xref: /openbmc/linux/drivers/gpu/vga/vga_switcheroo.c (revision 99efde6c)
1 /*
2  * vga_switcheroo.c - Support for laptop with dual GPU using one set of outputs
3  *
4  * Copyright (c) 2010 Red Hat Inc.
5  * Author : Dave Airlie <airlied@redhat.com>
6  *
7  * Copyright (c) 2015 Lukas Wunner <lukas@wunner.de>
8  *
9  * Permission is hereby granted, free of charge, to any person obtaining a
10  * copy of this software and associated documentation files (the "Software"),
11  * to deal in the Software without restriction, including without limitation
12  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
13  * and/or sell copies of the Software, and to permit persons to whom the
14  * Software is furnished to do so, subject to the following conditions:
15  *
16  * The above copyright notice and this permission notice (including the next
17  * paragraph) shall be included in all copies or substantial portions of the
18  * Software.
19  *
20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
23  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
25  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26  * DEALINGS
27  * IN THE SOFTWARE.
28  *
29  */
30 
31 #define pr_fmt(fmt) "vga_switcheroo: " fmt
32 
33 #include <linux/apple-gmux.h>
34 #include <linux/console.h>
35 #include <linux/debugfs.h>
36 #include <linux/fb.h>
37 #include <linux/fs.h>
38 #include <linux/fbcon.h>
39 #include <linux/module.h>
40 #include <linux/pci.h>
41 #include <linux/pm_domain.h>
42 #include <linux/pm_runtime.h>
43 #include <linux/seq_file.h>
44 #include <linux/uaccess.h>
45 #include <linux/vgaarb.h>
46 #include <linux/vga_switcheroo.h>
47 
48 /**
49  * DOC: Overview
50  *
51  * vga_switcheroo is the Linux subsystem for laptop hybrid graphics.
52  * These come in two flavors:
53  *
54  * * muxed: Dual GPUs with a multiplexer chip to switch outputs between GPUs.
55  * * muxless: Dual GPUs but only one of them is connected to outputs.
56  *   The other one is merely used to offload rendering, its results
57  *   are copied over PCIe into the framebuffer. On Linux this is
58  *   supported with DRI PRIME.
59  *
60  * Hybrid graphics started to appear in the late Naughties and were initially
61  * all muxed. Newer laptops moved to a muxless architecture for cost reasons.
62  * A notable exception is the MacBook Pro which continues to use a mux.
63  * Muxes come with varying capabilities: Some switch only the panel, others
64  * can also switch external displays. Some switch all display pins at once
65  * while others can switch just the DDC lines. (To allow EDID probing
66  * for the inactive GPU.) Also, muxes are often used to cut power to the
67  * discrete GPU while it is not used.
68  *
69  * DRM drivers register GPUs with vga_switcheroo, these are henceforth called
70  * clients. The mux is called the handler. Muxless machines also register a
71  * handler to control the power state of the discrete GPU, its ->switchto
72  * callback is a no-op for obvious reasons. The discrete GPU is often equipped
73  * with an HDA controller for the HDMI/DP audio signal, this will also
74  * register as a client so that vga_switcheroo can take care of the correct
75  * suspend/resume order when changing the discrete GPU's power state. In total
76  * there can thus be up to three clients: Two vga clients (GPUs) and one audio
77  * client (on the discrete GPU). The code is mostly prepared to support
78  * machines with more than two GPUs should they become available.
79  *
80  * The GPU to which the outputs are currently switched is called the
81  * active client in vga_switcheroo parlance. The GPU not in use is the
82  * inactive client. When the inactive client's DRM driver is loaded,
83  * it will be unable to probe the panel's EDID and hence depends on
84  * VBIOS to provide its display modes. If the VBIOS modes are bogus or
85  * if there is no VBIOS at all (which is common on the MacBook Pro),
86  * a client may alternatively request that the DDC lines are temporarily
87  * switched to it, provided that the handler supports this. Switching
88  * only the DDC lines and not the entire output avoids unnecessary
89  * flickering.
90  */
91 
92 /**
93  * struct vga_switcheroo_client - registered client
94  * @pdev: client pci device
95  * @fb_info: framebuffer to which console is remapped on switching
96  * @pwr_state: current power state if manual power control is used.
97  *	For driver power control, call vga_switcheroo_pwr_state().
98  * @ops: client callbacks
99  * @id: client identifier. Determining the id requires the handler,
100  *	so gpus are initially assigned VGA_SWITCHEROO_UNKNOWN_ID
101  *	and later given their true id in vga_switcheroo_enable()
102  * @active: whether the outputs are currently switched to this client
103  * @driver_power_control: whether power state is controlled by the driver's
104  *	runtime pm. If true, writing ON and OFF to the vga_switcheroo debugfs
105  *	interface is a no-op so as not to interfere with runtime pm
106  * @list: client list
107  * @vga_dev: pci device, indicate which GPU is bound to current audio client
108  *
109  * Registered client. A client can be either a GPU or an audio device on a GPU.
110  * For audio clients, the @fb_info and @active members are bogus. For GPU
111  * clients, the @vga_dev is bogus.
112  */
113 struct vga_switcheroo_client {
114 	struct pci_dev *pdev;
115 	struct fb_info *fb_info;
116 	enum vga_switcheroo_state pwr_state;
117 	const struct vga_switcheroo_client_ops *ops;
118 	enum vga_switcheroo_client_id id;
119 	bool active;
120 	bool driver_power_control;
121 	struct list_head list;
122 	struct pci_dev *vga_dev;
123 };
124 
125 /*
126  * protects access to struct vgasr_priv
127  */
128 static DEFINE_MUTEX(vgasr_mutex);
129 
130 /**
131  * struct vgasr_priv - vga_switcheroo private data
132  * @active: whether vga_switcheroo is enabled.
133  *	Prerequisite is the registration of two GPUs and a handler
134  * @delayed_switch_active: whether a delayed switch is pending
135  * @delayed_client_id: client to which a delayed switch is pending
136  * @debugfs_root: directory for vga_switcheroo debugfs interface
137  * @registered_clients: number of registered GPUs
138  *	(counting only vga clients, not audio clients)
139  * @clients: list of registered clients
140  * @handler: registered handler
141  * @handler_flags: flags of registered handler
142  * @mux_hw_lock: protects mux state
143  *	(in particular while DDC lines are temporarily switched)
144  * @old_ddc_owner: client to which DDC lines will be switched back on unlock
145  *
146  * vga_switcheroo private data. Currently only one vga_switcheroo instance
147  * per system is supported.
148  */
149 struct vgasr_priv {
150 	bool active;
151 	bool delayed_switch_active;
152 	enum vga_switcheroo_client_id delayed_client_id;
153 
154 	struct dentry *debugfs_root;
155 
156 	int registered_clients;
157 	struct list_head clients;
158 
159 	const struct vga_switcheroo_handler *handler;
160 	enum vga_switcheroo_handler_flags_t handler_flags;
161 	struct mutex mux_hw_lock;
162 	int old_ddc_owner;
163 };
164 
165 #define ID_BIT_AUDIO		0x100
166 #define client_is_audio(c)		((c)->id & ID_BIT_AUDIO)
167 #define client_is_vga(c)		(!client_is_audio(c))
168 #define client_id(c)		((c)->id & ~ID_BIT_AUDIO)
169 
170 static void vga_switcheroo_debugfs_init(struct vgasr_priv *priv);
171 static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv);
172 
173 /* only one switcheroo per system */
174 static struct vgasr_priv vgasr_priv = {
175 	.clients = LIST_HEAD_INIT(vgasr_priv.clients),
176 	.mux_hw_lock = __MUTEX_INITIALIZER(vgasr_priv.mux_hw_lock),
177 };
178 
vga_switcheroo_ready(void)179 static bool vga_switcheroo_ready(void)
180 {
181 	/* we're ready if we get two clients + handler */
182 	return !vgasr_priv.active &&
183 	       vgasr_priv.registered_clients == 2 && vgasr_priv.handler;
184 }
185 
vga_switcheroo_enable(void)186 static void vga_switcheroo_enable(void)
187 {
188 	int ret;
189 	struct vga_switcheroo_client *client;
190 
191 	/* call the handler to init */
192 	if (vgasr_priv.handler->init)
193 		vgasr_priv.handler->init();
194 
195 	list_for_each_entry(client, &vgasr_priv.clients, list) {
196 		if (!client_is_vga(client) ||
197 		     client_id(client) != VGA_SWITCHEROO_UNKNOWN_ID)
198 			continue;
199 
200 		ret = vgasr_priv.handler->get_client_id(client->pdev);
201 		if (ret < 0)
202 			return;
203 
204 		client->id = ret;
205 	}
206 
207 	list_for_each_entry(client, &vgasr_priv.clients, list) {
208 		if (!client_is_audio(client) ||
209 		     client_id(client) != VGA_SWITCHEROO_UNKNOWN_ID)
210 			continue;
211 
212 		ret = vgasr_priv.handler->get_client_id(client->vga_dev);
213 		if (ret < 0)
214 			return;
215 
216 		client->id = ret | ID_BIT_AUDIO;
217 		if (client->ops->gpu_bound)
218 			client->ops->gpu_bound(client->pdev, ret);
219 	}
220 
221 	vga_switcheroo_debugfs_init(&vgasr_priv);
222 	vgasr_priv.active = true;
223 }
224 
225 /**
226  * vga_switcheroo_register_handler() - register handler
227  * @handler: handler callbacks
228  * @handler_flags: handler flags
229  *
230  * Register handler. Enable vga_switcheroo if two vga clients have already
231  * registered.
232  *
233  * Return: 0 on success, -EINVAL if a handler was already registered.
234  */
vga_switcheroo_register_handler(const struct vga_switcheroo_handler * handler,enum vga_switcheroo_handler_flags_t handler_flags)235 int vga_switcheroo_register_handler(
236 			  const struct vga_switcheroo_handler *handler,
237 			  enum vga_switcheroo_handler_flags_t handler_flags)
238 {
239 	mutex_lock(&vgasr_mutex);
240 	if (vgasr_priv.handler) {
241 		mutex_unlock(&vgasr_mutex);
242 		return -EINVAL;
243 	}
244 
245 	vgasr_priv.handler = handler;
246 	vgasr_priv.handler_flags = handler_flags;
247 	if (vga_switcheroo_ready()) {
248 		pr_info("enabled\n");
249 		vga_switcheroo_enable();
250 	}
251 	mutex_unlock(&vgasr_mutex);
252 	return 0;
253 }
254 EXPORT_SYMBOL(vga_switcheroo_register_handler);
255 
256 /**
257  * vga_switcheroo_unregister_handler() - unregister handler
258  *
259  * Unregister handler. Disable vga_switcheroo.
260  */
vga_switcheroo_unregister_handler(void)261 void vga_switcheroo_unregister_handler(void)
262 {
263 	mutex_lock(&vgasr_mutex);
264 	mutex_lock(&vgasr_priv.mux_hw_lock);
265 	vgasr_priv.handler_flags = 0;
266 	vgasr_priv.handler = NULL;
267 	if (vgasr_priv.active) {
268 		pr_info("disabled\n");
269 		vga_switcheroo_debugfs_fini(&vgasr_priv);
270 		vgasr_priv.active = false;
271 	}
272 	mutex_unlock(&vgasr_priv.mux_hw_lock);
273 	mutex_unlock(&vgasr_mutex);
274 }
275 EXPORT_SYMBOL(vga_switcheroo_unregister_handler);
276 
277 /**
278  * vga_switcheroo_handler_flags() - obtain handler flags
279  *
280  * Helper for clients to obtain the handler flags bitmask.
281  *
282  * Return: Handler flags. A value of 0 means that no handler is registered
283  * or that the handler has no special capabilities.
284  */
vga_switcheroo_handler_flags(void)285 enum vga_switcheroo_handler_flags_t vga_switcheroo_handler_flags(void)
286 {
287 	return vgasr_priv.handler_flags;
288 }
289 EXPORT_SYMBOL(vga_switcheroo_handler_flags);
290 
register_client(struct pci_dev * pdev,const struct vga_switcheroo_client_ops * ops,enum vga_switcheroo_client_id id,struct pci_dev * vga_dev,bool active,bool driver_power_control)291 static int register_client(struct pci_dev *pdev,
292 			   const struct vga_switcheroo_client_ops *ops,
293 			   enum vga_switcheroo_client_id id,
294 			   struct pci_dev *vga_dev,
295 			   bool active,
296 			   bool driver_power_control)
297 {
298 	struct vga_switcheroo_client *client;
299 
300 	client = kzalloc(sizeof(*client), GFP_KERNEL);
301 	if (!client)
302 		return -ENOMEM;
303 
304 	client->pwr_state = VGA_SWITCHEROO_ON;
305 	client->pdev = pdev;
306 	client->ops = ops;
307 	client->id = id;
308 	client->active = active;
309 	client->driver_power_control = driver_power_control;
310 	client->vga_dev = vga_dev;
311 
312 	mutex_lock(&vgasr_mutex);
313 	list_add_tail(&client->list, &vgasr_priv.clients);
314 	if (client_is_vga(client))
315 		vgasr_priv.registered_clients++;
316 
317 	if (vga_switcheroo_ready()) {
318 		pr_info("enabled\n");
319 		vga_switcheroo_enable();
320 	}
321 	mutex_unlock(&vgasr_mutex);
322 	return 0;
323 }
324 
325 /**
326  * vga_switcheroo_register_client - register vga client
327  * @pdev: client pci device
328  * @ops: client callbacks
329  * @driver_power_control: whether power state is controlled by the driver's
330  *	runtime pm
331  *
332  * Register vga client (GPU). Enable vga_switcheroo if another GPU and a
333  * handler have already registered. The power state of the client is assumed
334  * to be ON. Beforehand, vga_switcheroo_client_probe_defer() shall be called
335  * to ensure that all prerequisites are met.
336  *
337  * Return: 0 on success, -ENOMEM on memory allocation error.
338  */
vga_switcheroo_register_client(struct pci_dev * pdev,const struct vga_switcheroo_client_ops * ops,bool driver_power_control)339 int vga_switcheroo_register_client(struct pci_dev *pdev,
340 				   const struct vga_switcheroo_client_ops *ops,
341 				   bool driver_power_control)
342 {
343 	return register_client(pdev, ops, VGA_SWITCHEROO_UNKNOWN_ID, NULL,
344 			       pdev == vga_default_device(),
345 			       driver_power_control);
346 }
347 EXPORT_SYMBOL(vga_switcheroo_register_client);
348 
349 /**
350  * vga_switcheroo_register_audio_client - register audio client
351  * @pdev: client pci device
352  * @ops: client callbacks
353  * @vga_dev:  pci device which is bound to current audio client
354  *
355  * Register audio client (audio device on a GPU). The client is assumed
356  * to use runtime PM. Beforehand, vga_switcheroo_client_probe_defer()
357  * shall be called to ensure that all prerequisites are met.
358  *
359  * Return: 0 on success, -ENOMEM on memory allocation error, -EINVAL on getting
360  * client id error.
361  */
vga_switcheroo_register_audio_client(struct pci_dev * pdev,const struct vga_switcheroo_client_ops * ops,struct pci_dev * vga_dev)362 int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
363 			const struct vga_switcheroo_client_ops *ops,
364 			struct pci_dev *vga_dev)
365 {
366 	enum vga_switcheroo_client_id id = VGA_SWITCHEROO_UNKNOWN_ID;
367 
368 	/*
369 	 * if vga_switcheroo has enabled, that mean two GPU clients and also
370 	 * handler are registered. Get audio client id from bound GPU client
371 	 * id directly, otherwise, set it as VGA_SWITCHEROO_UNKNOWN_ID,
372 	 * it will set to correct id in later when vga_switcheroo_enable()
373 	 * is called.
374 	 */
375 	mutex_lock(&vgasr_mutex);
376 	if (vgasr_priv.active) {
377 		id = vgasr_priv.handler->get_client_id(vga_dev);
378 		if (id < 0) {
379 			mutex_unlock(&vgasr_mutex);
380 			return -EINVAL;
381 		}
382 		/* notify if GPU has been already bound */
383 		if (ops->gpu_bound)
384 			ops->gpu_bound(pdev, id);
385 	}
386 	mutex_unlock(&vgasr_mutex);
387 
388 	return register_client(pdev, ops, id | ID_BIT_AUDIO, vga_dev,
389 			       false, true);
390 }
391 EXPORT_SYMBOL(vga_switcheroo_register_audio_client);
392 
393 static struct vga_switcheroo_client *
find_client_from_pci(struct list_head * head,struct pci_dev * pdev)394 find_client_from_pci(struct list_head *head, struct pci_dev *pdev)
395 {
396 	struct vga_switcheroo_client *client;
397 
398 	list_for_each_entry(client, head, list)
399 		if (client->pdev == pdev)
400 			return client;
401 	return NULL;
402 }
403 
404 static struct vga_switcheroo_client *
find_client_from_id(struct list_head * head,enum vga_switcheroo_client_id client_id)405 find_client_from_id(struct list_head *head,
406 		    enum vga_switcheroo_client_id client_id)
407 {
408 	struct vga_switcheroo_client *client;
409 
410 	list_for_each_entry(client, head, list)
411 		if (client->id == client_id)
412 			return client;
413 	return NULL;
414 }
415 
416 static struct vga_switcheroo_client *
find_active_client(struct list_head * head)417 find_active_client(struct list_head *head)
418 {
419 	struct vga_switcheroo_client *client;
420 
421 	list_for_each_entry(client, head, list)
422 		if (client->active)
423 			return client;
424 	return NULL;
425 }
426 
427 /**
428  * vga_switcheroo_client_probe_defer() - whether to defer probing a given client
429  * @pdev: client pci device
430  *
431  * Determine whether any prerequisites are not fulfilled to probe a given
432  * client. Drivers shall invoke this early on in their ->probe callback
433  * and return %-EPROBE_DEFER if it evaluates to %true. Thou shalt not
434  * register the client ere thou hast called this.
435  *
436  * Return: %true if probing should be deferred, otherwise %false.
437  */
vga_switcheroo_client_probe_defer(struct pci_dev * pdev)438 bool vga_switcheroo_client_probe_defer(struct pci_dev *pdev)
439 {
440 	if ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY) {
441 		/*
442 		 * apple-gmux is needed on pre-retina MacBook Pro
443 		 * to probe the panel if pdev is the inactive GPU.
444 		 */
445 		if (apple_gmux_present() && pdev != vga_default_device() &&
446 		    !vgasr_priv.handler_flags)
447 			return true;
448 	}
449 
450 	return false;
451 }
452 EXPORT_SYMBOL(vga_switcheroo_client_probe_defer);
453 
454 static enum vga_switcheroo_state
vga_switcheroo_pwr_state(struct vga_switcheroo_client * client)455 vga_switcheroo_pwr_state(struct vga_switcheroo_client *client)
456 {
457 	if (client->driver_power_control)
458 		if (pm_runtime_enabled(&client->pdev->dev) &&
459 		    pm_runtime_active(&client->pdev->dev))
460 			return VGA_SWITCHEROO_ON;
461 		else
462 			return VGA_SWITCHEROO_OFF;
463 	else
464 		return client->pwr_state;
465 }
466 
467 /**
468  * vga_switcheroo_get_client_state() - obtain power state of a given client
469  * @pdev: client pci device
470  *
471  * Obtain power state of a given client as seen from vga_switcheroo.
472  * The function is only called from hda_intel.c.
473  *
474  * Return: Power state.
475  */
vga_switcheroo_get_client_state(struct pci_dev * pdev)476 enum vga_switcheroo_state vga_switcheroo_get_client_state(struct pci_dev *pdev)
477 {
478 	struct vga_switcheroo_client *client;
479 	enum vga_switcheroo_state ret;
480 
481 	mutex_lock(&vgasr_mutex);
482 	client = find_client_from_pci(&vgasr_priv.clients, pdev);
483 	if (!client)
484 		ret = VGA_SWITCHEROO_NOT_FOUND;
485 	else
486 		ret = vga_switcheroo_pwr_state(client);
487 	mutex_unlock(&vgasr_mutex);
488 	return ret;
489 }
490 EXPORT_SYMBOL(vga_switcheroo_get_client_state);
491 
492 /**
493  * vga_switcheroo_unregister_client() - unregister client
494  * @pdev: client pci device
495  *
496  * Unregister client. Disable vga_switcheroo if this is a vga client (GPU).
497  */
vga_switcheroo_unregister_client(struct pci_dev * pdev)498 void vga_switcheroo_unregister_client(struct pci_dev *pdev)
499 {
500 	struct vga_switcheroo_client *client;
501 
502 	mutex_lock(&vgasr_mutex);
503 	client = find_client_from_pci(&vgasr_priv.clients, pdev);
504 	if (client) {
505 		if (client_is_vga(client))
506 			vgasr_priv.registered_clients--;
507 		list_del(&client->list);
508 		kfree(client);
509 	}
510 	if (vgasr_priv.active && vgasr_priv.registered_clients < 2) {
511 		pr_info("disabled\n");
512 		vga_switcheroo_debugfs_fini(&vgasr_priv);
513 		vgasr_priv.active = false;
514 	}
515 	mutex_unlock(&vgasr_mutex);
516 }
517 EXPORT_SYMBOL(vga_switcheroo_unregister_client);
518 
519 /**
520  * vga_switcheroo_client_fb_set() - set framebuffer of a given client
521  * @pdev: client pci device
522  * @info: framebuffer
523  *
524  * Set framebuffer of a given client. The console will be remapped to this
525  * on switching.
526  */
vga_switcheroo_client_fb_set(struct pci_dev * pdev,struct fb_info * info)527 void vga_switcheroo_client_fb_set(struct pci_dev *pdev,
528 				 struct fb_info *info)
529 {
530 	struct vga_switcheroo_client *client;
531 
532 	mutex_lock(&vgasr_mutex);
533 	client = find_client_from_pci(&vgasr_priv.clients, pdev);
534 	if (client)
535 		client->fb_info = info;
536 	mutex_unlock(&vgasr_mutex);
537 }
538 EXPORT_SYMBOL(vga_switcheroo_client_fb_set);
539 
540 /**
541  * vga_switcheroo_lock_ddc() - temporarily switch DDC lines to a given client
542  * @pdev: client pci device
543  *
544  * Temporarily switch DDC lines to the client identified by @pdev
545  * (but leave the outputs otherwise switched to where they are).
546  * This allows the inactive client to probe EDID. The DDC lines must
547  * afterwards be switched back by calling vga_switcheroo_unlock_ddc(),
548  * even if this function returns an error.
549  *
550  * Return: Previous DDC owner on success or a negative int on error.
551  * Specifically, %-ENODEV if no handler has registered or if the handler
552  * does not support switching the DDC lines. Also, a negative value
553  * returned by the handler is propagated back to the caller.
554  * The return value has merely an informational purpose for any caller
555  * which might be interested in it. It is acceptable to ignore the return
556  * value and simply rely on the result of the subsequent EDID probe,
557  * which will be %NULL if DDC switching failed.
558  */
vga_switcheroo_lock_ddc(struct pci_dev * pdev)559 int vga_switcheroo_lock_ddc(struct pci_dev *pdev)
560 {
561 	enum vga_switcheroo_client_id id;
562 
563 	mutex_lock(&vgasr_priv.mux_hw_lock);
564 	if (!vgasr_priv.handler || !vgasr_priv.handler->switch_ddc) {
565 		vgasr_priv.old_ddc_owner = -ENODEV;
566 		return -ENODEV;
567 	}
568 
569 	id = vgasr_priv.handler->get_client_id(pdev);
570 	vgasr_priv.old_ddc_owner = vgasr_priv.handler->switch_ddc(id);
571 	return vgasr_priv.old_ddc_owner;
572 }
573 EXPORT_SYMBOL(vga_switcheroo_lock_ddc);
574 
575 /**
576  * vga_switcheroo_unlock_ddc() - switch DDC lines back to previous owner
577  * @pdev: client pci device
578  *
579  * Switch DDC lines back to the previous owner after calling
580  * vga_switcheroo_lock_ddc(). This must be called even if
581  * vga_switcheroo_lock_ddc() returned an error.
582  *
583  * Return: Previous DDC owner on success (i.e. the client identifier of @pdev)
584  * or a negative int on error.
585  * Specifically, %-ENODEV if no handler has registered or if the handler
586  * does not support switching the DDC lines. Also, a negative value
587  * returned by the handler is propagated back to the caller.
588  * Finally, invoking this function without calling vga_switcheroo_lock_ddc()
589  * first is not allowed and will result in %-EINVAL.
590  */
vga_switcheroo_unlock_ddc(struct pci_dev * pdev)591 int vga_switcheroo_unlock_ddc(struct pci_dev *pdev)
592 {
593 	enum vga_switcheroo_client_id id;
594 	int ret = vgasr_priv.old_ddc_owner;
595 
596 	if (WARN_ON_ONCE(!mutex_is_locked(&vgasr_priv.mux_hw_lock)))
597 		return -EINVAL;
598 
599 	if (vgasr_priv.old_ddc_owner >= 0) {
600 		id = vgasr_priv.handler->get_client_id(pdev);
601 		if (vgasr_priv.old_ddc_owner != id)
602 			ret = vgasr_priv.handler->switch_ddc(
603 						     vgasr_priv.old_ddc_owner);
604 	}
605 	mutex_unlock(&vgasr_priv.mux_hw_lock);
606 	return ret;
607 }
608 EXPORT_SYMBOL(vga_switcheroo_unlock_ddc);
609 
610 /**
611  * DOC: Manual switching and manual power control
612  *
613  * In this mode of use, the file /sys/kernel/debug/vgaswitcheroo/switch
614  * can be read to retrieve the current vga_switcheroo state and commands
615  * can be written to it to change the state. The file appears as soon as
616  * two GPU drivers and one handler have registered with vga_switcheroo.
617  * The following commands are understood:
618  *
619  * * OFF: Power off the device not in use.
620  * * ON: Power on the device not in use.
621  * * IGD: Switch to the integrated graphics device.
622  *   Power on the integrated GPU if necessary, power off the discrete GPU.
623  *   Prerequisite is that no user space processes (e.g. Xorg, alsactl)
624  *   have opened device files of the GPUs or the audio client. If the
625  *   switch fails, the user may invoke lsof(8) or fuser(1) on /dev/dri/
626  *   and /dev/snd/controlC1 to identify processes blocking the switch.
627  * * DIS: Switch to the discrete graphics device.
628  * * DIGD: Delayed switch to the integrated graphics device.
629  *   This will perform the switch once the last user space process has
630  *   closed the device files of the GPUs and the audio client.
631  * * DDIS: Delayed switch to the discrete graphics device.
632  * * MIGD: Mux-only switch to the integrated graphics device.
633  *   Does not remap console or change the power state of either gpu.
634  *   If the integrated GPU is currently off, the screen will turn black.
635  *   If it is on, the screen will show whatever happens to be in VRAM.
636  *   Either way, the user has to blindly enter the command to switch back.
637  * * MDIS: Mux-only switch to the discrete graphics device.
638  *
639  * For GPUs whose power state is controlled by the driver's runtime pm,
640  * the ON and OFF commands are a no-op (see next section).
641  *
642  * For muxless machines, the IGD/DIS, DIGD/DDIS and MIGD/MDIS commands
643  * should not be used.
644  */
645 
vga_switcheroo_show(struct seq_file * m,void * v)646 static int vga_switcheroo_show(struct seq_file *m, void *v)
647 {
648 	struct vga_switcheroo_client *client;
649 	int i = 0;
650 
651 	mutex_lock(&vgasr_mutex);
652 	list_for_each_entry(client, &vgasr_priv.clients, list) {
653 		seq_printf(m, "%d:%s%s:%c:%s%s:%s\n", i,
654 			   client_id(client) == VGA_SWITCHEROO_DIS ? "DIS" :
655 								     "IGD",
656 			   client_is_vga(client) ? "" : "-Audio",
657 			   client->active ? '+' : ' ',
658 			   client->driver_power_control ? "Dyn" : "",
659 			   vga_switcheroo_pwr_state(client) ? "Pwr" : "Off",
660 			   pci_name(client->pdev));
661 		i++;
662 	}
663 	mutex_unlock(&vgasr_mutex);
664 	return 0;
665 }
666 
vga_switcheroo_debugfs_open(struct inode * inode,struct file * file)667 static int vga_switcheroo_debugfs_open(struct inode *inode, struct file *file)
668 {
669 	return single_open(file, vga_switcheroo_show, NULL);
670 }
671 
vga_switchon(struct vga_switcheroo_client * client)672 static int vga_switchon(struct vga_switcheroo_client *client)
673 {
674 	if (client->driver_power_control)
675 		return 0;
676 	if (vgasr_priv.handler->power_state)
677 		vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_ON);
678 	/* call the driver callback to turn on device */
679 	client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_ON);
680 	client->pwr_state = VGA_SWITCHEROO_ON;
681 	return 0;
682 }
683 
vga_switchoff(struct vga_switcheroo_client * client)684 static int vga_switchoff(struct vga_switcheroo_client *client)
685 {
686 	if (client->driver_power_control)
687 		return 0;
688 	/* call the driver callback to turn off device */
689 	client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_OFF);
690 	if (vgasr_priv.handler->power_state)
691 		vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_OFF);
692 	client->pwr_state = VGA_SWITCHEROO_OFF;
693 	return 0;
694 }
695 
set_audio_state(enum vga_switcheroo_client_id id,enum vga_switcheroo_state state)696 static void set_audio_state(enum vga_switcheroo_client_id id,
697 			    enum vga_switcheroo_state state)
698 {
699 	struct vga_switcheroo_client *client;
700 
701 	client = find_client_from_id(&vgasr_priv.clients, id | ID_BIT_AUDIO);
702 	if (client)
703 		client->ops->set_gpu_state(client->pdev, state);
704 }
705 
706 /* stage one happens before delay */
vga_switchto_stage1(struct vga_switcheroo_client * new_client)707 static int vga_switchto_stage1(struct vga_switcheroo_client *new_client)
708 {
709 	struct vga_switcheroo_client *active;
710 
711 	active = find_active_client(&vgasr_priv.clients);
712 	if (!active)
713 		return 0;
714 
715 	if (vga_switcheroo_pwr_state(new_client) == VGA_SWITCHEROO_OFF)
716 		vga_switchon(new_client);
717 
718 	vga_set_default_device(new_client->pdev);
719 	return 0;
720 }
721 
722 /* post delay */
vga_switchto_stage2(struct vga_switcheroo_client * new_client)723 static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
724 {
725 	int ret;
726 	struct vga_switcheroo_client *active;
727 
728 	active = find_active_client(&vgasr_priv.clients);
729 	if (!active)
730 		return 0;
731 
732 	active->active = false;
733 
734 	/* let HDA controller autosuspend if GPU uses driver power control */
735 	if (!active->driver_power_control)
736 		set_audio_state(active->id, VGA_SWITCHEROO_OFF);
737 
738 	if (new_client->fb_info)
739 		fbcon_remap_all(new_client->fb_info);
740 
741 	mutex_lock(&vgasr_priv.mux_hw_lock);
742 	ret = vgasr_priv.handler->switchto(new_client->id);
743 	mutex_unlock(&vgasr_priv.mux_hw_lock);
744 	if (ret)
745 		return ret;
746 
747 	if (new_client->ops->reprobe)
748 		new_client->ops->reprobe(new_client->pdev);
749 
750 	if (vga_switcheroo_pwr_state(active) == VGA_SWITCHEROO_ON)
751 		vga_switchoff(active);
752 
753 	/* let HDA controller autoresume if GPU uses driver power control */
754 	if (!new_client->driver_power_control)
755 		set_audio_state(new_client->id, VGA_SWITCHEROO_ON);
756 
757 	new_client->active = true;
758 	return 0;
759 }
760 
check_can_switch(void)761 static bool check_can_switch(void)
762 {
763 	struct vga_switcheroo_client *client;
764 
765 	list_for_each_entry(client, &vgasr_priv.clients, list) {
766 		if (!client->ops->can_switch(client->pdev)) {
767 			pr_err("client %x refused switch\n", client->id);
768 			return false;
769 		}
770 	}
771 	return true;
772 }
773 
774 static ssize_t
vga_switcheroo_debugfs_write(struct file * filp,const char __user * ubuf,size_t cnt,loff_t * ppos)775 vga_switcheroo_debugfs_write(struct file *filp, const char __user *ubuf,
776 			     size_t cnt, loff_t *ppos)
777 {
778 	char usercmd[64];
779 	int ret;
780 	bool delay = false, can_switch;
781 	bool just_mux = false;
782 	enum vga_switcheroo_client_id client_id = VGA_SWITCHEROO_UNKNOWN_ID;
783 	struct vga_switcheroo_client *client = NULL;
784 
785 	if (cnt > 63)
786 		cnt = 63;
787 
788 	if (copy_from_user(usercmd, ubuf, cnt))
789 		return -EFAULT;
790 
791 	mutex_lock(&vgasr_mutex);
792 
793 	if (!vgasr_priv.active) {
794 		cnt = -EINVAL;
795 		goto out;
796 	}
797 
798 	/* pwr off the device not in use */
799 	if (strncmp(usercmd, "OFF", 3) == 0) {
800 		list_for_each_entry(client, &vgasr_priv.clients, list) {
801 			if (client->active || client_is_audio(client))
802 				continue;
803 			if (client->driver_power_control)
804 				continue;
805 			set_audio_state(client->id, VGA_SWITCHEROO_OFF);
806 			if (client->pwr_state == VGA_SWITCHEROO_ON)
807 				vga_switchoff(client);
808 		}
809 		goto out;
810 	}
811 	/* pwr on the device not in use */
812 	if (strncmp(usercmd, "ON", 2) == 0) {
813 		list_for_each_entry(client, &vgasr_priv.clients, list) {
814 			if (client->active || client_is_audio(client))
815 				continue;
816 			if (client->driver_power_control)
817 				continue;
818 			if (client->pwr_state == VGA_SWITCHEROO_OFF)
819 				vga_switchon(client);
820 			set_audio_state(client->id, VGA_SWITCHEROO_ON);
821 		}
822 		goto out;
823 	}
824 
825 	/* request a delayed switch - test can we switch now */
826 	if (strncmp(usercmd, "DIGD", 4) == 0) {
827 		client_id = VGA_SWITCHEROO_IGD;
828 		delay = true;
829 	}
830 
831 	if (strncmp(usercmd, "DDIS", 4) == 0) {
832 		client_id = VGA_SWITCHEROO_DIS;
833 		delay = true;
834 	}
835 
836 	if (strncmp(usercmd, "IGD", 3) == 0)
837 		client_id = VGA_SWITCHEROO_IGD;
838 
839 	if (strncmp(usercmd, "DIS", 3) == 0)
840 		client_id = VGA_SWITCHEROO_DIS;
841 
842 	if (strncmp(usercmd, "MIGD", 4) == 0) {
843 		just_mux = true;
844 		client_id = VGA_SWITCHEROO_IGD;
845 	}
846 	if (strncmp(usercmd, "MDIS", 4) == 0) {
847 		just_mux = true;
848 		client_id = VGA_SWITCHEROO_DIS;
849 	}
850 
851 	if (client_id == VGA_SWITCHEROO_UNKNOWN_ID)
852 		goto out;
853 	client = find_client_from_id(&vgasr_priv.clients, client_id);
854 	if (!client)
855 		goto out;
856 
857 	vgasr_priv.delayed_switch_active = false;
858 
859 	if (just_mux) {
860 		mutex_lock(&vgasr_priv.mux_hw_lock);
861 		ret = vgasr_priv.handler->switchto(client_id);
862 		mutex_unlock(&vgasr_priv.mux_hw_lock);
863 		goto out;
864 	}
865 
866 	if (client->active)
867 		goto out;
868 
869 	/* okay we want a switch - test if devices are willing to switch */
870 	can_switch = check_can_switch();
871 
872 	if (can_switch == false && delay == false)
873 		goto out;
874 
875 	if (can_switch) {
876 		ret = vga_switchto_stage1(client);
877 		if (ret)
878 			pr_err("switching failed stage 1 %d\n", ret);
879 
880 		ret = vga_switchto_stage2(client);
881 		if (ret)
882 			pr_err("switching failed stage 2 %d\n", ret);
883 
884 	} else {
885 		pr_info("setting delayed switch to client %d\n", client->id);
886 		vgasr_priv.delayed_switch_active = true;
887 		vgasr_priv.delayed_client_id = client_id;
888 
889 		ret = vga_switchto_stage1(client);
890 		if (ret)
891 			pr_err("delayed switching stage 1 failed %d\n", ret);
892 	}
893 
894 out:
895 	mutex_unlock(&vgasr_mutex);
896 	return cnt;
897 }
898 
899 static const struct file_operations vga_switcheroo_debugfs_fops = {
900 	.owner = THIS_MODULE,
901 	.open = vga_switcheroo_debugfs_open,
902 	.write = vga_switcheroo_debugfs_write,
903 	.read = seq_read,
904 	.llseek = seq_lseek,
905 	.release = single_release,
906 };
907 
vga_switcheroo_debugfs_fini(struct vgasr_priv * priv)908 static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv)
909 {
910 	debugfs_remove_recursive(priv->debugfs_root);
911 	priv->debugfs_root = NULL;
912 }
913 
vga_switcheroo_debugfs_init(struct vgasr_priv * priv)914 static void vga_switcheroo_debugfs_init(struct vgasr_priv *priv)
915 {
916 	/* already initialised */
917 	if (priv->debugfs_root)
918 		return;
919 
920 	priv->debugfs_root = debugfs_create_dir("vgaswitcheroo", NULL);
921 
922 	debugfs_create_file("switch", 0644, priv->debugfs_root, NULL,
923 			    &vga_switcheroo_debugfs_fops);
924 }
925 
926 /**
927  * vga_switcheroo_process_delayed_switch() - helper for delayed switching
928  *
929  * Process a delayed switch if one is pending. DRM drivers should call this
930  * from their ->lastclose callback.
931  *
932  * Return: 0 on success. -EINVAL if no delayed switch is pending, if the client
933  * has unregistered in the meantime or if there are other clients blocking the
934  * switch. If the actual switch fails, an error is reported and 0 is returned.
935  */
vga_switcheroo_process_delayed_switch(void)936 int vga_switcheroo_process_delayed_switch(void)
937 {
938 	struct vga_switcheroo_client *client;
939 	int ret;
940 	int err = -EINVAL;
941 
942 	mutex_lock(&vgasr_mutex);
943 	if (!vgasr_priv.delayed_switch_active)
944 		goto err;
945 
946 	pr_info("processing delayed switch to %d\n",
947 		vgasr_priv.delayed_client_id);
948 
949 	client = find_client_from_id(&vgasr_priv.clients,
950 				     vgasr_priv.delayed_client_id);
951 	if (!client || !check_can_switch())
952 		goto err;
953 
954 	ret = vga_switchto_stage2(client);
955 	if (ret)
956 		pr_err("delayed switching failed stage 2 %d\n", ret);
957 
958 	vgasr_priv.delayed_switch_active = false;
959 	err = 0;
960 err:
961 	mutex_unlock(&vgasr_mutex);
962 	return err;
963 }
964 EXPORT_SYMBOL(vga_switcheroo_process_delayed_switch);
965 
966 /**
967  * DOC: Driver power control
968  *
969  * In this mode of use, the discrete GPU automatically powers up and down at
970  * the discretion of the driver's runtime pm. On muxed machines, the user may
971  * still influence the muxer state by way of the debugfs interface, however
972  * the ON and OFF commands become a no-op for the discrete GPU.
973  *
974  * This mode is the default on Nvidia HybridPower/Optimus and ATI PowerXpress.
975  * Specifying nouveau.runpm=0, radeon.runpm=0 or amdgpu.runpm=0 on the kernel
976  * command line disables it.
977  *
978  * After the GPU has been suspended, the handler needs to be called to cut
979  * power to the GPU. Likewise it needs to reinstate power before the GPU
980  * can resume. This is achieved by vga_switcheroo_init_domain_pm_ops(),
981  * which augments the GPU's suspend/resume functions by the requisite
982  * calls to the handler.
983  *
984  * When the audio device resumes, the GPU needs to be woken. This is achieved
985  * by a PCI quirk which calls device_link_add() to declare a dependency on the
986  * GPU. That way, the GPU is kept awake whenever and as long as the audio
987  * device is in use.
988  *
989  * On muxed machines, if the mux is initially switched to the discrete GPU,
990  * the user ends up with a black screen when the GPU powers down after boot.
991  * As a workaround, the mux is forced to the integrated GPU on runtime suspend,
992  * cf. https://bugs.freedesktop.org/show_bug.cgi?id=75917
993  */
994 
vga_switcheroo_power_switch(struct pci_dev * pdev,enum vga_switcheroo_state state)995 static void vga_switcheroo_power_switch(struct pci_dev *pdev,
996 					enum vga_switcheroo_state state)
997 {
998 	struct vga_switcheroo_client *client;
999 
1000 	if (!vgasr_priv.handler->power_state)
1001 		return;
1002 
1003 	client = find_client_from_pci(&vgasr_priv.clients, pdev);
1004 	if (!client)
1005 		return;
1006 
1007 	if (!client->driver_power_control)
1008 		return;
1009 
1010 	vgasr_priv.handler->power_state(client->id, state);
1011 }
1012 
1013 /* switcheroo power domain */
vga_switcheroo_runtime_suspend(struct device * dev)1014 static int vga_switcheroo_runtime_suspend(struct device *dev)
1015 {
1016 	struct pci_dev *pdev = to_pci_dev(dev);
1017 	int ret;
1018 
1019 	ret = dev->bus->pm->runtime_suspend(dev);
1020 	if (ret)
1021 		return ret;
1022 	mutex_lock(&vgasr_mutex);
1023 	if (vgasr_priv.handler->switchto) {
1024 		mutex_lock(&vgasr_priv.mux_hw_lock);
1025 		vgasr_priv.handler->switchto(VGA_SWITCHEROO_IGD);
1026 		mutex_unlock(&vgasr_priv.mux_hw_lock);
1027 	}
1028 	pci_bus_set_current_state(pdev->bus, PCI_D3cold);
1029 	vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_OFF);
1030 	mutex_unlock(&vgasr_mutex);
1031 	return 0;
1032 }
1033 
vga_switcheroo_runtime_resume(struct device * dev)1034 static int vga_switcheroo_runtime_resume(struct device *dev)
1035 {
1036 	struct pci_dev *pdev = to_pci_dev(dev);
1037 
1038 	mutex_lock(&vgasr_mutex);
1039 	vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_ON);
1040 	mutex_unlock(&vgasr_mutex);
1041 	pci_resume_bus(pdev->bus);
1042 	return dev->bus->pm->runtime_resume(dev);
1043 }
1044 
1045 /**
1046  * vga_switcheroo_init_domain_pm_ops() - helper for driver power control
1047  * @dev: vga client device
1048  * @domain: power domain
1049  *
1050  * Helper for GPUs whose power state is controlled by the driver's runtime pm.
1051  * After the GPU has been suspended, the handler needs to be called to cut
1052  * power to the GPU. Likewise it needs to reinstate power before the GPU
1053  * can resume. To this end, this helper augments the suspend/resume functions
1054  * by the requisite calls to the handler. It needs only be called on platforms
1055  * where the power switch is separate to the device being powered down.
1056  */
vga_switcheroo_init_domain_pm_ops(struct device * dev,struct dev_pm_domain * domain)1057 int vga_switcheroo_init_domain_pm_ops(struct device *dev,
1058 				      struct dev_pm_domain *domain)
1059 {
1060 	/* copy over all the bus versions */
1061 	if (dev->bus && dev->bus->pm) {
1062 		domain->ops = *dev->bus->pm;
1063 		domain->ops.runtime_suspend = vga_switcheroo_runtime_suspend;
1064 		domain->ops.runtime_resume = vga_switcheroo_runtime_resume;
1065 
1066 		dev_pm_domain_set(dev, domain);
1067 		return 0;
1068 	}
1069 	dev_pm_domain_set(dev, NULL);
1070 	return -EINVAL;
1071 }
1072 EXPORT_SYMBOL(vga_switcheroo_init_domain_pm_ops);
1073 
vga_switcheroo_fini_domain_pm_ops(struct device * dev)1074 void vga_switcheroo_fini_domain_pm_ops(struct device *dev)
1075 {
1076 	dev_pm_domain_set(dev, NULL);
1077 }
1078 EXPORT_SYMBOL(vga_switcheroo_fini_domain_pm_ops);
1079