eeepc-wmi: add backlight support

Add backlight support for WMI based Eee PC laptops.
Signed-off-by: Yong Wang <yong.y.wang@intel.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Reviewed-by: Corentin Chary <corentincj@iksaif.net>

drivers/platform/x86/eeepc-wmi.c

@@ -32,6 +32,8 @@
 #include <linux/slab.h>
 #include <linux/input.h>
 #include <linux/input/sparse-keymap.h>
+#include <linux/fb.h>
+#include <linux/backlight.h>
 #include <linux/platform_device.h>
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
@@ -43,14 +45,21 @@ MODULE_DESCRIPTION("Eee PC WMI Hotkey Driver");
 MODULE_LICENSE("GPL");
 
 #define EEEPC_WMI_EVENT_GUID	"ABBC0F72-8EA1-11D1-00A0-C90629100000"
+#define EEEPC_WMI_MGMT_GUID	"97845ED0-4E6D-11DE-8A39-0800200C9A66"
 
 MODULE_ALIAS("wmi:"EEEPC_WMI_EVENT_GUID);
+MODULE_ALIAS("wmi:"EEEPC_WMI_MGMT_GUID);
 
 #define NOTIFY_BRNUP_MIN	0x11
 #define NOTIFY_BRNUP_MAX	0x1f
 #define NOTIFY_BRNDOWN_MIN	0x20
 #define NOTIFY_BRNDOWN_MAX	0x2e
 
+#define EEEPC_WMI_METHODID_DEVS	0x53564544
+#define EEEPC_WMI_METHODID_DSTS	0x53544344
+
+#define EEEPC_WMI_DEVID_BACKLIGHT	0x00050012
+
 static const struct key_entry eeepc_wmi_keymap[] = {
 	/* Sleep already handled via generic ACPI code */
 	{ KE_KEY, 0x5d, { KEY_WLAN } },
@@ -63,44 +72,18 @@ static const struct key_entry eeepc_wmi_keymap[] = {
 	{ KE_END, 0},
 };
 
+struct bios_args {
+	u32	dev_id;
+	u32	ctrl_param;
+};
+
 struct eeepc_wmi {
 	struct input_dev *inputdev;
+	struct backlight_device *backlight_device;
 };
 
 static struct platform_device *platform_device;
 
-static void eeepc_wmi_notify(u32 value, void *context)
-{
-	struct eeepc_wmi *eeepc = context;
-	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
-	union acpi_object *obj;
-	acpi_status status;
-	int code;
-
-	status = wmi_get_event_data(value, &response);
-	if (status != AE_OK) {
-		pr_err("bad event status 0x%x\n", status);
-		return;
-	}
-
-	obj = (union acpi_object *)response.pointer;
-
-	if (obj && obj->type == ACPI_TYPE_INTEGER) {
-		code = obj->integer.value;
-
-		if (code >= NOTIFY_BRNUP_MIN && code <= NOTIFY_BRNUP_MAX)
-			code = NOTIFY_BRNUP_MIN;
-		else if (code >= NOTIFY_BRNDOWN_MIN && code <= NOTIFY_BRNDOWN_MAX)
-			code = NOTIFY_BRNDOWN_MIN;
-
-		if (!sparse_keymap_report_event(eeepc->inputdev,
-						code, 1, true))
-			pr_info("Unknown key %x pressed\n", code);
-	}
-
-	kfree(obj);
-}
-
 static int eeepc_wmi_input_init(struct eeepc_wmi *eeepc)
 {
 	int err;
@@ -141,6 +124,174 @@ static void eeepc_wmi_input_exit(struct eeepc_wmi *eeepc)
 	eeepc->inputdev = NULL;
 }
 
+static acpi_status eeepc_wmi_get_devstate(u32 dev_id, u32 *ctrl_param)
+{
+	struct acpi_buffer input = { (acpi_size)sizeof(u32), &dev_id };
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	acpi_status status;
+	u32 tmp;
+
+	status = wmi_evaluate_method(EEEPC_WMI_MGMT_GUID,
+			1, EEEPC_WMI_METHODID_DSTS, &input, &output);
+
+	if (ACPI_FAILURE(status))
+		return status;
+
+	obj = (union acpi_object *)output.pointer;
+	if (obj && obj->type == ACPI_TYPE_INTEGER)
+		tmp = (u32)obj->integer.value;
+	else
+		tmp = 0;
+
+	if (ctrl_param)
+		*ctrl_param = tmp;
+
+	kfree(obj);
+
+	return status;
+
+}
+
+static acpi_status eeepc_wmi_set_devstate(u32 dev_id, u32 ctrl_param)
+{
+	struct bios_args args = {
+		.dev_id = dev_id,
+		.ctrl_param = ctrl_param,
+	};
+	struct acpi_buffer input = { (acpi_size)sizeof(args), &args };
+	acpi_status status;
+
+	status = wmi_evaluate_method(EEEPC_WMI_MGMT_GUID,
+			1, EEEPC_WMI_METHODID_DEVS, &input, NULL);
+
+	return status;
+}
+
+static int read_brightness(struct backlight_device *bd)
+{
+	static u32 ctrl_param;
+	acpi_status status;
+
+	status = eeepc_wmi_get_devstate(EEEPC_WMI_DEVID_BACKLIGHT, &ctrl_param);
+
+	if (ACPI_FAILURE(status))
+		return -1;
+	else
+		return ctrl_param & 0xFF;
+}
+
+static int update_bl_status(struct backlight_device *bd)
+{
+
+	static u32 ctrl_param;
+	acpi_status status;
+
+	ctrl_param = bd->props.brightness;
+
+	status = eeepc_wmi_set_devstate(EEEPC_WMI_DEVID_BACKLIGHT, ctrl_param);
+
+	if (ACPI_FAILURE(status))
+		return -1;
+	else
+		return 0;
+}
+
+static const struct backlight_ops eeepc_wmi_bl_ops = {
+	.get_brightness = read_brightness,
+	.update_status = update_bl_status,
+};
+
+static int eeepc_wmi_backlight_notify(struct eeepc_wmi *eeepc, int code)
+{
+	struct backlight_device *bd = eeepc->backlight_device;
+	int old = bd->props.brightness;
+	int new;
+
+	if (code >= NOTIFY_BRNUP_MIN && code <= NOTIFY_BRNUP_MAX)
+		new = code - NOTIFY_BRNUP_MIN + 1;
+	else if (code >= NOTIFY_BRNDOWN_MIN && code <= NOTIFY_BRNDOWN_MAX)
+		new = code - NOTIFY_BRNDOWN_MIN;
+
+	bd->props.brightness = new;
+	backlight_update_status(bd);
+	backlight_force_update(bd, BACKLIGHT_UPDATE_HOTKEY);
+
+	return old;
+}
+
+static int eeepc_wmi_backlight_init(struct eeepc_wmi *eeepc)
+{
+	struct backlight_device *bd;
+	struct backlight_properties props;
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.max_brightness = 15;
+	bd = backlight_device_register(EEEPC_WMI_FILE,
+				       &platform_device->dev, eeepc,
+				       &eeepc_wmi_bl_ops, &props);
+	if (IS_ERR(bd)) {
+		pr_err("Could not register backlight device\n");
+		return PTR_ERR(bd);
+	}
+
+	eeepc->backlight_device = bd;
+
+	bd->props.brightness = read_brightness(bd);
+	bd->props.power = FB_BLANK_UNBLANK;
+	backlight_update_status(bd);
+
+	return 0;
+}
+
+static void eeepc_wmi_backlight_exit(struct eeepc_wmi *eeepc)
+{
+	if (eeepc->backlight_device)
+		backlight_device_unregister(eeepc->backlight_device);
+
+	eeepc->backlight_device = NULL;
+}
+
+static void eeepc_wmi_notify(u32 value, void *context)
+{
+	struct eeepc_wmi *eeepc = context;
+	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	acpi_status status;
+	int code;
+	int orig_code;
+
+	status = wmi_get_event_data(value, &response);
+	if (status != AE_OK) {
+		pr_err("bad event status 0x%x\n", status);
+		return;
+	}
+
+	obj = (union acpi_object *)response.pointer;
+
+	if (obj && obj->type == ACPI_TYPE_INTEGER) {
+		code = obj->integer.value;
+		orig_code = code;
+
+		if (code >= NOTIFY_BRNUP_MIN && code <= NOTIFY_BRNUP_MAX)
+			code = NOTIFY_BRNUP_MIN;
+		else if (code >= NOTIFY_BRNDOWN_MIN &&
+			 code <= NOTIFY_BRNDOWN_MAX)
+			code = NOTIFY_BRNDOWN_MIN;
+
+		if (code == NOTIFY_BRNUP_MIN || code == NOTIFY_BRNDOWN_MIN) {
+			if (!acpi_video_backlight_support())
+				eeepc_wmi_backlight_notify(eeepc, orig_code);
+		}
+
+		if (!sparse_keymap_report_event(eeepc->inputdev,
+						code, 1, true))
+			pr_info("Unknown key %x pressed\n", code);
+	}
+
+	kfree(obj);
+}
+
 static int __devinit eeepc_wmi_platform_probe(struct platform_device *device)
 {
 	struct eeepc_wmi *eeepc;
@@ -151,7 +302,14 @@ static int __devinit eeepc_wmi_platform_probe(struct platform_device *device)
 
 	err = eeepc_wmi_input_init(eeepc);
 	if (err)
-		return err;
+		goto error_input;
+
+	if (!acpi_video_backlight_support()) {
+		err = eeepc_wmi_backlight_init(eeepc);
+		if (err)
+			goto error_backlight;
+	} else
+		pr_info("Backlight controlled by ACPI video driver\n");
 
 	status = wmi_install_notify_handler(EEEPC_WMI_EVENT_GUID,
 					eeepc_wmi_notify, eeepc);
@@ -165,8 +323,10 @@ static int __devinit eeepc_wmi_platform_probe(struct platform_device *device)
 	return 0;
 
 error_wmi:
+	eeepc_wmi_backlight_exit(eeepc);
+error_backlight:
 	eeepc_wmi_input_exit(eeepc);
-
+error_input:
 	return err;
 }
 
@@ -176,6 +336,7 @@ static int __devexit eeepc_wmi_platform_remove(struct platform_device *device)
 
 	eeepc = platform_get_drvdata(device);
 	wmi_remove_notify_handler(EEEPC_WMI_EVENT_GUID);
+	eeepc_wmi_backlight_exit(eeepc);
 	eeepc_wmi_input_exit(eeepc);
 
 	return 0;
@@ -195,7 +356,8 @@ static int __init eeepc_wmi_init(void)
 	struct eeepc_wmi *eeepc;
 	int err;
 
-	if (!wmi_has_guid(EEEPC_WMI_EVENT_GUID)) {
+	if (!wmi_has_guid(EEEPC_WMI_EVENT_GUID) ||
+	    !wmi_has_guid(EEEPC_WMI_MGMT_GUID)) {
 		pr_warning("No known WMI GUID found\n");
 		return -ENODEV;
 	}