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Subject[PATCH v7 3/8] Loongson: YeeLoong: add backlight driver
Date
From: Wu Zhangjin <wuzhangjin@gmail.com>

This patch adds YeeLoong Backlight Driver, it provides standard
interface(/sys/class/backlight/) for user-space applications(e.g.
kpowersave, gnome-power-manager) to control the brightness of the
backlight.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
---
drivers/platform/mips/Kconfig | 1 +
drivers/platform/mips/yeeloong_laptop.c | 79 +++++++++++++++++++++++++++++++
2 files changed, 80 insertions(+), 0 deletions(-)
diff --git a/drivers/platform/mips/Kconfig b/drivers/platform/mips/Kconfig
index 76f0250..f7a3705 100644
--- a/drivers/platform/mips/Kconfig
+++ b/drivers/platform/mips/Kconfig
@@ -17,6 +17,7 @@ if MIPS_PLATFORM_DEVICES
config LEMOTE_YEELOONG2F
tristate "Lemote YeeLoong Laptop"
depends on LEMOTE_MACH2F
+ select BACKLIGHT_CLASS_DEVICE
default m
help
YeeLoong netbook is a mini laptop made by Lemote, which is basically
diff --git a/drivers/platform/mips/yeeloong_laptop.c b/drivers/platform/mips/yeeloong_laptop.c
index 85fc7ed..fbc4ebb 100644
--- a/drivers/platform/mips/yeeloong_laptop.c
+++ b/drivers/platform/mips/yeeloong_laptop.c
@@ -11,6 +11,77 @@

#include <linux/err.h>
#include <linux/platform_device.h>
+#include <linux/backlight.h> /* for backlight subdriver */
+#include <linux/fb.h>
+
+#include <ec_kb3310b.h>
+
+/* backlight subdriver */
+#define MAX_BRIGHTNESS 8
+
+static int yeeloong_set_brightness(struct backlight_device *bd)
+{
+ unsigned int level, current_level;
+ static unsigned int old_level;
+
+ level = (bd->props.fb_blank == FB_BLANK_UNBLANK &&
+ bd->props.power == FB_BLANK_UNBLANK) ?
+ bd->props.brightness : 0;
+
+ if (level > MAX_BRIGHTNESS)
+ level = MAX_BRIGHTNESS;
+ else if (level < 0)
+ level = 0;
+
+ /* Avoid to modify the brightness when EC is tuning it */
+ current_level = ec_read(REG_DISPLAY_BRIGHTNESS);
+ if ((old_level == current_level) && (old_level != level))
+ ec_write(REG_DISPLAY_BRIGHTNESS, level);
+ old_level = level;
+
+ return 0;
+}
+
+static int yeeloong_get_brightness(struct backlight_device *bd)
+{
+ return (int)ec_read(REG_DISPLAY_BRIGHTNESS);
+}
+
+static struct backlight_ops backlight_ops = {
+ .get_brightness = yeeloong_get_brightness,
+ .update_status = yeeloong_set_brightness,
+};
+
+static struct backlight_device *yeeloong_backlight_dev;
+
+static int yeeloong_backlight_init(void)
+{
+ int ret;
+
+ yeeloong_backlight_dev = backlight_device_register("backlight0", NULL,
+ NULL, &backlight_ops);
+
+ if (IS_ERR(yeeloong_backlight_dev)) {
+ ret = PTR_ERR(yeeloong_backlight_dev);
+ yeeloong_backlight_dev = NULL;
+ return ret;
+ }
+
+ yeeloong_backlight_dev->props.max_brightness = MAX_BRIGHTNESS;
+ yeeloong_backlight_dev->props.brightness =
+ yeeloong_get_brightness(yeeloong_backlight_dev);
+ backlight_update_status(yeeloong_backlight_dev);
+
+ return 0;
+}
+
+static void yeeloong_backlight_exit(void)
+{
+ if (yeeloong_backlight_dev) {
+ backlight_device_unregister(yeeloong_backlight_dev);
+ yeeloong_backlight_dev = NULL;
+ }
+}

static struct platform_device_id platform_device_ids[] = {
{
@@ -42,11 +113,19 @@ static int __init yeeloong_init(void)
return ret;
}

+ ret = yeeloong_backlight_init();
+ if (ret) {
+ pr_err("Fail to register yeeloong backlight driver.\n");
+ yeeloong_backlight_exit();
+ return ret;
+ }
+
return 0;
}

static void __exit yeeloong_exit(void)
{
+ yeeloong_backlight_exit();
platform_driver_unregister(&platform_driver);

pr_info("Unload YeeLoong Platform Specific Driver.\n");
--
1.6.2.1


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