1/*
2 *  Copyright (C) 2008       SuSE Linux Products GmbH
3 *                           Thomas Renninger <trenn@suse.de>
4 *
5 *  May be copied or modified under the terms of the GNU General Public License
6 *
7 * video_detect.c:
8 * Provides acpi_is_video_device() for early scanning of ACPI devices in scan.c
9 * There a Linux specific (Spec does not provide a HID for video devices) is
10 * assigned
11 *
12 * After PCI devices are glued with ACPI devices
13 * acpi_get_pci_dev() can be called to identify ACPI graphics
14 * devices for which a real graphics card is plugged in
15 *
16 * Now acpi_video_get_capabilities() can be called to check which
17 * capabilities the graphics cards plugged in support. The check for general
18 * video capabilities will be triggered by the first caller of
19 * acpi_video_get_capabilities(NULL); which will happen when the first
20 * backlight switching supporting driver calls:
21 * acpi_video_backlight_support();
22 *
23 * Depending on whether ACPI graphics extensions (cmp. ACPI spec Appendix B)
24 * are available, video.ko should be used to handle the device.
25 *
26 * Otherwise vendor specific drivers like thinkpad_acpi, asus-laptop,
27 * sony_acpi,... can take care about backlight brightness.
28 *
29 * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)
30 * this file will not be compiled, acpi_video_get_capabilities() and
31 * acpi_video_backlight_support() will always return 0 and vendor specific
32 * drivers always can handle backlight.
33 *
34 */
35
36#include <linux/export.h>
37#include <linux/acpi.h>
38#include <linux/dmi.h>
39#include <linux/pci.h>
40
41#define PREFIX "ACPI: "
42
43ACPI_MODULE_NAME("video");
44#define _COMPONENT		ACPI_VIDEO_COMPONENT
45
46static long acpi_video_support;
47static bool acpi_video_caps_checked;
48
49static acpi_status
50acpi_backlight_cap_match(acpi_handle handle, u32 level, void *context,
51			  void **retyurn_value)
52{
53	long *cap = context;
54	acpi_handle h_dummy;
55
56	if (ACPI_SUCCESS(acpi_get_handle(handle, "_BCM", &h_dummy)) &&
57	    ACPI_SUCCESS(acpi_get_handle(handle, "_BCL", &h_dummy))) {
58		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found generic backlight "
59				  "support\n"));
60		*cap |= ACPI_VIDEO_BACKLIGHT;
61		if (ACPI_FAILURE(acpi_get_handle(handle, "_BQC", &h_dummy)))
62			printk(KERN_WARNING FW_BUG PREFIX "No _BQC method, "
63				"cannot determine initial brightness\n");
64		/* We have backlight support, no need to scan further */
65		return AE_CTRL_TERMINATE;
66	}
67	return 0;
68}
69
70/* Returns true if the device is a video device which can be handled by
71 * video.ko.
72 * The device will get a Linux specific CID added in scan.c to
73 * identify the device as an ACPI graphics device
74 * Be aware that the graphics device may not be physically present
75 * Use acpi_video_get_capabilities() to detect general ACPI video
76 * capabilities of present cards
77 */
78long acpi_is_video_device(struct acpi_device *device)
79{
80	acpi_handle h_dummy;
81	long video_caps = 0;
82
83	if (!device)
84		return 0;
85
86	/* Is this device able to support video switching ? */
87	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOD", &h_dummy)) ||
88	    ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOS", &h_dummy)))
89		video_caps |= ACPI_VIDEO_OUTPUT_SWITCHING;
90
91	/* Is this device able to retrieve a video ROM ? */
92	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_ROM", &h_dummy)))
93		video_caps |= ACPI_VIDEO_ROM_AVAILABLE;
94
95	/* Is this device able to configure which video head to be POSTed ? */
96	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_VPO", &h_dummy)) &&
97	    ACPI_SUCCESS(acpi_get_handle(device->handle, "_GPD", &h_dummy)) &&
98	    ACPI_SUCCESS(acpi_get_handle(device->handle, "_SPD", &h_dummy)))
99		video_caps |= ACPI_VIDEO_DEVICE_POSTING;
100
101	/* Only check for backlight functionality if one of the above hit. */
102	if (video_caps)
103		acpi_walk_namespace(ACPI_TYPE_DEVICE, device->handle,
104				    ACPI_UINT32_MAX, acpi_backlight_cap_match, NULL,
105				    &video_caps, NULL);
106
107	return video_caps;
108}
109EXPORT_SYMBOL(acpi_is_video_device);
110
111static acpi_status
112find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
113{
114	long *cap = context;
115	struct pci_dev *dev;
116	struct acpi_device *acpi_dev;
117
118	const struct acpi_device_id video_ids[] = {
119		{ACPI_VIDEO_HID, 0},
120		{"", 0},
121	};
122	if (acpi_bus_get_device(handle, &acpi_dev))
123		return AE_OK;
124
125	if (!acpi_match_device_ids(acpi_dev, video_ids)) {
126		dev = acpi_get_pci_dev(handle);
127		if (!dev)
128			return AE_OK;
129		pci_dev_put(dev);
130		*cap |= acpi_is_video_device(acpi_dev);
131	}
132	return AE_OK;
133}
134
135/*
136 * Returns the video capabilities of a specific ACPI graphics device
137 *
138 * if NULL is passed as argument all ACPI devices are enumerated and
139 * all graphics capabilities of physically present devices are
140 * summarized and returned. This is cached and done only once.
141 */
142long acpi_video_get_capabilities(acpi_handle graphics_handle)
143{
144	long caps = 0;
145	struct acpi_device *tmp_dev;
146	acpi_status status;
147
148	if (acpi_video_caps_checked && graphics_handle == NULL)
149		return acpi_video_support;
150
151	if (!graphics_handle) {
152		/* Only do the global walk through all graphics devices once */
153		acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
154				    ACPI_UINT32_MAX, find_video, NULL,
155				    &caps, NULL);
156		/* There might be boot param flags set already... */
157		acpi_video_support |= caps;
158		acpi_video_caps_checked = 1;
159		/* Add blacklists here. Be careful to use the right *DMI* bits
160		 * to still be able to override logic via boot params, e.g.:
161		 *
162		 *   if (dmi_name_in_vendors("XY")) {
163		 *	acpi_video_support |=
164		 *		ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
165		 *}
166		 */
167	} else {
168		status = acpi_bus_get_device(graphics_handle, &tmp_dev);
169		if (ACPI_FAILURE(status)) {
170			ACPI_EXCEPTION((AE_INFO, status, "Invalid device"));
171			return 0;
172		}
173		acpi_walk_namespace(ACPI_TYPE_DEVICE, graphics_handle,
174				    ACPI_UINT32_MAX, find_video, NULL,
175				    &caps, NULL);
176	}
177	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "We have 0x%lX video support %s %s\n",
178			  graphics_handle ? caps : acpi_video_support,
179			  graphics_handle ? "on device " : "in general",
180			  graphics_handle ? acpi_device_bid(tmp_dev) : ""));
181	return caps;
182}
183EXPORT_SYMBOL(acpi_video_get_capabilities);
184
185/* Returns true if video.ko can do backlight switching */
186int acpi_video_backlight_support(void)
187{
188	/*
189	 * We must check whether the ACPI graphics device is physically plugged
190	 * in. Therefore this must be called after binding PCI and ACPI devices
191	 */
192	if (!acpi_video_caps_checked)
193		acpi_video_get_capabilities(NULL);
194
195	/* First check for boot param -> highest prio */
196	if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR)
197		return 0;
198	else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO)
199		return 1;
200
201	/* Then check for DMI blacklist -> second highest prio */
202	if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VENDOR)
203		return 0;
204	else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VIDEO)
205		return 1;
206
207	/* Then go the default way */
208	return acpi_video_support & ACPI_VIDEO_BACKLIGHT;
209}
210EXPORT_SYMBOL(acpi_video_backlight_support);
211
212/*
213 * Use acpi_backlight=vendor/video to force that backlight switching
214 * is processed by vendor specific acpi drivers or video.ko driver.
215 */
216static int __init acpi_backlight(char *str)
217{
218	if (str == NULL || *str == '\0')
219		return 1;
220	else {
221		if (!strcmp("vendor", str))
222			acpi_video_support |=
223				ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
224		if (!strcmp("video", str))
225			acpi_video_support |=
226				ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO;
227	}
228	return 1;
229}
230__setup("acpi_backlight=", acpi_backlight);
231