gpio: reorganize drivers

Sort the gpio makefile and enforce the naming convention gpio-*.c for
gpio drivers.

v2: cleaned up filenames in Kconfig and comment blocks
v3: fixup use of BASIC_MMIO to GENERIC_GPIO for mxc

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 768 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
new file mode 100644
index 000000000000..a610864b7e13
--- /dev/null
+++ b/drivers/gpio/gpio-pca953x.c
@@ -0,0 +1,768 @@
+/*
+ *  PCA953x 4/8/16 bit I/O ports
+ *
+ *  Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
+ *  Copyright (C) 2007 Marvell International Ltd.
+ *
+ *  Derived from drivers/i2c/chips/pca9539.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/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/i2c.h>
+#include <linux/i2c/pca953x.h>
+#include <linux/slab.h>
+#ifdef CONFIG_OF_GPIO
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
+#endif
+
+#define PCA953X_INPUT           0
+#define PCA953X_OUTPUT          1
+#define PCA953X_INVERT          2
+#define PCA953X_DIRECTION       3
+
+#define PCA957X_IN              0
+#define PCA957X_INVRT           1
+#define PCA957X_BKEN            2
+#define PCA957X_PUPD            3
+#define PCA957X_CFG             4
+#define PCA957X_OUT             5
+#define PCA957X_MSK             6
+#define PCA957X_INTS            7
+
+#define PCA_GPIO_MASK           0x00FF
+#define PCA_INT                 0x0100
+#define PCA953X_TYPE            0x1000
+#define PCA957X_TYPE            0x2000
+
+static const struct i2c_device_id pca953x_id[] = {
+        { "pca9534", 8  | PCA953X_TYPE | PCA_INT, },
+        { "pca9535", 16 | PCA953X_TYPE | PCA_INT, },
+        { "pca9536", 4  | PCA953X_TYPE, },
+        { "pca9537", 4  | PCA953X_TYPE | PCA_INT, },
+        { "pca9538", 8  | PCA953X_TYPE | PCA_INT, },
+        { "pca9539", 16 | PCA953X_TYPE | PCA_INT, },
+        { "pca9554", 8  | PCA953X_TYPE | PCA_INT, },
+        { "pca9555", 16 | PCA953X_TYPE | PCA_INT, },
+        { "pca9556", 8  | PCA953X_TYPE, },
+        { "pca9557", 8  | PCA953X_TYPE, },
+        { "pca9574", 8  | PCA957X_TYPE | PCA_INT, },
+        { "pca9575", 16 | PCA957X_TYPE | PCA_INT, },
+
+        { "max7310", 8  | PCA953X_TYPE, },
+        { "max7312", 16 | PCA953X_TYPE | PCA_INT, },
+        { "max7313", 16 | PCA953X_TYPE | PCA_INT, },
+        { "max7315", 8  | PCA953X_TYPE | PCA_INT, },
+        { "pca6107", 8  | PCA953X_TYPE | PCA_INT, },
+        { "tca6408", 8  | PCA953X_TYPE | PCA_INT, },
+        { "tca6416", 16 | PCA953X_TYPE | PCA_INT, },
+        /* NYET:  { "tca6424", 24, }, */
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, pca953x_id);
+
+struct pca953x_chip {
+        unsigned gpio_start;
+        uint16_t reg_output;
+        uint16_t reg_direction;
+        struct mutex i2c_lock;
+
+#ifdef CONFIG_GPIO_PCA953X_IRQ
+        struct mutex irq_lock;
+        uint16_t irq_mask;
+        uint16_t irq_stat;
+        uint16_t irq_trig_raise;
+        uint16_t irq_trig_fall;
+        int      irq_base;
+#endif
+
+        struct i2c_client *client;
+        struct pca953x_platform_data *dyn_pdata;
+        struct gpio_chip gpio_chip;
+        const char *const *names;
+        int     chip_type;
+};
+
+static int pca953x_write_reg(struct pca953x_chip *chip, int reg, uint16_t val)
+{
+        int ret = 0;
+
+        if (chip->gpio_chip.ngpio <= 8)
+                ret = i2c_smbus_write_byte_data(chip->client, reg, val);
+        else {
+                switch (chip->chip_type) {
+                case PCA953X_TYPE:
+                        ret = i2c_smbus_write_word_data(chip->client,
+                                                        reg << 1, val);
+                        break;
+                case PCA957X_TYPE:
+                        ret = i2c_smbus_write_byte_data(chip->client, reg << 1,
+                                                        val & 0xff);
+                        if (ret < 0)
+                                break;
+                        ret = i2c_smbus_write_byte_data(chip->client,
+                                                        (reg << 1) + 1,
+                                                        (val & 0xff00) >> 8);
+                        break;
+                }
+        }
+
+        if (ret < 0) {
+                dev_err(&chip->client->dev, "failed writing register\n");
+                return ret;
+        }
+
+        return 0;
+}
+
+static int pca953x_read_reg(struct pca953x_chip *chip, int reg, uint16_t *val)
+{
+        int ret;
+
+        if (chip->gpio_chip.ngpio <= 8)
+                ret = i2c_smbus_read_byte_data(chip->client, reg);
+        else
+                ret = i2c_smbus_read_word_data(chip->client, reg << 1);
+
+        if (ret < 0) {
+                dev_err(&chip->client->dev, "failed reading register\n");
+                return ret;
+        }
+
+        *val = (uint16_t)ret;
+        return 0;
+}
+
+static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
+{
+        struct pca953x_chip *chip;
+        uint16_t reg_val;
+        int ret, offset = 0;
+
+        chip = container_of(gc, struct pca953x_chip, gpio_chip);
+
+        mutex_lock(&chip->i2c_lock);
+        reg_val = chip->reg_direction | (1u << off);
+
+        switch (chip->chip_type) {
+        case PCA953X_TYPE:
+                offset = PCA953X_DIRECTION;
+                break;
+        case PCA957X_TYPE:
+                offset = PCA957X_CFG;
+                break;
+        }
+        ret = pca953x_write_reg(chip, offset, reg_val);
+        if (ret)
+                goto exit;
+
+        chip->reg_direction = reg_val;
+        ret = 0;
+exit:
+        mutex_unlock(&chip->i2c_lock);
+        return ret;
+}
+
+static int pca953x_gpio_direction_output(struct gpio_chip *gc,
+                unsigned off, int val)
+{
+        struct pca953x_chip *chip;
+        uint16_t reg_val;
+        int ret, offset = 0;
+
+        chip = container_of(gc, struct pca953x_chip, gpio_chip);
+
+        mutex_lock(&chip->i2c_lock);
+        /* set output level */
+        if (val)
+                reg_val = chip->reg_output | (1u << off);
+        else
+                reg_val = chip->reg_output & ~(1u << off);
+
+        switch (chip->chip_type) {
+        case PCA953X_TYPE:
+                offset = PCA953X_OUTPUT;
+                break;
+        case PCA957X_TYPE:
+                offset = PCA957X_OUT;
+                break;
+        }
+        ret = pca953x_write_reg(chip, offset, reg_val);
+        if (ret)
+                goto exit;
+
+        chip->reg_output = reg_val;
+
+        /* then direction */
+        reg_val = chip->reg_direction & ~(1u << off);
+        switch (chip->chip_type) {
+        case PCA953X_TYPE:
+                offset = PCA953X_DIRECTION;
+                break;
+        case PCA957X_TYPE:
+                offset = PCA957X_CFG;
+                break;
+        }
+        ret = pca953x_write_reg(chip, offset, reg_val);
+        if (ret)
+                goto exit;
+
+        chip->reg_direction = reg_val;
+        ret = 0;
+exit:
+        mutex_unlock(&chip->i2c_lock);
+        return ret;
+}
+
+static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off)
+{
+        struct pca953x_chip *chip;
+        uint16_t reg_val;
+        int ret, offset = 0;
+
+        chip = container_of(gc, struct pca953x_chip, gpio_chip);
+
+        mutex_lock(&chip->i2c_lock);
+        switch (chip->chip_type) {
+        case PCA953X_TYPE:
+                offset = PCA953X_INPUT;
+                break;
+        case PCA957X_TYPE:
+                offset = PCA957X_IN;
+                break;
+        }
+        ret = pca953x_read_reg(chip, offset, &reg_val);
+        mutex_unlock(&chip->i2c_lock);
+        if (ret < 0) {
+                /* NOTE:  diagnostic already emitted; that's all we should
+                 * do unless gpio_*_value_cansleep() calls become different
+                 * from their nonsleeping siblings (and report faults).
+                 */
+                return 0;
+        }
+
+        return (reg_val & (1u << off)) ? 1 : 0;
+}
+
+static void pca953x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
+{
+        struct pca953x_chip *chip;
+        uint16_t reg_val;
+        int ret, offset = 0;
+
+        chip = container_of(gc, struct pca953x_chip, gpio_chip);
+
+        mutex_lock(&chip->i2c_lock);
+        if (val)
+                reg_val = chip->reg_output | (1u << off);
+        else
+                reg_val = chip->reg_output & ~(1u << off);
+
+        switch (chip->chip_type) {
+        case PCA953X_TYPE:
+                offset = PCA953X_OUTPUT;
+                break;
+        case PCA957X_TYPE:
+                offset = PCA957X_OUT;
+                break;
+        }
+        ret = pca953x_write_reg(chip, offset, reg_val);
+        if (ret)
+                goto exit;
+
+        chip->reg_output = reg_val;
+exit:
+        mutex_unlock(&chip->i2c_lock);
+}
+
+static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
+{
+        struct gpio_chip *gc;
+
+        gc = &chip->gpio_chip;
+
+        gc->direction_input  = pca953x_gpio_direction_input;
+        gc->direction_output = pca953x_gpio_direction_output;
+        gc->get = pca953x_gpio_get_value;
+        gc->set = pca953x_gpio_set_value;
+        gc->can_sleep = 1;
+
+        gc->base = chip->gpio_start;
+        gc->ngpio = gpios;
+        gc->label = chip->client->name;
+        gc->dev = &chip->client->dev;
+        gc->owner = THIS_MODULE;
+        gc->names = chip->names;
+}
+
+#ifdef CONFIG_GPIO_PCA953X_IRQ
+static int pca953x_gpio_to_irq(struct gpio_chip *gc, unsigned off)
+{
+        struct pca953x_chip *chip;
+
+        chip = container_of(gc, struct pca953x_chip, gpio_chip);
+        return chip->irq_base + off;
+}
+
+static void pca953x_irq_mask(struct irq_data *d)
+{
+        struct pca953x_chip *chip = irq_data_get_irq_chip_data(d);
+
+        chip->irq_mask &= ~(1 << (d->irq - chip->irq_base));
+}
+
+static void pca953x_irq_unmask(struct irq_data *d)
+{
+        struct pca953x_chip *chip = irq_data_get_irq_chip_data(d);
+
+        chip->irq_mask |= 1 << (d->irq - chip->irq_base);
+}
+
+static void pca953x_irq_bus_lock(struct irq_data *d)
+{
+        struct pca953x_chip *chip = irq_data_get_irq_chip_data(d);
+
+        mutex_lock(&chip->irq_lock);
+}
+
+static void pca953x_irq_bus_sync_unlock(struct irq_data *d)
+{
+        struct pca953x_chip *chip = irq_data_get_irq_chip_data(d);
+        uint16_t new_irqs;
+        uint16_t level;
+
+        /* Look for any newly setup interrupt */
+        new_irqs = chip->irq_trig_fall | chip->irq_trig_raise;
+        new_irqs &= ~chip->reg_direction;
+
+        while (new_irqs) {
+                level = __ffs(new_irqs);
+                pca953x_gpio_direction_input(&chip->gpio_chip, level);
+                new_irqs &= ~(1 << level);
+        }
+
+        mutex_unlock(&chip->irq_lock);
+}
+
+static int pca953x_irq_set_type(struct irq_data *d, unsigned int type)
+{
+        struct pca953x_chip *chip = irq_data_get_irq_chip_data(d);
+        uint16_t level = d->irq - chip->irq_base;
+        uint16_t mask = 1 << level;
+
+        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 pca953x_irq_chip = {
+        .name                   = "pca953x",
+        .irq_mask               = pca953x_irq_mask,
+        .irq_unmask             = pca953x_irq_unmask,
+        .irq_bus_lock           = pca953x_irq_bus_lock,
+        .irq_bus_sync_unlock    = pca953x_irq_bus_sync_unlock,
+        .irq_set_type           = pca953x_irq_set_type,
+};
+
+static uint16_t pca953x_irq_pending(struct pca953x_chip *chip)
+{
+        uint16_t cur_stat;
+        uint16_t old_stat;
+        uint16_t pending;
+        uint16_t trigger;
+        int ret, offset = 0;
+
+        switch (chip->chip_type) {
+        case PCA953X_TYPE:
+                offset = PCA953X_INPUT;
+                break;
+        case PCA957X_TYPE:
+                offset = PCA957X_IN;
+                break;
+        }
+        ret = pca953x_read_reg(chip, offset, &cur_stat);
+        if (ret)
+                return 0;
+
+        /* Remove output pins from the equation */
+        cur_stat &= chip->reg_direction;
+
+        old_stat = chip->irq_stat;
+        trigger = (cur_stat ^ old_stat) & chip->irq_mask;
+
+        if (!trigger)
+                return 0;
+
+        chip->irq_stat = cur_stat;
+
+        pending = (old_stat & chip->irq_trig_fall) |
+                  (cur_stat & chip->irq_trig_raise);
+        pending &= trigger;
+
+        return pending;
+}
+
+static irqreturn_t pca953x_irq_handler(int irq, void *devid)
+{
+        struct pca953x_chip *chip = devid;
+        uint16_t pending;
+        uint16_t level;
+
+        pending = pca953x_irq_pending(chip);
+
+        if (!pending)
+                return IRQ_HANDLED;
+
+        do {
+                level = __ffs(pending);
+                generic_handle_irq(level + chip->irq_base);
+
+                pending &= ~(1 << level);
+        } while (pending);
+
+        return IRQ_HANDLED;
+}
+
+static int pca953x_irq_setup(struct pca953x_chip *chip,
+                             const struct i2c_device_id *id)
+{
+        struct i2c_client *client = chip->client;
+        struct pca953x_platform_data *pdata = client->dev.platform_data;
+        int ret, offset = 0;
+
+        if (pdata->irq_base != -1
+                        && (id->driver_data & PCA_INT)) {
+                int lvl;
+
+                switch (chip->chip_type) {
+                case PCA953X_TYPE:
+                        offset = PCA953X_INPUT;
+                        break;
+                case PCA957X_TYPE:
+                        offset = PCA957X_IN;
+                        break;
+                }
+                ret = pca953x_read_reg(chip, offset, &chip->irq_stat);
+                if (ret)
+                        goto out_failed;
+
+                /*
+                 * There is no way to know which GPIO line generated the
+                 * interrupt.  We have to rely on the previous read for
+                 * this purpose.
+                 */
+                chip->irq_stat &= chip->reg_direction;
+                chip->irq_base = pdata->irq_base;
+                mutex_init(&chip->irq_lock);
+
+                for (lvl = 0; lvl < chip->gpio_chip.ngpio; lvl++) {
+                        int irq = lvl + chip->irq_base;
+
+                        irq_set_chip_data(irq, chip);
+                        irq_set_chip_and_handler(irq, &pca953x_irq_chip,
+                                                 handle_simple_irq);
+#ifdef CONFIG_ARM
+                        set_irq_flags(irq, IRQF_VALID);
+#else
+                        irq_set_noprobe(irq);
+#endif
+                }
+
+                ret = request_threaded_irq(client->irq,
+                                           NULL,
+                                           pca953x_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);
+                        goto out_failed;
+                }
+
+                chip->gpio_chip.to_irq = pca953x_gpio_to_irq;
+        }
+
+        return 0;
+
+out_failed:
+        chip->irq_base = -1;
+        return ret;
+}
+
+static void pca953x_irq_teardown(struct pca953x_chip *chip)
+{
+        if (chip->irq_base != -1)
+                free_irq(chip->client->irq, chip);
+}
+#else /* CONFIG_GPIO_PCA953X_IRQ */
+static int pca953x_irq_setup(struct pca953x_chip *chip,
+                             const struct i2c_device_id *id)
+{
+        struct i2c_client *client = chip->client;
+        struct pca953x_platform_data *pdata = client->dev.platform_data;
+
+        if (pdata->irq_base != -1 && (id->driver_data & PCA_INT))
+                dev_warn(&client->dev, "interrupt support not compiled in\n");
+
+        return 0;
+}
+
+static void pca953x_irq_teardown(struct pca953x_chip *chip)
+{
+}
+#endif
+
+/*
+ * Handlers for alternative sources of platform_data
+ */
+#ifdef CONFIG_OF_GPIO
+/*
+ * Translate OpenFirmware node properties into platform_data
+ */
+static struct pca953x_platform_data *
+pca953x_get_alt_pdata(struct i2c_client *client)
+{
+        struct pca953x_platform_data *pdata;
+        struct device_node *node;
+        const __be32 *val;
+        int size;
+
+        node = client->dev.of_node;
+        if (node == NULL)
+                return NULL;
+
+        pdata = kzalloc(sizeof(struct pca953x_platform_data), GFP_KERNEL);
+        if (pdata == NULL) {
+                dev_err(&client->dev, "Unable to allocate platform_data\n");
+                return NULL;
+        }
+
+        pdata->gpio_base = -1;
+        val = of_get_property(node, "linux,gpio-base", &size);
+        if (val) {
+                if (size != sizeof(*val))
+                        dev_warn(&client->dev, "%s: wrong linux,gpio-base\n",
+                                 node->full_name);
+                else
+                        pdata->gpio_base = be32_to_cpup(val);
+        }
+
+        val = of_get_property(node, "polarity", NULL);
+        if (val)
+                pdata->invert = *val;
+
+        return pdata;
+}
+#else
+static struct pca953x_platform_data *
+pca953x_get_alt_pdata(struct i2c_client *client)
+{
+        return NULL;
+}
+#endif
+
+static int __devinit device_pca953x_init(struct pca953x_chip *chip, int invert)
+{
+        int ret;
+
+        ret = pca953x_read_reg(chip, PCA953X_OUTPUT, &chip->reg_output);
+        if (ret)
+                goto out;
+
+        ret = pca953x_read_reg(chip, PCA953X_DIRECTION,
+                               &chip->reg_direction);
+        if (ret)
+                goto out;
+
+        /* set platform specific polarity inversion */
+        ret = pca953x_write_reg(chip, PCA953X_INVERT, invert);
+        if (ret)
+                goto out;
+        return 0;
+out:
+        return ret;
+}
+
+static int __devinit device_pca957x_init(struct pca953x_chip *chip, int invert)
+{
+        int ret;
+        uint16_t val = 0;
+
+        /* Let every port in proper state, that could save power */
+        pca953x_write_reg(chip, PCA957X_PUPD, 0x0);
+        pca953x_write_reg(chip, PCA957X_CFG, 0xffff);
+        pca953x_write_reg(chip, PCA957X_OUT, 0x0);
+
+        ret = pca953x_read_reg(chip, PCA957X_IN, &val);
+        if (ret)
+                goto out;
+        ret = pca953x_read_reg(chip, PCA957X_OUT, &chip->reg_output);
+        if (ret)
+                goto out;
+        ret = pca953x_read_reg(chip, PCA957X_CFG, &chip->reg_direction);
+        if (ret)
+                goto out;
+
+        /* set platform specific polarity inversion */
+        pca953x_write_reg(chip, PCA957X_INVRT, invert);
+
+        /* To enable register 6, 7 to controll pull up and pull down */
+        pca953x_write_reg(chip, PCA957X_BKEN, 0x202);
+
+        return 0;
+out:
+        return ret;
+}
+
+static int __devinit pca953x_probe(struct i2c_client *client,
+                                   const struct i2c_device_id *id)
+{
+        struct pca953x_platform_data *pdata;
+        struct pca953x_chip *chip;
+        int ret = 0;
+
+        chip = kzalloc(sizeof(struct pca953x_chip), GFP_KERNEL);
+        if (chip == NULL)
+                return -ENOMEM;
+
+        pdata = client->dev.platform_data;
+        if (pdata == NULL) {
+                pdata = pca953x_get_alt_pdata(client);
+                /*
+                 * Unlike normal platform_data, this is allocated
+                 * dynamically and must be freed in the driver
+                 */
+                chip->dyn_pdata = pdata;
+        }
+
+        if (pdata == NULL) {
+                dev_dbg(&client->dev, "no platform data\n");
+                ret = -EINVAL;
+                goto out_failed;
+        }
+
+        chip->client = client;
+
+        chip->gpio_start = pdata->gpio_base;
+
+        chip->names = pdata->names;
+        chip->chip_type = id->driver_data & (PCA953X_TYPE | PCA957X_TYPE);
+
+        mutex_init(&chip->i2c_lock);
+
+        /* initialize cached registers from their original values.
+         * we can't share this chip with another i2c master.
+         */
+        pca953x_setup_gpio(chip, id->driver_data & PCA_GPIO_MASK);
+
+        if (chip->chip_type == PCA953X_TYPE)
+                device_pca953x_init(chip, pdata->invert);
+        else if (chip->chip_type == PCA957X_TYPE)
+                device_pca957x_init(chip, pdata->invert);
+        else
+                goto out_failed;
+
+        ret = pca953x_irq_setup(chip, id);
+        if (ret)
+                goto out_failed;
+
+        ret = gpiochip_add(&chip->gpio_chip);
+        if (ret)
+                goto out_failed_irq;
+
+        if (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_irq:
+        pca953x_irq_teardown(chip);
+out_failed:
+        kfree(chip->dyn_pdata);
+        kfree(chip);
+        return ret;
+}
+
+static int pca953x_remove(struct i2c_client *client)
+{
+        struct pca953x_platform_data *pdata = client->dev.platform_data;
+        struct pca953x_chip *chip = i2c_get_clientdata(client);
+        int ret = 0;
+
+        if (pdata->teardown) {
+                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;
+                }
+        }
+
+        ret = gpiochip_remove(&chip->gpio_chip);
+        if (ret) {
+                dev_err(&client->dev, "%s failed, %d\n",
+                                "gpiochip_remove()", ret);
+                return ret;
+        }
+
+        pca953x_irq_teardown(chip);
+        kfree(chip->dyn_pdata);
+        kfree(chip);
+        return 0;
+}
+
+static struct i2c_driver pca953x_driver = {
+        .driver = {
+                .name   = "pca953x",
+        },
+        .probe          = pca953x_probe,
+        .remove         = pca953x_remove,
+        .id_table       = pca953x_id,
+};
+
+static int __init pca953x_init(void)
+{
+        return i2c_add_driver(&pca953x_driver);
+}
+/* register after i2c postcore initcall and before
+ * subsys initcalls that may rely on these GPIOs
+ */
+subsys_initcall(pca953x_init);
+
+static void __exit pca953x_exit(void)
+{
+        i2c_del_driver(&pca953x_driver);
+}
+module_exit(pca953x_exit);
+
+MODULE_AUTHOR("eric miao <eric.miao@marvell.com>");
+MODULE_DESCRIPTION("GPIO expander driver for PCA953x");
+MODULE_LICENSE("GPL");