omapfb: lcd_ams_delta: add support for contrast control

The patch extends the Amstrad Delta LCD panel driver with optional support for
changing contrast using standard LCD class device API instead of setting it
silently to a default value at panel enable. It also allows for lowering power
consumption by turning off OMAP_PWL_CLK_ENABLE via lcd_ops.set_power callback.

Created and tested against linux-omap for-next,
commit 155a75d9725e66e5ec8a383822957dee52427057.

Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>

drivers/video/omap/lcd_ams_delta.c

@@ -24,6 +24,7 @@
 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/delay.h>
+#include <linux/lcd.h>
 
 #include <plat/board-ams-delta.h>
 #include <mach/hardware.h>
@@ -32,6 +33,71 @@
 
 #define AMS_DELTA_DEFAULT_CONTRAST	112
 
+#define AMS_DELTA_MAX_CONTRAST		0x00FF
+#define AMS_DELTA_LCD_POWER		0x0100
+
+
+/* LCD class device section */
+
+static int ams_delta_lcd;
+
+static int ams_delta_lcd_set_power(struct lcd_device *dev, int power)
+{
+	if (power == FB_BLANK_UNBLANK) {
+		if (!(ams_delta_lcd & AMS_DELTA_LCD_POWER)) {
+			omap_writeb(ams_delta_lcd & AMS_DELTA_MAX_CONTRAST,
+					OMAP_PWL_ENABLE);
+			omap_writeb(1, OMAP_PWL_CLK_ENABLE);
+			ams_delta_lcd |= AMS_DELTA_LCD_POWER;
+		}
+	} else {
+		if (ams_delta_lcd & AMS_DELTA_LCD_POWER) {
+			omap_writeb(0, OMAP_PWL_ENABLE);
+			omap_writeb(0, OMAP_PWL_CLK_ENABLE);
+			ams_delta_lcd &= ~AMS_DELTA_LCD_POWER;
+		}
+	}
+	return 0;
+}
+
+static int ams_delta_lcd_set_contrast(struct lcd_device *dev, int value)
+{
+	if ((value >= 0) && (value <= AMS_DELTA_MAX_CONTRAST)) {
+		omap_writeb(value, OMAP_PWL_ENABLE);
+		ams_delta_lcd &= ~AMS_DELTA_MAX_CONTRAST;
+		ams_delta_lcd |= value;
+	}
+	return 0;
+}
+
+#ifdef CONFIG_LCD_CLASS_DEVICE
+static int ams_delta_lcd_get_power(struct lcd_device *dev)
+{
+	if (ams_delta_lcd & AMS_DELTA_LCD_POWER)
+		return FB_BLANK_UNBLANK;
+	else
+		return FB_BLANK_POWERDOWN;
+}
+
+static int ams_delta_lcd_get_contrast(struct lcd_device *dev)
+{
+	if (!(ams_delta_lcd & AMS_DELTA_LCD_POWER))
+		return 0;
+
+	return ams_delta_lcd & AMS_DELTA_MAX_CONTRAST;
+}
+
+static struct lcd_ops ams_delta_lcd_ops = {
+	.get_power = ams_delta_lcd_get_power,
+	.set_power = ams_delta_lcd_set_power,
+	.get_contrast = ams_delta_lcd_get_contrast,
+	.set_contrast = ams_delta_lcd_set_contrast,
+};
+#endif
+
+
+/* omapfb panel section */
+
 static int ams_delta_panel_init(struct lcd_panel *panel,
 		struct omapfb_device *fbdev)
 {
@@ -48,10 +114,6 @@ static int ams_delta_panel_enable(struct lcd_panel *panel)
 			AMS_DELTA_LATCH2_LCD_NDISP);
 	ams_delta_latch2_write(AMS_DELTA_LATCH2_LCD_VBLEN,
 			AMS_DELTA_LATCH2_LCD_VBLEN);
-
-	omap_writeb(1, OMAP_PWL_CLK_ENABLE);
-	omap_writeb(AMS_DELTA_DEFAULT_CONTRAST, OMAP_PWL_ENABLE);
-
 	return 0;
 }
 
@@ -91,8 +153,31 @@ static struct lcd_panel ams_delta_panel = {
 	.get_caps	= ams_delta_panel_get_caps,
 };
 
+
+/* platform driver section */
+
 static int ams_delta_panel_probe(struct platform_device *pdev)
 {
+	struct lcd_device *lcd_device = NULL;
+#ifdef CONFIG_LCD_CLASS_DEVICE
+	int ret;
+
+	lcd_device = lcd_device_register("omapfb", &pdev->dev, NULL,
+						&ams_delta_lcd_ops);
+
+	if (IS_ERR(lcd_device)) {
+		ret = PTR_ERR(lcd_device);
+		dev_err(&pdev->dev, "failed to register device\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, lcd_device);
+	lcd_device->props.max_contrast = AMS_DELTA_MAX_CONTRAST;
+#endif
+
+	ams_delta_lcd_set_contrast(lcd_device, AMS_DELTA_DEFAULT_CONTRAST);
+	ams_delta_lcd_set_power(lcd_device, FB_BLANK_UNBLANK);
+
 	omapfb_register_panel(&ams_delta_panel);
 	return 0;
 }