// SPDX-License-Identifier: GPL-2.0-only
/*
 * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
 *
 * Copyright 2016 ArcticSand, Inc.
 * Author : Brian Dodge <bdodge@arcticsand.com>
 */

#include <linux/backlight.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/slab.h>

enum arcxcnn_chip_id {
        ARC2C0608
};

/**
 * struct arcxcnn_platform_data
 * @name                : Backlight driver name (NULL will use default)
 * @initial_brightness  : initial value of backlight brightness
 * @leden               : initial LED string enables, upper bit is global on/off
 * @led_config_0        : fading speed (period between intensity steps)
 * @led_config_1        : misc settings, see datasheet
 * @dim_freq            : pwm dimming frequency if in pwm mode
 * @comp_config         : misc config, see datasheet
 * @filter_config       : RC/PWM filter config, see datasheet
 * @trim_config         : full scale current trim, see datasheet
 */
struct arcxcnn_platform_data {
        const char *name;
        u16 initial_brightness;
        u8      leden;
        u8      led_config_0;
        u8      led_config_1;
        u8      dim_freq;
        u8      comp_config;
        u8      filter_config;
        u8      trim_config;
};

#define ARCXCNN_CMD             0x00    /* Command Register */
#define ARCXCNN_CMD_STDBY       0x80    /*   I2C Standby */
#define ARCXCNN_CMD_RESET       0x40    /*   Reset */
#define ARCXCNN_CMD_BOOST       0x10    /*   Boost */
#define ARCXCNN_CMD_OVP_MASK    0x0C    /*   --- Over Voltage Threshold */
#define ARCXCNN_CMD_OVP_XXV     0x0C    /*   <rsvrd> Over Voltage Threshold */
#define ARCXCNN_CMD_OVP_20V     0x08    /*   20v Over Voltage Threshold */
#define ARCXCNN_CMD_OVP_24V     0x04    /*   24v Over Voltage Threshold */
#define ARCXCNN_CMD_OVP_31V     0x00    /*   31.4v Over Voltage Threshold */
#define ARCXCNN_CMD_EXT_COMP    0x01    /*   part (0) or full (1) ext. comp */

#define ARCXCNN_CONFIG          0x01    /* Configuration */
#define ARCXCNN_STATUS1         0x02    /* Status 1 */
#define ARCXCNN_STATUS2         0x03    /* Status 2 */
#define ARCXCNN_FADECTRL        0x04    /* Fading Control */
#define ARCXCNN_ILED_CONFIG     0x05    /* ILED Configuration */
#define ARCXCNN_ILED_DIM_PWM    0x00    /*   config dim mode pwm */
#define ARCXCNN_ILED_DIM_INT    0x04    /*   config dim mode internal */
#define ARCXCNN_LEDEN           0x06    /* LED Enable Register */
#define ARCXCNN_LEDEN_ISETEXT   0x80    /*   Full-scale current set extern */
#define ARCXCNN_LEDEN_MASK      0x3F    /*   LED string enables mask */
#define ARCXCNN_LEDEN_BITS      0x06    /*   Bits of LED string enables */
#define ARCXCNN_LEDEN_LED1      0x01
#define ARCXCNN_LEDEN_LED2      0x02
#define ARCXCNN_LEDEN_LED3      0x04
#define ARCXCNN_LEDEN_LED4      0x08
#define ARCXCNN_LEDEN_LED5      0x10
#define ARCXCNN_LEDEN_LED6      0x20

#define ARCXCNN_WLED_ISET_LSB   0x07    /* LED ISET LSB (in upper nibble) */
#define ARCXCNN_WLED_ISET_LSB_SHIFT 0x04  /* ISET LSB Left Shift */
#define ARCXCNN_WLED_ISET_MSB   0x08    /* LED ISET MSB (8 bits) */

#define ARCXCNN_DIMFREQ         0x09
#define ARCXCNN_COMP_CONFIG     0x0A
#define ARCXCNN_FILT_CONFIG     0x0B
#define ARCXCNN_IMAXTUNE        0x0C
#define ARCXCNN_ID_MSB          0x1E
#define ARCXCNN_ID_LSB          0x1F

#define MAX_BRIGHTNESS          4095
#define INIT_BRIGHT             60

struct arcxcnn {
        struct i2c_client *client;
        struct backlight_device *bl;
        struct device *dev;
        struct arcxcnn_platform_data *pdata;
};

static int arcxcnn_update_field(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
{
        int ret;
        u8 tmp;

        ret = i2c_smbus_read_byte_data(lp->client, reg);
        if (ret < 0) {
                dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
                return ret;
        }

        tmp = (u8)ret;
        tmp &= ~mask;
        tmp |= data & mask;

        return i2c_smbus_write_byte_data(lp->client, reg, tmp);
}

static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
{
        int ret;
        u8 val;

        /* lower nibble of brightness goes in upper nibble of LSB register */
        val = (brightness & 0xF) << ARCXCNN_WLED_ISET_LSB_SHIFT;
        ret = i2c_smbus_write_byte_data(lp->client,
                ARCXCNN_WLED_ISET_LSB, val);
        if (ret < 0)
                return ret;

        /* remaining 8 bits of brightness go in MSB register */
        val = (brightness >> 4);
        return i2c_smbus_write_byte_data(lp->client,
                ARCXCNN_WLED_ISET_MSB, val);
}

static int arcxcnn_bl_update_status(struct backlight_device *bl)
{
        struct arcxcnn *lp = bl_get_data(bl);
        u32 brightness = backlight_get_brightness(bl);
        int ret;

        ret = arcxcnn_set_brightness(lp, brightness);
        if (ret)
                return ret;

        /* set power-on/off/save modes */
        return arcxcnn_update_field(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY,
                (bl->props.power == 0) ? 0 : ARCXCNN_CMD_STDBY);
}

static const struct backlight_ops arcxcnn_bl_ops = {
        .options = BL_CORE_SUSPENDRESUME,
        .update_status = arcxcnn_bl_update_status,
};

static int arcxcnn_backlight_register(struct arcxcnn *lp)
{
        struct backlight_properties *props;
        const char *name = lp->pdata->name ? : "arctic_bl";

        props = devm_kzalloc(lp->dev, sizeof(*props), GFP_KERNEL);
        if (!props)
                return -ENOMEM;

        props->type = BACKLIGHT_PLATFORM;
        props->max_brightness = MAX_BRIGHTNESS;

        if (lp->pdata->initial_brightness > props->max_brightness)
                lp->pdata->initial_brightness = props->max_brightness;

        props->brightness = lp->pdata->initial_brightness;

        lp->bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
                                       &arcxcnn_bl_ops, props);
        return PTR_ERR_OR_ZERO(lp->bl);
}

static void arcxcnn_parse_dt(struct arcxcnn *lp)
{
        struct device *dev = lp->dev;
        struct device_node *node = dev->of_node;
        u32 prog_val, num_entry, entry, sources[ARCXCNN_LEDEN_BITS];
        int ret;

        /* device tree entry isn't required, defaults are OK */
        if (!node)
                return;

        ret = of_property_read_string(node, "label", &lp->pdata->name);
        if (ret < 0)
                lp->pdata->name = NULL;

        ret = of_property_read_u32(node, "default-brightness", &prog_val);
        if (ret == 0)
                lp->pdata->initial_brightness = prog_val;

        ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
        if (ret == 0)
                lp->pdata->led_config_0 = (u8)prog_val;

        ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
        if (ret == 0)
                lp->pdata->led_config_1 = (u8)prog_val;

        ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
        if (ret == 0)
                lp->pdata->dim_freq = (u8)prog_val;

        ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
        if (ret == 0)
                lp->pdata->comp_config = (u8)prog_val;

        ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
        if (ret == 0)
                lp->pdata->filter_config = (u8)prog_val;

        ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
        if (ret == 0)
                lp->pdata->trim_config = (u8)prog_val;

        ret = of_property_count_u32_elems(node, "led-sources");
        if (ret < 0) {
                lp->pdata->leden = ARCXCNN_LEDEN_MASK; /* all on is default */
        } else {
                num_entry = ret;
                if (num_entry > ARCXCNN_LEDEN_BITS)
                        num_entry = ARCXCNN_LEDEN_BITS;

                ret = of_property_read_u32_array(node, "led-sources", sources,
                                        num_entry);
                if (ret < 0) {
                        dev_err(dev, "led-sources node is invalid.\n");
                        return;
                }

                lp->pdata->leden = 0;

                /* for each enable in source, set bit in led enable */
                for (entry = 0; entry < num_entry; entry++) {
                        u8 onbit = 1 << sources[entry];

                        lp->pdata->leden |= onbit;
                }
        }
}

static int arcxcnn_probe(struct i2c_client *cl)
{
        struct arcxcnn *lp;
        int ret;

        if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
                return -EIO;

        lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
        if (!lp)
                return -ENOMEM;

        lp->client = cl;
        lp->dev = &cl->dev;
        lp->pdata = dev_get_platdata(&cl->dev);

        /* reset the device */
        ret = i2c_smbus_write_byte_data(lp->client,
                ARCXCNN_CMD, ARCXCNN_CMD_RESET);
        if (ret)
                goto probe_err;

        if (!lp->pdata) {
                lp->pdata = devm_kzalloc(lp->dev,
                                sizeof(*lp->pdata), GFP_KERNEL);
                if (!lp->pdata)
                        return -ENOMEM;

                /* Setup defaults based on power-on defaults */
                lp->pdata->name = NULL;
                lp->pdata->initial_brightness = INIT_BRIGHT;
                lp->pdata->leden = ARCXCNN_LEDEN_MASK;

                lp->pdata->led_config_0 = i2c_smbus_read_byte_data(
                        lp->client, ARCXCNN_FADECTRL);

                lp->pdata->led_config_1 = i2c_smbus_read_byte_data(
                        lp->client, ARCXCNN_ILED_CONFIG);
                /* insure dim mode is not default pwm */
                lp->pdata->led_config_1 |= ARCXCNN_ILED_DIM_INT;

                lp->pdata->dim_freq = i2c_smbus_read_byte_data(
                        lp->client, ARCXCNN_DIMFREQ);

                lp->pdata->comp_config = i2c_smbus_read_byte_data(
                        lp->client, ARCXCNN_COMP_CONFIG);

                lp->pdata->filter_config = i2c_smbus_read_byte_data(
                        lp->client, ARCXCNN_FILT_CONFIG);

                lp->pdata->trim_config = i2c_smbus_read_byte_data(
                        lp->client, ARCXCNN_IMAXTUNE);

                if (IS_ENABLED(CONFIG_OF))
                        arcxcnn_parse_dt(lp);
        }

        i2c_set_clientdata(cl, lp);

        /* constrain settings to what is possible */
        if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
                lp->pdata->initial_brightness = MAX_BRIGHTNESS;

        /* set initial brightness */
        ret = arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
        if (ret)
                goto probe_err;

        /* set other register values directly */
        ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FADECTRL,
                lp->pdata->led_config_0);
        if (ret)
                goto probe_err;

        ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_ILED_CONFIG,
                lp->pdata->led_config_1);
        if (ret)
                goto probe_err;

        ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_DIMFREQ,
                lp->pdata->dim_freq);
        if (ret)
                goto probe_err;

        ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_COMP_CONFIG,
                lp->pdata->comp_config);
        if (ret)
                goto probe_err;

        ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FILT_CONFIG,
                lp->pdata->filter_config);
        if (ret)
                goto probe_err;

        ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_IMAXTUNE,
                lp->pdata->trim_config);
        if (ret)
                goto probe_err;

        /* set initial LED Enables */
        arcxcnn_update_field(lp, ARCXCNN_LEDEN,
                ARCXCNN_LEDEN_MASK, lp->pdata->leden);

        ret = arcxcnn_backlight_register(lp);
        if (ret)
                goto probe_register_err;

        backlight_update_status(lp->bl);

        return 0;

probe_register_err:
        dev_err(lp->dev,
                "failed to register backlight.\n");

probe_err:
        dev_err(lp->dev,
                "failure ret: %d\n", ret);
        return ret;
}

static void arcxcnn_remove(struct i2c_client *cl)
{
        struct arcxcnn *lp = i2c_get_clientdata(cl);

        /* disable all strings (ignore errors) */
        i2c_smbus_write_byte_data(lp->client,
                ARCXCNN_LEDEN, 0x00);
        /* reset the device (ignore errors) */
        i2c_smbus_write_byte_data(lp->client,
                ARCXCNN_CMD, ARCXCNN_CMD_RESET);

        lp->bl->props.brightness = 0;

        backlight_update_status(lp->bl);
}

static const struct of_device_id arcxcnn_dt_ids[] = {
        { .compatible = "arc,arc2c0608" },
        { }
};
MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);

static const struct i2c_device_id arcxcnn_ids[] = {
        {"arc2c0608", ARC2C0608},
        { }
};
MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);

static struct i2c_driver arcxcnn_driver = {
        .driver = {
                .name = "arcxcnn_bl",
                .of_match_table = arcxcnn_dt_ids,
        },
        .probe = arcxcnn_probe,
        .remove = arcxcnn_remove,
        .id_table = arcxcnn_ids,
};
module_i2c_driver(arcxcnn_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Brian Dodge <bdodge@arcticsand.com>");
MODULE_DESCRIPTION("ARCXCNN Backlight driver");