/*
 *  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");