Export a function to convert HSV color values to RGB.
It's intended to be called by drivers for RGB LEDs.
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
---
v2:
- move hsv -> rgb conversion to separate file
- remove flag LED_DEV_CAP_RGB
v3:
- call led_hsv_to_rgb only if LED_DEV_CAP_HSV is set
This is needed in cases when we have monochrome and color LEDs
as well in a system.
v4:
- Export led_hsv_to_rgb and let the device driver call it instead
of doing the conversion in the core
v5:
- don't ignore led_cdev->brightness_get silently if LED_DEV_CAP_RGB
is set but warn
v6:
- no changes
v7:
- remove "for now" in WARN_ON comment
- move position of WARN_ON
---
drivers/leds/led-class.c | 6 ++++++
drivers/leds/led-rgb-core.c | 36 ++++++++++++++++++++++++++++++++++++
include/linux/leds.h | 8 ++++++++
3 files changed, 50 insertions(+)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 8a3748a..adcd8f6 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -205,6 +205,12 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
if (ret)
dev_warn(parent, "Led %s renamed to %s due to name collision",
led_cdev->name, dev_name(led_cdev->dev));
+ /*
+ * Reading back the color is not supported as multiple
+ * HSV -> RGB -> HSV conversions may distort the color due to
+ * rounding issues in the conversion algorithm
+ */
+ WARN_ON(led_cdev->flags & LED_DEV_CAP_RGB && led_cdev->brightness_get);
#ifdef CONFIG_LEDS_TRIGGERS
init_rwsem(&led_cdev->trigger_lock);
diff --git a/drivers/leds/led-rgb-core.c b/drivers/leds/led-rgb-core.c
index cbd8b35..cdb7ba6 100644
--- a/drivers/leds/led-rgb-core.c
+++ b/drivers/leds/led-rgb-core.c
@@ -37,3 +37,39 @@ enum led_brightness led_confine_brightness(struct led_classdev *led_cdev,
return brightness |
min(value & LED_BRIGHTNESS_MASK, led_cdev->max_brightness);
}
+
+enum led_brightness led_hsv_to_rgb(enum led_brightness hsv)
+{
+ int h = min_t(int, (hsv >> 16) & 0xff, 251);
+ int s = (hsv >> 8) & 0xff;
+ int v = hsv & 0xff;
+ int f, p, q, t, r, g, b;
+
+ if (!v)
+ return 0;
+ if (!s)
+ return (v << 16) + (v << 8) + v;
+
+ f = DIV_ROUND_CLOSEST((h % 42) * 255, 42);
+ p = v - DIV_ROUND_CLOSEST(s * v, 255);
+ q = v - DIV_ROUND_CLOSEST(f * s * v, 255 * 255);
+ t = v - DIV_ROUND_CLOSEST((255 - f) * s * v, 255 * 255);
+
+ switch (h / 42) {
+ case 0:
+ r = v; g = t; b = p; break;
+ case 1:
+ r = q; g = v; b = p; break;
+ case 2:
+ r = p; g = v; b = t; break;
+ case 3:
+ r = p; g = q; b = v; break;
+ case 4:
+ r = t; g = p; b = v; break;
+ case 5:
+ r = v; g = p; b = q; break;
+ }
+
+ return (r << 16) + (g << 8) + b;
+}
+EXPORT_SYMBOL_GPL(led_hsv_to_rgb);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 58e8299..58e22e6 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -226,6 +226,14 @@ static inline bool led_sysfs_is_disabled(struct led_classdev *led_cdev)
return led_cdev->flags & LED_SYSFS_DISABLE;
}
+/**
+ * led_hsv_to_rgb - convert a hsv color value to rgb color model
+ * @hsv: the hsv value to convert
+ *
+ * Returns: the resulting rgb value
+ */
+enum led_brightness led_hsv_to_rgb(enum led_brightness hsv);
+
/*
* LED Triggers
*/
--
2.7.1
--
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