This adds a small backlight layer. It provides a backlight device
on which the brightness parameter can be used to adjust the brightness.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
drivers/video/Kconfig | 4 +++
drivers/video/Makefile | 1 +
drivers/video/backlight.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++
include/video/backlight.h | 20 +++++++++++
4 files changed, 115 insertions(+)
create mode 100644 drivers/video/backlight.c
create mode 100644 include/video/backlight.h
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index f096a54..e108d8a 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -93,4 +93,8 @@ config DRIVER_VIDEO_EDID
This enabled support for reading and parsing EDID data from an attached
monitor.
+config DRIVER_VIDEO_BACKLIGHT
+ bool "Add backlight support"
+ help
+ Enable this for backlight support.
endif
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index ae9f6e5..0655b0f 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -1,6 +1,7 @@
obj-$(CONFIG_VIDEO) += fb.o
obj-$(CONFIG_DRIVER_VIDEO_EDID) += edid.o
obj-$(CONFIG_OFDEVICE) += of_display_timing.o
+obj-$(CONFIG_DRIVER_VIDEO_BACKLIGHT) += backlight.o
obj-$(CONFIG_DRIVER_VIDEO_ATMEL) += atmel_lcdfb.o atmel_lcdfb_core.o
obj-$(CONFIG_DRIVER_VIDEO_ATMEL_HLCD) += atmel_hlcdfb.o atmel_lcdfb_core.o
diff --git a/drivers/video/backlight.c b/drivers/video/backlight.c
new file mode 100644
index 0000000..ddde6f8
--- /dev/null
+++ b/drivers/video/backlight.c
@@ -0,0 +1,90 @@
+#include <common.h>
+#include <driver.h>
+#include <linux/list.h>
+#include <video/backlight.h>
+
+static LIST_HEAD(backlights);
+
+int backlight_set_brightness(struct backlight_device *bl, int brightness)
+{
+ int ret, step, i, num_steps;
+
+ if (brightness > bl->brightness_max)
+ brightness = bl->brightness_max;
+
+ if (brightness == bl->brightness_cur)
+ return 0;
+
+ if (brightness > bl->brightness_cur)
+ step = 1;
+ else
+ step = -1;
+
+ i = bl->brightness_cur;
+
+ num_steps = abs(brightness - bl->brightness_cur);
+
+ while (1) {
+ i += step;
+
+ ret = bl->brightness_set(bl, i);
+ if (ret)
+ return ret;
+
+ if (i == brightness)
+ break;
+
+ udelay(100000 / num_steps);
+ }
+
+
+ bl->brightness_cur = bl->brightness = brightness;
+
+ return ret;
+}
+
+int backlight_set_brightness_default(struct backlight_device *bl)
+{
+ int ret;
+
+ ret = backlight_set_brightness(bl, bl->brightness_default);
+
+ return ret;
+}
+
+static int backlight_brightness_set(struct param_d *p, void *priv)
+{
+ struct backlight_device *bl = priv;
+
+ return backlight_set_brightness(bl, bl->brightness);
+}
+
+int backlight_register(struct backlight_device *bl)
+{
+ int ret;
+
+ sprintf(bl->dev.name, "backlight");
+ bl->dev.id = DEVICE_ID_DYNAMIC;
+
+ ret = register_device(&bl->dev);
+ if (ret)
+ return ret;
+
+ dev_add_param_int(&bl->dev, "brightness", backlight_brightness_set,
+ NULL, &bl->brightness, "%d", bl);
+
+ list_add_tail(&bl->list, &backlights);
+
+ return ret;
+}
+
+struct backlight_device *of_backlight_find(struct device_node *node)
+{
+ struct backlight_device *bl;
+
+ list_for_each_entry(bl, &backlights, list)
+ if (bl->node == node)
+ return bl;
+
+ return NULL;
+}
diff --git a/include/video/backlight.h b/include/video/backlight.h
new file mode 100644
index 0000000..56e0341
--- /dev/null
+++ b/include/video/backlight.h
@@ -0,0 +1,20 @@
+#ifndef __VIDEO_BACKLIGHT_H
+#define __VIDEO_BACKLIGHT_H
+
+struct backlight_device {
+ int brightness;
+ int brightness_cur;
+ int brightness_max;
+ int brightness_default;
+ int (*brightness_set)(struct backlight_device *, int brightness);
+ struct list_head list;
+ struct device_d dev;
+ struct device_node *node;
+};
+
+int backlight_set_brightness(struct backlight_device *, int brightness);
+int backlight_set_brightness_default(struct backlight_device *);
+int backlight_register(struct backlight_device *);
+struct backlight_device *of_backlight_find(struct device_node *node);
+
+#endif /* __VIDEO_BACKLIGHT_H */
--
2.1.4
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