[PATCH v3] Platform: Samsung Q10 backlight driver

[Frederick van der Wyck]

This driver adds backlight control on the Samsung Q10 laptop,
which does not support the SABI interface. Also tested
successfully on Samsung Q20, Samsung Q25 and Dell Latitude X200.

v3: Add Samsung Q20 and Samsung Q25 to dmi check.

v2: Changes suggested by Greg and Dmitry, in particular use i8042 instead 
of port IO and add DMI detection.

v1: The Samsung Q10 does not support the SABI interface, so the
samsung-laptop driver cannot be used to control the
backlight. Backlight control is not exposed via ACPI either. This
driver works in the same way as the SMI handler triggered by
pressing the brightness function keys.


Signed-off-by: Frederick van der Wyck <fvanderwyck@xxxxxxxxx>
---
 drivers/platform/x86/Kconfig       |    7 ++
 drivers/platform/x86/Makefile      |    1 +
 drivers/platform/x86/samsung-q10.c |  196 ++++++++++++++++++++++++++++++++++++
 3 files changed, 204 insertions(+), 0 deletions(-)
 create mode 100644 drivers/platform/x86/samsung-q10.c

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 45e0191..d52968f 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -769,4 +769,11 @@ config INTEL_OAKTRAIL
 	  enable/disable the Camera, WiFi, BT etc. devices. If in doubt, say Y
 	  here; it will only load on supported platforms.
 
+config SAMSUNG_Q10
+	tristate "Samsung Q10 Extras"
+	select BACKLIGHT_CLASS_DEVICE
+	---help---
+	  This driver provides support for backlight control on Samsung Q10
+	  and related laptops, including Dell Latitude X200.
+
 endif # X86_PLATFORM_DEVICES
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index afc1f83..293a320 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -44,3 +44,4 @@ obj-$(CONFIG_SAMSUNG_LAPTOP)	+= samsung-laptop.o
 obj-$(CONFIG_MXM_WMI)		+= mxm-wmi.o
 obj-$(CONFIG_INTEL_MID_POWER_BUTTON)	+= intel_mid_powerbtn.o
 obj-$(CONFIG_INTEL_OAKTRAIL)	+= intel_oaktrail.o
+obj-$(CONFIG_SAMSUNG_Q10)	+= samsung-q10.o
diff --git a/drivers/platform/x86/samsung-q10.c b/drivers/platform/x86/samsung-q10.c
new file mode 100644
index 0000000..54cf3d6
--- /dev/null
+++ b/drivers/platform/x86/samsung-q10.c
@@ -0,0 +1,196 @@
+/*
+ *  Driver for Samsung Q10 and related laptops: controls the backlight
+ *
+ *  Copyright (c) 2011 Frederick van der Wyck <fvanderwyck@xxxxxxxxx>
+ *
+ *  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/platform_device.h>
+#include <linux/backlight.h>
+#include <linux/i8042.h>
+#include <linux/dmi.h>
+
+#define SAMSUNGQ10_BL_MAX_INTENSITY      255
+#define SAMSUNGQ10_BL_DEFAULT_INTENSITY  185
+
+#define SAMSUNGQ10_BL_8042_CMD           0xbe
+#define SAMSUNGQ10_BL_8042_DATA          { 0x89, 0x91 }
+
+static int samsungq10_bl_brightness;
+
+static bool force;
+module_param(force, bool, 0);
+MODULE_PARM_DESC(force,
+		"Disable the DMI check and force the driver to be loaded");
+
+static int samsungq10_bl_set_intensity(struct backlight_device *bd)
+{
+
+	int brightness = bd->props.brightness;
+	unsigned char c[3] = SAMSUNGQ10_BL_8042_DATA;
+
+	c[2] = (unsigned char)brightness;
+	i8042_lock_chip();
+	i8042_command(c, (0x30 << 8) | SAMSUNGQ10_BL_8042_CMD);
+	i8042_unlock_chip();
+	samsungq10_bl_brightness = brightness;
+
+	return 0;
+}
+
+static int samsungq10_bl_get_intensity(struct backlight_device *bd)
+{
+	return samsungq10_bl_brightness;
+}
+
+static const struct backlight_ops samsungq10_bl_ops = {
+	.get_brightness = samsungq10_bl_get_intensity,
+	.update_status	= samsungq10_bl_set_intensity,
+};
+
+#ifdef CONFIG_PM_SLEEP
+static int samsungq10_suspend(struct device *dev)
+{
+	return 0;
+}
+
+static int samsungq10_resume(struct device *dev)
+{
+
+	struct backlight_device *bd = dev_get_drvdata(dev);
+
+	samsungq10_bl_set_intensity(bd);
+	return 0;
+}
+#else
+#define samsungq10_suspend NULL
+#define samsungq10_resume  NULL
+#endif
+
+static SIMPLE_DEV_PM_OPS(samsungq10_pm_ops,
+			  samsungq10_suspend, samsungq10_resume);
+
+static int __devinit samsungq10_probe(struct platform_device *pdev)
+{
+
+	struct backlight_properties props;
+	struct backlight_device *bd;
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = SAMSUNGQ10_BL_MAX_INTENSITY;
+	bd = backlight_device_register("samsung", &pdev->dev, NULL,
+				       &samsungq10_bl_ops, &props);
+	if (IS_ERR(bd))
+		return PTR_ERR(bd);
+
+	platform_set_drvdata(pdev, bd);
+
+	bd->props.brightness = SAMSUNGQ10_BL_DEFAULT_INTENSITY;
+	samsungq10_bl_set_intensity(bd);
+
+	return 0;
+}
+
+static int __devexit samsungq10_remove(struct platform_device *pdev)
+{
+
+	struct backlight_device *bd = platform_get_drvdata(pdev);
+
+	bd->props.brightness = SAMSUNGQ10_BL_DEFAULT_INTENSITY;
+	samsungq10_bl_set_intensity(bd);
+
+	backlight_device_unregister(bd);
+
+	return 0;
+}
+
+static struct platform_driver samsungq10_driver = {
+	.driver		= {
+		.name	= KBUILD_MODNAME,
+		.owner	= THIS_MODULE,
+		.pm	= &samsungq10_pm_ops,
+	},
+	.probe		= samsungq10_probe,
+	.remove		= __devexit_p(samsungq10_remove),
+};
+
+static struct platform_device *samsungq10_device;
+
+static int __init dmi_check_callback(const struct dmi_system_id *id)
+{
+	printk(KERN_INFO KBUILD_MODNAME ": found model '%s'\n", id->ident);
+	return 0;
+}
+
+static struct dmi_system_id __initdata samsungq10_dmi_table[] = {
+	{
+		.ident = "Samsung Q10",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Samsung"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "SQ10"),
+		},
+		.callback = dmi_check_callback,
+	},
+	{
+		.ident = "Samsung Q20",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG Electronics"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "SENS Q20"),
+		},
+		.callback = dmi_check_callback,
+	},
+	{
+		.ident = "Samsung Q25",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG Electronics"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "NQ25"),
+		},
+		.callback = dmi_check_callback,
+	},
+	{
+		.ident = "Dell Latitude X200",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "X200"),
+		},
+		.callback = dmi_check_callback,
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(dmi, samsungq10_dmi_table);
+
+static int __init samsungq10_init(void)
+{
+	if (!force && !dmi_check_system(samsungq10_dmi_table))
+		return -ENODEV;
+
+	samsungq10_device = platform_create_bundle(&samsungq10_driver,
+						   samsungq10_probe,
+						   NULL, 0, NULL, 0);
+
+	if (IS_ERR(samsungq10_device))
+		return PTR_ERR(samsungq10_device);
+
+	return 0;
+}
+
+static void __exit samsungq10_exit(void)
+{
+	platform_device_unregister(samsungq10_device);
+	platform_driver_unregister(&samsungq10_driver);
+}
+
+module_init(samsungq10_init);
+module_exit(samsungq10_exit);
+
+MODULE_AUTHOR("Frederick van der Wyck <fvanderwyck@xxxxxxxxx>");
+MODULE_DESCRIPTION("Samsung Q10 Driver");
+MODULE_LICENSE("GPL");
-- 
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