TLC59116F: Some questions when using the driver

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2014 Belkin Inc.
 * Copyright 2015 Andrew Lunn <andrew@lunn.ch>
 */

#include <linux/i2c.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>

#define TLC591XX_MAX_LEDS       16
#define TLC591XX_MAX_BRIGHTNESS 256

#define TLC591XX_REG_MODE1      0x00
#define MODE1_RESPON_ADDR_MASK  0xF0
#define MODE1_NORMAL_MODE       (0 << 4)
#define MODE1_SPEED_MODE        (1 << 4)

#define TLC591XX_REG_MODE2      0x01
#define MODE2_DIM               (0 << 5)
#define MODE2_BLINK             (1 << 5)
#define MODE2_OCH_STOP          (0 << 3)
#define MODE2_OCH_ACK           (1 << 3)

#define TLC591XX_REG_PWM(x)     (0x02 + (x))

#define TLC591XX_REG_GRPPWM     0x12
#define TLC591XX_REG_GRPFREQ    0x13

/* LED Driver Output State, determine the source that drives LED outputs */
#define LEDOUT_OFF              0x0     /* Output LOW */
#define LEDOUT_ON               0x1     /* Output HI-Z */
#define LEDOUT_DIM              0x2     /* Dimming */
#define LEDOUT_BLINK            0x3     /* Blinking */
#define LEDOUT_MASK             0x3

#define ldev_to_led(c)          container_of(c, struct tlc591xx_led, ldev)

struct tlc591xx_led {
        bool active;
        unsigned int led_no;
        struct led_classdev ldev;
        struct tlc591xx_priv *priv;
};

struct tlc591xx_priv {
        struct tlc591xx_led leds[TLC591XX_MAX_LEDS];
        struct regmap *regmap;
        unsigned int reg_ledout_offset;
};

struct tlc591xx {
        unsigned int max_leds;
        unsigned int reg_ledout_offset;
};

static const struct tlc591xx tlc59116 = {
        .max_leds = 16,
        .reg_ledout_offset = 0x14,
};

static const struct tlc591xx tlc59108 = {
        .max_leds = 8,
        .reg_ledout_offset = 0x0c,
};

static int
tlc591xx_set_mode(struct regmap *regmap, u8 mode)
{
        int err;
        u8 val;

        err = regmap_write(regmap, TLC591XX_REG_MODE1, MODE1_NORMAL_MODE);
        if (err)
                return err;

        val = MODE2_OCH_STOP | mode;

        return regmap_write(regmap, TLC591XX_REG_MODE2, val);
}

static int
tlc591xx_set_ledout(struct tlc591xx_priv *priv, struct tlc591xx_led *led,
                    u8 val)
{
        unsigned int i = (led->led_no % 4) * 2;
        unsigned int mask = LEDOUT_MASK << i;
        unsigned int addr = priv->reg_ledout_offset + (led->led_no >> 2);

        val = val << i;

        return regmap_update_bits(priv->regmap, addr, mask, val);
}

static int
tlc591xx_set_pwm(struct tlc591xx_priv *priv, struct tlc591xx_led *led,
                 u8 brightness)
{
        u8 pwm = TLC591XX_REG_PWM(led->led_no);

        return regmap_write(priv->regmap, pwm, brightness);
}

static int
tlc591xx_brightness_set(struct led_classdev *led_cdev,
                        enum led_brightness brightness)
{
        struct tlc591xx_led *led = ldev_to_led(led_cdev);
        struct tlc591xx_priv *priv = led->priv;
        int err;

        switch ((int)brightness) {
        case 0:
                err = tlc591xx_set_ledout(priv, led, LEDOUT_OFF);
                break;
        case TLC591XX_MAX_BRIGHTNESS:
                err = tlc591xx_set_ledout(priv, led, LEDOUT_ON);
                break;
        default:
                err = tlc591xx_set_ledout(priv, led, LEDOUT_DIM);
                if (!err)
                        err = tlc591xx_set_pwm(priv, led, brightness);
        }

        return err;
}

static void
tlc591xx_destroy_devices(struct tlc591xx_priv *priv, unsigned int j)
{
        int i = j;

        while (--i >= 0) {
                if (priv->leds[i].active)
                        led_classdev_unregister(&priv->leds[i].ldev);
        }
}

static int
tlc591xx_configure(struct device *dev,
                   struct tlc591xx_priv *priv,
                   const struct tlc591xx *tlc591xx)
{
        unsigned int i;
        int err = 0;

        tlc591xx_set_mode(priv->regmap, MODE2_DIM);
        for (i = 0; i < TLC591XX_MAX_LEDS; i++) {
                struct tlc591xx_led *led = &priv->leds[i];

                if (!led->active)
                        continue;

                led->priv = priv;
                led->led_no = i;
                led->ldev.brightness_set_blocking = tlc591xx_brightness_set;
                led->ldev.max_brightness = TLC591XX_MAX_BRIGHTNESS;
                err = led_classdev_register(dev, &led->ldev);
                if (err < 0) {
                        dev_err(dev, "couldn't register LED %s\n",
                                led->ldev.name);
                        goto exit;
                }
        }

        return 0;

exit:
        tlc591xx_destroy_devices(priv, i);
        return err;
}

static const struct regmap_config tlc591xx_regmap = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = 0x1e,
};

static const struct of_device_id of_tlc591xx_leds_match[] = {
        { .compatible = "ti,tlc59116",
          .data = &tlc59116 },
        { .compatible = "ti,tlc59108",
          .data = &tlc59108 },
        {},
};
MODULE_DEVICE_TABLE(of, of_tlc591xx_leds_match);

static int
tlc591xx_probe(struct i2c_client *client,
               const struct i2c_device_id *id)
{
        struct device_node *np = client->dev.of_node, *child;
        struct device *dev = &client->dev;
        const struct of_device_id *match;
        const struct tlc591xx *tlc591xx;
        struct tlc591xx_priv *priv;
        int err, count, reg;

        match = of_match_device(of_tlc591xx_leds_match, dev);
        if (!match)
                return -ENODEV;

        tlc591xx = match->data;
        if (!np)
                return -ENODEV;

        count = of_get_child_count(np);
        if (!count || count > tlc591xx->max_leds)
                return -EINVAL;

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->regmap = devm_regmap_init_i2c(client, &tlc591xx_regmap);
        if (IS_ERR(priv->regmap)) {
                err = PTR_ERR(priv->regmap);
                dev_err(dev, "Failed to allocate register map: %d\n", err);
                return err;
        }
        priv->reg_ledout_offset = tlc591xx->reg_ledout_offset;

        i2c_set_clientdata(client, priv);

        for_each_child_of_node(np, child) {
                err = of_property_read_u32(child, "reg", &reg);
                if (err) {
                        of_node_put(child);
                        return err;
                }
                if (reg < 0 || reg >= tlc591xx->max_leds ||
                    priv->leds[reg].active) {
                        of_node_put(child);
                        return -EINVAL;
                }
                priv->leds[reg].active = true;
                priv->leds[reg].ldev.name =
                        of_get_property(child, "label", NULL) ? : child->name;
                priv->leds[reg].ldev.default_trigger =
                        of_get_property(child, "linux,default-trigger", NULL);
        }
        return tlc591xx_configure(dev, priv, tlc591xx);
}

static int
tlc591xx_remove(struct i2c_client *client)
{
        struct tlc591xx_priv *priv = i2c_get_clientdata(client);

        tlc591xx_destroy_devices(priv, TLC591XX_MAX_LEDS);

        return 0;
}

static const struct i2c_device_id tlc591xx_id[] = {
        { "tlc59116" },
        { "tlc59108" },
        {},
};
MODULE_DEVICE_TABLE(i2c, tlc591xx_id);

static struct i2c_driver tlc591xx_driver = {
        .driver = {
                .name = "tlc591xx",
                .of_match_table = of_match_ptr(of_tlc591xx_leds_match),
        },
        .probe = tlc591xx_probe,
        .remove = tlc591xx_remove,
        .id_table = tlc591xx_id,
};

module_i2c_driver(tlc591xx_driver);

MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("TLC591XX LED driver");