Initial import

1 files changed, 764 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-max732x.c b/drivers/gpio/gpio-max732x.c
new file mode 100644
index 000000000..0fa4543c5
--- /dev/null
+++ b/drivers/gpio/gpio-max732x.c
@@ -0,0 +1,764 @@
+/*
+ *  MAX732x I2C Port Expander with 8/16 I/O
+ *
+ *  Copyright (C) 2007 Marvell International Ltd.
+ *  Copyright (C) 2008 Jack Ren <jack.ren@marvell.com>
+ *  Copyright (C) 2008 Eric Miao <eric.miao@marvell.com>
+ *  Copyright (C) 2015 Linus Walleij <linus.walleij@linaro.org>
+ *
+ *  Derived from drivers/gpio/pca953x.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; version 2 of the License.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/gpio/driver.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/i2c/max732x.h>
+#include <linux/of.h>
+
+
+/*
+ * Each port of MAX732x (including MAX7319) falls into one of the
+ * following three types:
+ *
+ *   - Push Pull Output
+ *   - Input
+ *   - Open Drain I/O
+ *
+ * designated by 'O', 'I' and 'P' individually according to MAXIM's
+ * datasheets. 'I' and 'P' ports are interrupt capables, some with
+ * a dedicated interrupt mask.
+ *
+ * There are two groups of I/O ports, each group usually includes
+ * up to 8 I/O ports, and is accessed by a specific I2C address:
+ *
+ *   - Group A : by I2C address 0b'110xxxx
+ *   - Group B : by I2C address 0b'101xxxx
+ *
+ * where 'xxxx' is decided by the connections of pin AD2/AD0.  The
+ * address used also affects the initial state of output signals.
+ *
+ * Within each group of ports, there are five known combinations of
+ * I/O ports: 4I4O, 4P4O, 8I, 8P, 8O, see the definitions below for
+ * the detailed organization of these ports. Only Goup A is interrupt
+ * capable.
+ *
+ * GPIO numbers start from 'gpio_base + 0' to 'gpio_base + 8/16',
+ * and GPIOs from GROUP_A are numbered before those from GROUP_B
+ * (if there are two groups).
+ *
+ * NOTE: MAX7328/MAX7329 are drop-in replacements for PCF8574/a, so
+ * they are not supported by this driver.
+ */
+
+#define PORT_NONE	0x0	/* '/' No Port */
+#define PORT_OUTPUT	0x1	/* 'O' Push-Pull, Output Only */
+#define PORT_INPUT	0x2	/* 'I' Input Only */
+#define PORT_OPENDRAIN	0x3	/* 'P' Open-Drain, I/O */
+
+#define IO_4I4O		0x5AA5	/* O7 O6 I5 I4 I3 I2 O1 O0 */
+#define IO_4P4O		0x5FF5	/* O7 O6 P5 P4 P3 P2 O1 O0 */
+#define IO_8I		0xAAAA	/* I7 I6 I5 I4 I3 I2 I1 I0 */
+#define IO_8P		0xFFFF	/* P7 P6 P5 P4 P3 P2 P1 P0 */
+#define IO_8O		0x5555	/* O7 O6 O5 O4 O3 O2 O1 O0 */
+
+#define GROUP_A(x)	((x) & 0xffff)	/* I2C Addr: 0b'110xxxx */
+#define GROUP_B(x)	((x) << 16)	/* I2C Addr: 0b'101xxxx */
+
+#define INT_NONE	0x0	/* No interrupt capability */
+#define INT_NO_MASK	0x1	/* Has interrupts, no mask */
+#define INT_INDEP_MASK	0x2	/* Has interrupts, independent mask */
+#define INT_MERGED_MASK 0x3	/* Has interrupts, merged mask */
+
+#define INT_CAPS(x)	(((uint64_t)(x)) << 32)
+
+enum {
+	MAX7319,
+	MAX7320,
+	MAX7321,
+	MAX7322,
+	MAX7323,
+	MAX7324,
+	MAX7325,
+	MAX7326,
+	MAX7327,
+};
+
+static uint64_t max732x_features[] = {
+	[MAX7319] = GROUP_A(IO_8I) | INT_CAPS(INT_MERGED_MASK),
+	[MAX7320] = GROUP_B(IO_8O),
+	[MAX7321] = GROUP_A(IO_8P) | INT_CAPS(INT_NO_MASK),
+	[MAX7322] = GROUP_A(IO_4I4O) | INT_CAPS(INT_MERGED_MASK),
+	[MAX7323] = GROUP_A(IO_4P4O) | INT_CAPS(INT_INDEP_MASK),
+	[MAX7324] = GROUP_A(IO_8I) | GROUP_B(IO_8O) | INT_CAPS(INT_MERGED_MASK),
+	[MAX7325] = GROUP_A(IO_8P) | GROUP_B(IO_8O) | INT_CAPS(INT_NO_MASK),
+	[MAX7326] = GROUP_A(IO_4I4O) | GROUP_B(IO_8O) | INT_CAPS(INT_MERGED_MASK),
+	[MAX7327] = GROUP_A(IO_4P4O) | GROUP_B(IO_8O) | INT_CAPS(INT_NO_MASK),
+};
+
+static const struct i2c_device_id max732x_id[] = {
+	{ "max7319", MAX7319 },
+	{ "max7320", MAX7320 },
+	{ "max7321", MAX7321 },
+	{ "max7322", MAX7322 },
+	{ "max7323", MAX7323 },
+	{ "max7324", MAX7324 },
+	{ "max7325", MAX7325 },
+	{ "max7326", MAX7326 },
+	{ "max7327", MAX7327 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, max732x_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id max732x_of_table[] = {
+	{ .compatible = "maxim,max7319" },
+	{ .compatible = "maxim,max7320" },
+	{ .compatible = "maxim,max7321" },
+	{ .compatible = "maxim,max7322" },
+	{ .compatible = "maxim,max7323" },
+	{ .compatible = "maxim,max7324" },
+	{ .compatible = "maxim,max7325" },
+	{ .compatible = "maxim,max7326" },
+	{ .compatible = "maxim,max7327" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max732x_of_table);
+#endif
+
+struct max732x_chip {
+	struct gpio_chip gpio_chip;
+
+	struct i2c_client *client;	/* "main" client */
+	struct i2c_client *client_dummy;
+	struct i2c_client *client_group_a;
+	struct i2c_client *client_group_b;
+
+	unsigned int	mask_group_a;
+	unsigned int	dir_input;
+	unsigned int	dir_output;
+
+	struct mutex	lock;
+	uint8_t		reg_out[2];
+
+#ifdef CONFIG_GPIO_MAX732X_IRQ
+	struct mutex		irq_lock;
+	uint8_t			irq_mask;
+	uint8_t			irq_mask_cur;
+	uint8_t			irq_trig_raise;
+	uint8_t			irq_trig_fall;
+	uint8_t			irq_features;
+#endif
+};
+
+static inline struct max732x_chip *to_max732x(struct gpio_chip *gc)
+{
+	return container_of(gc, struct max732x_chip, gpio_chip);
+}
+
+static int max732x_writeb(struct max732x_chip *chip, int group_a, uint8_t val)
+{
+	struct i2c_client *client;
+	int ret;
+
+	client = group_a ? chip->client_group_a : chip->client_group_b;
+	ret = i2c_smbus_write_byte(client, val);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed writing\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int max732x_readb(struct max732x_chip *chip, int group_a, uint8_t *val)
+{
+	struct i2c_client *client;
+	int ret;
+
+	client = group_a ? chip->client_group_a : chip->client_group_b;
+	ret = i2c_smbus_read_byte(client);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed reading\n");
+		return ret;
+	}
+
+	*val = (uint8_t)ret;
+	return 0;
+}
+
+static inline int is_group_a(struct max732x_chip *chip, unsigned off)
+{
+	return (1u << off) & chip->mask_group_a;
+}
+
+static int max732x_gpio_get_value(struct gpio_chip *gc, unsigned off)
+{
+	struct max732x_chip *chip = to_max732x(gc);
+	uint8_t reg_val;
+	int ret;
+
+	ret = max732x_readb(chip, is_group_a(chip, off), &reg_val);
+	if (ret < 0)
+		return 0;
+
+	return reg_val & (1u << (off & 0x7));
+}
+
+static void max732x_gpio_set_mask(struct gpio_chip *gc, unsigned off, int mask,
+				  int val)
+{
+	struct max732x_chip *chip = to_max732x(gc);
+	uint8_t reg_out;
+	int ret;
+
+	mutex_lock(&chip->lock);
+
+	reg_out = (off > 7) ? chip->reg_out[1] : chip->reg_out[0];
+	reg_out = (reg_out & ~mask) | (val & mask);
+
+	ret = max732x_writeb(chip, is_group_a(chip, off), reg_out);
+	if (ret < 0)
+		goto out;
+
+	/* update the shadow register then */
+	if (off > 7)
+		chip->reg_out[1] = reg_out;
+	else
+		chip->reg_out[0] = reg_out;
+out:
+	mutex_unlock(&chip->lock);
+}
+
+static void max732x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
+{
+	unsigned base = off & ~0x7;
+	uint8_t mask = 1u << (off & 0x7);
+
+	max732x_gpio_set_mask(gc, base, mask, val << (off & 0x7));
+}
+
+static void max732x_gpio_set_multiple(struct gpio_chip *gc,
+				      unsigned long *mask, unsigned long *bits)
+{
+	unsigned mask_lo = mask[0] & 0xff;
+	unsigned mask_hi = (mask[0] >> 8) & 0xff;
+
+	if (mask_lo)
+		max732x_gpio_set_mask(gc, 0, mask_lo, bits[0] & 0xff);
+	if (mask_hi)
+		max732x_gpio_set_mask(gc, 8, mask_hi, (bits[0] >> 8) & 0xff);
+}
+
+static int max732x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
+{
+	struct max732x_chip *chip = to_max732x(gc);
+	unsigned int mask = 1u << off;
+
+	if ((mask & chip->dir_input) == 0) {
+		dev_dbg(&chip->client->dev, "%s port %d is output only\n",
+			chip->client->name, off);
+		return -EACCES;
+	}
+
+	/*
+	 * Open-drain pins must be set to high impedance (which is
+	 * equivalent to output-high) to be turned into an input.
+	 */
+	if ((mask & chip->dir_output))
+		max732x_gpio_set_value(gc, off, 1);
+
+	return 0;
+}
+
+static int max732x_gpio_direction_output(struct gpio_chip *gc,
+		unsigned off, int val)
+{
+	struct max732x_chip *chip = to_max732x(gc);
+	unsigned int mask = 1u << off;
+
+	if ((mask & chip->dir_output) == 0) {
+		dev_dbg(&chip->client->dev, "%s port %d is input only\n",
+			chip->client->name, off);
+		return -EACCES;
+	}
+
+	max732x_gpio_set_value(gc, off, val);
+	return 0;
+}
+
+#ifdef CONFIG_GPIO_MAX732X_IRQ
+static int max732x_writew(struct max732x_chip *chip, uint16_t val)
+{
+	int ret;
+
+	val = cpu_to_le16(val);
+
+	ret = i2c_master_send(chip->client_group_a, (char *)&val, 2);
+	if (ret < 0) {
+		dev_err(&chip->client_group_a->dev, "failed writing\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int max732x_readw(struct max732x_chip *chip, uint16_t *val)
+{
+	int ret;
+
+	ret = i2c_master_recv(chip->client_group_a, (char *)val, 2);
+	if (ret < 0) {
+		dev_err(&chip->client_group_a->dev, "failed reading\n");
+		return ret;
+	}
+
+	*val = le16_to_cpu(*val);
+	return 0;
+}
+
+static void max732x_irq_update_mask(struct max732x_chip *chip)
+{
+	uint16_t msg;
+
+	if (chip->irq_mask == chip->irq_mask_cur)
+		return;
+
+	chip->irq_mask = chip->irq_mask_cur;
+
+	if (chip->irq_features == INT_NO_MASK)
+		return;
+
+	mutex_lock(&chip->lock);
+
+	switch (chip->irq_features) {
+	case INT_INDEP_MASK:
+		msg = (chip->irq_mask << 8) | chip->reg_out[0];
+		max732x_writew(chip, msg);
+		break;
+
+	case INT_MERGED_MASK:
+		msg = chip->irq_mask | chip->reg_out[0];
+		max732x_writeb(chip, 1, (uint8_t)msg);
+		break;
+	}
+
+	mutex_unlock(&chip->lock);
+}
+
+static void max732x_irq_mask(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct max732x_chip *chip = to_max732x(gc);
+
+	chip->irq_mask_cur &= ~(1 << d->hwirq);
+}
+
+static void max732x_irq_unmask(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct max732x_chip *chip = to_max732x(gc);
+
+	chip->irq_mask_cur |= 1 << d->hwirq;
+}
+
+static void max732x_irq_bus_lock(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct max732x_chip *chip = to_max732x(gc);
+
+	mutex_lock(&chip->irq_lock);
+	chip->irq_mask_cur = chip->irq_mask;
+}
+
+static void max732x_irq_bus_sync_unlock(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct max732x_chip *chip = to_max732x(gc);
+	uint16_t new_irqs;
+	uint16_t level;
+
+	max732x_irq_update_mask(chip);
+
+	new_irqs = chip->irq_trig_fall | chip->irq_trig_raise;
+	while (new_irqs) {
+		level = __ffs(new_irqs);
+		max732x_gpio_direction_input(&chip->gpio_chip, level);
+		new_irqs &= ~(1 << level);
+	}
+
+	mutex_unlock(&chip->irq_lock);
+}
+
+static int max732x_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct max732x_chip *chip = to_max732x(gc);
+	uint16_t off = d->hwirq;
+	uint16_t mask = 1 << off;
+
+	if (!(mask & chip->dir_input)) {
+		dev_dbg(&chip->client->dev, "%s port %d is output only\n",
+			chip->client->name, off);
+		return -EACCES;
+	}
+
+	if (!(type & IRQ_TYPE_EDGE_BOTH)) {
+		dev_err(&chip->client->dev, "irq %d: unsupported type %d\n",
+			d->irq, type);
+		return -EINVAL;
+	}
+
+	if (type & IRQ_TYPE_EDGE_FALLING)
+		chip->irq_trig_fall |= mask;
+	else
+		chip->irq_trig_fall &= ~mask;
+
+	if (type & IRQ_TYPE_EDGE_RISING)
+		chip->irq_trig_raise |= mask;
+	else
+		chip->irq_trig_raise &= ~mask;
+
+	return 0;
+}
+
+static struct irq_chip max732x_irq_chip = {
+	.name			= "max732x",
+	.irq_mask		= max732x_irq_mask,
+	.irq_unmask		= max732x_irq_unmask,
+	.irq_bus_lock		= max732x_irq_bus_lock,
+	.irq_bus_sync_unlock	= max732x_irq_bus_sync_unlock,
+	.irq_set_type		= max732x_irq_set_type,
+};
+
+static uint8_t max732x_irq_pending(struct max732x_chip *chip)
+{
+	uint8_t cur_stat;
+	uint8_t old_stat;
+	uint8_t trigger;
+	uint8_t pending;
+	uint16_t status;
+	int ret;
+
+	ret = max732x_readw(chip, &status);
+	if (ret)
+		return 0;
+
+	trigger = status >> 8;
+	trigger &= chip->irq_mask;
+
+	if (!trigger)
+		return 0;
+
+	cur_stat = status & 0xFF;
+	cur_stat &= chip->irq_mask;
+
+	old_stat = cur_stat ^ trigger;
+
+	pending = (old_stat & chip->irq_trig_fall) |
+		  (cur_stat & chip->irq_trig_raise);
+	pending &= trigger;
+
+	return pending;
+}
+
+static irqreturn_t max732x_irq_handler(int irq, void *devid)
+{
+	struct max732x_chip *chip = devid;
+	uint8_t pending;
+	uint8_t level;
+
+	pending = max732x_irq_pending(chip);
+
+	if (!pending)
+		return IRQ_HANDLED;
+
+	do {
+		level = __ffs(pending);
+		handle_nested_irq(irq_find_mapping(chip->gpio_chip.irqdomain,
+						   level));
+
+		pending &= ~(1 << level);
+	} while (pending);
+
+	return IRQ_HANDLED;
+}
+
+static int max732x_irq_setup(struct max732x_chip *chip,
+			     const struct i2c_device_id *id)
+{
+	struct i2c_client *client = chip->client;
+	struct max732x_platform_data *pdata = dev_get_platdata(&client->dev);
+	int has_irq = max732x_features[id->driver_data] >> 32;
+	int irq_base = 0;
+	int ret;
+
+	if (((pdata && pdata->irq_base) || client->irq)
+			&& has_irq != INT_NONE) {
+		if (pdata)
+			irq_base = pdata->irq_base;
+		chip->irq_features = has_irq;
+		mutex_init(&chip->irq_lock);
+
+		ret = devm_request_threaded_irq(&client->dev,
+					client->irq,
+					NULL,
+					max732x_irq_handler,
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					dev_name(&client->dev), chip);
+		if (ret) {
+			dev_err(&client->dev, "failed to request irq %d\n",
+				client->irq);
+			return ret;
+		}
+		ret =  gpiochip_irqchip_add(&chip->gpio_chip,
+					    &max732x_irq_chip,
+					    irq_base,
+					    handle_edge_irq,
+					    IRQ_TYPE_NONE);
+		if (ret) {
+			dev_err(&client->dev,
+				"could not connect irqchip to gpiochip\n");
+			return ret;
+		}
+		gpiochip_set_chained_irqchip(&chip->gpio_chip,
+					     &max732x_irq_chip,
+					     client->irq,
+					     NULL);
+	}
+
+	return 0;
+}
+
+#else /* CONFIG_GPIO_MAX732X_IRQ */
+static int max732x_irq_setup(struct max732x_chip *chip,
+			     const struct i2c_device_id *id)
+{
+	struct i2c_client *client = chip->client;
+	struct max732x_platform_data *pdata = dev_get_platdata(&client->dev);
+	int has_irq = max732x_features[id->driver_data] >> 32;
+
+	if (((pdata && pdata->irq_base) || client->irq) && has_irq != INT_NONE)
+		dev_warn(&client->dev, "interrupt support not compiled in\n");
+
+	return 0;
+}
+#endif
+
+static int max732x_setup_gpio(struct max732x_chip *chip,
+					const struct i2c_device_id *id,
+					unsigned gpio_start)
+{
+	struct gpio_chip *gc = &chip->gpio_chip;
+	uint32_t id_data = (uint32_t)max732x_features[id->driver_data];
+	int i, port = 0;
+
+	for (i = 0; i < 16; i++, id_data >>= 2) {
+		unsigned int mask = 1 << port;
+
+		switch (id_data & 0x3) {
+		case PORT_OUTPUT:
+			chip->dir_output |= mask;
+			break;
+		case PORT_INPUT:
+			chip->dir_input |= mask;
+			break;
+		case PORT_OPENDRAIN:
+			chip->dir_output |= mask;
+			chip->dir_input |= mask;
+			break;
+		default:
+			continue;
+		}
+
+		if (i < 8)
+			chip->mask_group_a |= mask;
+		port++;
+	}
+
+	if (chip->dir_input)
+		gc->direction_input = max732x_gpio_direction_input;
+	if (chip->dir_output) {
+		gc->direction_output = max732x_gpio_direction_output;
+		gc->set = max732x_gpio_set_value;
+		gc->set_multiple = max732x_gpio_set_multiple;
+	}
+	gc->get = max732x_gpio_get_value;
+	gc->can_sleep = true;
+
+	gc->base = gpio_start;
+	gc->ngpio = port;
+	gc->label = chip->client->name;
+	gc->owner = THIS_MODULE;
+
+	return port;
+}
+
+static struct max732x_platform_data *of_gpio_max732x(struct device *dev)
+{
+	struct max732x_platform_data *pdata;
+
+	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return NULL;
+
+	pdata->gpio_base = -1;
+
+	return pdata;
+}
+
+static int max732x_probe(struct i2c_client *client,
+				   const struct i2c_device_id *id)
+{
+	struct max732x_platform_data *pdata;
+	struct device_node *node;
+	struct max732x_chip *chip;
+	struct i2c_client *c;
+	uint16_t addr_a, addr_b;
+	int ret, nr_port;
+
+	pdata = dev_get_platdata(&client->dev);
+	node = client->dev.of_node;
+
+	if (!pdata && node)
+		pdata = of_gpio_max732x(&client->dev);
+
+	if (!pdata) {
+		dev_dbg(&client->dev, "no platform data\n");
+		return -EINVAL;
+	}
+
+	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
+	if (chip == NULL)
+		return -ENOMEM;
+	chip->client = client;
+
+	nr_port = max732x_setup_gpio(chip, id, pdata->gpio_base);
+	chip->gpio_chip.dev = &client->dev;
+
+	addr_a = (client->addr & 0x0f) | 0x60;
+	addr_b = (client->addr & 0x0f) | 0x50;
+
+	switch (client->addr & 0x70) {
+	case 0x60:
+		chip->client_group_a = client;
+		if (nr_port > 8) {
+			c = i2c_new_dummy(client->adapter, addr_b);
+			chip->client_group_b = chip->client_dummy = c;
+		}
+		break;
+	case 0x50:
+		chip->client_group_b = client;
+		if (nr_port > 8) {
+			c = i2c_new_dummy(client->adapter, addr_a);
+			chip->client_group_a = chip->client_dummy = c;
+		}
+		break;
+	default:
+		dev_err(&client->dev, "invalid I2C address specified %02x\n",
+				client->addr);
+		ret = -EINVAL;
+		goto out_failed;
+	}
+
+	if (nr_port > 8 && !chip->client_dummy) {
+		dev_err(&client->dev,
+			"Failed to allocate second group I2C device\n");
+		ret = -ENODEV;
+		goto out_failed;
+	}
+
+	mutex_init(&chip->lock);
+
+	max732x_readb(chip, is_group_a(chip, 0), &chip->reg_out[0]);
+	if (nr_port > 8)
+		max732x_readb(chip, is_group_a(chip, 8), &chip->reg_out[1]);
+
+	ret = gpiochip_add(&chip->gpio_chip);
+	if (ret)
+		goto out_failed;
+
+	ret = max732x_irq_setup(chip, id);
+	if (ret) {
+		gpiochip_remove(&chip->gpio_chip);
+		goto out_failed;
+	}
+
+	if (pdata && pdata->setup) {
+		ret = pdata->setup(client, chip->gpio_chip.base,
+				chip->gpio_chip.ngpio, pdata->context);
+		if (ret < 0)
+			dev_warn(&client->dev, "setup failed, %d\n", ret);
+	}
+
+	i2c_set_clientdata(client, chip);
+	return 0;
+
+out_failed:
+	if (chip->client_dummy)
+		i2c_unregister_device(chip->client_dummy);
+	return ret;
+}
+
+static int max732x_remove(struct i2c_client *client)
+{
+	struct max732x_platform_data *pdata = dev_get_platdata(&client->dev);
+	struct max732x_chip *chip = i2c_get_clientdata(client);
+
+	if (pdata && pdata->teardown) {
+		int ret;
+
+		ret = pdata->teardown(client, chip->gpio_chip.base,
+				chip->gpio_chip.ngpio, pdata->context);
+		if (ret < 0) {
+			dev_err(&client->dev, "%s failed, %d\n",
+					"teardown", ret);
+			return ret;
+		}
+	}
+
+	gpiochip_remove(&chip->gpio_chip);
+
+	/* unregister any dummy i2c_client */
+	if (chip->client_dummy)
+		i2c_unregister_device(chip->client_dummy);
+
+	return 0;
+}
+
+static struct i2c_driver max732x_driver = {
+	.driver = {
+		.name		= "max732x",
+		.owner		= THIS_MODULE,
+		.of_match_table	= of_match_ptr(max732x_of_table),
+	},
+	.probe		= max732x_probe,
+	.remove		= max732x_remove,
+	.id_table	= max732x_id,
+};
+
+static int __init max732x_init(void)
+{
+	return i2c_add_driver(&max732x_driver);
+}
+/* register after i2c postcore initcall and before
+ * subsys initcalls that may rely on these GPIOs
+ */
+subsys_initcall(max732x_init);
+
+static void __exit max732x_exit(void)
+{
+	i2c_del_driver(&max732x_driver);
+}
+module_exit(max732x_exit);
+
+MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
+MODULE_DESCRIPTION("GPIO expander driver for MAX732X");
+MODULE_LICENSE("GPL");