On 02/07/2016 11:45 AM, Heiner Kallweit wrote:
Add support for RGB LED's. Flag LED_DEV_CAP_RGB is used to instruct
the core to convert HSV to RGB on output.
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
---
drivers/leds/led-class.c | 3 +++
drivers/leds/led-core.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++-
include/linux/leds.h | 1 +
3 files changed, 51 insertions(+), 1 deletion(-)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 18a4558..f04efd2 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -193,6 +193,9 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
char name[64];
int ret;
+ if (led_cdev->flags & LED_DEV_CAP_RGB)
+ led_cdev->flags |= LED_DEV_CAP_COLOR;
+
ret = led_classdev_next_name(led_cdev->name, name, sizeof(name));
if (ret < 0)
return ret;
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 798e31e..6e1adc5 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -45,12 +45,50 @@ static inline enum led_brightness to_hsv(struct led_classdev *cdev,
return ret | min(value & LED_BRIGHTNESS_MASK, cdev->max_brightness);
}
+static enum led_brightness 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;
+}
+
This can be moved to led-hvs-core.c. Could you also share a reference
to the algorithm of hsv -> rgb conversion you implemented here?
static int led_set_output(struct led_classdev *cdev,
enum led_brightness value)
{
if (!cdev->brightness_set)
return -ENOTSUPP;
+ if (cdev->flags & LED_DEV_CAP_RGB)
+ value = hsv_to_rgb(value);
+
cdev->brightness_set(cdev, value);
return 0;
@@ -62,6 +100,9 @@ static int led_set_output_blocking(struct led_classdev *cdev,
if (!cdev->brightness_set_blocking)
return -ENOTSUPP;
+ if (cdev->flags & LED_DEV_CAP_RGB)
+ value = hsv_to_rgb(value);
+
return cdev->brightness_set_blocking(cdev, value);
}
@@ -320,7 +361,12 @@ int led_update_brightness(struct led_classdev *led_cdev)
{
int ret = 0;
- if (led_cdev->brightness_get) {
+ /*
+ * for now 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
+ */
+ if (led_cdev->brightness_get && !(led_cdev->flags & LED_DEV_CAP_RGB)) {
ret = led_cdev->brightness_get(led_cdev);
if (ret >= 0) {
led_cdev->brightness = ret;
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 8e7db72..24eae4b 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -51,6 +51,7 @@ struct led_classdev {
#define LED_DEV_CAP_FLASH (1 << 23)
#define LED_HW_PLUGGABLE (1 << 24)
#define LED_DEV_CAP_COLOR (1 << 25)
+#define LED_DEV_CAP_RGB (1 << 26)
Why two flags - COLOR and RGB? Their meaning is ambiguous.
/* Set LED brightness level
* Must not sleep. Use brightness_set_blocking for drivers
--
Best Regards,
Jacek Anaszewski
--
To unsubscribe from this list: send the line "unsubscribe linux-leds" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
