This patch add backlight control support to allow dimming the backlight
using the internal PWM. Currently the brightness is set fixed to a
maximum of 255.
Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxxxxxxxx>
---
Changes in v4:
* Add backlight support unconditionally
Changes in v3:
* Add a more descriptive commit message
Changes in v2:
* rebased to v3.15-rc4
drivers/video/fbdev/Kconfig | 1 +
drivers/video/fbdev/mx3fb.c | 81 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 82 insertions(+)
diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index e1f4727..d76b4af 100644
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig
@@ -2332,6 +2332,7 @@ config FB_MX3
select FB_CFB_FILLRECT
select FB_CFB_COPYAREA
select FB_CFB_IMAGEBLIT
+ select BACKLIGHT_CLASS_DEVICE
default y
help
This is a framebuffer device for the i.MX31 LCD Controller. So
diff --git a/drivers/video/fbdev/mx3fb.c b/drivers/video/fbdev/mx3fb.c
index 142e860..315e285 100644
--- a/drivers/video/fbdev/mx3fb.c
+++ b/drivers/video/fbdev/mx3fb.c
@@ -27,6 +27,7 @@
#include <linux/clk.h>
#include <linux/mutex.h>
#include <linux/dma/ipu-dma.h>
+#include <linux/backlight.h>
#include <linux/platform_data/dma-imx.h>
#include <linux/platform_data/video-mx3fb.h>
@@ -241,6 +242,7 @@ struct mx3fb_data {
void __iomem *reg_base;
spinlock_t lock;
struct device *dev;
+ struct backlight_device *bl;
uint32_t h_start_width;
uint32_t v_start_width;
@@ -271,6 +273,71 @@ struct mx3fb_info {
struct fb_var_screeninfo cur_var; /* current var info */
};
+static void sdc_set_brightness(struct mx3fb_data *mx3fb, uint8_t value);
+static u32 sdc_get_brightness(struct mx3fb_data *mx3fb);
+
+static int mx3fb_bl_get_brightness(struct backlight_device *bl)
+{
+ struct mx3fb_data *fbd = bl_get_data(bl);
+
+ return sdc_get_brightness(fbd);
+}
+
+static int mx3fb_bl_update_status(struct backlight_device *bl)
+{
+ struct mx3fb_data *fbd = bl_get_data(bl);
+ int brightness = bl->props.brightness;
+
+ if (bl->props.power != FB_BLANK_UNBLANK)
+ brightness = 0;
+ if (bl->props.fb_blank != FB_BLANK_UNBLANK)
+ brightness = 0;
+
+ fbd->backlight_level = (fbd->backlight_level & ~0xFF) | brightness;
+
+ sdc_set_brightness(fbd, fbd->backlight_level);
+
+ return 0;
+}
+
+static const struct backlight_ops mx3fb_lcdc_bl_ops = {
+ .update_status = mx3fb_bl_update_status,
+ .get_brightness = mx3fb_bl_get_brightness,
+};
+
+static void mx3fb_init_backlight(struct mx3fb_data *fbd)
+{
+ struct backlight_properties props;
+ struct backlight_device *bl;
+
+ if (fbd->bl)
+ return;
+
+ memset(&props, 0, sizeof(struct backlight_properties));
+ props.max_brightness = 0xff;
+ props.type = BACKLIGHT_RAW;
+ sdc_set_brightness(fbd, fbd->backlight_level);
+
+ bl = backlight_device_register("mx3fb-bl", fbd->dev, fbd,
+ &mx3fb_lcdc_bl_ops, &props);
+ if (IS_ERR(bl)) {
+ dev_err(fbd->dev, "error %ld on backlight register\n",
+ PTR_ERR(bl));
+ return;
+ }
+
+ fbd->bl = bl;
+ bl->props.power = FB_BLANK_UNBLANK;
+ bl->props.fb_blank = FB_BLANK_UNBLANK;
+ bl->props.brightness = mx3fb_bl_get_brightness(bl);
+}
+
+static void mx3fb_exit_backlight(struct mx3fb_data *fbd)
+{
+ if (fbd->bl)
+ backlight_device_unregister(fbd->bl);
+}
+
static void mx3fb_dma_done(void *);
/* Used fb-mode and bpp. Can be set on kernel command line, therefore file-static. */
@@ -628,6 +695,16 @@ static int sdc_set_global_alpha(struct mx3fb_data *mx3fb, bool enable, uint8_t a
return 0;
}
+static u32 sdc_get_brightness(struct mx3fb_data *mx3fb)
+{
+ u32 brightness;
+
+ brightness = mx3fb_read_reg(mx3fb, SDC_PWM_CTRL);
+ brightness = (brightness >> 16) & 0xFF;
+
+ return brightness;
+}
+
static void sdc_set_brightness(struct mx3fb_data *mx3fb, uint8_t value)
{
dev_dbg(mx3fb->dev, "%s: value = %d\n", __func__, value);
@@ -1534,6 +1611,8 @@ static int mx3fb_probe(struct platform_device *pdev)
if (ret < 0)
goto eisdc0;
+ mx3fb_init_backlight(mx3fb);
+
return 0;
eisdc0:
@@ -1557,6 +1636,8 @@ static int mx3fb_remove(struct platform_device *dev)
chan = &mx3_fbi->idmac_channel->dma_chan;
release_fbi(fbi);
+ mx3fb_exit_backlight(mx3fb);
+
dma_release_channel(chan);
dmaengine_put();
--
1.8.5.5
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