drivers/gpio/gpio-adnp.c - linux - Git at Google

 /*
  * Copyright (C) 2011-2012 Avionic Design GmbH
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #include <linux/gpio.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/irqdomain.h>
 #include <linux/module.h>
 #include <linux/of_irq.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>

 #define GPIO_DDR(gpio) (0x00 << (gpio)->reg_shift)
 #define GPIO_PLR(gpio) (0x01 << (gpio)->reg_shift)
 #define GPIO_IER(gpio) (0x02 << (gpio)->reg_shift)
 #define GPIO_ISR(gpio) (0x03 << (gpio)->reg_shift)
 #define GPIO_PTR(gpio) (0x04 << (gpio)->reg_shift)

 struct adnp {
 	struct i2c_client *client;
 	struct gpio_chip gpio;
 	unsigned int reg_shift;

 	struct mutex i2c_lock;

 	struct irq_domain *domain;
 	struct mutex irq_lock;

 	u8 *irq_enable;
 	u8 *irq_level;
 	u8 *irq_rise;
 	u8 *irq_fall;
 	u8 *irq_high;
 	u8 *irq_low;
 };

 static inline struct adnp *to_adnp(struct gpio_chip *chip)
 {
 	return container_of(chip, struct adnp, gpio);
 }

 static int adnp_read(struct adnp *adnp, unsigned offset, uint8_t *value)
 {
 	int err;

 	err = i2c_smbus_read_byte_data(adnp->client, offset);
 	if (err < 0) {
 		dev_err(adnp->gpio.dev, "%s failed: %d\n",
 			"i2c_smbus_read_byte_data()", err);
 		return err;
 	}

 	*value = err;
 	return 0;
 }

 static int adnp_write(struct adnp *adnp, unsigned offset, uint8_t value)
 {
 	int err;

 	err = i2c_smbus_write_byte_data(adnp->client, offset, value);
 	if (err < 0) {
 		dev_err(adnp->gpio.dev, "%s failed: %d\n",
 			"i2c_smbus_write_byte_data()", err);
 		return err;
 	}

 	return 0;
 }

 static int adnp_gpio_get(struct gpio_chip *chip, unsigned offset)
 {
 	struct adnp *adnp = to_adnp(chip);
 	unsigned int reg = offset >> adnp->reg_shift;
 	unsigned int pos = offset & 7;
 	u8 value;
 	int err;

 	err = adnp_read(adnp, GPIO_PLR(adnp) + reg, &value);
 	if (err < 0)
 		return err;

 	return (value & BIT(pos)) ? 1 : 0;
 }

 static void __adnp_gpio_set(struct adnp *adnp, unsigned offset, int value)
 {
 	unsigned int reg = offset >> adnp->reg_shift;
 	unsigned int pos = offset & 7;
 	int err;
 	u8 val;

 	err = adnp_read(adnp, GPIO_PLR(adnp) + reg, &val);
 	if (err < 0)
 		return;

 	if (value)
 		val |= BIT(pos);
 	else
 		val &= ~BIT(pos);

 	adnp_write(adnp, GPIO_PLR(adnp) + reg, val);
 }

 static void adnp_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
 {
 	struct adnp *adnp = to_adnp(chip);

 	mutex_lock(&adnp->i2c_lock);
 	__adnp_gpio_set(adnp, offset, value);
 	mutex_unlock(&adnp->i2c_lock);
 }

 static int adnp_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 {
 	struct adnp *adnp = to_adnp(chip);
 	unsigned int reg = offset >> adnp->reg_shift;
 	unsigned int pos = offset & 7;
 	u8 value;
 	int err;

 	mutex_lock(&adnp->i2c_lock);

 	err = adnp_read(adnp, GPIO_DDR(adnp) + reg, &value);
 	if (err < 0)
 		goto out;

 	value &= ~BIT(pos);

 	err = adnp_write(adnp, GPIO_DDR(adnp) + reg, value);
 	if (err < 0)
 		goto out;

 	err = adnp_read(adnp, GPIO_DDR(adnp) + reg, &value);
 	if (err < 0)
 		goto out;

 	if (err & BIT(pos))
 		err = -EACCES;

 	err = 0;

 out:
 	mutex_unlock(&adnp->i2c_lock);
 	return err;
 }

 static int adnp_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
 				      int value)
 {
 	struct adnp *adnp = to_adnp(chip);
 	unsigned int reg = offset >> adnp->reg_shift;
 	unsigned int pos = offset & 7;
 	int err;
 	u8 val;

 	mutex_lock(&adnp->i2c_lock);

 	err = adnp_read(adnp, GPIO_DDR(adnp) + reg, &val);
 	if (err < 0)
 		goto out;

 	val |= BIT(pos);

 	err = adnp_write(adnp, GPIO_DDR(adnp) + reg, val);
 	if (err < 0)
 		goto out;

 	err = adnp_read(adnp, GPIO_DDR(adnp) + reg, &val);
 	if (err < 0)
 		goto out;

 	if (!(val & BIT(pos))) {
 		err = -EPERM;
 		goto out;
 	}

 	__adnp_gpio_set(adnp, offset, value);
 	err = 0;

 out:
 	mutex_unlock(&adnp->i2c_lock);
 	return err;
 }

 static void adnp_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 {
 	struct adnp *adnp = to_adnp(chip);
 	unsigned int num_regs = 1 << adnp->reg_shift, i, j;
 	int err;

 	for (i = 0; i < num_regs; i++) {
 		u8 ddr, plr, ier, isr;

 		mutex_lock(&adnp->i2c_lock);

 		err = adnp_read(adnp, GPIO_DDR(adnp) + i, &ddr);
 		if (err < 0) {
 			mutex_unlock(&adnp->i2c_lock);
 			return;
 		}

 		err = adnp_read(adnp, GPIO_PLR(adnp) + i, &plr);
 		if (err < 0) {
 			mutex_unlock(&adnp->i2c_lock);
 			return;
 		}

 		err = adnp_read(adnp, GPIO_IER(adnp) + i, &ier);
 		if (err < 0) {
 			mutex_unlock(&adnp->i2c_lock);
 			return;
 		}

 		err = adnp_read(adnp, GPIO_ISR(adnp) + i, &isr);
 		if (err < 0) {
 			mutex_unlock(&adnp->i2c_lock);
 			return;
 		}

 		mutex_unlock(&adnp->i2c_lock);

 		for (j = 0; j < 8; j++) {
 			unsigned int bit = (i << adnp->reg_shift) + j;
 			const char *direction = "input ";
 			const char *level = "low ";
 			const char *interrupt = "disabled";
 			const char *pending = "";

 			if (ddr & BIT(j))
 				direction = "output";

 			if (plr & BIT(j))
 				level = "high";

 			if (ier & BIT(j))
 				interrupt = "enabled ";

 			if (isr & BIT(j))
 				pending = "pending";

 			seq_printf(s, "%2u: %s %s IRQ %s %s\n", bit,
 				   direction, level, interrupt, pending);
 		}
 	}
 }

 static int adnp_gpio_setup(struct adnp *adnp, unsigned int num_gpios)
 {
 	struct gpio_chip *chip = &adnp->gpio;

 	adnp->reg_shift = get_count_order(num_gpios) - 3;

 	chip->direction_input = adnp_gpio_direction_input;
 	chip->direction_output = adnp_gpio_direction_output;
 	chip->get = adnp_gpio_get;
 	chip->set = adnp_gpio_set;
 	chip->can_sleep = 1;

 	if (IS_ENABLED(CONFIG_DEBUG_FS))
 		chip->dbg_show = adnp_gpio_dbg_show;

 	chip->base = -1;
 	chip->ngpio = num_gpios;
 	chip->label = adnp->client->name;
 	chip->dev = &adnp->client->dev;
 	chip->of_node = chip->dev->of_node;
 	chip->owner = THIS_MODULE;

 	return 0;
 }

 static irqreturn_t adnp_irq(int irq, void *data)
 {
 	struct adnp *adnp = data;
 	unsigned int num_regs, i;

 	num_regs = 1 << adnp->reg_shift;

 	for (i = 0; i < num_regs; i++) {
 		unsigned int base = i << adnp->reg_shift, bit;
 		u8 changed, level, isr, ier;
 		unsigned long pending;
 		int err;

 		mutex_lock(&adnp->i2c_lock);

 		err = adnp_read(adnp, GPIO_PLR(adnp) + i, &level);
 		if (err < 0) {
 			mutex_unlock(&adnp->i2c_lock);
 			continue;
 		}

 		err = adnp_read(adnp, GPIO_ISR(adnp) + i, &isr);
 		if (err < 0) {
 			mutex_unlock(&adnp->i2c_lock);
 			continue;
 		}

 		err = adnp_read(adnp, GPIO_IER(adnp) + i, &ier);
 		if (err < 0) {
 			mutex_unlock(&adnp->i2c_lock);
 			continue;
 		}

 		mutex_unlock(&adnp->i2c_lock);

 		/* determine pins that changed levels */
 		changed = level ^ adnp->irq_level[i];

 		/* compute edge-triggered interrupts */
 		pending = changed & ((adnp->irq_fall[i] & ~level) |
 				     (adnp->irq_rise[i] & level));

 		/* add in level-triggered interrupts */
 		pending |= (adnp->irq_high[i] & level) |
 			   (adnp->irq_low[i] & ~level);

 		/* mask out non-pending and disabled interrupts */
 		pending &= isr & ier;

 		for_each_set_bit(bit, &pending, 8) {
 			unsigned int virq;
 			virq = irq_find_mapping(adnp->domain, base + bit);
 			handle_nested_irq(virq);
 		}
 	}

 	return IRQ_HANDLED;
 }

 static int adnp_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
 {
 	struct adnp *adnp = to_adnp(chip);
 	return irq_create_mapping(adnp->domain, offset);
 }

 static void adnp_irq_mask(struct irq_data *data)
 {
 	struct adnp *adnp = irq_data_get_irq_chip_data(data);
 	unsigned int reg = data->hwirq >> adnp->reg_shift;
 	unsigned int pos = data->hwirq & 7;

 	adnp->irq_enable[reg] &= ~BIT(pos);
 }

 static void adnp_irq_unmask(struct irq_data *data)
 {
 	struct adnp *adnp = irq_data_get_irq_chip_data(data);
 	unsigned int reg = data->hwirq >> adnp->reg_shift;
 	unsigned int pos = data->hwirq & 7;

 	adnp->irq_enable[reg] |= BIT(pos);
 }

 static int adnp_irq_set_type(struct irq_data *data, unsigned int type)
 {
 	struct adnp *adnp = irq_data_get_irq_chip_data(data);
 	unsigned int reg = data->hwirq >> adnp->reg_shift;
 	unsigned int pos = data->hwirq & 7;

 	if (type & IRQ_TYPE_EDGE_RISING)
 		adnp->irq_rise[reg] |= BIT(pos);
 	else
 		adnp->irq_rise[reg] &= ~BIT(pos);

 	if (type & IRQ_TYPE_EDGE_FALLING)
 		adnp->irq_fall[reg] |= BIT(pos);
 	else
 		adnp->irq_fall[reg] &= ~BIT(pos);

 	if (type & IRQ_TYPE_LEVEL_HIGH)
 		adnp->irq_high[reg] |= BIT(pos);
 	else
 		adnp->irq_high[reg] &= ~BIT(pos);

 	if (type & IRQ_TYPE_LEVEL_LOW)
 		adnp->irq_low[reg] |= BIT(pos);
 	else
 		adnp->irq_low[reg] &= ~BIT(pos);

 	return 0;
 }

 static void adnp_irq_bus_lock(struct irq_data *data)
 {
 	struct adnp *adnp = irq_data_get_irq_chip_data(data);

 	mutex_lock(&adnp->irq_lock);
 }

 static void adnp_irq_bus_unlock(struct irq_data *data)
 {
 	struct adnp *adnp = irq_data_get_irq_chip_data(data);
 	unsigned int num_regs = 1 << adnp->reg_shift, i;

 	mutex_lock(&adnp->i2c_lock);

 	for (i = 0; i < num_regs; i++)
 		adnp_write(adnp, GPIO_IER(adnp) + i, adnp->irq_enable[i]);

 	mutex_unlock(&adnp->i2c_lock);
 	mutex_unlock(&adnp->irq_lock);
 }

 static struct irq_chip adnp_irq_chip = {
 	.name = "gpio-adnp",
 	.irq_mask = adnp_irq_mask,
 	.irq_unmask = adnp_irq_unmask,
 	.irq_set_type = adnp_irq_set_type,
 	.irq_bus_lock = adnp_irq_bus_lock,
 	.irq_bus_sync_unlock = adnp_irq_bus_unlock,
 };

 static int adnp_irq_map(struct irq_domain *domain, unsigned int irq,
 			irq_hw_number_t hwirq)
 {
 	irq_set_chip_data(irq, domain->host_data);
 	irq_set_chip(irq, &adnp_irq_chip);
 	irq_set_nested_thread(irq, true);

 #ifdef CONFIG_ARM
 	set_irq_flags(irq, IRQF_VALID);
 #else
 	irq_set_noprobe(irq);
 #endif

 	return 0;
 }

 static const struct irq_domain_ops adnp_irq_domain_ops = {
 	.map = adnp_irq_map,
 	.xlate = irq_domain_xlate_twocell,
 };

 static int adnp_irq_setup(struct adnp *adnp)
 {
 	unsigned int num_regs = 1 << adnp->reg_shift, i;
 	struct gpio_chip *chip = &adnp->gpio;
 	int err;

 	mutex_init(&adnp->irq_lock);

 	/*
 	 * Allocate memory to keep track of the current level and trigger
 	 * modes of the interrupts. To avoid multiple allocations, a single
 	 * large buffer is allocated and pointers are setup to point at the
 	 * corresponding offsets. For consistency, the layout of the buffer
 	 * is chosen to match the register layout of the hardware in that
 	 * each segment contains the corresponding bits for all interrupts.
 	 */
 	adnp->irq_enable = devm_kzalloc(chip->dev, num_regs * 6, GFP_KERNEL);
 	if (!adnp->irq_enable)
 		return -ENOMEM;

 	adnp->irq_level = adnp->irq_enable + (num_regs * 1);
 	adnp->irq_rise = adnp->irq_enable + (num_regs * 2);
 	adnp->irq_fall = adnp->irq_enable + (num_regs * 3);
 	adnp->irq_high = adnp->irq_enable + (num_regs * 4);
 	adnp->irq_low = adnp->irq_enable + (num_regs * 5);

 	for (i = 0; i < num_regs; i++) {
 		/*
 		 * Read the initial level of all pins to allow the emulation
 		 * of edge triggered interrupts.
 		 */
 		err = adnp_read(adnp, GPIO_PLR(adnp) + i, &adnp->irq_level[i]);
 		if (err < 0)
 			return err;

 		/* disable all interrupts */
 		err = adnp_write(adnp, GPIO_IER(adnp) + i, 0);
 		if (err < 0)
 			return err;

 		adnp->irq_enable[i] = 0x00;
 	}

 	adnp->domain = irq_domain_add_linear(chip->of_node, chip->ngpio,
 					     &adnp_irq_domain_ops, adnp);

 	err = request_threaded_irq(adnp->client->irq, NULL, adnp_irq,
 				   IRQF_TRIGGER_RISING | IRQF_ONESHOT,
 				   dev_name(chip->dev), adnp);
 	if (err != 0) {
 		dev_err(chip->dev, "can't request IRQ#%d: %d\n",
 			adnp->client->irq, err);
 		goto error;
 	}

 	chip->to_irq = adnp_gpio_to_irq;
 	return 0;

 error:
 	irq_domain_remove(adnp->domain);
 	return err;
 }

 static void adnp_irq_teardown(struct adnp *adnp)
 {
 	unsigned int irq, i;

 	free_irq(adnp->client->irq, adnp);

 	for (i = 0; i < adnp->gpio.ngpio; i++) {
 		irq = irq_find_mapping(adnp->domain, i);
 		if (irq > 0)
 			irq_dispose_mapping(irq);
 	}

 	irq_domain_remove(adnp->domain);
 }

 static int adnp_i2c_probe(struct i2c_client *client,
 				    const struct i2c_device_id *id)
 {
 	struct device_node *np = client->dev.of_node;
 	struct adnp *adnp;
 	u32 num_gpios;
 	int err;

 	err = of_property_read_u32(np, "nr-gpios", &num_gpios);
 	if (err < 0)
 		return err;

 	client->irq = irq_of_parse_and_map(np, 0);
 	if (!client->irq)
 		return -EPROBE_DEFER;

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

 	mutex_init(&adnp->i2c_lock);
 	adnp->client = client;

 	err = adnp_gpio_setup(adnp, num_gpios);
 	if (err < 0)
 		return err;

 	if (of_find_property(np, "interrupt-controller", NULL)) {
 		err = adnp_irq_setup(adnp);
 		if (err < 0)
 			goto teardown;
 	}

 	err = gpiochip_add(&adnp->gpio);
 	if (err < 0)
 		goto teardown;

 	i2c_set_clientdata(client, adnp);
 	return 0;

 teardown:
 	if (of_find_property(np, "interrupt-controller", NULL))
 		adnp_irq_teardown(adnp);

 	return err;
 }

 static __devexit int adnp_i2c_remove(struct i2c_client *client)
 {
 	struct adnp *adnp = i2c_get_clientdata(client);
 	struct device_node *np = client->dev.of_node;
 	int err;

 	err = gpiochip_remove(&adnp->gpio);
 	if (err < 0) {
 		dev_err(&client->dev, "%s failed: %d\n", "gpiochip_remove()",
 			err);
 		return err;
 	}

 	if (of_find_property(np, "interrupt-controller", NULL))
 		adnp_irq_teardown(adnp);

 	return 0;
 }

 static const struct i2c_device_id adnp_i2c_id[] __devinitconst = {
 	{ "gpio-adnp" },
 	{ },
 };
 MODULE_DEVICE_TABLE(i2c, adnp_i2c_id);

 static const struct of_device_id adnp_of_match[] __devinitconst = {
 	{ .compatible = "ad,gpio-adnp", },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, adnp_of_match);

 static struct i2c_driver adnp_i2c_driver = {
 	.driver = {
 		.name = "gpio-adnp",
 		.owner = THIS_MODULE,
 		.of_match_table = of_match_ptr(adnp_of_match),
 	},
 	.probe = adnp_i2c_probe,
 	.remove = adnp_i2c_remove,
 	.id_table = adnp_i2c_id,
 };
 module_i2c_driver(adnp_i2c_driver);

 MODULE_DESCRIPTION("Avionic Design N-bit GPIO expander");
 MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
 MODULE_LICENSE("GPL");
	/*
	* Copyright (C) 2011-2012 Avionic Design GmbH
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/gpio.h>
	#include <linux/i2c.h>
	#include <linux/interrupt.h>
	#include <linux/irqdomain.h>
	#include <linux/module.h>
	#include <linux/of_irq.h>
	#include <linux/seq_file.h>
	#include <linux/slab.h>

	#define GPIO_DDR(gpio) (0x00 << (gpio)->reg_shift)
	#define GPIO_PLR(gpio) (0x01 << (gpio)->reg_shift)
	#define GPIO_IER(gpio) (0x02 << (gpio)->reg_shift)
	#define GPIO_ISR(gpio) (0x03 << (gpio)->reg_shift)
	#define GPIO_PTR(gpio) (0x04 << (gpio)->reg_shift)

	struct adnp {
	struct i2c_client *client;
	struct gpio_chip gpio;
	unsigned int reg_shift;

	struct mutex i2c_lock;

	struct irq_domain *domain;
	struct mutex irq_lock;

	u8 *irq_enable;
	u8 *irq_level;
	u8 *irq_rise;
	u8 *irq_fall;
	u8 *irq_high;
	u8 *irq_low;
	};

	static inline struct adnp to_adnp(struct gpio_chip chip)
	{
	return container_of(chip, struct adnp, gpio);
	}

	static int adnp_read(struct adnp adnp, unsigned offset, uint8_t value)
	{
	int err;

	err = i2c_smbus_read_byte_data(adnp->client, offset);
	if (err < 0) {
	dev_err(adnp->gpio.dev, "%s failed: %d\n",
	"i2c_smbus_read_byte_data()", err);
	return err;
	}

	*value = err;
	return 0;
	}

	static int adnp_write(struct adnp *adnp, unsigned offset, uint8_t value)
	{
	int err;

	err = i2c_smbus_write_byte_data(adnp->client, offset, value);
	if (err < 0) {
	dev_err(adnp->gpio.dev, "%s failed: %d\n",
	"i2c_smbus_write_byte_data()", err);
	return err;
	}

	return 0;
	}

	static int adnp_gpio_get(struct gpio_chip *chip, unsigned offset)
	{
	struct adnp *adnp = to_adnp(chip);
	unsigned int reg = offset >> adnp->reg_shift;
	unsigned int pos = offset & 7;
	u8 value;
	int err;

	err = adnp_read(adnp, GPIO_PLR(adnp) + reg, &value);
	if (err < 0)
	return err;

	return (value & BIT(pos)) ? 1 : 0;
	}

	static void __adnp_gpio_set(struct adnp *adnp, unsigned offset, int value)
	{
	unsigned int reg = offset >> adnp->reg_shift;
	unsigned int pos = offset & 7;
	int err;
	u8 val;

	err = adnp_read(adnp, GPIO_PLR(adnp) + reg, &val);
	if (err < 0)
	return;

	if (value)
	val \|= BIT(pos);
	else
	val &= ~BIT(pos);

	adnp_write(adnp, GPIO_PLR(adnp) + reg, val);
	}

	static void adnp_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
	{
	struct adnp *adnp = to_adnp(chip);

	mutex_lock(&adnp->i2c_lock);
	__adnp_gpio_set(adnp, offset, value);
	mutex_unlock(&adnp->i2c_lock);
	}

	static int adnp_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
	{
	struct adnp *adnp = to_adnp(chip);
	unsigned int reg = offset >> adnp->reg_shift;
	unsigned int pos = offset & 7;
	u8 value;
	int err;

	mutex_lock(&adnp->i2c_lock);

	err = adnp_read(adnp, GPIO_DDR(adnp) + reg, &value);
	if (err < 0)
	goto out;

	value &= ~BIT(pos);

	err = adnp_write(adnp, GPIO_DDR(adnp) + reg, value);
	if (err < 0)
	goto out;

	err = adnp_read(adnp, GPIO_DDR(adnp) + reg, &value);
	if (err < 0)
	goto out;

	if (err & BIT(pos))
	err = -EACCES;

	err = 0;

	out:
	mutex_unlock(&adnp->i2c_lock);
	return err;
	}

	static int adnp_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
	int value)
	{
	struct adnp *adnp = to_adnp(chip);
	unsigned int reg = offset >> adnp->reg_shift;
	unsigned int pos = offset & 7;
	int err;
	u8 val;

	mutex_lock(&adnp->i2c_lock);

	err = adnp_read(adnp, GPIO_DDR(adnp) + reg, &val);
	if (err < 0)
	goto out;

	val \|= BIT(pos);

	err = adnp_write(adnp, GPIO_DDR(adnp) + reg, val);
	if (err < 0)
	goto out;

	err = adnp_read(adnp, GPIO_DDR(adnp) + reg, &val);
	if (err < 0)
	goto out;

	if (!(val & BIT(pos))) {
	err = -EPERM;
	goto out;
	}

	__adnp_gpio_set(adnp, offset, value);
	err = 0;

	out:
	mutex_unlock(&adnp->i2c_lock);
	return err;
	}

	static void adnp_gpio_dbg_show(struct seq_file s, struct gpio_chip chip)
	{
	struct adnp *adnp = to_adnp(chip);
	unsigned int num_regs = 1 << adnp->reg_shift, i, j;
	int err;

	for (i = 0; i < num_regs; i++) {
	u8 ddr, plr, ier, isr;

	mutex_lock(&adnp->i2c_lock);

	err = adnp_read(adnp, GPIO_DDR(adnp) + i, &ddr);
	if (err < 0) {
	mutex_unlock(&adnp->i2c_lock);
	return;
	}

	err = adnp_read(adnp, GPIO_PLR(adnp) + i, &plr);
	if (err < 0) {
	mutex_unlock(&adnp->i2c_lock);
	return;
	}

	err = adnp_read(adnp, GPIO_IER(adnp) + i, &ier);
	if (err < 0) {
	mutex_unlock(&adnp->i2c_lock);
	return;
	}

	err = adnp_read(adnp, GPIO_ISR(adnp) + i, &isr);
	if (err < 0) {
	mutex_unlock(&adnp->i2c_lock);
	return;
	}

	mutex_unlock(&adnp->i2c_lock);

	for (j = 0; j < 8; j++) {
	unsigned int bit = (i << adnp->reg_shift) + j;
	const char *direction = "input ";
	const char *level = "low ";
	const char *interrupt = "disabled";
	const char *pending = "";

	if (ddr & BIT(j))
	direction = "output";

	if (plr & BIT(j))
	level = "high";

	if (ier & BIT(j))
	interrupt = "enabled ";

	if (isr & BIT(j))
	pending = "pending";

	seq_printf(s, "%2u: %s %s IRQ %s %s\n", bit,
	direction, level, interrupt, pending);
	}
	}
	}

	static int adnp_gpio_setup(struct adnp *adnp, unsigned int num_gpios)
	{
	struct gpio_chip *chip = &adnp->gpio;

	adnp->reg_shift = get_count_order(num_gpios) - 3;

	chip->direction_input = adnp_gpio_direction_input;
	chip->direction_output = adnp_gpio_direction_output;
	chip->get = adnp_gpio_get;
	chip->set = adnp_gpio_set;
	chip->can_sleep = 1;

	if (IS_ENABLED(CONFIG_DEBUG_FS))
	chip->dbg_show = adnp_gpio_dbg_show;

	chip->base = -1;
	chip->ngpio = num_gpios;
	chip->label = adnp->client->name;
	chip->dev = &adnp->client->dev;
	chip->of_node = chip->dev->of_node;
	chip->owner = THIS_MODULE;

	return 0;
	}

	static irqreturn_t adnp_irq(int irq, void *data)
	{
	struct adnp *adnp = data;
	unsigned int num_regs, i;

	num_regs = 1 << adnp->reg_shift;

	for (i = 0; i < num_regs; i++) {
	unsigned int base = i << adnp->reg_shift, bit;
	u8 changed, level, isr, ier;
	unsigned long pending;
	int err;

	mutex_lock(&adnp->i2c_lock);

	err = adnp_read(adnp, GPIO_PLR(adnp) + i, &level);
	if (err < 0) {
	mutex_unlock(&adnp->i2c_lock);
	continue;
	}

	err = adnp_read(adnp, GPIO_ISR(adnp) + i, &isr);
	if (err < 0) {
	mutex_unlock(&adnp->i2c_lock);
	continue;
	}

	err = adnp_read(adnp, GPIO_IER(adnp) + i, &ier);
	if (err < 0) {
	mutex_unlock(&adnp->i2c_lock);
	continue;
	}

	mutex_unlock(&adnp->i2c_lock);

	/* determine pins that changed levels */
	changed = level ^ adnp->irq_level[i];

	/* compute edge-triggered interrupts */
	pending = changed & ((adnp->irq_fall[i] & ~level) \|
	(adnp->irq_rise[i] & level));

	/* add in level-triggered interrupts */
	pending \|= (adnp->irq_high[i] & level) \|
	(adnp->irq_low[i] & ~level);

	/* mask out non-pending and disabled interrupts */
	pending &= isr & ier;

	for_each_set_bit(bit, &pending, 8) {
	unsigned int virq;
	virq = irq_find_mapping(adnp->domain, base + bit);
	handle_nested_irq(virq);
	}
	}

	return IRQ_HANDLED;
	}

	static int adnp_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
	{
	struct adnp *adnp = to_adnp(chip);
	return irq_create_mapping(adnp->domain, offset);
	}

	static void adnp_irq_mask(struct irq_data *data)
	{
	struct adnp *adnp = irq_data_get_irq_chip_data(data);
	unsigned int reg = data->hwirq >> adnp->reg_shift;
	unsigned int pos = data->hwirq & 7;

	adnp->irq_enable[reg] &= ~BIT(pos);
	}

	static void adnp_irq_unmask(struct irq_data *data)
	{
	struct adnp *adnp = irq_data_get_irq_chip_data(data);
	unsigned int reg = data->hwirq >> adnp->reg_shift;
	unsigned int pos = data->hwirq & 7;

	adnp->irq_enable[reg] \|= BIT(pos);
	}

	static int adnp_irq_set_type(struct irq_data *data, unsigned int type)
	{
	struct adnp *adnp = irq_data_get_irq_chip_data(data);
	unsigned int reg = data->hwirq >> adnp->reg_shift;
	unsigned int pos = data->hwirq & 7;

	if (type & IRQ_TYPE_EDGE_RISING)
	adnp->irq_rise[reg] \|= BIT(pos);
	else
	adnp->irq_rise[reg] &= ~BIT(pos);

	if (type & IRQ_TYPE_EDGE_FALLING)
	adnp->irq_fall[reg] \|= BIT(pos);
	else
	adnp->irq_fall[reg] &= ~BIT(pos);

	if (type & IRQ_TYPE_LEVEL_HIGH)
	adnp->irq_high[reg] \|= BIT(pos);
	else
	adnp->irq_high[reg] &= ~BIT(pos);

	if (type & IRQ_TYPE_LEVEL_LOW)
	adnp->irq_low[reg] \|= BIT(pos);
	else
	adnp->irq_low[reg] &= ~BIT(pos);

	return 0;
	}

	static void adnp_irq_bus_lock(struct irq_data *data)
	{
	struct adnp *adnp = irq_data_get_irq_chip_data(data);

	mutex_lock(&adnp->irq_lock);
	}

	static void adnp_irq_bus_unlock(struct irq_data *data)
	{
	struct adnp *adnp = irq_data_get_irq_chip_data(data);
	unsigned int num_regs = 1 << adnp->reg_shift, i;

	mutex_lock(&adnp->i2c_lock);

	for (i = 0; i < num_regs; i++)
	adnp_write(adnp, GPIO_IER(adnp) + i, adnp->irq_enable[i]);

	mutex_unlock(&adnp->i2c_lock);
	mutex_unlock(&adnp->irq_lock);
	}

	static struct irq_chip adnp_irq_chip = {
	.name = "gpio-adnp",
	.irq_mask = adnp_irq_mask,
	.irq_unmask = adnp_irq_unmask,
	.irq_set_type = adnp_irq_set_type,
	.irq_bus_lock = adnp_irq_bus_lock,
	.irq_bus_sync_unlock = adnp_irq_bus_unlock,
	};

	static int adnp_irq_map(struct irq_domain *domain, unsigned int irq,
	irq_hw_number_t hwirq)
	{
	irq_set_chip_data(irq, domain->host_data);
	irq_set_chip(irq, &adnp_irq_chip);
	irq_set_nested_thread(irq, true);

	#ifdef CONFIG_ARM
	set_irq_flags(irq, IRQF_VALID);
	#else
	irq_set_noprobe(irq);
	#endif

	return 0;
	}

	static const struct irq_domain_ops adnp_irq_domain_ops = {
	.map = adnp_irq_map,
	.xlate = irq_domain_xlate_twocell,
	};

	static int adnp_irq_setup(struct adnp *adnp)
	{
	unsigned int num_regs = 1 << adnp->reg_shift, i;
	struct gpio_chip *chip = &adnp->gpio;
	int err;

	mutex_init(&adnp->irq_lock);

	/*
	* Allocate memory to keep track of the current level and trigger
	* modes of the interrupts. To avoid multiple allocations, a single
	* large buffer is allocated and pointers are setup to point at the
	* corresponding offsets. For consistency, the layout of the buffer
	* is chosen to match the register layout of the hardware in that
	* each segment contains the corresponding bits for all interrupts.
	*/
	adnp->irq_enable = devm_kzalloc(chip->dev, num_regs * 6, GFP_KERNEL);
	if (!adnp->irq_enable)
	return -ENOMEM;

	adnp->irq_level = adnp->irq_enable + (num_regs * 1);
	adnp->irq_rise = adnp->irq_enable + (num_regs * 2);
	adnp->irq_fall = adnp->irq_enable + (num_regs * 3);
	adnp->irq_high = adnp->irq_enable + (num_regs * 4);
	adnp->irq_low = adnp->irq_enable + (num_regs * 5);

	for (i = 0; i < num_regs; i++) {
	/*
	* Read the initial level of all pins to allow the emulation
	* of edge triggered interrupts.
	*/
	err = adnp_read(adnp, GPIO_PLR(adnp) + i, &adnp->irq_level[i]);
	if (err < 0)
	return err;

	/* disable all interrupts */
	err = adnp_write(adnp, GPIO_IER(adnp) + i, 0);
	if (err < 0)
	return err;

	adnp->irq_enable[i] = 0x00;
	}

	adnp->domain = irq_domain_add_linear(chip->of_node, chip->ngpio,
	&adnp_irq_domain_ops, adnp);

	err = request_threaded_irq(adnp->client->irq, NULL, adnp_irq,
	IRQF_TRIGGER_RISING \| IRQF_ONESHOT,
	dev_name(chip->dev), adnp);
	if (err != 0) {
	dev_err(chip->dev, "can't request IRQ#%d: %d\n",
	adnp->client->irq, err);
	goto error;
	}

	chip->to_irq = adnp_gpio_to_irq;
	return 0;

	error:
	irq_domain_remove(adnp->domain);
	return err;
	}

	static void adnp_irq_teardown(struct adnp *adnp)
	{
	unsigned int irq, i;

	free_irq(adnp->client->irq, adnp);

	for (i = 0; i < adnp->gpio.ngpio; i++) {
	irq = irq_find_mapping(adnp->domain, i);
	if (irq > 0)
	irq_dispose_mapping(irq);
	}

	irq_domain_remove(adnp->domain);
	}

	static int adnp_i2c_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct device_node *np = client->dev.of_node;
	struct adnp *adnp;
	u32 num_gpios;
	int err;

	err = of_property_read_u32(np, "nr-gpios", &num_gpios);
	if (err < 0)
	return err;

	client->irq = irq_of_parse_and_map(np, 0);
	if (!client->irq)
	return -EPROBE_DEFER;

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

	mutex_init(&adnp->i2c_lock);
	adnp->client = client;

	err = adnp_gpio_setup(adnp, num_gpios);
	if (err < 0)
	return err;

	if (of_find_property(np, "interrupt-controller", NULL)) {
	err = adnp_irq_setup(adnp);
	if (err < 0)
	goto teardown;
	}

	err = gpiochip_add(&adnp->gpio);
	if (err < 0)
	goto teardown;

	i2c_set_clientdata(client, adnp);
	return 0;

	teardown:
	if (of_find_property(np, "interrupt-controller", NULL))
	adnp_irq_teardown(adnp);

	return err;
	}

	static __devexit int adnp_i2c_remove(struct i2c_client *client)
	{
	struct adnp *adnp = i2c_get_clientdata(client);
	struct device_node *np = client->dev.of_node;
	int err;

	err = gpiochip_remove(&adnp->gpio);
	if (err < 0) {
	dev_err(&client->dev, "%s failed: %d\n", "gpiochip_remove()",
	err);
	return err;
	}

	if (of_find_property(np, "interrupt-controller", NULL))
	adnp_irq_teardown(adnp);

	return 0;
	}

	static const struct i2c_device_id adnp_i2c_id[] __devinitconst = {
	{ "gpio-adnp" },
	{ },
	};
	MODULE_DEVICE_TABLE(i2c, adnp_i2c_id);

	static const struct of_device_id adnp_of_match[] __devinitconst = {
	{ .compatible = "ad,gpio-adnp", },
	{ },
	};
	MODULE_DEVICE_TABLE(of, adnp_of_match);

	static struct i2c_driver adnp_i2c_driver = {
	.driver = {
	.name = "gpio-adnp",
	.owner = THIS_MODULE,
	.of_match_table = of_match_ptr(adnp_of_match),
	},
	.probe = adnp_i2c_probe,
	.remove = adnp_i2c_remove,
	.id_table = adnp_i2c_id,
	};
	module_i2c_driver(adnp_i2c_driver);

	MODULE_DESCRIPTION("Avionic Design N-bit GPIO expander");
	MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
	MODULE_LICENSE("GPL");