root/drivers/leds/leds-cros_ec.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  ChromeOS EC LED Driver
 *
 *  Copyright (C) 2024 Thomas Weißschuh <linux@weissschuh.net>
 */

#include <linux/device.h>
#include <linux/leds.h>
#include <linux/led-class-multicolor.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>

static const char * const cros_ec_led_functions[] = {
        [EC_LED_ID_BATTERY_LED]            = LED_FUNCTION_CHARGING,
        [EC_LED_ID_POWER_LED]              = LED_FUNCTION_POWER,
        [EC_LED_ID_ADAPTER_LED]            = "adapter",
        [EC_LED_ID_LEFT_LED]               = "left",
        [EC_LED_ID_RIGHT_LED]              = "right",
        [EC_LED_ID_RECOVERY_HW_REINIT_LED] = "recovery-hw-reinit",
        [EC_LED_ID_SYSRQ_DEBUG_LED]        = "sysrq-debug",
};

static_assert(ARRAY_SIZE(cros_ec_led_functions) == EC_LED_ID_COUNT);

static const int cros_ec_led_to_linux_id[] = {
        [EC_LED_COLOR_RED]    = LED_COLOR_ID_RED,
        [EC_LED_COLOR_GREEN]  = LED_COLOR_ID_GREEN,
        [EC_LED_COLOR_BLUE]   = LED_COLOR_ID_BLUE,
        [EC_LED_COLOR_YELLOW] = LED_COLOR_ID_YELLOW,
        [EC_LED_COLOR_WHITE]  = LED_COLOR_ID_WHITE,
        [EC_LED_COLOR_AMBER]  = LED_COLOR_ID_AMBER,
};

static_assert(ARRAY_SIZE(cros_ec_led_to_linux_id) == EC_LED_COLOR_COUNT);

static const int cros_ec_linux_to_ec_id[] = {
        [LED_COLOR_ID_RED]    = EC_LED_COLOR_RED,
        [LED_COLOR_ID_GREEN]  = EC_LED_COLOR_GREEN,
        [LED_COLOR_ID_BLUE]   = EC_LED_COLOR_BLUE,
        [LED_COLOR_ID_YELLOW] = EC_LED_COLOR_YELLOW,
        [LED_COLOR_ID_WHITE]  = EC_LED_COLOR_WHITE,
        [LED_COLOR_ID_AMBER]  = EC_LED_COLOR_AMBER,
};

struct cros_ec_led_priv {
        struct led_classdev_mc led_mc_cdev;
        struct cros_ec_device *cros_ec;
        enum ec_led_id led_id;
};

static inline struct cros_ec_led_priv *cros_ec_led_cdev_to_priv(struct led_classdev *led_cdev)
{
        return container_of(lcdev_to_mccdev(led_cdev), struct cros_ec_led_priv, led_mc_cdev);
}

union cros_ec_led_cmd_data {
        struct ec_params_led_control req;
        struct ec_response_led_control resp;
};

static int cros_ec_led_send_cmd(struct cros_ec_device *cros_ec,
                                union cros_ec_led_cmd_data *arg)
{
        int ret;

        ret = cros_ec_cmd(cros_ec, 1, EC_CMD_LED_CONTROL, &arg->req,
                          sizeof(arg->req), &arg->resp, sizeof(arg->resp));
        if (ret < 0)
                return ret;

        return 0;
}

static int cros_ec_led_trigger_activate(struct led_classdev *led_cdev)
{
        struct cros_ec_led_priv *priv = cros_ec_led_cdev_to_priv(led_cdev);
        union cros_ec_led_cmd_data arg = {};

        arg.req.led_id = priv->led_id;
        arg.req.flags = EC_LED_FLAGS_AUTO;

        return cros_ec_led_send_cmd(priv->cros_ec, &arg);
}

static struct led_hw_trigger_type cros_ec_led_trigger_type;

static struct led_trigger cros_ec_led_trigger = {
        .name = "chromeos-auto",
        .trigger_type = &cros_ec_led_trigger_type,
        .activate = cros_ec_led_trigger_activate,
};

static int cros_ec_led_brightness_set_blocking(struct led_classdev *led_cdev,
                                               enum led_brightness brightness)
{
        struct cros_ec_led_priv *priv = cros_ec_led_cdev_to_priv(led_cdev);
        union cros_ec_led_cmd_data arg = {};
        enum ec_led_colors led_color;
        struct mc_subled *subled;
        size_t i;

        led_mc_calc_color_components(&priv->led_mc_cdev, brightness);

        arg.req.led_id = priv->led_id;

        for (i = 0; i < priv->led_mc_cdev.num_colors; i++) {
                subled = &priv->led_mc_cdev.subled_info[i];
                led_color = cros_ec_linux_to_ec_id[subled->color_index];
                arg.req.brightness[led_color] = subled->brightness;
        }

        return cros_ec_led_send_cmd(priv->cros_ec, &arg);
}

static int cros_ec_led_count_subleds(struct device *dev,
                                     struct ec_response_led_control *resp,
                                     unsigned int *max_brightness)
{
        unsigned int range, common_range = 0;
        int num_subleds = 0;
        size_t i;

        for (i = 0; i < EC_LED_COLOR_COUNT; i++) {
                range = resp->brightness_range[i];

                if (!range)
                        continue;

                num_subleds++;

                if (!common_range)
                        common_range = range;

                if (common_range != range) {
                        /* The multicolor LED API expects a uniform max_brightness */
                        dev_err(dev, "Inconsistent LED brightness values\n");
                        return -EINVAL;
                }
        }

        *max_brightness = common_range;
        return num_subleds;
}

static const char *cros_ec_led_get_color_name(struct led_classdev_mc *led_mc_cdev)
{
        int color;

        if (led_mc_cdev->num_colors == 1)
                color = led_mc_cdev->subled_info[0].color_index;
        else
                color = LED_COLOR_ID_MULTI;

        return led_get_color_name(color);
}

static int cros_ec_led_probe_one(struct device *dev, struct cros_ec_device *cros_ec,
                                 enum ec_led_id id)
{
        union cros_ec_led_cmd_data arg = {};
        struct cros_ec_led_priv *priv;
        struct led_classdev *led_cdev;
        struct mc_subled *subleds;
        int i, ret, num_subleds;
        size_t subled;

        arg.req.led_id = id;
        arg.req.flags = EC_LED_FLAGS_QUERY;
        ret = cros_ec_led_send_cmd(cros_ec, &arg);
        if (ret == -EINVAL)
                return 0; /* Unknown LED, skip */
        if (ret == -EOPNOTSUPP)
                return -ENODEV;
        if (ret < 0)
                return ret;

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

        num_subleds = cros_ec_led_count_subleds(dev, &arg.resp,
                                                &priv->led_mc_cdev.led_cdev.max_brightness);
        if (num_subleds < 0)
                return num_subleds;
        if (num_subleds == 0)
                return 0; /* LED without any colors, skip */

        priv->cros_ec = cros_ec;
        priv->led_id = id;

        subleds = devm_kcalloc(dev, num_subleds, sizeof(*subleds), GFP_KERNEL);
        if (!subleds)
                return -ENOMEM;

        subled = 0;
        for (i = 0; i < EC_LED_COLOR_COUNT; i++) {
                if (!arg.resp.brightness_range[i])
                        continue;

                subleds[subled].color_index = cros_ec_led_to_linux_id[i];
                if (subled == 0)
                        subleds[subled].intensity = 100;
                subled++;
        }

        priv->led_mc_cdev.subled_info = subleds;
        priv->led_mc_cdev.num_colors = num_subleds;

        led_cdev = &priv->led_mc_cdev.led_cdev;
        led_cdev->brightness_set_blocking = cros_ec_led_brightness_set_blocking;
        led_cdev->trigger_type = &cros_ec_led_trigger_type;
        led_cdev->default_trigger = cros_ec_led_trigger.name;
        led_cdev->hw_control_trigger = cros_ec_led_trigger.name;

        led_cdev->name = devm_kasprintf(dev, GFP_KERNEL, "chromeos:%s:%s",
                                        cros_ec_led_get_color_name(&priv->led_mc_cdev),
                                        cros_ec_led_functions[id]);
        if (!led_cdev->name)
                return -ENOMEM;

        return devm_led_classdev_multicolor_register(dev, &priv->led_mc_cdev);
}

static int cros_ec_led_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
        struct cros_ec_device *cros_ec = ec_dev->ec_dev;
        int i, ret = 0;

        ret = devm_led_trigger_register(dev, &cros_ec_led_trigger);
        if (ret)
                return ret;

        for (i = 0; i < EC_LED_ID_COUNT; i++) {
                ret = cros_ec_led_probe_one(dev, cros_ec, i);
                if (ret)
                        break;
        }

        return ret;
}

static const struct platform_device_id cros_ec_led_id[] = {
        { "cros-ec-led", 0 },
        {}
};

static struct platform_driver cros_ec_led_driver = {
        .driver.name    = "cros-ec-led",
        .probe          = cros_ec_led_probe,
        .id_table       = cros_ec_led_id,
};
module_platform_driver(cros_ec_led_driver);

MODULE_DEVICE_TABLE(platform, cros_ec_led_id);
MODULE_DESCRIPTION("ChromeOS EC LED Driver");
MODULE_AUTHOR("Thomas Weißschuh <linux@weissschuh.net");
MODULE_LICENSE("GPL");