/*
 *  max732x.c - 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>
 *
 *  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.h>

#include <linux/i2c.h>
#include <linux/i2c/max732x.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.
 *
 * 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.
 *
 * 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 */

static const struct i2c_device_id max732x_id[] = {
        { "max7319", GROUP_A(IO_8I) },
        { "max7320", GROUP_B(IO_8O) },
        { "max7321", GROUP_A(IO_8P) },
        { "max7322", GROUP_A(IO_4I4O) },
        { "max7323", GROUP_A(IO_4P4O) },
        { "max7324", GROUP_A(IO_8I) | GROUP_B(IO_8O) },
        { "max7325", GROUP_A(IO_8P) | GROUP_B(IO_8O) },
        { "max7326", GROUP_A(IO_4I4O) | GROUP_B(IO_8O) },
        { "max7327", GROUP_A(IO_4P4O) | GROUP_B(IO_8O) },
        { },
};
MODULE_DEVICE_TABLE(i2c, max732x_id);

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];
};

static int max732x_write(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_read(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;
        uint8_t reg_val;
        int ret;

        chip = container_of(gc, struct max732x_chip, gpio_chip);

        ret = max732x_read(chip, is_group_a(chip, off), &reg_val);
        if (ret < 0)
                return 0;

        return reg_val & (1u << (off & 0x7));
}

static void max732x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
{
        struct max732x_chip *chip;
        uint8_t reg_out, mask = 1u << (off & 0x7);
        int ret;

        chip = container_of(gc, struct max732x_chip, gpio_chip);

        mutex_lock(&chip->lock);

        reg_out = (off > 7) ? chip->reg_out[1] : chip->reg_out[0];
        reg_out = (val) ? reg_out | mask : reg_out & ~mask;

        ret = max732x_write(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 int max732x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
{
        struct max732x_chip *chip;
        unsigned int mask = 1u << off;

        chip = container_of(gc, struct max732x_chip, gpio_chip);

        if ((mask & chip->dir_input) == 0) {
                dev_dbg(&chip->client->dev, "%s port %d is output only\n",
                        chip->client->name, off);
                return -EACCES;
        }

        return 0;
}

static int max732x_gpio_direction_output(struct gpio_chip *gc,
                unsigned off, int val)
{
        struct max732x_chip *chip;
        unsigned int mask = 1u << off;

        chip = container_of(gc, struct max732x_chip, gpio_chip);

        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;
}

static int __devinit 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 = 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->get = max732x_gpio_get_value;
        gc->can_sleep = 1;

        gc->base = gpio_start;
        gc->ngpio = port;
        gc->label = chip->client->name;
        gc->owner = THIS_MODULE;

        return port;
}

static int __devinit max732x_probe(struct i2c_client *client,
                                   const struct i2c_device_id *id)
{
        struct max732x_platform_data *pdata;
        struct max732x_chip *chip;
        struct i2c_client *c;
        uint16_t addr_a, addr_b;
        int ret, nr_port;

        pdata = client->dev.platform_data;
        if (pdata == NULL) {
                dev_dbg(&client->dev, "no platform data\n");
                return -EINVAL;
        }

        chip = kzalloc(sizeof(struct max732x_chip), GFP_KERNEL);
        if (chip == NULL)
                return -ENOMEM;
        chip->client = client;

        nr_port = max732x_setup_gpio(chip, id, pdata->gpio_base);

        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 > 7) {
                        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 > 7) {
                        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;
        }

        mutex_init(&chip->lock);

        max732x_read(chip, is_group_a(chip, 0), &chip->reg_out[0]);
        if (nr_port > 7)
                max732x_read(chip, is_group_a(chip, 8), &chip->reg_out[1]);

        ret = gpiochip_add(&chip->gpio_chip);
        if (ret)
                goto out_failed;

        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:
        kfree(chip);
        return ret;
}

static int __devexit max732x_remove(struct i2c_client *client)
{
        struct max732x_platform_data *pdata = client->dev.platform_data;
        struct max732x_chip *chip = i2c_get_clientdata(client);
        int ret;

        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;
        }

        /* unregister any dummy i2c_client */
        if (chip->client_dummy)
                i2c_unregister_device(chip->client_dummy);

        kfree(chip);
        return 0;
}

static struct i2c_driver max732x_driver = {
        .driver = {
                .name   = "max732x",
                .owner  = THIS_MODULE,
        },
        .probe          = max732x_probe,
        .remove         = __devexit_p(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");