[PATCH v2] video: mx3fb: Add backlight support

[PATCH v2] video: mx3fb: Add backlight support

[Alexander Stein]

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
---
Changes in v2:
* rebased to v3.15-rc4

 drivers/video/fbdev/mx3fb.c | 98 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)

diff --git a/drivers/video/fbdev/mx3fb.c b/drivers/video/fbdev/mx3fb.c
index 142e860..10a7244 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>
@@ -34,6 +35,12 @@
 #include <asm/io.h>
 #include <asm/uaccess.h>
 
+#if defined(CONFIG_BACKLIGHT_CLASS_DEVICE) || \
+	(defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE) && \
+		defined(CONFIG_MX3FB_MODULE))
+#define PWM_BACKLIGHT_AVAILABLE
+#endif
+
 #define MX3FB_NAME		"mx3_sdc_fb"
 
 #define MX3FB_REG_OFFSET	0xB4
@@ -242,6 +249,10 @@ struct mx3fb_data {
 	spinlock_t		lock;
 	struct device		*dev;
 
+#ifdef PWM_BACKLIGHT_AVAILABLE
+	struct backlight_device	*bl;
+#endif
+
 	uint32_t		h_start_width;
 	uint32_t		v_start_width;
 	enum disp_data_mapping	disp_data_fmt;
@@ -271,6 +282,74 @@ struct mx3fb_info {
 	struct fb_var_screeninfo	cur_var; /* current var info */
 };
 
+static void sdc_set_brightness(struct mx3fb_data *mx3fb, uint8_t value);
+
+#ifdef PWM_BACKLIGHT_AVAILABLE
+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);
+}
+#endif
+
 static void mx3fb_dma_done(void *);
 
 /* Used fb-mode and bpp. Can be set on kernel command line, therefore file-static. */
@@ -628,6 +707,18 @@ static int sdc_set_global_alpha(struct mx3fb_data *mx3fb, bool enable, uint8_t a
 	return 0;
 }
 
+#ifdef PWM_BACKLIGHT_AVAILABLE
+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;
+}
+#endif
+
 static void sdc_set_brightness(struct mx3fb_data *mx3fb, uint8_t value)
 {
 	dev_dbg(mx3fb->dev, "%s: value = %d\n", __func__, value);
@@ -1534,6 +1625,9 @@ static int mx3fb_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto eisdc0;
 
+#ifdef PWM_BACKLIGHT_AVAILABLE
+	mx3fb_init_backlight(mx3fb);
+#endif
 	return 0;
 
 eisdc0:
@@ -1557,6 +1651,10 @@ static int mx3fb_remove(struct platform_device *dev)
 	chan = &mx3_fbi->idmac_channel->dma_chan;
 	release_fbi(fbi);
 
+#ifdef PWM_BACKLIGHT_AVAILABLE
+	mx3fb_exit_backlight(mx3fb);
+#endif
+
 	dma_release_channel(chan);
 	dmaengine_put();
 
-- 
1.8.5.5

Re: [PATCH v2] video: mx3fb: Add backlight support

[Tomi Valkeinen]

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Hi,

On 05/05/14 09:56, Alexander Stein wrote:
> Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
> ---

Please always have a commit description, even if it's more or less the
same as the subject.

Is the backlight PWM hardware part of the display hardware on mx3fb? If
so, I guess it's ok to have the backlight in the fb driver, as you're
doing here.

 Tomi



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Re: [PATCH v2] video: mx3fb: Add backlight support

[Tomi Valkeinen]

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On 08/05/14 13:47, Tomi Valkeinen wrote:
> Hi,
> 
> On 05/05/14 09:56, Alexander Stein wrote:
>> Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
>> ---
> 
> Please always have a commit description, even if it's more or less the
> same as the subject.

Oh, and I'd rather have a bit more explanation than "add backlight
support". The current driver seems to have some backlight code. So what
are you actually adding with this patch? Etc.

 Tomi



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