video: mx3fb: Add backlight control support

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@systec-electronic.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index 96f0f42..59c98bf 100644 (file)
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig
@@ -2336,6 +2336,7 @@ 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 ee95de8..c645a0a 100644 (file)
--- 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:
@@ -1556,6 +1635,8 @@ 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();