platform samsung-q10: use ACPI instead of direct EC calls

This patch changes the Samsung Q10 backlight driver to use ACPI methods
(the same ones as triggered by the brightness up/down function keys)
instead of direct EC calls. The advantage is that the brightness setting
is not lost on shutdown.
Signed-off-by: Frederick van der Wyck <fvanderwyck@gmail.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>

drivers/platform/x86/Kconfig

@@ -764,7 +764,7 @@ config INTEL_OAKTRAIL
 
 config SAMSUNG_Q10
 	tristate "Samsung Q10 Extras"
-	depends on SERIO_I8042
+	depends on ACPI
 	select BACKLIGHT_CLASS_DEVICE
 	---help---
 	  This driver provides support for backlight control on Samsung Q10

drivers/platform/x86/samsung-q10.c

@@ -14,16 +14,12 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/backlight.h>
-#include <linux/i8042.h>
 #include <linux/dmi.h>
+#include <acpi/acpi_drivers.h>
 
-#define SAMSUNGQ10_BL_MAX_INTENSITY      255
-#define SAMSUNGQ10_BL_DEFAULT_INTENSITY  185
+#define SAMSUNGQ10_BL_MAX_INTENSITY 7
 
-#define SAMSUNGQ10_BL_8042_CMD           0xbe
-#define SAMSUNGQ10_BL_8042_DATA          { 0x89, 0x91 }
-
-static int samsungq10_bl_brightness;
+static acpi_handle ec_handle;
 
 static bool force;
 module_param(force, bool, 0);
@@ -33,21 +29,26 @@ MODULE_PARM_DESC(force,
 static int samsungq10_bl_set_intensity(struct backlight_device *bd)
 {
 
-	int brightness = bd->props.brightness;
-	unsigned char c[3] = SAMSUNGQ10_BL_8042_DATA;
+	acpi_status status;
+	int i;
 
-	c[2] = (unsigned char)brightness;
-	i8042_lock_chip();
-	i8042_command(c, (0x30 << 8) | SAMSUNGQ10_BL_8042_CMD);
-	i8042_unlock_chip();
-	samsungq10_bl_brightness = brightness;
+	for (i = 0; i < SAMSUNGQ10_BL_MAX_INTENSITY; i++) {
+		status = acpi_evaluate_object(ec_handle, "_Q63", NULL, NULL);
+		if (ACPI_FAILURE(status))
+			return -EIO;
+	}
+	for (i = 0; i < bd->props.brightness; i++) {
+		status = acpi_evaluate_object(ec_handle, "_Q64", NULL, NULL);
+		if (ACPI_FAILURE(status))
+			return -EIO;
+	}
 
 	return 0;
 }
 
 static int samsungq10_bl_get_intensity(struct backlight_device *bd)
 {
-	return samsungq10_bl_brightness;
+	return bd->props.brightness;
 }
 
 static const struct backlight_ops samsungq10_bl_ops = {
@@ -55,28 +56,6 @@ static const struct backlight_ops samsungq10_bl_ops = {
 	.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 samsungq10_probe(struct platform_device *pdev)
 {
 
@@ -93,9 +72,6 @@ static int samsungq10_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, bd);
 
-	bd->props.brightness = SAMSUNGQ10_BL_DEFAULT_INTENSITY;
-	samsungq10_bl_set_intensity(bd);
-
 	return 0;
 }
 
@@ -104,9 +80,6 @@ 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_set_intensity(bd);
-
 	backlight_device_unregister(bd);
 
 	return 0;
@@ -116,7 +89,6 @@ static struct platform_driver samsungq10_driver = {
 	.driver		= {
 		.name	= KBUILD_MODNAME,
 		.owner	= THIS_MODULE,
-		.pm	= &samsungq10_pm_ops,
 	},
 	.probe		= samsungq10_probe,
 	.remove		= samsungq10_remove,
@@ -172,6 +144,11 @@ static int __init samsungq10_init(void)
 	if (!force && !dmi_check_system(samsungq10_dmi_table))
 		return -ENODEV;
 
+	ec_handle = ec_get_handle();
+
+	if (!ec_handle)
+		return -ENODEV;
+
 	samsungq10_device = platform_create_bundle(&samsungq10_driver,
 						   samsungq10_probe,
 						   NULL, 0, NULL, 0);