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Gmane
From: Greg KH <greg <at> kroah.com>
Subject: [PATCH] Samsung backlight driver
Newsgroups: gmane.linux.kernel
Date: Friday 14th August 2009 19:48:15 UTC (over 7 years ago)
From: Greg Kroah-Hartman <[email protected]>

This driver implements backlight controls for Samsung laptops that
currently do not have ACPI support for this control.

It has been tested on the N130 laptop and properly works there.

Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/platform/x86/Kconfig             |   12 ++
 drivers/platform/x86/Makefile            |    1 
 drivers/platform/x86/samsung-backlight.c |  146
+++++++++++++++++++++++++++++++
 3 files changed, 159 insertions(+)

--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -425,4 +425,16 @@ config ACPI_TOSHIBA
 
 	  If you have a legacy free Toshiba laptop (such as the Libretto L1
 	  series), say Y.
+
+config SAMSUNG_BACKLIGHT
+	tristate "Samsung Backlight driver"
+	depends on BACKLIGHT_CLASS_DEVICE
+	depends on DMI
+	---help---
+	  This driver adds support to control the backlight on a number of
+	  Samsung laptops, like the N130.
+
+	  It will only be loaded on laptops that properly need it, so it is
+	  safe to say Y here.
+
 endif # X86_PLATFORM_DEVICES
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_INTEL_MENLOW)	+= intel_menl
 obj-$(CONFIG_ACPI_WMI)		+= wmi.o
 obj-$(CONFIG_ACPI_ASUS)		+= asus_acpi.o
 obj-$(CONFIG_ACPI_TOSHIBA)	+= toshiba_acpi.o
+obj-$(CONFIG_SAMSUNG_BACKLIGHT)	+= samsung-backlight.o
--- /dev/null
+++ b/drivers/platform/x86/samsung-backlight.c
@@ -0,0 +1,146 @@
+/*
+ * Samsung N130 Laptop Backlight driver
+ *
+ * Copyright (C) 2009 Greg Kroah-Hartman ([email protected])
+ * Copyright (C) 2009 Novell Inc.
+ *
+ * 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 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#define MAX_BRIGHT	0xff
+#define OFFSET		0xf4
+
+static struct pci_dev *pci_device;
+static struct backlight_device *backlight_device;
+static int offset = OFFSET;
+static u8 current_brightness;
+
+static void read_brightness(void)
+{
+	if (!pci_device)
+		return;
+	pci_read_config_byte(pci_device, offset, ¤t_brightness);
+}
+
+static void set_brightness(void)
+{
+	if (!pci_device)
+		return;
+	pci_write_config_byte(pci_device, offset, current_brightness);
+}
+
+static int get_brightness(struct backlight_device *bd)
+{
+	return bd->props.brightness;
+}
+
+static int update_status(struct backlight_device *bd)
+{
+	if (!pci_device)
+		return -ENODEV;
+	if (!backlight_device)
+		return -ENODEV;
+
+	current_brightness = bd->props.brightness;
+	set_brightness();
+	return 0;
+}
+
+static struct backlight_ops backlight_ops = {
+	.get_brightness	= get_brightness,
+	.update_status	= update_status,
+};
+
+static int find_video_card(void)
+{
+	struct pci_dev *dev = NULL;
+
+	while ((dev = pci_get_device(0x8086, 0x27ae, dev)) != NULL) {
+		/* Found one, so let's save it off */
+		if (!pci_device)
+			pci_device = pci_dev_get(dev);
+	}
+
+	if (!pci_device)
+		return 0;
+
+	/* create a backlight device to talk to this one */
+	backlight_device = backlight_device_register("samsung",
+						     &pci_device->dev,
+						     NULL, &backlight_ops);
+	if (IS_ERR(backlight_device))
+		return PTR_ERR(backlight_device);
+	read_brightness();
+	backlight_device->props.max_brightness = MAX_BRIGHT;
+	backlight_device->props.brightness = current_brightness;
+	backlight_device->props.power = FB_BLANK_UNBLANK;
+	backlight_update_status(backlight_device);
+	return 0;
+}
+
+static void remove_video_card(void)
+{
+	if (!pci_device)
+		return;
+
+	backlight_device_unregister(backlight_device);
+	backlight_device = NULL;
+
+	/* we are done with the PCI device, put it back */
+	pci_dev_put(pci_device);
+	pci_device = NULL;
+}
+
+static int dmi_check_cb(const struct dmi_system_id *id)
+{
+	printk(KERN_INFO KBUILD_MODNAME ": found laptop model '%s'\n",
+		id->ident);
+	return 0;
+}
+
+static struct dmi_system_id __initdata samsung_dmi_table[] = {
+	{
+		.ident = "N130",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "N130"),
+			DMI_MATCH(DMI_BOARD_NAME, "N130"),
+		},
+		.callback = dmi_check_cb,
+	},
+	{ },
+};
+
+static int __init samsung_init(void)
+{
+	if (!dmi_check_system(samsung_dmi_table))
+		return -ENODEV;
+
+	return find_video_card();
+}
+
+static void __exit samsung_exit(void)
+{
+	remove_video_card();
+}
+
+module_init(samsung_init);
+module_exit(samsung_exit);
+
+MODULE_AUTHOR("Greg Kroah-Hartman <[email protected]>");
+MODULE_DESCRIPTION("Samsung N130 Backlight driver");
+MODULE_LICENSE("GPL");
+module_param(offset, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(offset, "The offset into the PCI device for the
brightness control");
+MODULE_ALIAS("dmi:*:svnSAMSUNGELECTRONICSCO.,LTD.:pnN130:*:rnN130:*");
 
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