/*
 * Driver for ISSI IS31FL32xx family of I2C LED controllers
 *
 * Copyright 2015 Allworx Corp.
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Datasheets:
 *   http://www.issi.com/US/product-analog-fxled-driver.shtml
 *   http://www.si-en.com/product.asp?parentid=890
 */

#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>

/* Used to indicate a device has no such register */
#define IS31FL32XX_REG_NONE 0xFF

/* Software Shutdown bit in Shutdown Register */
#define IS31FL32XX_SHUTDOWN_SSD_ENABLE  0
#define IS31FL32XX_SHUTDOWN_SSD_DISABLE BIT(0)

/* IS31FL3216 has a number of unique registers */
#define IS31FL3216_CONFIG_REG 0x00
#define IS31FL3216_LIGHTING_EFFECT_REG 0x03
#define IS31FL3216_CHANNEL_CONFIG_REG 0x04

/* Software Shutdown bit in 3216 Config Register */
#define IS31FL3216_CONFIG_SSD_ENABLE  BIT(7)
#define IS31FL3216_CONFIG_SSD_DISABLE 0

struct is31fl32xx_priv;
struct is31fl32xx_led_data {
        struct led_classdev cdev;
        u8 channel; /* 1-based, max priv->cdef->channels */
        struct is31fl32xx_priv *priv;
};

struct is31fl32xx_priv {
        const struct is31fl32xx_chipdef *cdef;
        struct i2c_client *client;
        unsigned int num_leds;
        struct is31fl32xx_led_data leds[0];
};

/**
 * struct is31fl32xx_chipdef - chip-specific attributes
 * @channels            : Number of LED channels
 * @shutdown_reg        : address of Shutdown register (optional)
 * @pwm_update_reg      : address of PWM Update register
 * @global_control_reg  : address of Global Control register (optional)
 * @reset_reg           : address of Reset register (optional)
 * @pwm_register_base   : address of first PWM register
 * @pwm_registers_reversed: : true if PWM registers count down instead of up
 * @led_control_register_base : address of first LED control register (optional)
 * @enable_bits_per_led_control_register: number of LEDs enable bits in each
 * @reset_func:         : pointer to reset function
 *
 * For all optional register addresses, the sentinel value %IS31FL32XX_REG_NONE
 * indicates that this chip has no such register.
 *
 * If non-NULL, @reset_func will be called during probing to set all
 * necessary registers to a known initialization state. This is needed
 * for chips that do not have a @reset_reg.
 *
 * @enable_bits_per_led_control_register must be >=1 if
 * @led_control_register_base != %IS31FL32XX_REG_NONE.
 */
struct is31fl32xx_chipdef {
        u8      channels;
        u8      shutdown_reg;
        u8      pwm_update_reg;
        u8      global_control_reg;
        u8      reset_reg;
        u8      pwm_register_base;
        bool    pwm_registers_reversed;
        u8      led_control_register_base;
        u8      enable_bits_per_led_control_register;
        int (*reset_func)(struct is31fl32xx_priv *priv);
        int (*sw_shutdown_func)(struct is31fl32xx_priv *priv, bool enable);
};

static const struct is31fl32xx_chipdef is31fl3236_cdef = {
        .channels                               = 36,
        .shutdown_reg                           = 0x00,
        .pwm_update_reg                         = 0x25,
        .global_control_reg                     = 0x4a,
        .reset_reg                              = 0x4f,
        .pwm_register_base                      = 0x01,
        .led_control_register_base              = 0x26,
        .enable_bits_per_led_control_register   = 1,
};

static const struct is31fl32xx_chipdef is31fl3235_cdef = {
        .channels                               = 28,
        .shutdown_reg                           = 0x00,
        .pwm_update_reg                         = 0x25,
        .global_control_reg                     = 0x4a,
        .reset_reg                              = 0x4f,
        .pwm_register_base                      = 0x05,
        .led_control_register_base              = 0x2a,
        .enable_bits_per_led_control_register   = 1,
};

static const struct is31fl32xx_chipdef is31fl3218_cdef = {
        .channels                               = 18,
        .shutdown_reg                           = 0x00,
        .pwm_update_reg                         = 0x16,
        .global_control_reg                     = IS31FL32XX_REG_NONE,
        .reset_reg                              = 0x17,
        .pwm_register_base                      = 0x01,
        .led_control_register_base              = 0x13,
        .enable_bits_per_led_control_register   = 6,
};

static int is31fl3216_reset(struct is31fl32xx_priv *priv);
static int is31fl3216_software_shutdown(struct is31fl32xx_priv *priv,
                                        bool enable);
static const struct is31fl32xx_chipdef is31fl3216_cdef = {
        .channels                               = 16,
        .shutdown_reg                           = IS31FL32XX_REG_NONE,
        .pwm_update_reg                         = 0xB0,
        .global_control_reg                     = IS31FL32XX_REG_NONE,
        .reset_reg                              = IS31FL32XX_REG_NONE,
        .pwm_register_base                      = 0x10,
        .pwm_registers_reversed                 = true,
        .led_control_register_base              = 0x01,
        .enable_bits_per_led_control_register   = 8,
        .reset_func                             = is31fl3216_reset,
        .sw_shutdown_func                       = is31fl3216_software_shutdown,
};

static int is31fl32xx_write(struct is31fl32xx_priv *priv, u8 reg, u8 val)
{
        int ret;

        dev_dbg(&priv->client->dev, "writing register 0x%02X=0x%02X", reg, val);

        ret =  i2c_smbus_write_byte_data(priv->client, reg, val);
        if (ret) {
                dev_err(&priv->client->dev,
                        "register write to 0x%02X failed (error %d)",
                        reg, ret);
        }
        return ret;
}

/*
 * Custom reset function for IS31FL3216 because it does not have a RESET
 * register the way that the other IS31FL32xx chips do. We don't bother
 * writing the GPIO and animation registers, because the registers we
 * do write ensure those will have no effect.
 */
static int is31fl3216_reset(struct is31fl32xx_priv *priv)
{
        unsigned int i;
        int ret;

        ret = is31fl32xx_write(priv, IS31FL3216_CONFIG_REG,
                               IS31FL3216_CONFIG_SSD_ENABLE);
        if (ret)
                return ret;
        for (i = 0; i < priv->cdef->channels; i++) {
                ret = is31fl32xx_write(priv, priv->cdef->pwm_register_base+i,
                                       0x00);
                if (ret)
                        return ret;
        }
        ret = is31fl32xx_write(priv, priv->cdef->pwm_update_reg, 0);
        if (ret)
                return ret;
        ret = is31fl32xx_write(priv, IS31FL3216_LIGHTING_EFFECT_REG, 0x00);
        if (ret)
                return ret;
        ret = is31fl32xx_write(priv, IS31FL3216_CHANNEL_CONFIG_REG, 0x00);
        if (ret)
                return ret;

        return 0;
}

/*
 * Custom Software-Shutdown function for IS31FL3216 because it does not have
 * a SHUTDOWN register the way that the other IS31FL32xx chips do.
 * We don't bother doing a read/modify/write on the CONFIG register because
 * we only ever use a value of '0' for the other fields in that register.
 */
static int is31fl3216_software_shutdown(struct is31fl32xx_priv *priv,
                                        bool enable)
{
        u8 value = enable ? IS31FL3216_CONFIG_SSD_ENABLE :
                            IS31FL3216_CONFIG_SSD_DISABLE;

        return is31fl32xx_write(priv, IS31FL3216_CONFIG_REG, value);
}

/*
 * NOTE: A mutex is not needed in this function because:
 * - All referenced data is read-only after probe()
 * - The I2C core has a mutex on to protect the bus
 * - There are no read/modify/write operations
 * - Intervening operations between the write of the PWM register
 *   and the Update register are harmless.
 *
 * Example:
 *      PWM_REG_1 write 16
 *      UPDATE_REG write 0
 *      PWM_REG_2 write 128
 *      UPDATE_REG write 0
 *   vs:
 *      PWM_REG_1 write 16
 *      PWM_REG_2 write 128
 *      UPDATE_REG write 0
 *      UPDATE_REG write 0
 * are equivalent. Poking the Update register merely applies all PWM
 * register writes up to that point.
 */
static int is31fl32xx_brightness_set(struct led_classdev *led_cdev,
                                     enum led_brightness brightness)
{
        const struct is31fl32xx_led_data *led_data =
                container_of(led_cdev, struct is31fl32xx_led_data, cdev);
        const struct is31fl32xx_chipdef *cdef = led_data->priv->cdef;
        u8 pwm_register_offset;
        int ret;

        dev_dbg(led_cdev->dev, "%s: %d\n", __func__, brightness);

        /* NOTE: led_data->channel is 1-based */
        if (cdef->pwm_registers_reversed)
                pwm_register_offset = cdef->channels - led_data->channel;
        else
                pwm_register_offset = led_data->channel - 1;

        ret = is31fl32xx_write(led_data->priv,
                               cdef->pwm_register_base + pwm_register_offset,
                               brightness);
        if (ret)
                return ret;

        return is31fl32xx_write(led_data->priv, cdef->pwm_update_reg, 0);
}

static int is31fl32xx_reset_regs(struct is31fl32xx_priv *priv)
{
        const struct is31fl32xx_chipdef *cdef = priv->cdef;
        int ret;

        if (cdef->reset_reg != IS31FL32XX_REG_NONE) {
                ret = is31fl32xx_write(priv, cdef->reset_reg, 0);
                if (ret)
                        return ret;
        }

        if (cdef->reset_func)
                return cdef->reset_func(priv);

        return 0;
}

static int is31fl32xx_software_shutdown(struct is31fl32xx_priv *priv,
                                        bool enable)
{
        const struct is31fl32xx_chipdef *cdef = priv->cdef;
        int ret;

        if (cdef->shutdown_reg != IS31FL32XX_REG_NONE) {
                u8 value = enable ? IS31FL32XX_SHUTDOWN_SSD_ENABLE :
                                    IS31FL32XX_SHUTDOWN_SSD_DISABLE;
                ret = is31fl32xx_write(priv, cdef->shutdown_reg, value);
                if (ret)
                        return ret;
        }

        if (cdef->sw_shutdown_func)
                return cdef->sw_shutdown_func(priv, enable);

        return 0;
}

static int is31fl32xx_init_regs(struct is31fl32xx_priv *priv)
{
        const struct is31fl32xx_chipdef *cdef = priv->cdef;
        int ret;

        ret = is31fl32xx_reset_regs(priv);
        if (ret)
                return ret;

        /*
         * Set enable bit for all channels.
         * We will control state with PWM registers alone.
         */
        if (cdef->led_control_register_base != IS31FL32XX_REG_NONE) {
                u8 value =
                    GENMASK(cdef->enable_bits_per_led_control_register-1, 0);
                u8 num_regs = cdef->channels /
                                cdef->enable_bits_per_led_control_register;
                int i;

                for (i = 0; i < num_regs; i++) {
                        ret = is31fl32xx_write(priv,
                                               cdef->led_control_register_base+i,
                                               value);
                        if (ret)
                                return ret;
                }
        }

        ret = is31fl32xx_software_shutdown(priv, false);
        if (ret)
                return ret;

        if (cdef->global_control_reg != IS31FL32XX_REG_NONE) {
                ret = is31fl32xx_write(priv, cdef->global_control_reg, 0x00);
                if (ret)
                        return ret;
        }

        return 0;
}

static inline size_t sizeof_is31fl32xx_priv(int num_leds)
{
        return sizeof(struct is31fl32xx_priv) +
                      (sizeof(struct is31fl32xx_led_data) * num_leds);
}

static int is31fl32xx_parse_child_dt(const struct device *dev,
                                     const struct device_node *child,
                                     struct is31fl32xx_led_data *led_data)
{
        struct led_classdev *cdev = &led_data->cdev;
        int ret = 0;
        u32 reg;

        if (of_property_read_string(child, "label", &cdev->name))
                cdev->name = child->name;

        ret = of_property_read_u32(child, "reg", &reg);
        if (ret || reg < 1 || reg > led_data->priv->cdef->channels) {
                dev_err(dev,
                        "Child node %s does not have a valid reg property\n",
                        child->full_name);
                return -EINVAL;
        }
        led_data->channel = reg;

        of_property_read_string(child, "linux,default-trigger",
                                &cdev->default_trigger);

        cdev->brightness_set_blocking = is31fl32xx_brightness_set;

        return 0;
}

static struct is31fl32xx_led_data *is31fl32xx_find_led_data(
                                        struct is31fl32xx_priv *priv,
                                        u8 channel)
{
        size_t i;

        for (i = 0; i < priv->num_leds; i++) {
                if (priv->leds[i].channel == channel)
                        return &priv->leds[i];
        }

        return NULL;
}

static int is31fl32xx_parse_dt(struct device *dev,
                               struct is31fl32xx_priv *priv)
{
        struct device_node *child;
        int ret = 0;

        for_each_child_of_node(dev->of_node, child) {
                struct is31fl32xx_led_data *led_data =
                        &priv->leds[priv->num_leds];
                const struct is31fl32xx_led_data *other_led_data;

                led_data->priv = priv;

                ret = is31fl32xx_parse_child_dt(dev, child, led_data);
                if (ret)
                        goto err;

                /* Detect if channel is already in use by another child */
                other_led_data = is31fl32xx_find_led_data(priv,
                                                          led_data->channel);
                if (other_led_data) {
                        dev_err(dev,
                                "%s and %s both attempting to use channel %d\n",
                                led_data->cdev.name,
                                other_led_data->cdev.name,
                                led_data->channel);
                        goto err;
                }

                ret = devm_led_classdev_register(dev, &led_data->cdev);
                if (ret) {
                        dev_err(dev, "failed to register PWM led for %s: %d\n",
                                led_data->cdev.name, ret);
                        goto err;
                }

                priv->num_leds++;
        }

        return 0;

err:
        of_node_put(child);
        return ret;
}

static const struct of_device_id of_is31fl32xx_match[] = {
        { .compatible = "issi,is31fl3236", .data = &is31fl3236_cdef, },
        { .compatible = "issi,is31fl3235", .data = &is31fl3235_cdef, },
        { .compatible = "issi,is31fl3218", .data = &is31fl3218_cdef, },
        { .compatible = "si-en,sn3218",    .data = &is31fl3218_cdef, },
        { .compatible = "issi,is31fl3216", .data = &is31fl3216_cdef, },
        { .compatible = "si-en,sn3216",    .data = &is31fl3216_cdef, },
        {},
};

MODULE_DEVICE_TABLE(of, of_is31fl32xx_match);

static int is31fl32xx_probe(struct i2c_client *client,
                            const struct i2c_device_id *id)
{
        const struct is31fl32xx_chipdef *cdef;
        const struct of_device_id *of_dev_id;
        struct device *dev = &client->dev;
        struct is31fl32xx_priv *priv;
        int count;
        int ret = 0;

        of_dev_id = of_match_device(of_is31fl32xx_match, dev);
        if (!of_dev_id)
                return -EINVAL;

        cdef = of_dev_id->data;

        count = of_get_child_count(dev->of_node);
        if (!count)
                return -EINVAL;

        priv = devm_kzalloc(dev, sizeof_is31fl32xx_priv(count),
                            GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->client = client;
        priv->cdef = cdef;
        i2c_set_clientdata(client, priv);

        ret = is31fl32xx_init_regs(priv);
        if (ret)
                return ret;

        ret = is31fl32xx_parse_dt(dev, priv);
        if (ret)
                return ret;

        return 0;
}

static int is31fl32xx_remove(struct i2c_client *client)
{
        struct is31fl32xx_priv *priv = i2c_get_clientdata(client);

        return is31fl32xx_reset_regs(priv);
}

/*
 * i2c-core (and modalias) requires that id_table be properly filled,
 * even though it is not used for DeviceTree based instantiation.
 */
static const struct i2c_device_id is31fl32xx_id[] = {
        { "is31fl3236" },
        { "is31fl3235" },
        { "is31fl3218" },
        { "sn3218" },
        { "is31fl3216" },
        { "sn3216" },
        {},
};

MODULE_DEVICE_TABLE(i2c, is31fl32xx_id);

static struct i2c_driver is31fl32xx_driver = {
        .driver = {
                .name   = "is31fl32xx",
                .of_match_table = of_is31fl32xx_match,
        },
        .probe          = is31fl32xx_probe,
        .remove         = is31fl32xx_remove,
        .id_table       = is31fl32xx_id,
};

module_i2c_driver(is31fl32xx_driver);

MODULE_AUTHOR("David Rivshin <drivshin@allworx.com>");
MODULE_DESCRIPTION("ISSI IS31FL32xx LED driver");
MODULE_LICENSE("GPL v2");