/*
 * GPIO Chip driver for Analog Devices
 * ADP5588/ADP5587 I/O Expander and QWERTY Keypad Controller
 *
 * Copyright 2009-2010 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/irq.h>

#include <linux/i2c/adp5588.h>

#define DRV_NAME        "adp5588-gpio"

/*
 * Early pre 4.0 Silicon required to delay readout by at least 25ms,
 * since the Event Counter Register updated 25ms after the interrupt
 * asserted.
 */
#define WA_DELAYED_READOUT_REVID(rev)   ((rev) < 4)

struct adp5588_gpio {
        struct i2c_client *client;
        struct gpio_chip gpio_chip;
        struct mutex lock;      /* protect cached dir, dat_out */
        /* protect serialized access to the interrupt controller bus */
        struct mutex irq_lock;
        unsigned gpio_start;
        unsigned irq_base;
        uint8_t dat_out[3];
        uint8_t dir[3];
        uint8_t int_lvl[3];
        uint8_t int_en[3];
        uint8_t irq_mask[3];
        uint8_t irq_stat[3];
};

static int adp5588_gpio_read(struct i2c_client *client, u8 reg)
{
        int ret = i2c_smbus_read_byte_data(client, reg);

        if (ret < 0)
                dev_err(&client->dev, "Read Error\n");

        return ret;
}

static int adp5588_gpio_write(struct i2c_client *client, u8 reg, u8 val)
{
        int ret = i2c_smbus_write_byte_data(client, reg, val);

        if (ret < 0)
                dev_err(&client->dev, "Write Error\n");

        return ret;
}

static int adp5588_gpio_get_value(struct gpio_chip *chip, unsigned off)
{
        struct adp5588_gpio *dev =
            container_of(chip, struct adp5588_gpio, gpio_chip);
        unsigned bank = ADP5588_BANK(off);
        unsigned bit = ADP5588_BIT(off);
        int val;

        mutex_lock(&dev->lock);

        if (dev->dir[bank] & bit)
                val = dev->dat_out[bank];
        else
                val = adp5588_gpio_read(dev->client, GPIO_DAT_STAT1 + bank);

        mutex_unlock(&dev->lock);

        return !!(val & bit);
}

static void adp5588_gpio_set_value(struct gpio_chip *chip,
                                   unsigned off, int val)
{
        unsigned bank, bit;
        struct adp5588_gpio *dev =
            container_of(chip, struct adp5588_gpio, gpio_chip);

        bank = ADP5588_BANK(off);
        bit = ADP5588_BIT(off);

        mutex_lock(&dev->lock);
        if (val)
                dev->dat_out[bank] |= bit;
        else
                dev->dat_out[bank] &= ~bit;

        adp5588_gpio_write(dev->client, GPIO_DAT_OUT1 + bank,
                           dev->dat_out[bank]);
        mutex_unlock(&dev->lock);
}

static int adp5588_gpio_direction_input(struct gpio_chip *chip, unsigned off)
{
        int ret;
        unsigned bank;
        struct adp5588_gpio *dev =
            container_of(chip, struct adp5588_gpio, gpio_chip);

        bank = ADP5588_BANK(off);

        mutex_lock(&dev->lock);
        dev->dir[bank] &= ~ADP5588_BIT(off);
        ret = adp5588_gpio_write(dev->client, GPIO_DIR1 + bank, dev->dir[bank]);
        mutex_unlock(&dev->lock);

        return ret;
}

static int adp5588_gpio_direction_output(struct gpio_chip *chip,
                                         unsigned off, int val)
{
        int ret;
        unsigned bank, bit;
        struct adp5588_gpio *dev =
            container_of(chip, struct adp5588_gpio, gpio_chip);

        bank = ADP5588_BANK(off);
        bit = ADP5588_BIT(off);

        mutex_lock(&dev->lock);
        dev->dir[bank] |= bit;

        if (val)
                dev->dat_out[bank] |= bit;
        else
                dev->dat_out[bank] &= ~bit;

        ret = adp5588_gpio_write(dev->client, GPIO_DAT_OUT1 + bank,
                                 dev->dat_out[bank]);
        ret |= adp5588_gpio_write(dev->client, GPIO_DIR1 + bank,
                                 dev->dir[bank]);
        mutex_unlock(&dev->lock);

        return ret;
}

#ifdef CONFIG_GPIO_ADP5588_IRQ
static int adp5588_gpio_to_irq(struct gpio_chip *chip, unsigned off)
{
        struct adp5588_gpio *dev =
                container_of(chip, struct adp5588_gpio, gpio_chip);
        return dev->irq_base + off;
}

static void adp5588_irq_bus_lock(struct irq_data *d)
{
        struct adp5588_gpio *dev = irq_data_get_irq_chip_data(d);

        mutex_lock(&dev->irq_lock);
}

 /*
  * genirq core code can issue chip->mask/unmask from atomic context.
  * This doesn't work for slow busses where an access needs to sleep.
  * bus_sync_unlock() is therefore called outside the atomic context,
  * syncs the current irq mask state with the slow external controller
  * and unlocks the bus.
  */

static void adp5588_irq_bus_sync_unlock(struct irq_data *d)
{
        struct adp5588_gpio *dev = irq_data_get_irq_chip_data(d);
        int i;

        for (i = 0; i <= ADP5588_BANK(ADP5588_MAXGPIO); i++)
                if (dev->int_en[i] ^ dev->irq_mask[i]) {
                        dev->int_en[i] = dev->irq_mask[i];
                        adp5588_gpio_write(dev->client, GPIO_INT_EN1 + i,
                                           dev->int_en[i]);
                }

        mutex_unlock(&dev->irq_lock);
}

static void adp5588_irq_mask(struct irq_data *d)
{
        struct adp5588_gpio *dev = irq_data_get_irq_chip_data(d);
        unsigned gpio = d->irq - dev->irq_base;

        dev->irq_mask[ADP5588_BANK(gpio)] &= ~ADP5588_BIT(gpio);
}

static void adp5588_irq_unmask(struct irq_data *d)
{
        struct adp5588_gpio *dev = irq_data_get_irq_chip_data(d);
        unsigned gpio = d->irq - dev->irq_base;

        dev->irq_mask[ADP5588_BANK(gpio)] |= ADP5588_BIT(gpio);
}

static int adp5588_irq_set_type(struct irq_data *d, unsigned int type)
{
        struct adp5588_gpio *dev = irq_data_get_irq_chip_data(d);
        uint16_t gpio = d->irq - dev->irq_base;
        unsigned bank, bit;

        if ((type & IRQ_TYPE_EDGE_BOTH)) {
                dev_err(&dev->client->dev, "irq %d: unsupported type %d\n",
                        d->irq, type);
                return -EINVAL;
        }

        bank = ADP5588_BANK(gpio);
        bit = ADP5588_BIT(gpio);

        if (type & IRQ_TYPE_LEVEL_HIGH)
                dev->int_lvl[bank] |= bit;
        else if (type & IRQ_TYPE_LEVEL_LOW)
                dev->int_lvl[bank] &= ~bit;
        else
                return -EINVAL;

        adp5588_gpio_direction_input(&dev->gpio_chip, gpio);
        adp5588_gpio_write(dev->client, GPIO_INT_LVL1 + bank,
                           dev->int_lvl[bank]);

        return 0;
}

static struct irq_chip adp5588_irq_chip = {
        .name                   = "adp5588",
        .irq_mask               = adp5588_irq_mask,
        .irq_unmask             = adp5588_irq_unmask,
        .irq_bus_lock           = adp5588_irq_bus_lock,
        .irq_bus_sync_unlock    = adp5588_irq_bus_sync_unlock,
        .irq_set_type           = adp5588_irq_set_type,
};

static int adp5588_gpio_read_intstat(struct i2c_client *client, u8 *buf)
{
        int ret = i2c_smbus_read_i2c_block_data(client, GPIO_INT_STAT1, 3, buf);

        if (ret < 0)
                dev_err(&client->dev, "Read INT_STAT Error\n");

        return ret;
}

static irqreturn_t adp5588_irq_handler(int irq, void *devid)
{
        struct adp5588_gpio *dev = devid;
        unsigned status, bank, bit, pending;
        int ret;
        status = adp5588_gpio_read(dev->client, INT_STAT);

        if (status & ADP5588_GPI_INT) {
                ret = adp5588_gpio_read_intstat(dev->client, dev->irq_stat);
                if (ret < 0)
                        memset(dev->irq_stat, 0, ARRAY_SIZE(dev->irq_stat));

                for (bank = 0, bit = 0; bank <= ADP5588_BANK(ADP5588_MAXGPIO);
                        bank++, bit = 0) {
                        pending = dev->irq_stat[bank] & dev->irq_mask[bank];

                        while (pending) {
                                if (pending & (1 << bit)) {
                                        handle_nested_irq(dev->irq_base +
                                                          (bank << 3) + bit);
                                        pending &= ~(1 << bit);

                                }
                                bit++;
                        }
                }
        }

        adp5588_gpio_write(dev->client, INT_STAT, status); /* Status is W1C */

        return IRQ_HANDLED;
}

static int adp5588_irq_setup(struct adp5588_gpio *dev)
{
        struct i2c_client *client = dev->client;
        struct adp5588_gpio_platform_data *pdata =
                        dev_get_platdata(&client->dev);
        unsigned gpio;
        int ret;

        adp5588_gpio_write(client, CFG, ADP5588_AUTO_INC);
        adp5588_gpio_write(client, INT_STAT, -1); /* status is W1C */
        adp5588_gpio_read_intstat(client, dev->irq_stat); /* read to clear */

        dev->irq_base = pdata->irq_base;
        mutex_init(&dev->irq_lock);

        for (gpio = 0; gpio < dev->gpio_chip.ngpio; gpio++) {
                int irq = gpio + dev->irq_base;
                irq_set_chip_data(irq, dev);
                irq_set_chip_and_handler(irq, &adp5588_irq_chip,
                                         handle_level_irq);
                irq_set_nested_thread(irq, 1);
#ifdef CONFIG_ARM
                /*
                 * ARM needs us to explicitly flag the IRQ as VALID,
                 * once we do so, it will also set the noprobe.
                 */
                set_irq_flags(irq, IRQF_VALID);
#else
                irq_set_noprobe(irq);
#endif
        }

        ret = request_threaded_irq(client->irq,
                                   NULL,
                                   adp5588_irq_handler,
                                   IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                                   dev_name(&client->dev), dev);
        if (ret) {
                dev_err(&client->dev, "failed to request irq %d\n",
                        client->irq);
                goto out;
        }

        dev->gpio_chip.to_irq = adp5588_gpio_to_irq;
        adp5588_gpio_write(client, CFG,
                ADP5588_AUTO_INC | ADP5588_INT_CFG | ADP5588_GPI_INT);

        return 0;

out:
        dev->irq_base = 0;
        return ret;
}

static void adp5588_irq_teardown(struct adp5588_gpio *dev)
{
        if (dev->irq_base)
                free_irq(dev->client->irq, dev);
}

#else
static int adp5588_irq_setup(struct adp5588_gpio *dev)
{
        struct i2c_client *client = dev->client;
        dev_warn(&client->dev, "interrupt support not compiled in\n");

        return 0;
}

static void adp5588_irq_teardown(struct adp5588_gpio *dev)
{
}
#endif /* CONFIG_GPIO_ADP5588_IRQ */

static int adp5588_gpio_probe(struct i2c_client *client,
                                        const struct i2c_device_id *id)
{
        struct adp5588_gpio_platform_data *pdata =
                        dev_get_platdata(&client->dev);
        struct adp5588_gpio *dev;
        struct gpio_chip *gc;
        int ret, i, revid;

        if (pdata == NULL) {
                dev_err(&client->dev, "missing platform data\n");
                return -ENODEV;
        }

        if (!i2c_check_functionality(client->adapter,
                                        I2C_FUNC_SMBUS_BYTE_DATA)) {
                dev_err(&client->dev, "SMBUS Byte Data not Supported\n");
                return -EIO;
        }

        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (dev == NULL)
                return -ENOMEM;

        dev->client = client;

        gc = &dev->gpio_chip;
        gc->direction_input = adp5588_gpio_direction_input;
        gc->direction_output = adp5588_gpio_direction_output;
        gc->get = adp5588_gpio_get_value;
        gc->set = adp5588_gpio_set_value;
        gc->can_sleep = true;

        gc->base = pdata->gpio_start;
        gc->ngpio = ADP5588_MAXGPIO;
        gc->label = client->name;
        gc->owner = THIS_MODULE;
        gc->names = pdata->names;

        mutex_init(&dev->lock);

        ret = adp5588_gpio_read(dev->client, DEV_ID);
        if (ret < 0)
                goto err;

        revid = ret & ADP5588_DEVICE_ID_MASK;

        for (i = 0, ret = 0; i <= ADP5588_BANK(ADP5588_MAXGPIO); i++) {
                dev->dat_out[i] = adp5588_gpio_read(client, GPIO_DAT_OUT1 + i);
                dev->dir[i] = adp5588_gpio_read(client, GPIO_DIR1 + i);
                ret |= adp5588_gpio_write(client, KP_GPIO1 + i, 0);
                ret |= adp5588_gpio_write(client, GPIO_PULL1 + i,
                                (pdata->pullup_dis_mask >> (8 * i)) & 0xFF);
                ret |= adp5588_gpio_write(client, GPIO_INT_EN1 + i, 0);
                if (ret)
                        goto err;
        }

        if (pdata->irq_base) {
                if (WA_DELAYED_READOUT_REVID(revid)) {
                        dev_warn(&client->dev, "GPIO int not supported\n");
                } else {
                        ret = adp5588_irq_setup(dev);
                        if (ret)
                                goto err;
                }
        }

        ret = gpiochip_add(&dev->gpio_chip);
        if (ret)
                goto err_irq;

        dev_info(&client->dev, "IRQ Base: %d Rev.: %d\n",
                        pdata->irq_base, revid);

        if (pdata->setup) {
                ret = pdata->setup(client, gc->base, gc->ngpio, pdata->context);
                if (ret < 0)
                        dev_warn(&client->dev, "setup failed, %d\n", ret);
        }

        i2c_set_clientdata(client, dev);

        return 0;

err_irq:
        adp5588_irq_teardown(dev);
err:
        kfree(dev);
        return ret;
}

static int adp5588_gpio_remove(struct i2c_client *client)
{
        struct adp5588_gpio_platform_data *pdata =
                        dev_get_platdata(&client->dev);
        struct adp5588_gpio *dev = i2c_get_clientdata(client);
        int ret;

        if (pdata->teardown) {
                ret = pdata->teardown(client,
                                      dev->gpio_chip.base, dev->gpio_chip.ngpio,
                                      pdata->context);
                if (ret < 0) {
                        dev_err(&client->dev, "teardown failed %d\n", ret);
                        return ret;
                }
        }

        if (dev->irq_base)
                free_irq(dev->client->irq, dev);

        gpiochip_remove(&dev->gpio_chip);

        kfree(dev);
        return 0;
}

static const struct i2c_device_id adp5588_gpio_id[] = {
        {DRV_NAME, 0},
        {}
};

MODULE_DEVICE_TABLE(i2c, adp5588_gpio_id);

static struct i2c_driver adp5588_gpio_driver = {
        .driver = {
                   .name = DRV_NAME,
                   },
        .probe = adp5588_gpio_probe,
        .remove = adp5588_gpio_remove,
        .id_table = adp5588_gpio_id,
};

module_i2c_driver(adp5588_gpio_driver);

MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
MODULE_DESCRIPTION("GPIO ADP5588 Driver");
MODULE_LICENSE("GPL");