[PATCH] Add LCD backlight driver for OMAP

This adds a driver for the PWL module of OMAP CPUs in the Linux
backlight API. The driver allows changing the backlight instensity and
switching it off when system goes idle. The declaration of struct
omap_backlight_config is sent in a separate patch.
Signed-off-by: Andrzej Zaborowski <balrog@zabor.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/video/backlight/Kconfig

@@ -66,3 +66,11 @@ config BACKLIGHT_HP680
 	  If you have a HP Jornada 680, say y to enable the
 	  backlight driver.
 
+config BACKLIGHT_OMAP
+	tristate "OMAP LCD Backlight"
+	depends on BACKLIGHT_DEVICE && (ARCH_OMAP1 || ARCH_OMAP2)
+	default y
+	help
+	  This driver controls the LCD backlight level and power
+	  for the PWL module of OMAP processors.  Say Y if you plan
+	  to use power saving.

drivers/video/backlight/Makefile

@@ -5,3 +5,4 @@ obj-$(CONFIG_BACKLIGHT_CLASS_DEVICE) += backlight.o
 obj-$(CONFIG_BACKLIGHT_CORGI)	+= corgi_bl.o
 obj-$(CONFIG_BACKLIGHT_HP680)	+= hp680_bl.o
 obj-$(CONFIG_BACKLIGHT_LOCOMO)	+= locomolcd.o
+obj-$(CONFIG_BACKLIGHT_OMAP)	+= omap_bl.o

drivers/video/backlight/omap_bl.c

+/*
+ * drivers/video/backlight/omap_bl.c
+ *
+ * Backlight driver for OMAP based boards.
+ *
+ * Copyright (c) 2006 Andrzej Zaborowski  <balrog@zabor.org>
+ *
+ * This package is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This package is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this package; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/fb.h>
+#include <linux/backlight.h>
+
+#include <asm/arch/hardware.h>
+#include <asm/arch/board.h>
+#include <asm/arch/mux.h>
+
+#define OMAPBL_MAX_INTENSITY		0xff
+
+struct omap_backlight {
+	int powermode;
+	int current_intensity;
+
+	struct device *dev;
+	struct omap_backlight_config *pdata;
+};
+
+static void inline omapbl_send_intensity(int intensity)
+{
+	omap_writeb(intensity, OMAP_PWL_ENABLE);
+}
+
+static void inline omapbl_send_enable(int enable)
+{
+	omap_writeb(enable, OMAP_PWL_CLK_ENABLE);
+}
+
+static void omapbl_blank(struct omap_backlight *bl, int mode)
+{
+	if (bl->pdata->set_power)
+		bl->pdata->set_power(bl->dev, mode);
+
+	switch (mode) {
+	case FB_BLANK_NORMAL:
+	case FB_BLANK_VSYNC_SUSPEND:
+	case FB_BLANK_HSYNC_SUSPEND:
+	case FB_BLANK_POWERDOWN:
+		omapbl_send_intensity(0);
+		omapbl_send_enable(0);
+		break;
+
+	case FB_BLANK_UNBLANK:
+		omapbl_send_intensity(bl->current_intensity);
+		omapbl_send_enable(1);
+		break;
+	}
+}
+
+#ifdef CONFIG_PM
+static int omapbl_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct backlight_device *dev = platform_get_drvdata(pdev);
+	struct omap_backlight *bl = class_get_devdata(&dev->class_dev);
+
+	omapbl_blank(bl, FB_BLANK_POWERDOWN);
+	return 0;
+}
+
+static int omapbl_resume(struct platform_device *pdev)
+{
+	struct backlight_device *dev = platform_get_drvdata(pdev);
+	struct omap_backlight *bl = class_get_devdata(&dev->class_dev);
+
+	omapbl_blank(bl, bl->powermode);
+	return 0;
+}
+#else
+#define omapbl_suspend	NULL
+#define omapbl_resume	NULL
+#endif
+
+static int omapbl_set_power(struct backlight_device *dev, int state)
+{
+	struct omap_backlight *bl = class_get_devdata(&dev->class_dev);
+
+	omapbl_blank(bl, state);
+	bl->powermode = state;
+
+	return 0;
+}
+
+static int omapbl_update_status(struct backlight_device *dev)
+{
+	struct omap_backlight *bl = class_get_devdata(&dev->class_dev);
+
+	if (bl->current_intensity != dev->props->brightness) {
+		if (dev->props->brightness > OMAPBL_MAX_INTENSITY ||
+				dev->props->brightness < 0)
+			return -EPERM;	/* Leave current_intensity untouched */
+
+		if (bl->powermode == FB_BLANK_UNBLANK)
+			omapbl_send_intensity(dev->props->brightness);
+		bl->current_intensity = dev->props->brightness;
+	}
+
+	if (dev->props->fb_blank != bl->powermode)
+		omapbl_set_power(dev, dev->props->fb_blank);
+
+	return 0;
+}
+
+static int omapbl_get_intensity(struct backlight_device *dev)
+{
+	struct omap_backlight *bl = class_get_devdata(&dev->class_dev);
+	return bl->current_intensity;
+}
+
+static struct backlight_properties omapbl_data = {
+	.owner		= THIS_MODULE,
+	.get_brightness	= omapbl_get_intensity,
+	.update_status	= omapbl_update_status,
+};
+
+static int omapbl_probe(struct platform_device *pdev)
+{
+	struct backlight_device *dev;
+	struct omap_backlight *bl;
+	struct omap_backlight_config *pdata = pdev->dev.platform_data;
+
+	omapbl_data.check_fb = pdata->check_fb;
+
+	bl = kzalloc(sizeof(struct omap_backlight), GFP_KERNEL);
+	if (unlikely(!bl))
+		return -ENOMEM;
+
+	dev = backlight_device_register("omap-bl", bl, &omapbl_data);
+	if (IS_ERR(dev)) {
+		kfree(bl);
+		return PTR_ERR(dev);
+	}
+
+	bl->powermode = FB_BLANK_POWERDOWN;
+	bl->current_intensity = 0;
+
+	bl->pdata = pdata;
+	bl->dev = &pdev->dev;
+
+	platform_set_drvdata(pdev, dev);
+
+	omap_cfg_reg(PWL);	/* Conflicts with UART3 */
+
+	omapbl_data.fb_blank = FB_BLANK_UNBLANK;
+	omapbl_data.brightness = pdata->default_intensity;
+	omapbl_update_status(dev);
+
+	printk(KERN_INFO "OMAP LCD backlight initialised\n");
+
+	return 0;
+}
+
+static int omapbl_remove(struct platform_device *pdev)
+{
+	struct backlight_device *dev = platform_get_drvdata(pdev);
+	struct omap_backlight *bl = class_get_devdata(&dev->class_dev);
+
+	backlight_device_unregister(dev);
+	kfree(bl);
+
+	return 0;
+}
+
+static struct platform_driver omapbl_driver = {
+	.probe		= omapbl_probe,
+	.remove		= omapbl_remove,
+	.suspend	= omapbl_suspend,
+	.resume		= omapbl_resume,
+	.driver		= {
+		.name	= "omap-bl",
+	},
+};
+
+static int __init omapbl_init(void)
+{
+	return platform_driver_register(&omapbl_driver);
+}
+
+static void __exit omapbl_exit(void)
+{
+	platform_driver_unregister(&omapbl_driver);
+}
+
+module_init(omapbl_init);
+module_exit(omapbl_exit);
+
+MODULE_AUTHOR("Andrzej Zaborowski <balrog@zabor.org>");
+MODULE_DESCRIPTION("OMAP LCD Backlight driver");
+MODULE_LICENSE("GPL");