[RFC 1/2] leds: core: Add led_mc_set_brightness() function

[Hans de Goede <hdegoede@redhat.com>]

Add a new led_mc_set_brightness() function for in kernel color/brightness
changing of multi-color LEDs.

led-class-multicolor can be build as a module and led_mc_set_brightness()
will have builtin callers, so put led_mc_set_brightness() inside led-core
instead, just like how led_set_brightness() is part of the core and not
of the led-class object.

This also adds a new LED_MULTI_COLOR led_classdev flag to allow
led_mc_set_brightness() to verify that it is operating on a multi-color
LED classdev, avoiding casting the passed in LED classdev to a multi-color
LED classdev, when it actually is not a multi-color LED.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/leds/led-class-multicolor.c |  1 +
 drivers/leds/led-core.c             | 31 +++++++++++++++++++++++++++++
 include/linux/leds.h                | 20 +++++++++++++++++++
 3 files changed, 52 insertions(+)

diff --git a/drivers/leds/led-class-multicolor.c b/drivers/leds/led-class-multicolor.c
index ec62a4811613..df01c0e66c8b 100644
--- a/drivers/leds/led-class-multicolor.c
+++ b/drivers/leds/led-class-multicolor.c
@@ -134,6 +134,7 @@ int led_classdev_multicolor_register_ext(struct device *parent,
 		return -EINVAL;
 
 	led_cdev = &mcled_cdev->led_cdev;
+	led_cdev->flags |= LED_MULTI_COLOR;
 	mcled_cdev->led_cdev.groups = led_multicolor_groups;
 
 	return led_classdev_register_ext(parent, led_cdev, init_data);
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 89c9806cc97f..5889753ebc74 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -8,6 +8,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/led-class-multicolor.h>
 #include <linux/leds.h>
 #include <linux/list.h>
 #include <linux/module.h>
@@ -362,6 +363,36 @@ int led_set_brightness_sync(struct led_classdev *led_cdev, unsigned int value)
 }
 EXPORT_SYMBOL_GPL(led_set_brightness_sync);
 
+/*
+ * This is a led-core function because just like led_set_brightness()
+ * it is used in kernel by e.g. triggers.
+ */
+void led_mc_set_brightness(struct led_classdev *led_cdev,
+			   unsigned int *intensity_value, unsigned int num_colors,
+			   unsigned int brightness)
+{
+	struct led_classdev_mc *mcled_cdev;
+	unsigned int i;
+
+	if (!(led_cdev->flags & LED_MULTI_COLOR)) {
+		dev_err_once(led_cdev->dev, "%s: error not a multi-color LED\n",  __func__);
+		return;
+	}
+
+	mcled_cdev = lcdev_to_mccdev(led_cdev);
+	if (num_colors != mcled_cdev->num_colors) {
+		dev_err_once(led_cdev->dev, "%s: error num_colors mismatch %d != %d\n",
+			     __func__, num_colors, mcled_cdev->num_colors);
+		return;
+	}
+
+	for (i = 0; i < mcled_cdev->num_colors; i++)
+		mcled_cdev->subled_info[i].intensity = intensity_value[i];
+
+	led_set_brightness(led_cdev, brightness);
+}
+EXPORT_SYMBOL_GPL(led_mc_set_brightness);
+
 int led_update_brightness(struct led_classdev *led_cdev)
 {
 	int ret;
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 4754b02d3a2c..fed88eb9e170 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -115,6 +115,7 @@ struct led_classdev {
 #define LED_BRIGHT_HW_CHANGED	BIT(21)
 #define LED_RETAIN_AT_SHUTDOWN	BIT(22)
 #define LED_INIT_DEFAULT_TRIGGER BIT(23)
+#define LED_MULTI_COLOR		BIT(24)
 
 	/* set_brightness_work / blink_timer flags, atomic, private. */
 	unsigned long		work_flags;
@@ -392,6 +393,25 @@ void led_set_brightness(struct led_classdev *led_cdev, unsigned int brightness);
  */
 int led_set_brightness_sync(struct led_classdev *led_cdev, unsigned int value);
 
+/**
+ * led_mc_set_brightness - set mc LED color intensity values and brightness
+ * @led_cdev: the LED to set
+ * @intensity_value: array of per color intensity values to set
+ * @num_colors: amount of entries in intensity_value array
+ * @brightness: the brightness to set the LED to
+ *
+ * Set a multi-color LED's per color intensity values and brightness.
+ * If necessary, this cancels the software blink timer. This function is
+ * guaranteed not to sleep.
+ *
+ * Calling this function on a non multi-color led_classdev or with the wrong
+ * num_colors value is an error. In this case an error will be logged once
+ * and the call will do nothing.
+ */
+void led_mc_set_brightness(struct led_classdev *led_cdev,
+			   unsigned int *intensity_value, unsigned int num_colors,
+			   unsigned int brightness);
+
 /**
  * led_update_brightness - update LED brightness
  * @led_cdev: the LED to query
-- 
2.43.2