[PATCH v3 4/5] leds: Add ChromeOS EC driver

Thomas Weißschuh
2024-06-13T14:48:47Z

The ChromeOS Embedded Controller exposes an LED control command.
Expose its functionality through the leds subsystem.

The LEDs are exposed as multicolor devices.
A hardware trigger, which is active by default, is provided to let the
EC itself take over control over the LED.

The driver is designed to be probed via the cros_ec mfd device.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
MAINTAINERS | 5 +
drivers/leds/Kconfig | 15 +++
drivers/leds/Makefile | 1 +
drivers/leds/leds-cros_ec.c | 299 ++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 320 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index aacccb376c28..8bc3491a08af 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5135,6 +5135,11 @@ S: Maintained
F: Documentation/devicetree/bindings/sound/google,cros-ec-codec.yaml
F: sound/soc/codecs/cros_ec_codec.*

+CHROMEOS EC LED DRIVER
+M: Thomas Weißschuh <thomas@weissschuh.net>
+S: Maintained
+F: drivers/leds/leds-cros_ec.c
+
CHROMEOS EC SUBDRIVERS
M: Benson Leung <bleung@chromium.org>
R: Guenter Roeck <groeck@chromium.org>
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 05e6af88b88c..aa2fec9a34ed 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -179,6 +179,21 @@ config LEDS_CR0014114
To compile this driver as a module, choose M here: the module
will be called leds-cr0014114.

+config LEDS_CROS_EC
+ tristate "LED Support for ChromeOS EC"
+ depends on MFD_CROS_EC_DEV
+ depends on LEDS_CLASS_MULTICOLOR
+ select LEDS_TRIGGERS
+ default MFD_CROS_EC_DEV
+ help
+ This option enables support for LEDs managed by ChromeOS ECs.
+ All LEDs exposed by the EC are supported in multicolor mode.
+ A hardware trigger to switch back to the automatic behaviour is
+ provided.
+
+ To compile this driver as a module, choose M here: the module
+ will be called leds-cros_ec.
+
config LEDS_EL15203000
tristate "LED Support for Crane EL15203000"
depends on LEDS_CLASS
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index effdfc6f1e95..3491904e13f7 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_LEDS_CLEVO_MAIL) += leds-clevo-mail.o
obj-$(CONFIG_LEDS_COBALT_QUBE) += leds-cobalt-qube.o
obj-$(CONFIG_LEDS_COBALT_RAQ) += leds-cobalt-raq.o
obj-$(CONFIG_LEDS_CPCAP) += leds-cpcap.o
+obj-$(CONFIG_LEDS_CROS_EC) += leds-cros_ec.o
obj-$(CONFIG_LEDS_DA903X) += leds-da903x.o
obj-$(CONFIG_LEDS_DA9052) += leds-da9052.o
obj-$(CONFIG_LEDS_GPIO) += leds-gpio.o
diff --git a/drivers/leds/leds-cros_ec.c b/drivers/leds/leds-cros_ec.c
new file mode 100644
index 000000000000..7bb21a587713
--- /dev/null
+++ b/drivers/leds/leds-cros_ec.c
@@ -0,0 +1,299 @@
+// 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>
+
+#define DRV_NAME "cros-ec-led"
+
+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;
+} __packed;
+
+static int cros_ec_led_send_cmd(struct cros_ec_device *cros_ec,
+ union cros_ec_led_cmd_data *arg)
+{
+ int ret;
+ struct {
+ struct cros_ec_command msg;
+ union cros_ec_led_cmd_data data;
+ } __packed buf = {
+ .msg = {
+ .version = 1,
+ .command = EC_CMD_LED_CONTROL,
+ .insize = sizeof(arg->resp),
+ .outsize = sizeof(arg->req),
+ },
+ .data.req = arg->req
+ };
+
+ ret = cros_ec_cmd_xfer_status(cros_ec, &buf.msg);
+ if (ret < 0)
+ return ret;
+
+ arg->resp = buf.data.resp;
+
+ 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_warn(dev, "Inconsistent LED brightness values\n");
+ return -EINVAL;
+ }
+ }
+
+ if (!num_subleds)
+ 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_led(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 ret, num_subleds;
+ size_t i, subled;
+
+ arg.req.led_id = id;
+ arg.req.flags = EC_LED_FLAGS_QUERY;
+ ret = cros_ec_led_send_cmd(cros_ec, &arg);
+ /* Unknown LED, skip */
+ if (ret == -EINVAL)
+ return 0;
+ 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;
+
+ 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 ret = 0;
+ size_t i;
+
+ for (i = 0; i < EC_LED_ID_COUNT; i++) {
+ ret = cros_ec_led_probe_led(dev, cros_ec, i);
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+
+static const struct platform_device_id cros_ec_led_id[] = {
+ { DRV_NAME, 0 },
+ {}
+};
+
+static struct platform_driver cros_ec_led_driver = {
+ .driver.name = DRV_NAME,
+ .probe = cros_ec_led_probe,
+ .id_table = cros_ec_led_id,
+};
+
+static int __init cros_ec_led_init(void)
+{
+ int ret;
+
+ ret = led_trigger_register(&cros_ec_led_trigger);
+ if (ret)
+ return ret;
+
+ ret = platform_driver_register(&cros_ec_led_driver);
+ if (ret)
+ led_trigger_unregister(&cros_ec_led_trigger);
+
+ return ret;
+};
+module_init(cros_ec_led_init);
+
+static void __exit cros_ec_led_exit(void)
+{
+ platform_driver_unregister(&cros_ec_led_driver);
+ led_trigger_unregister(&cros_ec_led_trigger);
+};
+module_exit(cros_ec_led_exit);
+
+MODULE_DEVICE_TABLE(platform, cros_ec_led_id);
+MODULE_DESCRIPTION("ChromeOS EC LED Driver");
+MODULE_AUTHOR("Thomas Weißschuh <linux@weissschuh.net");
+MODULE_LICENSE("GPL");

--
2.45.2