Re: [PATCH] [RESEND] Add Dell laptop backlight brightness display

[Matthew Garrett <mjg59@srcf.ucam.org>]

On Mon, Feb 06, 2006 at 10:37:55PM -0500, Dmitry Torokhov wrote:

> This is not gonna work - dellbl_* vs hpbl_*

Good point. Third time's the charm?

-- 
Matthew Garrett | mjg59@srcf.ucam.org

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index e4f84eb..0f83183 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -56,4 +56,12 @@ config BACKLIGHT_HP
 	default n
 	help
 	  Allows userspace applications to read the current screen brightness
-	  on HP laptops
\ No newline at end of file
+	  on HP laptops
+
+config BACKLIGHT_DELL
+	tristate "Dell Laptop Backlight Driver"
+	depends on BACKLIGHT_DEVICE && X86
+	default n
+	help
+	  Allows userspace applications to read the current screen brightness
+	  on Dell laptops
\ No newline at end of file
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 93ac108..f337f01 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -4,4 +4,5 @@ obj-$(CONFIG_LCD_CLASS_DEVICE)     += lc
 obj-$(CONFIG_BACKLIGHT_CLASS_DEVICE) += backlight.o
 obj-$(CONFIG_BACKLIGHT_CORGI)	+= corgi_bl.o
 obj-$(CONFIG_SHARP_LOCOMO)	+= locomolcd.o
-obj-$(CONFIG_BACKLIGHT_HP) 	+= hp_bl.o
\ No newline at end of file
+obj-$(CONFIG_BACKLIGHT_HP) 	+= hp_bl.o
+obj-$(CONFIG_BACKLIGHT_DELL) 	+= dell_bl.o
\ No newline at end of file
diff --git a/drivers/video/backlight/dell_bl.c b/drivers/video/backlight/dell_bl.c
new file mode 100644
index 0000000..a97a4b8
--- /dev/null
+++ b/drivers/video/backlight/dell_bl.c
@@ -0,0 +1,92 @@
+/*
+ *  Backlight Driver for Dell laptops
+ *
+ *  Copyright (c) 2006 Matthew Garrett
+ *
+ *  Based on corgi_bl.c, Copyright (c) 2004-2005 Richard Purdie
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/fb.h>
+#include <linux/backlight.h>
+#include <linux/dmi.h>
+#include <linux/nvram.h>
+
+static struct backlight_properties dellbl_data;
+
+static struct dmi_system_id __initdata delllcd_device_table[] = {
+	{
+		.ident = "Dell",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_CHASSIS_TYPE, "Portable"),
+		},		
+	},
+	{ }
+};
+
+
+static int dellbl_get_intensity(struct backlight_device *bd)
+{
+	/* The backlight interface doesn't give us a means of providing
+	   more than one brightness value, so we put the AC value in the
+	   top bits of the brightness and the DC value in the bottom bits */
+
+	int value;
+	int combined;
+
+	value = nvram_read_byte(0x53);
+
+	value &= 0xf0; // Brightness is in the upper 4 bits
+	combined = value << 12;
+
+	value = nvram_read_byte(0x16);
+	
+	outb(0x99, 0x72);
+	value = inb(0x73);
+
+	value &= 0x0f; // Brightness is in the lower 4 bits
+	combined |= value;
+
+	return combined;
+}
+
+static struct backlight_properties dellbl_data = {
+	.owner		= THIS_MODULE,
+	.get_brightness = dellbl_get_intensity,
+	.max_brightness = 0xe,
+};
+
+static struct backlight_device *dell_backlight_device;
+
+static int __init dellbl_init(void)
+{
+	if (!dmi_check_system(delllcd_device_table))
+		return -ENODEV;	
+
+	dell_backlight_device = backlight_device_register ("dell-bl",
+		NULL, &dellbl_data);
+	if (IS_ERR (dell_backlight_device))
+		return PTR_ERR (dell_backlight_device);
+
+	return 0;
+}
+
+static void __exit dellbl_exit(void)
+{
+	backlight_device_unregister(dell_backlight_device);
+}
+
+module_init(dellbl_init);
+module_exit(dellbl_exit);
+
+MODULE_AUTHOR("Matthew Garrett <mjg59@srcf.ucam.org>");
+MODULE_DESCRIPTION("Dell Backlight Driver");
+MODULE_LICENSE("GPL");