- a/drivers/pinctrl/bcm/Makefile
+++ b/drivers/pinctrl/bcm/Makefile
@@ -4,3 +4,4 @@ obj-$(CONFIG_PINCTRL_BCM281XX)		+= pinctrl-bcm281xx.o
 obj-$(CONFIG_PINCTRL_BCM2835)		+= pinctrl-bcm2835.o
 obj-$(CONFIG_PINCTRL_CYGNUS_GPIO)	+= pinctrl-cygnus-gpio.o
 obj-$(CONFIG_PINCTRL_CYGNUS_MUX)	+= pinctrl-cygnus-mux.o
+obj-$(CONFIG_PINCTRL_NSP_GPIO)		+= pinctrl-nsp-gpio.o
diff --git a/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c
new file mode 100644
index 000000000000..06b7aaf3548c
--- /dev/null
+++ b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c
@@ -0,0 +1,749 @@
+/*
+ * Copyright (C) 2015 Broadcom Corporation
+ *
+ * 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 version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * This file contains the Broadcom Northstar Plus (NSP) GPIO driver that
+ * supports the chipCommonA GPIO controller. Basic PINCONF such as bias,
+ * pull up/down, slew and drive strength are also supported in this driver.
+ *
+ * Pins from the chipCommonA  GPIO can be individually muxed to GPIO function,
+ * through the interaction with the NSP IOMUX controller.
+ */
+
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/pinctrl/pinconf.h>
+#include <linux/pinctrl/pinconf-generic.h>
+#include <linux/pinctrl/pinctrl.h>
+#include <linux/slab.h>
+
+#include "../pinctrl-utils.h"
+
+#define NSP_CHIP_A_INT_STATUS		0x00
+#define NSP_CHIP_A_INT_MASK		0x04
+#define NSP_GPIO_DATA_IN		0x40
+#define NSP_GPIO_DATA_OUT		0x44
+#define NSP_GPIO_OUT_EN			0x48
+#define NSP_GPIO_INT_POLARITY		0x50
+#define NSP_GPIO_INT_MASK		0x54
+#define NSP_GPIO_EVENT			0x58
+#define NSP_GPIO_EVENT_INT_MASK		0x5c
+#define NSP_GPIO_EVENT_INT_POLARITY	0x64
+#define NSP_CHIP_A_GPIO_INT_BIT		0x01
+
+/* I/O parameters offset for chipcommon A GPIO */
+#define NSP_GPIO_DRV_CTRL		0x00
+#define NSP_GPIO_HYSTERESIS_EN		0x10
+#define NSP_GPIO_SLEW_RATE_EN		0x14
+#define NSP_PULL_UP_EN			0x18
+#define NSP_PULL_DOWN_EN		0x1c
+#define GPIO_DRV_STRENGTH_BITS		0x03
+
+/*
+ * nsp GPIO core
+ *
+ * @dev: pointer to device
+ * @base: I/O register base for nsp GPIO controller
+ * @io_ctrl: I/O register base for PINCONF support outside the GPIO block
+ * @gc: GPIO chip
+ * @pctl: pointer to pinctrl_dev
+ * @pctldesc: pinctrl descriptor
+ * @irq_domain: pointer to irq domain
+ * @lock: lock to protect access to I/O registers
+ */
+struct nsp_gpio {
+	struct device *dev;
+	void __iomem *base;
+	void __iomem *io_ctrl;
+	struct gpio_chip gc;
+	struct pinctrl_dev *pctl;
+	struct pinctrl_desc pctldesc;
+	struct irq_domain *irq_domain;
+	spinlock_t lock;
+};
+
+enum base_type {
+	REG,
+	IO_CTRL
+};
+
+static inline struct nsp_gpio *to_nsp_gpio(struct gpio_chip *gc)
+{
+	return container_of(gc, struct nsp_gpio, gc);
+}
+
+/*
+ * Mapping from PINCONF pins to GPIO pins is 1-to-1
+ */
+static inline unsigned nsp_pin_to_gpio(unsigned pin)
+{
+	return pin;
+}
+
+/*
+ *  nsp_set_bit - set or clear one bit (corresponding to the GPIO pin) in a
+ *  nsp GPIO register
+ *
+ *  @nsp_gpio: nsp GPIO device
+ *  @base_type: reg base to modify
+ *  @reg: register offset
+ *  @gpio: GPIO pin
+ *  @set: set or clear
+ */
+static inline void nsp_set_bit(struct nsp_gpio *chip, enum base_type address,
+			       unsigned int reg, unsigned gpio, bool set)
+{
+	u32 val;
+	void __iomem *base_address;
+
+	if (address == IO_CTRL)
+		base_address = chip->io_ctrl;
+	else
+		base_address = chip->base;
+
+	val = readl(base_address + reg);
+	if (set)
+		val |= BIT(gpio);
+	else
+		val &= ~BIT(gpio);
+
+	writel(val, base_address + reg);
+}
+
+/*
+ *  nsp_get_bit - get one bit (corresponding to the GPIO pin) in a
+ *  nsp GPIO register
+ */
+static inline bool nsp_get_bit(struct nsp_gpio *chip, enum base_type address,
+			       unsigned int reg, unsigned gpio)
+{
+	if (address == IO_CTRL)
+		return !!(readl(chip->io_ctrl + reg) & BIT(gpio));
+	else
+		return !!(readl(chip->base + reg) & BIT(gpio));
+}
+
+static irqreturn_t nsp_gpio_irq_handler(int irq, void *data)
+{
+	struct nsp_gpio *chip = (struct nsp_gpio *)data;
+	struct gpio_chip gc = chip->gc;
+	int bit;
+	unsigned long int_bits = 0;
+	u32 int_status;
+
+	/* go through the entire GPIOs and handle all interrupts */
+	int_status = readl(chip->base + NSP_CHIP_A_INT_STATUS);
+	if (int_status & NSP_CHIP_A_GPIO_INT_BIT) {
+		unsigned int event, level;
+
+		/* Get level and edge interrupts */
+		event = readl(chip->base + NSP_GPIO_EVENT_INT_MASK) &
+			      readl(chip->base + NSP_GPIO_EVENT);
+		level = readl(chip->base + NSP_GPIO_DATA_IN) ^
+			      readl(chip->base + NSP_GPIO_INT_POLARITY);
+		level &= readl(chip->base + NSP_GPIO_INT_MASK);
+		int_bits = level | event;
+
+		for_each_set_bit(bit, &int_bits, gc.ngpio) {
+			/*
+			 * Clear the interrupt before invoking the
+			 * handler, so we do not leave any window
+			 */
+			writel(BIT(bit), chip->base + NSP_GPIO_EVENT);
+			generic_handle_irq(
+				irq_linear_revmap(chip->irq_domain, bit));
+		}
+	}
+
+	return  int_bits ? IRQ_HANDLED : IRQ_NONE;
+}
+
+static void nsp_gpio_irq_ack(struct irq_data *d)
+{
+	struct nsp_gpio *chip = irq_data_get_irq_chip_data(d);
+	unsigned gpio = d->hwirq;
+	u32 val = BIT(gpio);
+	u32 trigger_type;
+
+	trigger_type = irq_get_trigger_type(d->irq);
+	if (trigger_type & (IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
+		nsp_set_bit(chip, REG, NSP_GPIO_EVENT, gpio, val);
+}
+
+/*
+ *  nsp_gpio_irq_set_mask - mask/unmask a GPIO interrupt
+ *
+ *  @d: IRQ chip data
+ *  @unmask: mask/unmask GPIO interrupt
+ */
+static void nsp_gpio_irq_set_mask(struct irq_data *d, bool unmask)
+{
+	struct nsp_gpio *chip = irq_data_get_irq_chip_data(d);
+	unsigned gpio = d->hwirq;
+	u32 trigger_type;
+
+	trigger_type = irq_get_trigger_type(d->irq);
+	if (trigger_type & (IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
+		nsp_set_bit(chip, REG, NSP_GPIO_EVENT_INT_MASK, gpio, unmask);
+	else
+		nsp_set_bit(chip, REG, NSP_GPIO_INT_MASK, gpio, unmask);
+}
+
+static void nsp_gpio_irq_mask(struct irq_data *d)
+{
+	struct nsp_gpio *chip = irq_data_get_irq_chip_data(d);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	nsp_gpio_irq_set_mask(d, false);
+	spin_unlock_irqrestore(&chip->lock, flags);
+}
+
+static void nsp_gpio_irq_unmask(struct irq_data *d)
+{
+	struct nsp_gpio *chip = irq_data_get_irq_chip_data(d);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	nsp_gpio_irq_set_mask(d, true);
+	spin_unlock_irqrestore(&chip->lock, flags);
+}
+
+static int nsp_gpio_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct nsp_gpio *chip = irq_data_get_irq_chip_data(d);
+	unsigned gpio = d->hwirq;
+	bool level_low;
+	bool falling;
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	falling = nsp_get_bit(chip, REG, NSP_GPIO_EVENT_INT_POLARITY, gpio);
+	level_low = nsp_get_bit(chip, REG, NSP_GPIO_INT_POLARITY, gpio);
+
+	switch (type & IRQ_TYPE_SENSE_MASK) {
+	case IRQ_TYPE_EDGE_RISING:
+		falling = false;
+		break;
+
+	case IRQ_TYPE_EDGE_FALLING:
+		falling = true;
+		break;
+
+	case IRQ_TYPE_LEVEL_HIGH:
+		level_low = false;
+		break;
+
+	case IRQ_TYPE_LEVEL_LOW:
+		level_low = true;
+		break;
+
+	default:
+		dev_err(chip->dev, "invalid GPIO IRQ type 0x%x\n",
+			type);
+		spin_unlock_irqrestore(&chip->lock, flags);
+		return -EINVAL;
+	}
+
+	nsp_set_bit(chip, REG, NSP_GPIO_EVENT_INT_POLARITY, gpio, falling);
+	nsp_set_bit(chip, REG, NSP_GPIO_INT_POLARITY, gpio, level_low);
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	dev_dbg(chip->dev, "gpio:%u level_low:%s falling:%s\n", gpio,
+		level_low ? "true" : "false", falling ? "true" : "false");
+	return 0;
+}
+
+static struct irq_chip nsp_gpio_irq_chip = {
+	.name = "gpio-a",
+	.irq_enable = nsp_gpio_irq_unmask,
+	.irq_disable = nsp_gpio_irq_mask,
+	.irq_ack = nsp_gpio_irq_ack,
+	.irq_mask = nsp_gpio_irq_mask,
+	.irq_unmask = nsp_gpio_irq_unmask,
+	.irq_set_type = nsp_gpio_irq_set_type,
+};
+
+/*
+ * Request the nsp IOMUX pinmux controller to mux individual pins to GPIO
+ */
+static int nsp_gpio_request(struct gpio_chip *gc, unsigned offset)
+{
+	unsigned gpio = gc->base + offset;
+
+	return pinctrl_request_gpio(gpio);
+}
+
+static void nsp_gpio_free(struct gpio_chip *gc, unsigned offset)
+{
+	unsigned gpio = gc->base + offset;
+
+	pinctrl_free_gpio(gpio);
+}
+
+static int nsp_gpio_direction_input(struct gpio_chip *gc, unsigned gpio)
+{
+	struct nsp_gpio *chip = to_nsp_gpio(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	nsp_set_bit(chip, REG, NSP_GPIO_OUT_EN, gpio, false);
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	dev_dbg(chip->dev, "gpio:%u set input\n", gpio);
+	return 0;
+}
+
+static int nsp_gpio_direction_output(struct gpio_chip *gc, unsigned gpio,
+				     int val)
+{
+	struct nsp_gpio *chip = to_nsp_gpio(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	nsp_set_bit(chip, REG, NSP_GPIO_OUT_EN, gpio, true);
+	nsp_set_bit(chip, REG, NSP_GPIO_DATA_OUT, gpio, !!(val));
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	dev_dbg(chip->dev, "gpio:%u set output, value:%d\n", gpio, val);
+	return 0;
+}
+
+static void nsp_gpio_set(struct gpio_chip *gc, unsigned gpio, int val)
+{
+	struct nsp_gpio *chip = to_nsp_gpio(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	nsp_set_bit(chip, REG, NSP_GPIO_DATA_OUT, gpio, !!(val));
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	dev_dbg(chip->dev, "gpio:%u set, value:%d\n", gpio, val);
+}
+
+static int nsp_gpio_get(struct gpio_chip *gc, unsigned gpio)
+{
+	struct nsp_gpio *chip = to_nsp_gpio(gc);
+
+	return !!(readl(chip->base + NSP_GPIO_DATA_IN) & BIT(gpio));
+}
+
+static int nsp_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
+{
+	struct nsp_gpio *chip = to_nsp_gpio(gc);
+
+	return irq_linear_revmap(chip->irq_domain, offset);
+}
+
+static int nsp_get_groups_count(struct pinctrl_dev *pctldev)
+{
+	return 1;
+}
+
+/*
+ * Only one group: "gpio_grp", since this local pinctrl device only performs
+ * GPIO specific PINCONF configurations
+ */
+static const char *nsp_get_group_name(struct pinctrl_dev *pctldev,
+				      unsigned selector)
+{
+	return "gpio_grp";
+}
+
+static const struct pinctrl_ops nsp_pctrl_ops = {
+	.get_groups_count = nsp_get_groups_count,
+	.get_group_name = nsp_get_group_name,
+	.dt_node_to_map = pinconf_generic_dt_node_to_map_pin,
+	.dt_free_map = pinctrl_utils_dt_free_map,
+};
+
+static int nsp_gpio_set_slew(struct nsp_gpio *chip, unsigned gpio, u16 slew)
+{
+	if (slew)
+		nsp_set_bit(chip, IO_CTRL, NSP_GPIO_SLEW_RATE_EN, gpio, true);
+	else
+		nsp_set_bit(chip, IO_CTRL, NSP_GPIO_SLEW_RATE_EN, gpio, false);
+
+	return 0;
+}
+
+static int nsp_gpio_set_pull(struct nsp_gpio *chip, unsigned gpio,
+			     bool pull_up, bool pull_down)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	nsp_set_bit(chip, IO_CTRL, NSP_PULL_DOWN_EN, gpio, pull_down);
+	nsp_set_bit(chip, IO_CTRL, NSP_PULL_UP_EN, gpio, pull_up);
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	dev_dbg(chip->dev, "gpio:%u set pullup:%d pulldown: %d\n",
+		gpio, pull_up, pull_down);
+	return 0;
+}
+
+static void nsp_gpio_get_pull(struct nsp_gpio *chip, unsigned gpio,
+			      bool *pull_up, bool *pull_down)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	*pull_up = nsp_get_bit(chip, IO_CTRL, NSP_PULL_UP_EN, gpio);
+	*pull_down = nsp_get_bit(chip, IO_CTRL, NSP_PULL_DOWN_EN, gpio);
+	spin_unlock_irqrestore(&chip->lock, flags);
+}
+
+static int nsp_gpio_set_strength(struct nsp_gpio *chip, unsigned gpio,
+				 u16 strength)
+{
+	u32 offset, shift, i;
+	u32 val;
+	unsigned long flags;
+
+	/* make sure drive strength is supported */
+	if (strength < 2 || strength > 16 || (strength % 2))
+		return -ENOTSUPP;
+
+	shift = gpio;
+	offset = NSP_GPIO_DRV_CTRL;
+	dev_dbg(chip->dev, "gpio:%u set drive strength:%d mA\n", gpio,
+		strength);
+	spin_lock_irqsave(&chip->lock, flags);
+	strength = (strength / 2) - 1;
+	for (i = GPIO_DRV_STRENGTH_BITS; i > 0; i--) {
+		val = readl(chip->io_ctrl + offset);
+		val &= ~BIT(shift);
+		val |= ((strength >> (i-1)) & 0x1) << shift;
+		writel(val, chip->io_ctrl + offset);
+		offset += 4;
+	}
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	return 0;
+}
+
+static int nsp_gpio_get_strength(struct nsp_gpio *chip, unsigned gpio,
+				 u16 *strength)
+{
+	unsigned int i, offset, shift;
+	u32 val;
+	unsigned long flags;
+
+	offset = NSP_GPIO_DRV_CTRL;
+	shift = gpio;
+
+	spin_lock_irqsave(&chip->lock, flags);
+	*strength = 0;
+	for (i = (GPIO_DRV_STRENGTH_BITS - 1); i >= 0; i--) {
+		val = readl(chip->io_ctrl + offset) & BIT(shift);
+		val >>= shift;
+		*strength += (val << i);
+		offset += 4;
+	}
+
+	/* convert to mA */
+	*strength = (*strength + 1) * 2;
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	return 0;
+}
+
+int nsp_pin_config_group_get(struct pinctrl_dev *pctldev, unsigned selector,
+			     unsigned long *config)
+{
+	return 0;
+}
+
+int nsp_pin_config_group_set(struct pinctrl_dev *pctldev, unsigned selector,
+			     unsigned long *configs, unsigned num_configs)
+{
+	return 0;
+}
+
+static int nsp_pin_config_get(struct pinctrl_dev *pctldev, unsigned pin,
+			      unsigned long *config)
+{
+	struct nsp_gpio *chip = pinctrl_dev_get_drvdata(pctldev);
+	enum pin_config_param param = pinconf_to_config_param(*config);
+	unsigned int gpio;
+	u16 arg = 0;
+	bool pull_up, pull_down;
+	int ret;
+
+	gpio = nsp_pin_to_gpio(pin);
+	switch (param) {
+	case PIN_CONFIG_BIAS_DISABLE:
+		nsp_gpio_get_pull(chip, gpio, &pull_up, &pull_down);
+		if ((pull_up == false) && (pull_down == false))
+			return 0;
+		else
+			return -EINVAL;
+
+	case PIN_CONFIG_BIAS_PULL_UP:
+		nsp_gpio_get_pull(chip, gpio, &pull_up, &pull_down);
+		if (pull_up)
+			return 0;
+		else
+			return -EINVAL;
+
+	case PIN_CONFIG_BIAS_PULL_DOWN:
+		nsp_gpio_get_pull(chip, gpio, &pull_up, &pull_down);
+		if (pull_down)
+			return 0;
+		else
+			return -EINVAL;
+
+	case PIN_CONFIG_DRIVE_STRENGTH:
+		ret = nsp_gpio_get_strength(chip, gpio, &arg);
+		if (ret)
+			return ret;
+		*config = pinconf_to_config_packed(param, arg);
+		return 0;
+
+	default:
+		return -ENOTSUPP;
+	}
+}
+
+static int nsp_pin_config_set(struct pinctrl_dev *pctldev, unsigned pin,
+			      unsigned long *configs, unsigned num_configs)
+{
+	struct nsp_gpio *chip = pinctrl_dev_get_drvdata(pctldev);
+	enum pin_config_param param;
+	u16 arg;
+	unsigned int i, gpio;
+	int ret = -ENOTSUPP;
+
+	gpio = nsp_pin_to_gpio(pin);
+	for (i = 0; i < num_configs; i++) {
+		param = pinconf_to_config_param(configs[i]);
+		arg = pinconf_to_config_argument(configs[i]);
+
+		switch (param) {
+		case PIN_CONFIG_BIAS_DISABLE:
+			ret = nsp_gpio_set_pull(chip, gpio, false, false);
+			if (ret < 0)
+				goto out;
+			break;
+
+		case PIN_CONFIG_BIAS_PULL_UP:
+			ret = nsp_gpio_set_pull(chip, gpio, true, false);
+			if (ret < 0)
+				goto out;
+			break;
+
+		case PIN_CONFIG_BIAS_PULL_DOWN:
+			ret = nsp_gpio_set_pull(chip, gpio, false, true);
+			if (ret < 0)
+				goto out;
+			break;
+
+		case PIN_CONFIG_DRIVE_STRENGTH:
+			ret = nsp_gpio_set_strength(chip, gpio, arg);
+			if (ret < 0)
+				goto out;
+			break;
+
+		case PIN_CONFIG_SLEW_RATE:
+			ret = nsp_gpio_set_slew(chip, gpio, arg);
+			if (ret < 0)
+				goto out;
+			break;
+
+		default:
+			dev_err(chip->dev, "invalid configuration\n");
+			return -ENOTSUPP;
+		}
+	}
+
+out:
+	return ret;
+}
+
+static const struct pinconf_ops nsp_pconf_ops = {
+	.is_generic = true,
+	.pin_config_get = nsp_pin_config_get,
+	.pin_config_set = nsp_pin_config_set,
+	.pin_config_group_get = nsp_pin_config_group_get,
+	.pin_config_group_set = nsp_pin_config_group_set,
+};
+
+/*
+ * NSP GPIO controller supports some PINCONF related configurations such as
+ * pull up, pull down, slew and drive strength, when the pin is configured
+ * to GPIO.
+ *
+ * Here a local pinctrl device is created with simple 1-to-1 pin mapping to the
+ * local GPIO pins
+ */
+static int nsp_gpio_register_pinconf(struct nsp_gpio *chip)
+{
+	struct pinctrl_desc *pctldesc = &chip->pctldesc;
+	struct pinctrl_pin_desc *pins;
+	struct gpio_chip *gc = &chip->gc;
+	int i;
+
+	pins = devm_kcalloc(chip->dev, gc->ngpio, sizeof(*pins), GFP_KERNEL);
+	if (!pins)
+		return -ENOMEM;
+	for (i = 0; i < gc->ngpio; i++) {
+		pins[i].number = i;
+		pins[i].name = devm_kasprintf(chip->dev, GFP_KERNEL,
+					      "gpio-%d", i);
+		if (!pins[i].name)
+			return -ENOMEM;
+	}
+	pctldesc->name = dev_name(chip->dev);
+	pctldesc->pctlops = &nsp_pctrl_ops;
+	pctldesc->pins = pins;
+	pctldesc->npins = gc->ngpio;
+	pctldesc->confops = &nsp_pconf_ops;
+
+	chip->pctl = pinctrl_register(pctldesc, chip->dev, chip);
+	if (IS_ERR(chip->pctl)) {
+		dev_err(chip->dev, "unable to register pinctrl device\n");
+		return PTR_ERR(chip->pctl);
+	}
+
+	return 0;
+}
+
+static const struct of_device_id nsp_gpio_of_match[] = {
+	{.compatible = "brcm,nsp-gpio-a",},
+	{}
+};
+
+static int nsp_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct nsp_gpio *chip;
+	struct gpio_chip *gc;
+	u32 val, count;
+	int irq, ret;
+
+	if (of_property_read_u32(pdev->dev.of_node, "ngpios", &val)) {
+		dev_err(&pdev->dev, "Missing ngpios OF property\n");
+		return -ENODEV;
+	}
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->dev = dev;
+	platform_set_drvdata(pdev, chip);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	chip->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(chip->base)) {
+		dev_err(dev, "unable to map I/O memory\n");
+		return PTR_ERR(chip->base);
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	chip->io_ctrl = devm_ioremap_resource(dev, res);
+	if (IS_ERR(chip->io_ctrl)) {
+		dev_err(dev, "unable to map I/O memory\n");
+		return PTR_ERR(chip->io_ctrl);
+	}
+
+	spin_lock_init(&chip->lock);
+	gc = &chip->gc;
+	gc->base = -1;
+	gc->can_sleep = false;
+	gc->ngpio = val;
+	gc->label = dev_name(dev);
+	gc->dev = dev;
+	gc->of_node = dev->of_node;
+	gc->request = nsp_gpio_request;
+	gc->free = nsp_gpio_free;
+	gc->direction_input = nsp_gpio_direction_input;
+	gc->direction_output = nsp_gpio_direction_output;
+	gc->set = nsp_gpio_set;
+	gc->get = nsp_gpio_get;
+	gc->to_irq = nsp_gpio_to_irq;
+
+	/* optional GPIO interrupt support */
+	irq = platform_get_irq(pdev, 0);
+	if (irq > 0) {
+		/* Create irq domain so that each pin can be assigned an IRQ.*/
+		chip->irq_domain = irq_domain_add_linear(gc->of_node, gc->ngpio,
+							 &irq_domain_simple_ops,
+							 chip);
+		if (!chip->irq_domain) {
+			dev_err(&pdev->dev, "Couldn't allocate IRQ domain\n");
+			return -ENXIO;
+		}
+
+		/* Map each gpio to an IRQ and set the handler for gpiolib. */
+		for (count = 0; count < gc->ngpio; count++) {
+			int irq = irq_create_mapping(chip->irq_domain, count);
+
+			irq_set_chip_and_handler(irq, &nsp_gpio_irq_chip,
+						 handle_simple_irq);
+			set_irq_flags(irq, IRQF_VALID);
+			irq_set_chip_data(irq, chip);
+		}
+
+		/* Install ISR for this GPIO controller. */
+		ret = devm_request_irq(&pdev->dev, irq, nsp_gpio_irq_handler,
+				       IRQF_SHARED, "gpio-a", chip);
+		if (ret) {
+			dev_err(&pdev->dev, "Unable to request IRQ%d: %d\n",
+				irq, ret);
+			goto err_rm_gpiochip;
+		}
+
+		val = readl(chip->base + NSP_CHIP_A_INT_MASK);
+		val = val | NSP_CHIP_A_GPIO_INT_BIT;
+		writel(val, (chip->base + NSP_CHIP_A_INT_MASK));
+	}
+
+	ret = gpiochip_add(gc);
+	if (ret < 0) {
+		dev_err(dev, "unable to add GPIO chip\n");
+		return ret;
+	}
+
+	ret = nsp_gpio_register_pinconf(chip);
+	if (ret) {
+		dev_err(dev, "unable to register pinconf\n");
+		goto err_rm_gpiochip;
+	}
+
+	return 0;
+
+err_rm_gpiochip:
+	gpiochip_remove(gc);
+
+	return ret;
+}
+
+static struct platform_driver nsp_gpio_driver = {
+	.driver = {
+		.name = "nsp-gpio-a",
+		.of_match_table = nsp_gpio_of_match,
+	},
+	.probe = nsp_gpio_probe,
+};
+
+static int __init nsp_gpio_init(void)
+{
+	return platform_driver_probe(&nsp_gpio_driver, nsp_gpio_probe);
+}
+arch_initcall_sync(nsp_gpio_init);