glamo_fb: Implement screen blanking

This patch implements fb_blank() for the glamo-fb driver, which switches off
the pixel clock (DCLK) for power saving.

We currently delay the actual pixel clock switch until we enter
FB_BLANK_POWERDOWN, since the backlight fade is slow and we don't want the
user to see artefacts on the screen while the backlight is fading out.

So since the X server first sends FB_BLANK_{V,H}SYNC_SUSPEND, we start the
backlight fade here, and only once we get FB_BLANK_POWERDOWN the pixel clock is
disabled.

There are no measurements yet, but the power savings should be double, since
there is no longer any  generation of the high-frequency LCM signals, and
there are no video-related SDRAM accesses anymore.

Signed-off-by: Harald Welte <laforge@openmoko.org>

3 files changed, 66 insertions, 1 deletions

diff --git a/drivers/mfd/glamo/glamo-core.c b/drivers/mfd/glamo/glamo-core.c
index 0fea4f4ea0e..77e25a65a9b 100644
--- a/drivers/mfd/glamo/glamo-core.c
+++ b/drivers/mfd/glamo/glamo-core.c
@@ -526,6 +526,38 @@ int glamo_engine_disable(struct glamo_core *glamo, enum glamo_engine engine)
 }
 EXPORT_SYMBOL_GPL(glamo_engine_disable);
 
+static const u_int16_t engine_clock_regs[__NUM_GLAMO_ENGINES] = {
+	[GLAMO_ENGINE_LCD]	= GLAMO_REG_CLOCK_LCD,
+	[GLAMO_ENGINE_MMC]	= GLAMO_REG_CLOCK_MMC,
+	[GLAMO_ENGINE_ISP]	= GLAMO_REG_CLOCK_ISP,
+	[GLAMO_ENGINE_JPEG]	= GLAMO_REG_CLOCK_JPEG,
+	[GLAMO_ENGINE_3D]	= GLAMO_REG_CLOCK_3D,
+	[GLAMO_ENGINE_2D]	= GLAMO_REG_CLOCK_2D,
+	[GLAMO_ENGINE_MPEG_ENC] = GLAMO_REG_CLOCK_MPEG,
+	[GLAMO_ENGINE_MPEG_DEC] = GLAMO_REG_CLOCK_MPEG,
+};
+
+void glamo_engine_clkreg_set(struct glamo_core *glamo,
+			     enum glamo_engine engine,
+			     u_int16_t mask, u_int16_t val)
+{
+	reg_set_bit_mask(glamo, engine_clock_regs[engine], mask, val);
+}
+EXPORT_SYMBOL_GPL(glamo_engine_clkreg_set);
+
+u_int16_t glamo_engine_clkreg_get(struct glamo_core *glamo,
+				  enum glamo_engine engine)
+{
+	u_int16_t val;
+
+	spin_lock(&glamo->lock);
+	val = __reg_read(glamo, engine_clock_regs[engine]);
+	spin_unlock(&glamo->lock);
+
+	return val;
+}
+EXPORT_SYMBOL_GPL(glamo_engine_clkreg_get);
+
 struct glamo_script reset_regs[] = {
 	[GLAMO_ENGINE_LCD] = {
 		GLAMO_REG_CLOCK_LCD, GLAMO_CLOCK_LCD_RESET
diff --git a/drivers/mfd/glamo/glamo-core.h b/drivers/mfd/glamo/glamo-core.h
index ce8d4c7e79e..4c52bc44eaf 100644
--- a/drivers/mfd/glamo/glamo-core.h
+++ b/drivers/mfd/glamo/glamo-core.h
@@ -96,4 +96,10 @@ void glamo_engine_reset(struct glamo_core *glamo, enum glamo_engine engine);
 int glamo_engine_reclock(struct glamo_core *glamo,
 			 enum glamo_engine engine, int ps);
 
+void glamo_engine_clkreg_set(struct glamo_core *glamo,
+			     enum glamo_engine engine,
+			     u_int16_t mask, u_int16_t val);
+
+u_int16_t glamo_engine_clkreg_get(struct glamo_core *glamo,
+				  enum glamo_engine engine);
 #endif /* __GLAMO_CORE_H */
diff --git a/drivers/mfd/glamo/glamo-fb.c b/drivers/mfd/glamo/glamo-fb.c
index 0bc6a1be63f..1ae933e9a3e 100644
--- a/drivers/mfd/glamo/glamo-fb.c
+++ b/drivers/mfd/glamo/glamo-fb.c
@@ -422,7 +422,34 @@ static int glamofb_set_par(struct fb_info *info)
 
 static int glamofb_blank(int blank_mode, struct fb_info *info)
 {
-	/* FIXME */
+	struct glamofb_handle *gfb = info->par;
+	struct glamo_core *gcore = gfb->mach_info->glamo;
+
+	dev_dbg(gfb->dev, "glamofb_blank(%u)\n", blank_mode);
+
+	switch (blank_mode) {
+	case FB_BLANK_VSYNC_SUSPEND:
+	case FB_BLANK_HSYNC_SUSPEND:
+		/* FIXME: add pdata hook/flag to indicate whether
+		 * we should already switch off pixel clock here */
+		break;
+	case FB_BLANK_POWERDOWN:
+		/* disable the pixel clock */
+		glamo_engine_clkreg_set(gcore, GLAMO_ENGINE_LCD,
+					GLAMO_CLOCK_LCD_EN_DCLK, 0);
+		break;
+	case FB_BLANK_UNBLANK:
+	case FB_BLANK_NORMAL:
+		/* enable the pixel clock */
+		glamo_engine_clkreg_set(gcore, GLAMO_ENGINE_LCD,
+					GLAMO_CLOCK_LCD_EN_DCLK,
+					GLAMO_CLOCK_LCD_EN_DCLK);
+		break;
+	}
+
+	/* FIXME: once we have proper clock management in glamo-core,
+	 * we can determine if other units need MCLK1 or the PLL, and
+	 * disable it if not used. */
 	return 0;
 }