backlight: add backlight type

There may be multiple ways of controlling the backlight on a given
machine.  Allow drivers to expose the type of interface they are
providing, making it possible for userspace to make appropriate policy
decisions.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: David Airlie <airlied@linux.ie>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

59 files changed, 111 insertions, 2 deletions

diff --git a/Documentation/ABI/stable/sysfs-class-backlight b/Documentation/ABI/stable/sysfs-class-backlight
index 4d637e1c4ff..70302f370e7 100644
--- a/Documentation/ABI/stable/sysfs-class-backlight
+++ b/Documentation/ABI/stable/sysfs-class-backlight
@@ -34,3 +34,23 @@ Contact:	Richard Purdie <rpurdie@rpsys.net>
 Description:
 		Maximum brightness for <backlight>.
 Users:		HAL
+
+What:		/sys/class/backlight/<backlight>/type
+Date:		September 2010
+KernelVersion:	2.6.37
+Contact:	Matthew Garrett <mjg@redhat.com>
+Description:
+		The type of interface controlled by <backlight>.
+		"firmware": The driver uses a standard firmware interface
+		"platform": The driver uses a platform-specific interface
+		"raw": The driver controls hardware registers directly
+
+		In the general case, when multiple backlight
+		interfaces are available for a single device, firmware
+		control should be preferred to platform control should
+		be preferred to raw control. Using a firmware
+		interface reduces the probability of confusion with
+		the hardware and the OS independently updating the
+		backlight state. Platform interfaces are mostly a
+		holdover from pre-standardisation of firmware
+		interfaces.
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 90f8f7676d1..a9eec8c95a1 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -795,6 +795,7 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
 		count++;
 
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_FIRMWARE;
 		props.max_brightness = device->brightness->count - 3;
 		device->backlight = backlight_device_register(name, NULL, device,
 							      &acpi_backlight_ops,
diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index d3a9c6e0247..18d7bcc54ce 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -98,6 +98,7 @@ static int nouveau_nv40_backlight_init(struct drm_device *dev)
 		return 0;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 31;
 	bd = backlight_device_register("nv_backlight", &dev->pdev->dev, dev,
 				       &nv40_bl_ops, &props);
@@ -121,6 +122,7 @@ static int nouveau_nv50_backlight_init(struct drm_device *dev)
 		return 0;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 1025;
 	bd = backlight_device_register("nv_backlight", &dev->pdev->dev, dev,
 				       &nv50_bl_ops, &props);
diff --git a/drivers/hid/hid-picolcd.c b/drivers/hid/hid-picolcd.c
index de9cf21b349..657da5a3d5c 100644
--- a/drivers/hid/hid-picolcd.c
+++ b/drivers/hid/hid-picolcd.c
@@ -944,6 +944,7 @@ static int picolcd_init_backlight(struct picolcd_data *data, struct hid_report *
 	}
 
 	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	bdev = backlight_device_register(dev_name(dev), dev, data,
 			&picolcd_blops, &props);
diff --git a/drivers/macintosh/via-pmu-backlight.c b/drivers/macintosh/via-pmu-backlight.c
index ade1e656bfb..b1d91170ded 100644
--- a/drivers/macintosh/via-pmu-backlight.c
+++ b/drivers/macintosh/via-pmu-backlight.c
@@ -163,6 +163,7 @@ void __init pmu_backlight_init()
 	snprintf(name, sizeof(name), "pmubl");
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, NULL, NULL, &pmu_backlight_data,
 				       &props);
diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
index ad3d099bf5c..c9784705f6a 100644
--- a/drivers/platform/x86/acer-wmi.c
+++ b/drivers/platform/x86/acer-wmi.c
@@ -1031,6 +1031,7 @@ static int __devinit acer_backlight_init(struct device *dev)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = max_brightness;
 	bd = backlight_device_register("acer-wmi", dev, NULL, &acer_bl_ops,
 				       &props);
diff --git a/drivers/platform/x86/asus-laptop.c b/drivers/platform/x86/asus-laptop.c
index f3aa6a7fdab..5a6f7d7575d 100644
--- a/drivers/platform/x86/asus-laptop.c
+++ b/drivers/platform/x86/asus-laptop.c
@@ -667,6 +667,7 @@ static int asus_backlight_init(struct asus_laptop *asus)
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.max_brightness = 15;
+	props.type = BACKLIGHT_PLATFORM;
 
 	bd = backlight_device_register(ASUS_LAPTOP_FILE,
 				       &asus->platform_device->dev, asus,
diff --git a/drivers/platform/x86/asus_acpi.c b/drivers/platform/x86/asus_acpi.c
index fe495939c30..f503607c064 100644
--- a/drivers/platform/x86/asus_acpi.c
+++ b/drivers/platform/x86/asus_acpi.c
@@ -1507,6 +1507,7 @@ static int __init asus_acpi_init(void)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 15;
 	asus_backlight_device = backlight_device_register("asus", NULL, NULL,
 							  &asus_backlight_data,
diff --git a/drivers/platform/x86/classmate-laptop.c b/drivers/platform/x86/classmate-laptop.c
index 91113542522..94f93b621d7 100644
--- a/drivers/platform/x86/classmate-laptop.c
+++ b/drivers/platform/x86/classmate-laptop.c
@@ -564,6 +564,7 @@ static int cmpc_ipml_add(struct acpi_device *acpi)
 		return -ENOMEM;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 7;
 	ipml->bd = backlight_device_register("cmpc_bl", &acpi->dev,
 					     acpi->handle, &cmpc_bl_ops,
diff --git a/drivers/platform/x86/compal-laptop.c b/drivers/platform/x86/compal-laptop.c
index 034572b980c..eb95878fa58 100644
--- a/drivers/platform/x86/compal-laptop.c
+++ b/drivers/platform/x86/compal-laptop.c
@@ -970,6 +970,7 @@ static int __init compal_init(void)
 	if (!acpi_video_backlight_support()) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = BACKLIGHT_LEVEL_MAX;
 		compalbl_device = backlight_device_register(DRIVER_NAME,
 							    NULL, NULL,
diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index ad24ef36f9f..de301aa8e5c 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -671,6 +671,7 @@ static int __init dell_init(void)
 	if (max_intensity) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = max_intensity;
 		dell_backlight_device = backlight_device_register("dell_backlight",
 								  &platform_device->dev,
diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c
index 49d9ad708f8..6605beac0d0 100644
--- a/drivers/platform/x86/eeepc-laptop.c
+++ b/drivers/platform/x86/eeepc-laptop.c
@@ -1147,6 +1147,7 @@ static int eeepc_backlight_init(struct eeepc_laptop *eeepc)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 15;
 	bd = backlight_device_register(EEEPC_LAPTOP_FILE,
 				       &eeepc->platform_device->dev, eeepc,
diff --git a/drivers/platform/x86/fujitsu-laptop.c b/drivers/platform/x86/fujitsu-laptop.c
index 95e3b0948e9..493054c2dbe 100644
--- a/drivers/platform/x86/fujitsu-laptop.c
+++ b/drivers/platform/x86/fujitsu-laptop.c
@@ -1128,6 +1128,7 @@ static int __init fujitsu_init(void)
 
 		memset(&props, 0, sizeof(struct backlight_properties));
 		max_brightness = fujitsu->max_brightness;
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = max_brightness - 1;
 		fujitsu->bl_device = backlight_device_register("fujitsu-laptop",
 							       NULL, NULL,
diff --git a/drivers/platform/x86/msi-laptop.c b/drivers/platform/x86/msi-laptop.c
index 7e9bb6df9d3..142d3857931 100644
--- a/drivers/platform/x86/msi-laptop.c
+++ b/drivers/platform/x86/msi-laptop.c
@@ -804,6 +804,7 @@ static int __init msi_init(void)
 	} else {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = MSI_LCD_LEVEL_MAX - 1;
 		msibl_device = backlight_device_register("msi-laptop-bl", NULL,
 							 NULL, &msibl_ops,
diff --git a/drivers/platform/x86/msi-wmi.c b/drivers/platform/x86/msi-wmi.c
index 35278ad7e62..d5419c9ec07 100644
--- a/drivers/platform/x86/msi-wmi.c
+++ b/drivers/platform/x86/msi-wmi.c
@@ -254,6 +254,7 @@ static int __init msi_wmi_init(void)
 	if (!acpi_video_backlight_support()) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = ARRAY_SIZE(backlight_map) - 1;
 		backlight = backlight_device_register(DRV_NAME, NULL, NULL,
 						      &msi_backlight_ops,
diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index cc1e0ba104d..05be30ee158 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -602,6 +602,7 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 	}
 	/* initialize backlight */
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = pcc->sinf[SINF_AC_MAX_BRIGHT];
 	pcc->backlight = backlight_device_register("panasonic", NULL, pcc,
 						   &pcc_backlight_ops, &props);
diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
index 5e83370b081..13d8d63bcca 100644
--- a/drivers/platform/x86/sony-laptop.c
+++ b/drivers/platform/x86/sony-laptop.c
@@ -1305,8 +1305,9 @@ static int sony_nc_add(struct acpi_device *device)
 		       "controlled by ACPI video driver\n");
 	} else if (ACPI_SUCCESS(acpi_get_handle(sony_nc_acpi_handle, "GBRT",
 						&handle))) {
-							struct backlight_properties props;
+		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = SONY_MAX_BRIGHTNESS - 1;
 		sony_backlight_device = backlight_device_register("sony", NULL,
 								  NULL,
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index eb9922385ef..947bdcaa0ce 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -6307,6 +6307,7 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 		return 1;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = bright_maxlvl;
 	props.brightness = b & TP_EC_BACKLIGHT_LVLMSK;
 	ibm_backlight_device = backlight_device_register(TPACPI_BACKLIGHT_DEV_NAME,
diff --git a/drivers/platform/x86/toshiba_acpi.c b/drivers/platform/x86/toshiba_acpi.c
index 209cced786c..63f42a22e10 100644
--- a/drivers/platform/x86/toshiba_acpi.c
+++ b/drivers/platform/x86/toshiba_acpi.c
@@ -1018,6 +1018,7 @@ static int __init toshiba_acpi_init(void)
 		create_toshiba_proc_entries();
 	}
 
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = HCI_LCD_BRIGHTNESS_LEVELS - 1;
 	toshiba_backlight_device = backlight_device_register("toshiba",
 							     &toshiba_acpi.p_dev->dev,
diff --git a/drivers/staging/olpc_dcon/olpc_dcon.c b/drivers/staging/olpc_dcon/olpc_dcon.c
index b90c2cf3e24..750fe5045ef 100644
--- a/drivers/staging/olpc_dcon/olpc_dcon.c
+++ b/drivers/staging/olpc_dcon/olpc_dcon.c
@@ -574,6 +574,7 @@ static const struct backlight_ops dcon_bl_ops = {
 
 static struct backlight_properties dcon_bl_props = {
 	.max_brightness = 15,
+	.type = BACKLIGHT_RAW,
 	.power = FB_BLANK_UNBLANK,
 };
 
diff --git a/drivers/staging/samsung-laptop/samsung-laptop.c b/drivers/staging/samsung-laptop/samsung-laptop.c
index 6607a89ccb4..25294462b8b 100644
--- a/drivers/staging/samsung-laptop/samsung-laptop.c
+++ b/drivers/staging/samsung-laptop/samsung-laptop.c
@@ -781,6 +781,7 @@ static int __init samsung_init(void)
 
 	/* create a backlight device to talk to this one */
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = sabi_config->max_brightness;
 	backlight_device = backlight_device_register("samsung", &sdev->dev,
 						     NULL, &backlight_ops,
diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c
index 1fa6ce3e4a2..68ab460a735 100644
--- a/drivers/usb/misc/appledisplay.c
+++ b/drivers/usb/misc/appledisplay.c
@@ -282,6 +282,7 @@ static int appledisplay_probe(struct usb_interface *iface,
 	snprintf(bl_name, sizeof(bl_name), "appledisplay%d",
 		atomic_inc_return(&count_displays) - 1);
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	pdata->bd = backlight_device_register(bl_name, NULL, pdata,
 					      &appledisplay_bl_data, &props);
diff --git a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c
index bac16345021..4b4e8dadd6b 100644
--- a/drivers/video/atmel_lcdfb.c
+++ b/drivers/video/atmel_lcdfb.c
@@ -127,6 +127,7 @@ static void init_backlight(struct atmel_lcdfb_info *sinfo)
 		return;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	bl = backlight_device_register("backlight", &sinfo->pdev->dev, sinfo,
 				       &atmel_lcdc_bl_ops, &props);
diff --git a/drivers/video/aty/aty128fb.c b/drivers/video/aty/aty128fb.c
index 4cb6a576c56..b0b2ac33534 100644
--- a/drivers/video/aty/aty128fb.c
+++ b/drivers/video/aty/aty128fb.c
@@ -1818,6 +1818,7 @@ static void aty128_bl_init(struct aty128fb_par *par)
 	snprintf(name, sizeof(name), "aty128bl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &aty128_bl_data,
 				       &props);
diff --git a/drivers/video/aty/atyfb_base.c b/drivers/video/aty/atyfb_base.c
index 94e293fce1d..d437b3daf1f 100644
--- a/drivers/video/aty/atyfb_base.c
+++ b/drivers/video/aty/atyfb_base.c
@@ -2241,6 +2241,7 @@ static void aty_bl_init(struct atyfb_par *par)
 	snprintf(name, sizeof(name), "atybl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &aty_bl_data,
 				       &props);
diff --git a/drivers/video/aty/radeon_backlight.c b/drivers/video/aty/radeon_backlight.c
index 9b811ddbce8..db572df7e1e 100644
--- a/drivers/video/aty/radeon_backlight.c
+++ b/drivers/video/aty/radeon_backlight.c
@@ -158,6 +158,7 @@ void radeonfb_bl_init(struct radeonfb_info *rinfo)
 	snprintf(name, sizeof(name), "radeonbl%d", rinfo->info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, rinfo->info->dev, pdata,
 				       &radeon_bl_data, &props);
diff --git a/drivers/video/backlight/88pm860x_bl.c b/drivers/video/backlight/88pm860x_bl.c
index b224396b86d..e59623a15f3 100644
--- a/drivers/video/backlight/88pm860x_bl.c
+++ b/drivers/video/backlight/88pm860x_bl.c
@@ -227,6 +227,7 @@ static int pm860x_backlight_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = MAX_BRIGHTNESS;
 	bl = backlight_device_register(name, &pdev->dev, data,
 					&pm860x_backlight_ops, &props);
diff --git a/drivers/video/backlight/adp5520_bl.c b/drivers/video/backlight/adp5520_bl.c
index 9f436e014f8..af3119707db 100644
--- a/drivers/video/backlight/adp5520_bl.c
+++ b/drivers/video/backlight/adp5520_bl.c
@@ -303,6 +303,7 @@ static int __devinit adp5520_bl_probe(struct platform_device *pdev)
 	mutex_init(&data->lock);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = ADP5020_MAX_BRIGHTNESS;
 	bl = backlight_device_register(pdev->name, data->master, data,
 				       &adp5520_bl_ops, &props);
diff --git a/drivers/video/backlight/adp8860_bl.c b/drivers/video/backlight/adp8860_bl.c
index 734c650a47c..d2a96a421ff 100644
--- a/drivers/video/backlight/adp8860_bl.c
+++ b/drivers/video/backlight/adp8860_bl.c
@@ -709,6 +709,7 @@ static int __devinit adp8860_probe(struct i2c_client *client,
 	i2c_set_clientdata(client, data);
 
 	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = ADP8860_MAX_BRIGHTNESS;
 
 	mutex_init(&data->lock);
diff --git a/drivers/video/backlight/adx_bl.c b/drivers/video/backlight/adx_bl.c
index fe9af129c5d..c861c41af44 100644
--- a/drivers/video/backlight/adx_bl.c
+++ b/drivers/video/backlight/adx_bl.c
@@ -104,6 +104,7 @@ static int __devinit adx_backlight_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	bldev = backlight_device_register(dev_name(&pdev->dev), &pdev->dev,
 					  bl, &adx_backlight_ops, &props);
diff --git a/drivers/video/backlight/atmel-pwm-bl.c b/drivers/video/backlight/atmel-pwm-bl.c
index e6a66dab088..0443a4f7185 100644
--- a/drivers/video/backlight/atmel-pwm-bl.c
+++ b/drivers/video/backlight/atmel-pwm-bl.c
@@ -168,6 +168,7 @@ static int atmel_pwm_bl_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;
 	bldev = backlight_device_register("atmel-pwm-bl", &pdev->dev, pwmbl,
 					  &atmel_pwm_bl_ops, &props);
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 08703299ef6..80d292fb92d 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -19,6 +19,12 @@
 #include <asm/backlight.h>
 #endif
 
+static const char const *backlight_types[] = {
+	[BACKLIGHT_RAW] = "raw",
+	[BACKLIGHT_PLATFORM] = "platform",
+	[BACKLIGHT_FIRMWARE] = "firmware",