/*
 * Retu/Tahvo MFD driver
 *
 * Copyright (C) 2004, 2005 Nokia Corporation
 *
 * Based on code written by Juha Yrjölä, David Weinehall and Mikko Ylinen.
 * Rewritten by Aaro Koskinen.
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License. See the file "COPYING" in the main directory of this
 * archive for more details.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/mfd/core.h>
#include <linux/mfd/retu.h>
#include <linux/interrupt.h>
#include <linux/moduleparam.h>

/* Registers */
#define RETU_REG_ASICR          0x00            /* ASIC ID and revision */
#define RETU_REG_ASICR_VILMA    (1 << 7)        /* Bit indicating Vilma */
#define RETU_REG_IDR            0x01            /* Interrupt ID */
#define RETU_REG_IMR            0x02            /* Interrupt mask (Retu) */
#define TAHVO_REG_IMR           0x03            /* Interrupt mask (Tahvo) */

/* Interrupt sources */
#define RETU_INT_PWR            0               /* Power button */

struct retu_dev {
        struct regmap                   *regmap;
        struct device                   *dev;
        struct mutex                    mutex;
        struct regmap_irq_chip_data     *irq_data;
};

static const struct resource retu_pwrbutton_res[] = {
        {
                .name   = "retu-pwrbutton",
                .start  = RETU_INT_PWR,
                .end    = RETU_INT_PWR,
                .flags  = IORESOURCE_IRQ,
        },
};

static const struct mfd_cell retu_devs[] = {
        {
                .name           = "retu-wdt"
        },
        {
                .name           = "retu-pwrbutton",
                .resources      = retu_pwrbutton_res,
                .num_resources  = ARRAY_SIZE(retu_pwrbutton_res),
        }
};

static const struct regmap_irq retu_irqs[] = {
        [RETU_INT_PWR] = {
                .mask = 1 << RETU_INT_PWR,
        }
};

static const struct regmap_irq_chip retu_irq_chip = {
        .name           = "RETU",
        .irqs           = retu_irqs,
        .num_irqs       = ARRAY_SIZE(retu_irqs),
        .num_regs       = 1,
        .status_base    = RETU_REG_IDR,
        .mask_base      = RETU_REG_IMR,
        .ack_base       = RETU_REG_IDR,
};

/* Retu device registered for the power off. */
static struct retu_dev *retu_pm_power_off;

static const struct resource tahvo_usb_res[] = {
        {
                .name   = "tahvo-usb",
                .start  = TAHVO_INT_VBUS,
                .end    = TAHVO_INT_VBUS,
                .flags  = IORESOURCE_IRQ,
        },
};

static const struct mfd_cell tahvo_devs[] = {
        {
                .name           = "tahvo-usb",
                .resources      = tahvo_usb_res,
                .num_resources  = ARRAY_SIZE(tahvo_usb_res),
        },
};

static const struct regmap_irq tahvo_irqs[] = {
        [TAHVO_INT_VBUS] = {
                .mask = 1 << TAHVO_INT_VBUS,
        }
};

static const struct regmap_irq_chip tahvo_irq_chip = {
        .name           = "TAHVO",
        .irqs           = tahvo_irqs,
        .num_irqs       = ARRAY_SIZE(tahvo_irqs),
        .num_regs       = 1,
        .status_base    = RETU_REG_IDR,
        .mask_base      = TAHVO_REG_IMR,
        .ack_base       = RETU_REG_IDR,
};

static const struct retu_data {
        char                    *chip_name;
        char                    *companion_name;
        const struct regmap_irq_chip    *irq_chip;
        const struct mfd_cell   *children;
        int                     nchildren;
} retu_data[] = {
        [0] = {
                .chip_name      = "Retu",
                .companion_name = "Vilma",
                .irq_chip       = &retu_irq_chip,
                .children       = retu_devs,
                .nchildren      = ARRAY_SIZE(retu_devs),
        },
        [1] = {
                .chip_name      = "Tahvo",
                .companion_name = "Betty",
                .irq_chip       = &tahvo_irq_chip,
                .children       = tahvo_devs,
                .nchildren      = ARRAY_SIZE(tahvo_devs),
        }
};

int retu_read(struct retu_dev *rdev, u8 reg)
{
        int ret;
        int value;

        mutex_lock(&rdev->mutex);
        ret = regmap_read(rdev->regmap, reg, &value);
        mutex_unlock(&rdev->mutex);

        return ret ? ret : value;
}
EXPORT_SYMBOL_GPL(retu_read);

int retu_write(struct retu_dev *rdev, u8 reg, u16 data)
{
        int ret;

        mutex_lock(&rdev->mutex);
        ret = regmap_write(rdev->regmap, reg, data);
        mutex_unlock(&rdev->mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(retu_write);

static void retu_power_off(void)
{
        struct retu_dev *rdev = retu_pm_power_off;
        int reg;

        mutex_lock(&retu_pm_power_off->mutex);

        /* Ignore power button state */
        regmap_read(rdev->regmap, RETU_REG_CC1, &reg);
        regmap_write(rdev->regmap, RETU_REG_CC1, reg | 2);

        /* Expire watchdog immediately */
        regmap_write(rdev->regmap, RETU_REG_WATCHDOG, 0);

        /* Wait for poweroff */
        for (;;)
                cpu_relax();

        mutex_unlock(&retu_pm_power_off->mutex);
}

static int retu_regmap_read(void *context, const void *reg, size_t reg_size,
                            void *val, size_t val_size)
{
        int ret;
        struct device *dev = context;
        struct i2c_client *i2c = to_i2c_client(dev);

        BUG_ON(reg_size != 1 || val_size != 2);

        ret = i2c_smbus_read_word_data(i2c, *(u8 const *)reg);
        if (ret < 0)
                return ret;

        *(u16 *)val = ret;
        return 0;
}

static int retu_regmap_write(void *context, const void *data, size_t count)
{
        u8 reg;
        u16 val;
        struct device *dev = context;
        struct i2c_client *i2c = to_i2c_client(dev);

        BUG_ON(count != sizeof(reg) + sizeof(val));
        memcpy(&reg, data, sizeof(reg));
        memcpy(&val, data + sizeof(reg), sizeof(val));
        return i2c_smbus_write_word_data(i2c, reg, val);
}

static const struct regmap_bus retu_bus = {
        .read = retu_regmap_read,
        .write = retu_regmap_write,
        .val_format_endian_default = REGMAP_ENDIAN_NATIVE,
};

static const struct regmap_config retu_config = {
        .reg_bits = 8,
        .val_bits = 16,
};

static int retu_probe(struct i2c_client *i2c)
{
        struct retu_data const *rdat;
        struct retu_dev *rdev;
        int ret;

        if (i2c->addr > ARRAY_SIZE(retu_data))
                return -ENODEV;
        rdat = &retu_data[i2c->addr - 1];

        rdev = devm_kzalloc(&i2c->dev, sizeof(*rdev), GFP_KERNEL);
        if (rdev == NULL)
                return -ENOMEM;

        i2c_set_clientdata(i2c, rdev);
        rdev->dev = &i2c->dev;
        mutex_init(&rdev->mutex);
        rdev->regmap = devm_regmap_init(&i2c->dev, &retu_bus, &i2c->dev,
                                        &retu_config);
        if (IS_ERR(rdev->regmap))
                return PTR_ERR(rdev->regmap);

        ret = retu_read(rdev, RETU_REG_ASICR);
        if (ret < 0) {
                dev_err(rdev->dev, "could not read %s revision: %d\n",
                        rdat->chip_name, ret);
                return ret;
        }

        dev_info(rdev->dev, "%s%s%s v%d.%d found\n", rdat->chip_name,
                 (ret & RETU_REG_ASICR_VILMA) ? " & " : "",
                 (ret & RETU_REG_ASICR_VILMA) ? rdat->companion_name : "",
                 (ret >> 4) & 0x7, ret & 0xf);

        /* Mask all interrupts. */
        ret = retu_write(rdev, rdat->irq_chip->mask_base, 0xffff);
        if (ret < 0)
                return ret;

        ret = regmap_add_irq_chip(rdev->regmap, i2c->irq, IRQF_ONESHOT, -1,
                                  rdat->irq_chip, &rdev->irq_data);
        if (ret < 0)
                return ret;

        ret = mfd_add_devices(rdev->dev, -1, rdat->children, rdat->nchildren,
                              NULL, regmap_irq_chip_get_base(rdev->irq_data),
                              NULL);
        if (ret < 0) {
                regmap_del_irq_chip(i2c->irq, rdev->irq_data);
                return ret;
        }

        if (i2c->addr == 1 && !pm_power_off) {
                retu_pm_power_off = rdev;
                pm_power_off      = retu_power_off;
        }

        return 0;
}

static void retu_remove(struct i2c_client *i2c)
{
        struct retu_dev *rdev = i2c_get_clientdata(i2c);

        if (retu_pm_power_off == rdev) {
                pm_power_off      = NULL;
                retu_pm_power_off = NULL;
        }
        mfd_remove_devices(rdev->dev);
        regmap_del_irq_chip(i2c->irq, rdev->irq_data);
}

static const struct i2c_device_id retu_id[] = {
        { "retu" },
        { "tahvo" },
        { }
};
MODULE_DEVICE_TABLE(i2c, retu_id);

static const struct of_device_id retu_of_match[] = {
        { .compatible = "nokia,retu" },
        { .compatible = "nokia,tahvo" },
        { }
};
MODULE_DEVICE_TABLE(of, retu_of_match);

static struct i2c_driver retu_driver = {
        .driver         = {
                .name = "retu-mfd",
                .of_match_table = retu_of_match,
        },
        .probe          = retu_probe,
        .remove         = retu_remove,
        .id_table       = retu_id,
};
module_i2c_driver(retu_driver);

MODULE_DESCRIPTION("Retu MFD driver");
MODULE_AUTHOR("Juha Yrjölä");
MODULE_AUTHOR("David Weinehall");
MODULE_AUTHOR("Mikko Ylinen");
MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
MODULE_LICENSE("GPL");