Message-ID: <50587903.9060507@gmail.com>
Date:	Tue, 18 Sep 2012 08:37:07 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Thierry Reding <thierry.reding@...onic-design.de>
CC:	Linus Walleij <linus.walleij@...ricsson.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] gpio: Add Avionic Design N-bit GPIO expander support

On 09/18/2012 03:57 AM, Thierry Reding wrote:
> This commit adds a driver for the Avionic Design N-bit GPIO expander.
> The expander provides a variable number of GPIO pins with interrupt
> support.
> 
> Cc: Grant Likely <grant.likely@...retlab.ca>
> Cc: Rob Herring <rob.herring@...xeda.com>
> Cc: devicetree-discuss@...ts.ozlabs.org
> Cc: Linus Walleij <linus.walleij@...ricsson.com>
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Thierry Reding <thierry.reding@...onic-design.de>
> ---
> Changes in v2:
> - allow building the driver as a module
> - assign of_node unconditionally
> - use linear mapping IRQ domain
> - properly cleanup IRQ domain
> - add OF device table and annotate device tables
> - emulate rising and falling edge triggers
> - increase #gpio-cells to 2
> - drop support for !OF
> - use IS_ENABLED to conditionalize DEBUG_FS code
> 
> Changes in v3:
> - make IRQ support runtime configurable (interrupt-controller property)
> - drop interrupt-controller and #interrupt-cells from DT binding
> - add inline to_adnp() function to wrap container_of() macro
> - consistently use adnp as name for struct adnp variables
> - remove irq_mask_cur and rename irq_mask to irq_enable
> - fix a subtle deadlock in adnp_gpio_direction_output()
> - remove dynamic allocations from debugfs code
> - rename regs to num_regs to avoid confusion
> - annotate non-trivial code with comments
> - don't acquire mutex in adnp_gpio_get()
> - assume NO_IRQ == 0
> ---
>  .../devicetree/bindings/gpio/gpio-adnp.txt         |  30 +
>  drivers/gpio/Kconfig                               |  11 +
>  drivers/gpio/Makefile                              |   1 +
>  drivers/gpio/gpio-adnp.c                           | 611 +++++++++++++++++++++
>  4 files changed, 653 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/gpio-adnp.txt
>  create mode 100644 drivers/gpio/gpio-adnp.c
> 
> diff --git a/Documentation/devicetree/bindings/gpio/gpio-adnp.txt b/Documentation/devicetree/bindings/gpio/gpio-adnp.txt
> new file mode 100644
> index 0000000..5a09a21
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/gpio-adnp.txt
> @@ -0,0 +1,30 @@
> +Avionic Design N-bit GPIO expander bindings
> +
> +Required properties:
> +- compatible: should be "ad,gpio-adnp"
> +- reg: The I2C slave address for this device.
> +- interrupt-parent: phandle of the parent interrupt controller.
> +- interrupts: Interrupt specifier for the controllers interrupt.
> +- #gpio-cells: Should be 2. The first cell is the GPIO number and the
> +  second cell is used to specify optional parameters:
> +  - bit 0: polarity (0: normal, 1: inverted)

This contradicts the documentation changes you just submitted. That's
fine, but perhaps that documentation should say recommended encoding of
cells unless defined differently for an individual binding.

Otherwise,

Acked-by: Rob Herring <rob.herring@...xeda.com>

> +- gpio-controller: Marks the device as a GPIO controller
> +- nr-gpios: The number of pins supported by the controller.
> +
> +Example:
> +
> +	gpioext: gpio-controller@41 {
> +		compatible = "ad,gpio-adnp";
> +		reg = <0x41>;
> +
> +		interrupt-parent = <&gpio>;
> +		interrupts = <160 1>;
> +
> +		gpio-controller;
> +		#gpio-cells = <2>;
> +
> +		interrupt-controller;
> +		#interrupt-cells = <2>;
> +
> +		nr-gpios = <64>;
> +	};
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 95778f1..a2e2323 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -444,6 +444,17 @@ config GPIO_ADP5588_IRQ
>  	  Say yes here to enable the adp5588 to be used as an interrupt
>  	  controller. It requires the driver to be built in the kernel.
>  
> +config GPIO_ADNP
> +	tristate "Avionic Design N-bit GPIO expander"
> +	depends on I2C && OF
> +	help
> +	  This option enables support for N GPIOs found on Avionic Design
> +	  I2C GPIO expanders. The register space will be extended by powers
> +	  of two, so the controller will need to accomodate for that. For
> +	  example: if a controller provides 48 pins, 6 registers will be
> +	  enough to represent all pins, but the driver will assume a
> +	  register layout for 64 pins (8 registers).
> +
>  comment "PCI GPIO expanders:"
>  
>  config GPIO_CS5535
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 153cace..710f2b6 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -10,6 +10,7 @@ obj-$(CONFIG_GPIO_GENERIC)	+= gpio-generic.o
>  
>  obj-$(CONFIG_GPIO_74X164)	+= gpio-74x164.o
>  obj-$(CONFIG_GPIO_AB8500)	+= gpio-ab8500.o
> +obj-$(CONFIG_GPIO_ADNP)		+= gpio-adnp.o
>  obj-$(CONFIG_GPIO_ADP5520)	+= gpio-adp5520.o
>  obj-$(CONFIG_GPIO_ADP5588)	+= gpio-adp5588.o
>  obj-$(CONFIG_GPIO_AMD8111)	+= gpio-amd8111.o
> diff --git a/drivers/gpio/gpio-adnp.c b/drivers/gpio/gpio-adnp.c
> new file mode 100644
> index 0000000..3df8833
> --- /dev/null
> +++ b/drivers/gpio/gpio-adnp.c
> @@ -0,0 +1,611 @@
> +/*
> + * 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 __devinit 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 = __devexit_p(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@...onic-design.de>");
> +MODULE_LICENSE("GPL");
> 
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