drivers/gpio/gpio-altera.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (C) 2013 Altera Corporation
  * Based on gpio-mpc8xxx.c
  *
  * 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.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <linux/io.h>
 #include <linux/of_gpio.h>
 #include <linux/platform_device.h>

 #define ALTERA_GPIO_MAX_NGPIO		32
 #define ALTERA_GPIO_DATA		0x0
 #define ALTERA_GPIO_DIR			0x4
 #define ALTERA_GPIO_IRQ_MASK		0x8
 #define ALTERA_GPIO_EDGE_CAP		0xc

 /**
 * struct altera_gpio_chip
 * @mmchip		: memory mapped chip structure.
 * @gpio_lock		: synchronization lock so that new irq/set/get requests
 			  will be blocked until the current one completes.
 * @interrupt_trigger	: specifies the hardware configured IRQ trigger type
 			  (rising, falling, both, high)
 * @mapped_irq		: kernel mapped irq number.
 */
 struct altera_gpio_chip {
 	struct of_mm_gpio_chip mmchip;
 	spinlock_t gpio_lock;
 	int interrupt_trigger;
 	int mapped_irq;
 };

 static void altera_gpio_irq_unmask(struct irq_data *d)
 {
 	struct altera_gpio_chip *altera_gc;
 	struct of_mm_gpio_chip *mm_gc;
 	unsigned long flags;
 	u32 intmask;

 	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));
 	mm_gc = &altera_gc->mmchip;

 	spin_lock_irqsave(&altera_gc->gpio_lock, flags);
 	intmask = readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
 	/* Set ALTERA_GPIO_IRQ_MASK bit to unmask */
 	intmask |= BIT(irqd_to_hwirq(d));
 	writel(intmask, mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
 	spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);
 }

 static void altera_gpio_irq_mask(struct irq_data *d)
 {
 	struct altera_gpio_chip *altera_gc;
 	struct of_mm_gpio_chip *mm_gc;
 	unsigned long flags;
 	u32 intmask;

 	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));
 	mm_gc = &altera_gc->mmchip;

 	spin_lock_irqsave(&altera_gc->gpio_lock, flags);
 	intmask = readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
 	/* Clear ALTERA_GPIO_IRQ_MASK bit to mask */
 	intmask &= ~BIT(irqd_to_hwirq(d));
 	writel(intmask, mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
 	spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);
 }

 /**
  * This controller's IRQ type is synthesized in hardware, so this function
  * just checks if the requested set_type matches the synthesized IRQ type
  */
 static int altera_gpio_irq_set_type(struct irq_data *d,
 				   unsigned int type)
 {
 	struct altera_gpio_chip *altera_gc;

 	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));

 	if (type == IRQ_TYPE_NONE)
 		return 0;
 	if (type == IRQ_TYPE_LEVEL_HIGH &&
 		altera_gc->interrupt_trigger == IRQ_TYPE_LEVEL_HIGH)
 		return 0;
 	if (type == IRQ_TYPE_EDGE_RISING &&
 		altera_gc->interrupt_trigger == IRQ_TYPE_EDGE_RISING)
 		return 0;
 	if (type == IRQ_TYPE_EDGE_FALLING &&
 		altera_gc->interrupt_trigger == IRQ_TYPE_EDGE_FALLING)
 		return 0;
 	if (type == IRQ_TYPE_EDGE_BOTH &&
 		altera_gc->interrupt_trigger == IRQ_TYPE_EDGE_BOTH)
 		return 0;

 	return -EINVAL;
 }

 static unsigned int altera_gpio_irq_startup(struct irq_data *d)
 {
 	altera_gpio_irq_unmask(d);

 	return 0;
 }

 static struct irq_chip altera_irq_chip = {
 	.name		= "altera-gpio",
 	.irq_mask	= altera_gpio_irq_mask,
 	.irq_unmask	= altera_gpio_irq_unmask,
 	.irq_set_type	= altera_gpio_irq_set_type,
 	.irq_startup	= altera_gpio_irq_startup,
 	.irq_shutdown	= altera_gpio_irq_mask,
 };

 static int altera_gpio_get(struct gpio_chip *gc, unsigned offset)
 {
 	struct of_mm_gpio_chip *mm_gc;

 	mm_gc = to_of_mm_gpio_chip(gc);

 	return !!(readl(mm_gc->regs + ALTERA_GPIO_DATA) & BIT(offset));
 }

 static void altera_gpio_set(struct gpio_chip *gc, unsigned offset, int value)
 {
 	struct of_mm_gpio_chip *mm_gc;
 	struct altera_gpio_chip *chip;
 	unsigned long flags;
 	unsigned int data_reg;

 	mm_gc = to_of_mm_gpio_chip(gc);
 	chip = gpiochip_get_data(gc);

 	spin_lock_irqsave(&chip->gpio_lock, flags);
 	data_reg = readl(mm_gc->regs + ALTERA_GPIO_DATA);
 	if (value)
 		data_reg |= BIT(offset);
 	else
 		data_reg &= ~BIT(offset);
 	writel(data_reg, mm_gc->regs + ALTERA_GPIO_DATA);
 	spin_unlock_irqrestore(&chip->gpio_lock, flags);
 }

 static int altera_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
 {
 	struct of_mm_gpio_chip *mm_gc;
 	struct altera_gpio_chip *chip;
 	unsigned long flags;
 	unsigned int gpio_ddr;

 	mm_gc = to_of_mm_gpio_chip(gc);
 	chip = gpiochip_get_data(gc);

 	spin_lock_irqsave(&chip->gpio_lock, flags);
 	/* Set pin as input, assumes software controlled IP */
 	gpio_ddr = readl(mm_gc->regs + ALTERA_GPIO_DIR);
 	gpio_ddr &= ~BIT(offset);
 	writel(gpio_ddr, mm_gc->regs + ALTERA_GPIO_DIR);
 	spin_unlock_irqrestore(&chip->gpio_lock, flags);

 	return 0;
 }

 static int altera_gpio_direction_output(struct gpio_chip *gc,
 		unsigned offset, int value)
 {
 	struct of_mm_gpio_chip *mm_gc;
 	struct altera_gpio_chip *chip;
 	unsigned long flags;
 	unsigned int data_reg, gpio_ddr;

 	mm_gc = to_of_mm_gpio_chip(gc);
 	chip = gpiochip_get_data(gc);

 	spin_lock_irqsave(&chip->gpio_lock, flags);
 	/* Sets the GPIO value */
 	data_reg = readl(mm_gc->regs + ALTERA_GPIO_DATA);
 	if (value)
 		data_reg |= BIT(offset);
 	else
 		data_reg &= ~BIT(offset);
 	writel(data_reg, mm_gc->regs + ALTERA_GPIO_DATA);

 	/* Set pin as output, assumes software controlled IP */
 	gpio_ddr = readl(mm_gc->regs + ALTERA_GPIO_DIR);
 	gpio_ddr |= BIT(offset);
 	writel(gpio_ddr, mm_gc->regs + ALTERA_GPIO_DIR);
 	spin_unlock_irqrestore(&chip->gpio_lock, flags);

 	return 0;
 }

 static void altera_gpio_irq_edge_handler(struct irq_desc *desc)
 {
 	struct altera_gpio_chip *altera_gc;
 	struct irq_chip *chip;
 	struct of_mm_gpio_chip *mm_gc;
 	struct irq_domain *irqdomain;
 	unsigned long status;
 	int i;

 	altera_gc = gpiochip_get_data(irq_desc_get_handler_data(desc));
 	chip = irq_desc_get_chip(desc);
 	mm_gc = &altera_gc->mmchip;
 	irqdomain = altera_gc->mmchip.gc.irqdomain;

 	chained_irq_enter(chip, desc);

 	while ((status =
 	      (readl(mm_gc->regs + ALTERA_GPIO_EDGE_CAP) &
 	      readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK)))) {
 		writel(status, mm_gc->regs + ALTERA_GPIO_EDGE_CAP);
 		for_each_set_bit(i, &status, mm_gc->gc.ngpio) {
 			generic_handle_irq(irq_find_mapping(irqdomain, i));
 		}
 	}

 	chained_irq_exit(chip, desc);
 }


 static void altera_gpio_irq_leveL_high_handler(struct irq_desc *desc)
 {
 	struct altera_gpio_chip *altera_gc;
 	struct irq_chip *chip;
 	struct of_mm_gpio_chip *mm_gc;
 	struct irq_domain *irqdomain;
 	unsigned long status;
 	int i;

 	altera_gc = gpiochip_get_data(irq_desc_get_handler_data(desc));
 	chip = irq_desc_get_chip(desc);
 	mm_gc = &altera_gc->mmchip;
 	irqdomain = altera_gc->mmchip.gc.irqdomain;

 	chained_irq_enter(chip, desc);

 	status = readl(mm_gc->regs + ALTERA_GPIO_DATA);
 	status &= readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);

 	for_each_set_bit(i, &status, mm_gc->gc.ngpio) {
 		generic_handle_irq(irq_find_mapping(irqdomain, i));
 	}
 	chained_irq_exit(chip, desc);
 }

 static int altera_gpio_probe(struct platform_device *pdev)
 {
 	struct device_node *node = pdev->dev.of_node;
 	int reg, ret;
 	struct altera_gpio_chip *altera_gc;

 	altera_gc = devm_kzalloc(&pdev->dev, sizeof(*altera_gc), GFP_KERNEL);
 	if (!altera_gc)
 		return -ENOMEM;

 	spin_lock_init(&altera_gc->gpio_lock);

 	if (of_property_read_u32(node, "altr,ngpio", &reg))
 		/* By default assume maximum ngpio */
 		altera_gc->mmchip.gc.ngpio = ALTERA_GPIO_MAX_NGPIO;
 	else
 		altera_gc->mmchip.gc.ngpio = reg;

 	if (altera_gc->mmchip.gc.ngpio > ALTERA_GPIO_MAX_NGPIO) {
 		dev_warn(&pdev->dev,
 			"ngpio is greater than %d, defaulting to %d\n",
 			ALTERA_GPIO_MAX_NGPIO, ALTERA_GPIO_MAX_NGPIO);
 		altera_gc->mmchip.gc.ngpio = ALTERA_GPIO_MAX_NGPIO;
 	}

 	altera_gc->mmchip.gc.direction_input	= altera_gpio_direction_input;
 	altera_gc->mmchip.gc.direction_output	= altera_gpio_direction_output;
 	altera_gc->mmchip.gc.get		= altera_gpio_get;
 	altera_gc->mmchip.gc.set		= altera_gpio_set;
 	altera_gc->mmchip.gc.owner		= THIS_MODULE;
 	altera_gc->mmchip.gc.parent		= &pdev->dev;

 	ret = of_mm_gpiochip_add_data(node, &altera_gc->mmchip, altera_gc);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed adding memory mapped gpiochip\n");
 		return ret;
 	}

 	platform_set_drvdata(pdev, altera_gc);

 	altera_gc->mapped_irq = platform_get_irq(pdev, 0);

 	if (altera_gc->mapped_irq < 0)
 		goto skip_irq;

 	if (of_property_read_u32(node, "altr,interrupt-type", &reg)) {
 		ret = -EINVAL;
 		dev_err(&pdev->dev,
 			"altr,interrupt-type value not set in device tree\n");
 		goto teardown;
 	}
 	altera_gc->interrupt_trigger = reg;

 	ret = gpiochip_irqchip_add(&altera_gc->mmchip.gc, &altera_irq_chip, 0,
 		handle_simple_irq, IRQ_TYPE_NONE);

 	if (ret) {
 		dev_info(&pdev->dev, "could not add irqchip\n");
 		return ret;
 	}

 	gpiochip_set_chained_irqchip(&altera_gc->mmchip.gc,
 		&altera_irq_chip,
 		altera_gc->mapped_irq,
 		altera_gc->interrupt_trigger == IRQ_TYPE_LEVEL_HIGH ?
 		altera_gpio_irq_leveL_high_handler :
 		altera_gpio_irq_edge_handler);

 skip_irq:
 	return 0;
 teardown:
 	pr_err("%s: registration failed with status %d\n",
 		node->full_name, ret);

 	return ret;
 }

 static int altera_gpio_remove(struct platform_device *pdev)
 {
 	struct altera_gpio_chip *altera_gc = platform_get_drvdata(pdev);

 	of_mm_gpiochip_remove(&altera_gc->mmchip);

 	return 0;
 }

 static const struct of_device_id altera_gpio_of_match[] = {
 	{ .compatible = "altr,pio-1.0", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, altera_gpio_of_match);

 static struct platform_driver altera_gpio_driver = {
 	.driver = {
 		.name	= "altera_gpio",
 		.of_match_table = of_match_ptr(altera_gpio_of_match),
 	},
 	.probe		= altera_gpio_probe,
 	.remove		= altera_gpio_remove,
 };

 static int __init altera_gpio_init(void)
 {
 	return platform_driver_register(&altera_gpio_driver);
 }
 subsys_initcall(altera_gpio_init);

 static void __exit altera_gpio_exit(void)
 {
 	platform_driver_unregister(&altera_gpio_driver);
 }
 module_exit(altera_gpio_exit);

 MODULE_AUTHOR("Tien Hock Loh <thloh@altera.com>");
 MODULE_DESCRIPTION("Altera GPIO driver");
 MODULE_LICENSE("GPL");
	/*
	* Copyright (C) 2013 Altera Corporation
	* Based on gpio-mpc8xxx.c
	*
	* 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.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <linux/io.h>
	#include <linux/of_gpio.h>
	#include <linux/platform_device.h>

	#define ALTERA_GPIO_MAX_NGPIO 32
	#define ALTERA_GPIO_DATA 0x0
	#define ALTERA_GPIO_DIR 0x4
	#define ALTERA_GPIO_IRQ_MASK 0x8
	#define ALTERA_GPIO_EDGE_CAP 0xc

	/**
	* struct altera_gpio_chip
	* @mmchip : memory mapped chip structure.
	* @gpio_lock : synchronization lock so that new irq/set/get requests
	will be blocked until the current one completes.
	* @interrupt_trigger : specifies the hardware configured IRQ trigger type
	(rising, falling, both, high)
	* @mapped_irq : kernel mapped irq number.
	*/
	struct altera_gpio_chip {
	struct of_mm_gpio_chip mmchip;
	spinlock_t gpio_lock;
	int interrupt_trigger;
	int mapped_irq;
	};

	static void altera_gpio_irq_unmask(struct irq_data *d)
	{
	struct altera_gpio_chip *altera_gc;
	struct of_mm_gpio_chip *mm_gc;
	unsigned long flags;
	u32 intmask;

	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));
	mm_gc = &altera_gc->mmchip;

	spin_lock_irqsave(&altera_gc->gpio_lock, flags);
	intmask = readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
	/* Set ALTERA_GPIO_IRQ_MASK bit to unmask */
	intmask \|= BIT(irqd_to_hwirq(d));
	writel(intmask, mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
	spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);
	}

	static void altera_gpio_irq_mask(struct irq_data *d)
	{
	struct altera_gpio_chip *altera_gc;
	struct of_mm_gpio_chip *mm_gc;
	unsigned long flags;
	u32 intmask;

	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));
	mm_gc = &altera_gc->mmchip;

	spin_lock_irqsave(&altera_gc->gpio_lock, flags);
	intmask = readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
	/* Clear ALTERA_GPIO_IRQ_MASK bit to mask */
	intmask &= ~BIT(irqd_to_hwirq(d));
	writel(intmask, mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
	spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);
	}

	/**
	* This controller's IRQ type is synthesized in hardware, so this function
	* just checks if the requested set_type matches the synthesized IRQ type
	*/
	static int altera_gpio_irq_set_type(struct irq_data *d,
	unsigned int type)
	{
	struct altera_gpio_chip *altera_gc;

	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));

	if (type == IRQ_TYPE_NONE)
	return 0;
	if (type == IRQ_TYPE_LEVEL_HIGH &&
	altera_gc->interrupt_trigger == IRQ_TYPE_LEVEL_HIGH)
	return 0;
	if (type == IRQ_TYPE_EDGE_RISING &&
	altera_gc->interrupt_trigger == IRQ_TYPE_EDGE_RISING)
	return 0;
	if (type == IRQ_TYPE_EDGE_FALLING &&
	altera_gc->interrupt_trigger == IRQ_TYPE_EDGE_FALLING)
	return 0;
	if (type == IRQ_TYPE_EDGE_BOTH &&
	altera_gc->interrupt_trigger == IRQ_TYPE_EDGE_BOTH)
	return 0;

	return -EINVAL;
	}

	static unsigned int altera_gpio_irq_startup(struct irq_data *d)
	{
	altera_gpio_irq_unmask(d);

	return 0;
	}

	static struct irq_chip altera_irq_chip = {
	.name = "altera-gpio",
	.irq_mask = altera_gpio_irq_mask,
	.irq_unmask = altera_gpio_irq_unmask,
	.irq_set_type = altera_gpio_irq_set_type,
	.irq_startup = altera_gpio_irq_startup,
	.irq_shutdown = altera_gpio_irq_mask,
	};

	static int altera_gpio_get(struct gpio_chip *gc, unsigned offset)
	{
	struct of_mm_gpio_chip *mm_gc;

	mm_gc = to_of_mm_gpio_chip(gc);

	return !!(readl(mm_gc->regs + ALTERA_GPIO_DATA) & BIT(offset));
	}

	static void altera_gpio_set(struct gpio_chip *gc, unsigned offset, int value)
	{
	struct of_mm_gpio_chip *mm_gc;
	struct altera_gpio_chip *chip;
	unsigned long flags;
	unsigned int data_reg;

	mm_gc = to_of_mm_gpio_chip(gc);
	chip = gpiochip_get_data(gc);

	spin_lock_irqsave(&chip->gpio_lock, flags);
	data_reg = readl(mm_gc->regs + ALTERA_GPIO_DATA);
	if (value)
	data_reg \|= BIT(offset);
	else
	data_reg &= ~BIT(offset);
	writel(data_reg, mm_gc->regs + ALTERA_GPIO_DATA);
	spin_unlock_irqrestore(&chip->gpio_lock, flags);
	}

	static int altera_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
	{
	struct of_mm_gpio_chip *mm_gc;
	struct altera_gpio_chip *chip;
	unsigned long flags;
	unsigned int gpio_ddr;

	mm_gc = to_of_mm_gpio_chip(gc);
	chip = gpiochip_get_data(gc);

	spin_lock_irqsave(&chip->gpio_lock, flags);
	/* Set pin as input, assumes software controlled IP */
	gpio_ddr = readl(mm_gc->regs + ALTERA_GPIO_DIR);
	gpio_ddr &= ~BIT(offset);
	writel(gpio_ddr, mm_gc->regs + ALTERA_GPIO_DIR);
	spin_unlock_irqrestore(&chip->gpio_lock, flags);

	return 0;
	}

	static int altera_gpio_direction_output(struct gpio_chip *gc,
	unsigned offset, int value)
	{
	struct of_mm_gpio_chip *mm_gc;
	struct altera_gpio_chip *chip;
	unsigned long flags;
	unsigned int data_reg, gpio_ddr;

	mm_gc = to_of_mm_gpio_chip(gc);
	chip = gpiochip_get_data(gc);

	spin_lock_irqsave(&chip->gpio_lock, flags);
	/* Sets the GPIO value */
	data_reg = readl(mm_gc->regs + ALTERA_GPIO_DATA);
	if (value)
	data_reg \|= BIT(offset);
	else
	data_reg &= ~BIT(offset);
	writel(data_reg, mm_gc->regs + ALTERA_GPIO_DATA);

	/* Set pin as output, assumes software controlled IP */
	gpio_ddr = readl(mm_gc->regs + ALTERA_GPIO_DIR);
	gpio_ddr \|= BIT(offset);
	writel(gpio_ddr, mm_gc->regs + ALTERA_GPIO_DIR);
	spin_unlock_irqrestore(&chip->gpio_lock, flags);

	return 0;
	}

	static void altera_gpio_irq_edge_handler(struct irq_desc *desc)
	{
	struct altera_gpio_chip *altera_gc;
	struct irq_chip *chip;
	struct of_mm_gpio_chip *mm_gc;
	struct irq_domain *irqdomain;
	unsigned long status;
	int i;

	altera_gc = gpiochip_get_data(irq_desc_get_handler_data(desc));
	chip = irq_desc_get_chip(desc);
	mm_gc = &altera_gc->mmchip;
	irqdomain = altera_gc->mmchip.gc.irqdomain;

	chained_irq_enter(chip, desc);

	while ((status =
	(readl(mm_gc->regs + ALTERA_GPIO_EDGE_CAP) &
	readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK)))) {
	writel(status, mm_gc->regs + ALTERA_GPIO_EDGE_CAP);
	for_each_set_bit(i, &status, mm_gc->gc.ngpio) {
	generic_handle_irq(irq_find_mapping(irqdomain, i));
	}
	}

	chained_irq_exit(chip, desc);
	}


	static void altera_gpio_irq_leveL_high_handler(struct irq_desc *desc)
	{
	struct altera_gpio_chip *altera_gc;
	struct irq_chip *chip;
	struct of_mm_gpio_chip *mm_gc;
	struct irq_domain *irqdomain;
	unsigned long status;
	int i;

	altera_gc = gpiochip_get_data(irq_desc_get_handler_data(desc));
	chip = irq_desc_get_chip(desc);
	mm_gc = &altera_gc->mmchip;
	irqdomain = altera_gc->mmchip.gc.irqdomain;

	chained_irq_enter(chip, desc);

	status = readl(mm_gc->regs + ALTERA_GPIO_DATA);
	status &= readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);

	for_each_set_bit(i, &status, mm_gc->gc.ngpio) {
	generic_handle_irq(irq_find_mapping(irqdomain, i));
	}
	chained_irq_exit(chip, desc);
	}

	static int altera_gpio_probe(struct platform_device *pdev)
	{
	struct device_node *node = pdev->dev.of_node;
	int reg, ret;
	struct altera_gpio_chip *altera_gc;

	altera_gc = devm_kzalloc(&pdev->dev, sizeof(*altera_gc), GFP_KERNEL);
	if (!altera_gc)
	return -ENOMEM;

	spin_lock_init(&altera_gc->gpio_lock);

	if (of_property_read_u32(node, "altr,ngpio", &reg))
	/* By default assume maximum ngpio */
	altera_gc->mmchip.gc.ngpio = ALTERA_GPIO_MAX_NGPIO;
	else
	altera_gc->mmchip.gc.ngpio = reg;

	if (altera_gc->mmchip.gc.ngpio > ALTERA_GPIO_MAX_NGPIO) {
	dev_warn(&pdev->dev,
	"ngpio is greater than %d, defaulting to %d\n",
	ALTERA_GPIO_MAX_NGPIO, ALTERA_GPIO_MAX_NGPIO);
	altera_gc->mmchip.gc.ngpio = ALTERA_GPIO_MAX_NGPIO;
	}

	altera_gc->mmchip.gc.direction_input = altera_gpio_direction_input;
	altera_gc->mmchip.gc.direction_output = altera_gpio_direction_output;
	altera_gc->mmchip.gc.get = altera_gpio_get;
	altera_gc->mmchip.gc.set = altera_gpio_set;
	altera_gc->mmchip.gc.owner = THIS_MODULE;
	altera_gc->mmchip.gc.parent = &pdev->dev;

	ret = of_mm_gpiochip_add_data(node, &altera_gc->mmchip, altera_gc);
	if (ret) {
	dev_err(&pdev->dev, "Failed adding memory mapped gpiochip\n");
	return ret;
	}

	platform_set_drvdata(pdev, altera_gc);

	altera_gc->mapped_irq = platform_get_irq(pdev, 0);

	if (altera_gc->mapped_irq < 0)
	goto skip_irq;

	if (of_property_read_u32(node, "altr,interrupt-type", &reg)) {
	ret = -EINVAL;
	dev_err(&pdev->dev,
	"altr,interrupt-type value not set in device tree\n");
	goto teardown;
	}
	altera_gc->interrupt_trigger = reg;

	ret = gpiochip_irqchip_add(&altera_gc->mmchip.gc, &altera_irq_chip, 0,
	handle_simple_irq, IRQ_TYPE_NONE);

	if (ret) {
	dev_info(&pdev->dev, "could not add irqchip\n");
	return ret;
	}

	gpiochip_set_chained_irqchip(&altera_gc->mmchip.gc,
	&altera_irq_chip,
	altera_gc->mapped_irq,
	altera_gc->interrupt_trigger == IRQ_TYPE_LEVEL_HIGH ?
	altera_gpio_irq_leveL_high_handler :
	altera_gpio_irq_edge_handler);

	skip_irq:
	return 0;
	teardown:
	pr_err("%s: registration failed with status %d\n",
	node->full_name, ret);

	return ret;
	}

	static int altera_gpio_remove(struct platform_device *pdev)
	{
	struct altera_gpio_chip *altera_gc = platform_get_drvdata(pdev);

	of_mm_gpiochip_remove(&altera_gc->mmchip);

	return 0;
	}

	static const struct of_device_id altera_gpio_of_match[] = {
	{ .compatible = "altr,pio-1.0", },
	{},
	};
	MODULE_DEVICE_TABLE(of, altera_gpio_of_match);

	static struct platform_driver altera_gpio_driver = {
	.driver = {
	.name = "altera_gpio",
	.of_match_table = of_match_ptr(altera_gpio_of_match),
	},
	.probe = altera_gpio_probe,
	.remove = altera_gpio_remove,
	};

	static int __init altera_gpio_init(void)
	{
	return platform_driver_register(&altera_gpio_driver);
	}
	subsys_initcall(altera_gpio_init);

	static void __exit altera_gpio_exit(void)
	{
	platform_driver_unregister(&altera_gpio_driver);
	}
	module_exit(altera_gpio_exit);

	MODULE_AUTHOR("Tien Hock Loh <thloh@altera.com>");
	MODULE_DESCRIPTION("Altera GPIO driver");
	MODULE_LICENSE("GPL");