[PATCH] 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       |    8 ++
 drivers/platform/x86/Makefile      |    1 +
 drivers/platform/x86/samsung-q10.c |  152 ++++++++++++++++++++++++++++++++++++
 3 files changed, 161 insertions(+), 0 deletions(-)
 create mode 100644 drivers/platform/x86/samsung-q10.c

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. Please let me know any feedback towards 
getting this driver included.

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index faec777..7432817 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -639,4 +639,12 @@ 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
+	default n
+	---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..ec1e004
--- /dev/null
+++ b/drivers/platform/x86/samsung-q10.c
@@ -0,0 +1,152 @@
+/*
+ *  Driver for Samsung Q10: controls the backlight
+ *
+ *  Also works on Dell Latitude X200
+ *
+ *  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/io.h>
+
+#define SAMSUNGQ10_BL_MAX_INTENSITY 255
+#define SAMSUNGQ10_BL_DEFAULT_INTENSITY 185
+
+static int samsungq10_suspended;
+
+static void samsungq10_bl_send_intensity(struct backlight_device *bd)
+{
+	int brightness = bd->props.brightness;
+
+	if (!samsungq10_suspended) {
+		while (inb(0x64)&2)
+			;
+		outb_p(0xbe, 0x64);
+		while (inb(0x64)&2)
+			;
+		outb_p(0x89, 0x60);
+		while (inb(0x64)&2)
+			;
+		outb_p(0x91, 0x60);
+		while (inb(0x64)&2)
+			;
+		outb_p((unsigned char)brightness, 0x60);
+	};
+}
+
+#ifdef CONFIG_PM
+static int samsungq10_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	samsungq10_suspended = 1;
+	return 0;
+}
+
+static int samsungq10_resume(struct platform_device *pdev)
+{
+	struct backlight_device *bd = platform_get_drvdata(pdev);
+	samsungq10_suspended = 0;
+	samsungq10_bl_send_intensity(bd);
+	return 0;
+}
+#else
+#define samsungq10_suspend	NULL
+#define samsungq10_resume	NULL
+#endif
+
+static int samsungq10_bl_set_intensity(struct backlight_device *bd)
+{
+	samsungq10_bl_send_intensity(bd);
+	return 0;
+}
+
+static int samsungq10_bl_get_intensity(struct backlight_device *bd)
+{
+	return 0;
+}
+
+static const struct backlight_ops samsungq10_bl_ops = {
+	.get_brightness = samsungq10_bl_get_intensity,
+	.update_status	= samsungq10_bl_set_intensity,
+};
+
+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("samsungq10bl", &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_send_intensity(bd);
+
+	return 0;
+}
+
+static int samsungq10_remove(struct platform_device *pdev)
+{
+	struct backlight_device *bd = platform_get_drvdata(pdev);
+
+	bd->props.brightness = SAMSUNGQ10_BL_DEFAULT_INTENSITY;
+	samsungq10_bl_send_intensity(bd);
+
+	backlight_device_unregister(bd);
+
+	return 0;
+}
+
+static struct platform_driver samsungq10_driver = {
+	.probe		= samsungq10_probe,
+	.remove		= samsungq10_remove,
+	.suspend	= samsungq10_suspend,
+	.resume		= samsungq10_resume,
+	.driver		= {
+		.name	= "samsungq10",
+	},
+};
+
+static struct platform_device *samsungq10_device;
+
+static int __init samsungq10_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&samsungq10_driver);
+	if (ret)
+		return ret;
+	samsungq10_device = platform_device_register_simple("samsungq10", -1,
+							    NULL, 0);
+	if (IS_ERR(samsungq10_device)) {
+		platform_driver_unregister(&samsungq10_driver);
+		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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