[PATCH v2] Platform: Samsung Q10 backlight driver

[Frederick van der Wyck]

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

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 |  185 ++++++++++++++++++++++++++++++++++++
 3 files changed, 193 insertions(+), 0 deletions(-)
 create mode 100644 drivers/platform/x86/samsung-q10.c

I've made all the changes suggested by Greg and Dmitry in response to v1. 
Main changes:
(1) use i8042_command instead of port IO;
(2) DMI detect to auto-load and to restrict to supported hardware.
Description of v1:
The Samsung Q10 is an old model, which does not support the SABI interface, so
the samsung-laptop driver does not work. 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.

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index faec777..c390727 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -639,4 +639,11 @@ config XO1_RFKILL
 	  Support for enabling/disabling the WLAN interface on the OLPC XO-1
 	  laptop.
 
+config SAMSUNG_Q10
+	tristate "Samsung Q10 Extras"
+	select BACKLIGHT_CLASS_DEVICE
+	---help---
+          This driver provides support for backlight control on Samsung Q10
+          and some other laptops, including Dell Latitude X200.
+
 endif # X86_PLATFORM_DEVICES
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 9950ccc..2cd3e52 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -33,3 +33,4 @@ obj-$(CONFIG_INTEL_IPS)		+= intel_ips.o
 obj-$(CONFIG_GPIO_INTEL_PMIC)	+= intel_pmic_gpio.o
 obj-$(CONFIG_XO1_RFKILL)	+= xo1-rfkill.o
 obj-$(CONFIG_IBM_RTL)		+= ibm_rtl.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..c2b6647
--- /dev/null
+++ b/drivers/platform/x86/samsung-q10.c
@@ -0,0 +1,185 @@
+/*
+ *  Driver for Samsung Q10: 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 bool samsungq10_suspended;
+static int samsungq10_bl_brightness;
+
+static int 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;
+
+	if (!samsungq10_suspended) {
+		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
+static int samsungq10_suspend(struct device *dev)
+{
+	samsungq10_suspended = true;
+	return 0;
+}
+
+static int samsungq10_resume(struct device *dev)
+{
+
+	struct backlight_device *bd = dev_get_drvdata(dev);
+
+	samsungq10_suspended = false;
+	samsungq10_bl_set_intensity(bd);
+	return 0;
+}
+#else
+#define samsungq10_suspend NULL
+#define samsungq10_resume  NULL
+#endif
+
+static const struct dev_pm_ops samsungq10_pm_ops = {
+	.suspend	= samsungq10_suspend,
+	.resume		= 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.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	= "samsung",
+		.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 = "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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