1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  Gmux driver for Apple laptops
4  *
5  *  Copyright (C) Canonical Ltd. <seth.forshee@canonical.com>
6  *  Copyright (C) 2010-2012 Andreas Heider <andreas@meetr.de>
7  *  Copyright (C) 2015 Lukas Wunner <lukas@wunner.de>
8  */
9 
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 
12 #include <linux/module.h>
13 #include <linux/kernel.h>
14 #include <linux/init.h>
15 #include <linux/backlight.h>
16 #include <linux/acpi.h>
17 #include <linux/pnp.h>
18 #include <linux/apple_bl.h>
19 #include <linux/apple-gmux.h>
20 #include <linux/slab.h>
21 #include <linux/delay.h>
22 #include <linux/pci.h>
23 #include <linux/vga_switcheroo.h>
24 #include <asm/io.h>
25 
26 /**
27  * DOC: Overview
28  *
29  * gmux is a microcontroller built into the MacBook Pro to support dual GPUs:
30  * A `Lattice XP2`_ on pre-retinas, a `Renesas R4F2113`_ on retinas.
31  *
32  * (The MacPro6,1 2013 also has a gmux, however it is unclear why since it has
33  * dual GPUs but no built-in display.)
34  *
35  * gmux is connected to the LPC bus of the southbridge. Its I/O ports are
36  * accessed differently depending on the microcontroller: Driver functions
37  * to access a pre-retina gmux are infixed ``_pio_``, those for a retina gmux
38  * are infixed ``_index_``.
39  *
40  * .. _Lattice XP2:
41  *     http://www.latticesemi.com/en/Products/FPGAandCPLD/LatticeXP2.aspx
42  * .. _Renesas R4F2113:
43  *     http://www.renesas.com/products/mpumcu/h8s/h8s2100/h8s2113/index.jsp
44  */
45 
46 struct apple_gmux_data {
47 	unsigned long iostart;
48 	unsigned long iolen;
49 	bool indexed;
50 	struct mutex index_lock;
51 
52 	struct backlight_device *bdev;
53 
54 	/* switcheroo data */
55 	acpi_handle dhandle;
56 	int gpe;
57 	bool external_switchable;
58 	enum vga_switcheroo_client_id switch_state_display;
59 	enum vga_switcheroo_client_id switch_state_ddc;
60 	enum vga_switcheroo_client_id switch_state_external;
61 	enum vga_switcheroo_state power_state;
62 	struct completion powerchange_done;
63 };
64 
65 static struct apple_gmux_data *apple_gmux_data;
66 
67 /*
68  * gmux port offsets. Many of these are not yet used, but may be in the
69  * future, and it's useful to have them documented here anyhow.
70  */
71 #define GMUX_PORT_VERSION_MAJOR		0x04
72 #define GMUX_PORT_VERSION_MINOR		0x05
73 #define GMUX_PORT_VERSION_RELEASE	0x06
74 #define GMUX_PORT_SWITCH_DISPLAY	0x10
75 #define GMUX_PORT_SWITCH_GET_DISPLAY	0x11
76 #define GMUX_PORT_INTERRUPT_ENABLE	0x14
77 #define GMUX_PORT_INTERRUPT_STATUS	0x16
78 #define GMUX_PORT_SWITCH_DDC		0x28
79 #define GMUX_PORT_SWITCH_EXTERNAL	0x40
80 #define GMUX_PORT_SWITCH_GET_EXTERNAL	0x41
81 #define GMUX_PORT_DISCRETE_POWER	0x50
82 #define GMUX_PORT_MAX_BRIGHTNESS	0x70
83 #define GMUX_PORT_BRIGHTNESS		0x74
84 #define GMUX_PORT_VALUE			0xc2
85 #define GMUX_PORT_READ			0xd0
86 #define GMUX_PORT_WRITE			0xd4
87 
88 #define GMUX_MIN_IO_LEN			(GMUX_PORT_BRIGHTNESS + 4)
89 
90 #define GMUX_INTERRUPT_ENABLE		0xff
91 #define GMUX_INTERRUPT_DISABLE		0x00
92 
93 #define GMUX_INTERRUPT_STATUS_ACTIVE	0
94 #define GMUX_INTERRUPT_STATUS_DISPLAY	(1 << 0)
95 #define GMUX_INTERRUPT_STATUS_POWER	(1 << 2)
96 #define GMUX_INTERRUPT_STATUS_HOTPLUG	(1 << 3)
97 
98 #define GMUX_BRIGHTNESS_MASK		0x00ffffff
99 #define GMUX_MAX_BRIGHTNESS		GMUX_BRIGHTNESS_MASK
100 
101 static u8 gmux_pio_read8(struct apple_gmux_data *gmux_data, int port)
102 {
103 	return inb(gmux_data->iostart + port);
104 }
105 
106 static void gmux_pio_write8(struct apple_gmux_data *gmux_data, int port,
107 			       u8 val)
108 {
109 	outb(val, gmux_data->iostart + port);
110 }
111 
112 static u32 gmux_pio_read32(struct apple_gmux_data *gmux_data, int port)
113 {
114 	return inl(gmux_data->iostart + port);
115 }
116 
117 static void gmux_pio_write32(struct apple_gmux_data *gmux_data, int port,
118 			     u32 val)
119 {
120 	int i;
121 	u8 tmpval;
122 
123 	for (i = 0; i < 4; i++) {
124 		tmpval = (val >> (i * 8)) & 0xff;
125 		outb(tmpval, gmux_data->iostart + port + i);
126 	}
127 }
128 
129 static int gmux_index_wait_ready(struct apple_gmux_data *gmux_data)
130 {
131 	int i = 200;
132 	u8 gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
133 
134 	while (i && (gwr & 0x01)) {
135 		inb(gmux_data->iostart + GMUX_PORT_READ);
136 		gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
137 		udelay(100);
138 		i--;
139 	}
140 
141 	return !!i;
142 }
143 
144 static int gmux_index_wait_complete(struct apple_gmux_data *gmux_data)
145 {
146 	int i = 200;
147 	u8 gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
148 
149 	while (i && !(gwr & 0x01)) {
150 		gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
151 		udelay(100);
152 		i--;
153 	}
154 
155 	if (gwr & 0x01)
156 		inb(gmux_data->iostart + GMUX_PORT_READ);
157 
158 	return !!i;
159 }
160 
161 static u8 gmux_index_read8(struct apple_gmux_data *gmux_data, int port)
162 {
163 	u8 val;
164 
165 	mutex_lock(&gmux_data->index_lock);
166 	gmux_index_wait_ready(gmux_data);
167 	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
168 	gmux_index_wait_complete(gmux_data);
169 	val = inb(gmux_data->iostart + GMUX_PORT_VALUE);
170 	mutex_unlock(&gmux_data->index_lock);
171 
172 	return val;
173 }
174 
175 static void gmux_index_write8(struct apple_gmux_data *gmux_data, int port,
176 			      u8 val)
177 {
178 	mutex_lock(&gmux_data->index_lock);
179 	outb(val, gmux_data->iostart + GMUX_PORT_VALUE);
180 	gmux_index_wait_ready(gmux_data);
181 	outb(port & 0xff, gmux_data->iostart + GMUX_PORT_WRITE);
182 	gmux_index_wait_complete(gmux_data);
183 	mutex_unlock(&gmux_data->index_lock);
184 }
185 
186 static u32 gmux_index_read32(struct apple_gmux_data *gmux_data, int port)
187 {
188 	u32 val;
189 
190 	mutex_lock(&gmux_data->index_lock);
191 	gmux_index_wait_ready(gmux_data);
192 	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
193 	gmux_index_wait_complete(gmux_data);
194 	val = inl(gmux_data->iostart + GMUX_PORT_VALUE);
195 	mutex_unlock(&gmux_data->index_lock);
196 
197 	return val;
198 }
199 
200 static void gmux_index_write32(struct apple_gmux_data *gmux_data, int port,
201 			       u32 val)
202 {
203 	int i;
204 	u8 tmpval;
205 
206 	mutex_lock(&gmux_data->index_lock);
207 
208 	for (i = 0; i < 4; i++) {
209 		tmpval = (val >> (i * 8)) & 0xff;
210 		outb(tmpval, gmux_data->iostart + GMUX_PORT_VALUE + i);
211 	}
212 
213 	gmux_index_wait_ready(gmux_data);
214 	outb(port & 0xff, gmux_data->iostart + GMUX_PORT_WRITE);
215 	gmux_index_wait_complete(gmux_data);
216 	mutex_unlock(&gmux_data->index_lock);
217 }
218 
219 static u8 gmux_read8(struct apple_gmux_data *gmux_data, int port)
220 {
221 	if (gmux_data->indexed)
222 		return gmux_index_read8(gmux_data, port);
223 	else
224 		return gmux_pio_read8(gmux_data, port);
225 }
226 
227 static void gmux_write8(struct apple_gmux_data *gmux_data, int port, u8 val)
228 {
229 	if (gmux_data->indexed)
230 		gmux_index_write8(gmux_data, port, val);
231 	else
232 		gmux_pio_write8(gmux_data, port, val);
233 }
234 
235 static u32 gmux_read32(struct apple_gmux_data *gmux_data, int port)
236 {
237 	if (gmux_data->indexed)
238 		return gmux_index_read32(gmux_data, port);
239 	else
240 		return gmux_pio_read32(gmux_data, port);
241 }
242 
243 static void gmux_write32(struct apple_gmux_data *gmux_data, int port,
244 			     u32 val)
245 {
246 	if (gmux_data->indexed)
247 		gmux_index_write32(gmux_data, port, val);
248 	else
249 		gmux_pio_write32(gmux_data, port, val);
250 }
251 
252 static bool gmux_is_indexed(struct apple_gmux_data *gmux_data)
253 {
254 	u16 val;
255 
256 	outb(0xaa, gmux_data->iostart + 0xcc);
257 	outb(0x55, gmux_data->iostart + 0xcd);
258 	outb(0x00, gmux_data->iostart + 0xce);
259 
260 	val = inb(gmux_data->iostart + 0xcc) |
261 		(inb(gmux_data->iostart + 0xcd) << 8);
262 
263 	if (val == 0x55aa)
264 		return true;
265 
266 	return false;
267 }
268 
269 /**
270  * DOC: Backlight control
271  *
272  * On single GPU MacBooks, the PWM signal for the backlight is generated by
273  * the GPU. On dual GPU MacBook Pros by contrast, either GPU may be suspended
274  * to conserve energy. Hence the PWM signal needs to be generated by a separate
275  * backlight driver which is controlled by gmux. The earliest generation
276  * MBP5 2008/09 uses a `TI LP8543`_ backlight driver. All newer models
277  * use a `TI LP8545`_.
278  *
279  * .. _TI LP8543: https://www.ti.com/lit/ds/symlink/lp8543.pdf
280  * .. _TI LP8545: https://www.ti.com/lit/ds/symlink/lp8545.pdf
281  */
282 
283 static int gmux_get_brightness(struct backlight_device *bd)
284 {
285 	struct apple_gmux_data *gmux_data = bl_get_data(bd);
286 	return gmux_read32(gmux_data, GMUX_PORT_BRIGHTNESS) &
287 	       GMUX_BRIGHTNESS_MASK;
288 }
289 
290 static int gmux_update_status(struct backlight_device *bd)
291 {
292 	struct apple_gmux_data *gmux_data = bl_get_data(bd);
293 	u32 brightness = backlight_get_brightness(bd);
294 
295 	gmux_write32(gmux_data, GMUX_PORT_BRIGHTNESS, brightness);
296 
297 	return 0;
298 }
299 
300 static const struct backlight_ops gmux_bl_ops = {
301 	.options = BL_CORE_SUSPENDRESUME,
302 	.get_brightness = gmux_get_brightness,
303 	.update_status = gmux_update_status,
304 };
305 
306 /**
307  * DOC: Graphics mux
308  *
309  * On pre-retinas, the LVDS outputs of both GPUs feed into gmux which muxes
310  * either of them to the panel. One of the tricks gmux has up its sleeve is
311  * to lengthen the blanking interval of its output during a switch to
312  * synchronize it with the GPU switched to. This allows for a flicker-free
313  * switch that is imperceptible by the user (`US 8,687,007 B2`_).
314  *
315  * On retinas, muxing is no longer done by gmux itself, but by a separate
316  * chip which is controlled by gmux. The chip is triple sourced, it is
317  * either an `NXP CBTL06142`_, `TI HD3SS212`_ or `Pericom PI3VDP12412`_.
318  * The panel is driven with eDP instead of LVDS since the pixel clock
319  * required for retina resolution exceeds LVDS' limits.
320  *
321  * Pre-retinas are able to switch the panel's DDC pins separately.
322  * This is handled by a `TI SN74LV4066A`_ which is controlled by gmux.
323  * The inactive GPU can thus probe the panel's EDID without switching over
324  * the entire panel. Retinas lack this functionality as the chips used for
325  * eDP muxing are incapable of switching the AUX channel separately (see
326  * the linked data sheets, Pericom would be capable but this is unused).
327  * However the retina panel has the NO_AUX_HANDSHAKE_LINK_TRAINING bit set
328  * in its DPCD, allowing the inactive GPU to skip the AUX handshake and
329  * set up the output with link parameters pre-calibrated by the active GPU.
330  *
331  * The external DP port is only fully switchable on the first two unibody
332  * MacBook Pro generations, MBP5 2008/09 and MBP6 2010. This is done by an
333  * `NXP CBTL06141`_ which is controlled by gmux. It's the predecessor of the
334  * eDP mux on retinas, the difference being support for 2.7 versus 5.4 Gbit/s.
335  *
336  * The following MacBook Pro generations replaced the external DP port with a
337  * combined DP/Thunderbolt port and lost the ability to switch it between GPUs,
338  * connecting it either to the discrete GPU or the Thunderbolt controller.
339  * Oddly enough, while the full port is no longer switchable, AUX and HPD
340  * are still switchable by way of an `NXP CBTL03062`_ (on pre-retinas
341  * MBP8 2011 and MBP9 2012) or two `TI TS3DS10224`_ (on retinas) under the
342  * control of gmux. Since the integrated GPU is missing the main link,
343  * external displays appear to it as phantoms which fail to link-train.
344  *
345  * gmux receives the HPD signal of all display connectors and sends an
346  * interrupt on hotplug. On generations which cannot switch external ports,
347  * the discrete GPU can then be woken to drive the newly connected display.
348  * The ability to switch AUX on these generations could be used to improve
349  * reliability of hotplug detection by having the integrated GPU poll the
350  * ports while the discrete GPU is asleep, but currently we do not make use
351  * of this feature.
352  *
353  * Our switching policy for the external port is that on those generations
354  * which are able to switch it fully, the port is switched together with the
355  * panel when IGD / DIS commands are issued to vga_switcheroo. It is thus
356  * possible to drive e.g. a beamer on battery power with the integrated GPU.
357  * The user may manually switch to the discrete GPU if more performance is
358  * needed.
359  *
360  * On all newer generations, the external port can only be driven by the
361  * discrete GPU. If a display is plugged in while the panel is switched to
362  * the integrated GPU, *both* GPUs will be in use for maximum performance.
363  * To decrease power consumption, the user may manually switch to the
364  * discrete GPU, thereby suspending the integrated GPU.
365  *
366  * gmux' initial switch state on bootup is user configurable via the EFI
367  * variable ``gpu-power-prefs-fa4ce28d-b62f-4c99-9cc3-6815686e30f9`` (5th byte,
368  * 1 = IGD, 0 = DIS). Based on this setting, the EFI firmware tells gmux to
369  * switch the panel and the external DP connector and allocates a framebuffer
370  * for the selected GPU.
371  *
372  * .. _US 8,687,007 B2: https://pimg-fpiw.uspto.gov/fdd/07/870/086/0.pdf
373  * .. _NXP CBTL06141:   https://www.nxp.com/documents/data_sheet/CBTL06141.pdf
374  * .. _NXP CBTL06142:   https://www.nxp.com/documents/data_sheet/CBTL06141.pdf
375  * .. _TI HD3SS212:     https://www.ti.com/lit/ds/symlink/hd3ss212.pdf
376  * .. _Pericom PI3VDP12412: https://www.pericom.com/assets/Datasheets/PI3VDP12412.pdf
377  * .. _TI SN74LV4066A:  https://www.ti.com/lit/ds/symlink/sn74lv4066a.pdf
378  * .. _NXP CBTL03062:   http://pdf.datasheetarchive.com/indexerfiles/Datasheets-SW16/DSASW00308511.pdf
379  * .. _TI TS3DS10224:   https://www.ti.com/lit/ds/symlink/ts3ds10224.pdf
380  */
381 
382 static void gmux_read_switch_state(struct apple_gmux_data *gmux_data)
383 {
384 	if (gmux_read8(gmux_data, GMUX_PORT_SWITCH_DDC) == 1)
385 		gmux_data->switch_state_ddc = VGA_SWITCHEROO_IGD;
386 	else
387 		gmux_data->switch_state_ddc = VGA_SWITCHEROO_DIS;
388 
389 	if (gmux_read8(gmux_data, GMUX_PORT_SWITCH_DISPLAY) == 2)
390 		gmux_data->switch_state_display = VGA_SWITCHEROO_IGD;
391 	else
392 		gmux_data->switch_state_display = VGA_SWITCHEROO_DIS;
393 
394 	if (gmux_read8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL) == 2)
395 		gmux_data->switch_state_external = VGA_SWITCHEROO_IGD;
396 	else
397 		gmux_data->switch_state_external = VGA_SWITCHEROO_DIS;
398 }
399 
400 static void gmux_write_switch_state(struct apple_gmux_data *gmux_data)
401 {
402 	if (gmux_data->switch_state_ddc == VGA_SWITCHEROO_IGD)
403 		gmux_write8(gmux_data, GMUX_PORT_SWITCH_DDC, 1);
404 	else
405 		gmux_write8(gmux_data, GMUX_PORT_SWITCH_DDC, 2);
406 
407 	if (gmux_data->switch_state_display == VGA_SWITCHEROO_IGD)
408 		gmux_write8(gmux_data, GMUX_PORT_SWITCH_DISPLAY, 2);
409 	else
410 		gmux_write8(gmux_data, GMUX_PORT_SWITCH_DISPLAY, 3);
411 
412 	if (gmux_data->switch_state_external == VGA_SWITCHEROO_IGD)
413 		gmux_write8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 2);
414 	else
415 		gmux_write8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 3);
416 }
417 
418 static int gmux_switchto(enum vga_switcheroo_client_id id)
419 {
420 	apple_gmux_data->switch_state_ddc = id;
421 	apple_gmux_data->switch_state_display = id;
422 	if (apple_gmux_data->external_switchable)
423 		apple_gmux_data->switch_state_external = id;
424 
425 	gmux_write_switch_state(apple_gmux_data);
426 
427 	return 0;
428 }
429 
430 static int gmux_switch_ddc(enum vga_switcheroo_client_id id)
431 {
432 	enum vga_switcheroo_client_id old_ddc_owner =
433 		apple_gmux_data->switch_state_ddc;
434 
435 	if (id == old_ddc_owner)
436 		return id;
437 
438 	pr_debug("Switching DDC from %d to %d\n", old_ddc_owner, id);
439 	apple_gmux_data->switch_state_ddc = id;
440 
441 	if (id == VGA_SWITCHEROO_IGD)
442 		gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DDC, 1);
443 	else
444 		gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DDC, 2);
445 
446 	return old_ddc_owner;
447 }
448 
449 /**
450  * DOC: Power control
451  *
452  * gmux is able to cut power to the discrete GPU. It automatically takes care
453  * of the correct sequence to tear down and bring up the power rails for
454  * core voltage, VRAM and PCIe.
455  */
456 
457 static int gmux_set_discrete_state(struct apple_gmux_data *gmux_data,
458 				   enum vga_switcheroo_state state)
459 {
460 	reinit_completion(&gmux_data->powerchange_done);
461 
462 	if (state == VGA_SWITCHEROO_ON) {
463 		gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1);
464 		gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 3);
465 		pr_debug("Discrete card powered up\n");
466 	} else {
467 		gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1);
468 		gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 0);
469 		pr_debug("Discrete card powered down\n");
470 	}
471 
472 	gmux_data->power_state = state;
473 
474 	if (gmux_data->gpe >= 0 &&
475 	    !wait_for_completion_interruptible_timeout(&gmux_data->powerchange_done,
476 						       msecs_to_jiffies(200)))
477 		pr_warn("Timeout waiting for gmux switch to complete\n");
478 
479 	return 0;
480 }
481 
482 static int gmux_set_power_state(enum vga_switcheroo_client_id id,
483 				enum vga_switcheroo_state state)
484 {
485 	if (id == VGA_SWITCHEROO_IGD)
486 		return 0;
487 
488 	return gmux_set_discrete_state(apple_gmux_data, state);
489 }
490 
491 static enum vga_switcheroo_client_id gmux_get_client_id(struct pci_dev *pdev)
492 {
493 	/*
494 	 * Early Macbook Pros with switchable graphics use nvidia
495 	 * integrated graphics. Hardcode that the 9400M is integrated.
496 	 */
497 	if (pdev->vendor == PCI_VENDOR_ID_INTEL)
498 		return VGA_SWITCHEROO_IGD;
499 	else if (pdev->vendor == PCI_VENDOR_ID_NVIDIA &&
500 		 pdev->device == 0x0863)
501 		return VGA_SWITCHEROO_IGD;
502 	else
503 		return VGA_SWITCHEROO_DIS;
504 }
505 
506 static const struct vga_switcheroo_handler gmux_handler_indexed = {
507 	.switchto = gmux_switchto,
508 	.power_state = gmux_set_power_state,
509 	.get_client_id = gmux_get_client_id,
510 };
511 
512 static const struct vga_switcheroo_handler gmux_handler_classic = {
513 	.switchto = gmux_switchto,
514 	.switch_ddc = gmux_switch_ddc,
515 	.power_state = gmux_set_power_state,
516 	.get_client_id = gmux_get_client_id,
517 };
518 
519 /**
520  * DOC: Interrupt
521  *
522  * gmux is also connected to a GPIO pin of the southbridge and thereby is able
523  * to trigger an ACPI GPE. On the MBP5 2008/09 it's GPIO pin 22 of the Nvidia
524  * MCP79, on all following generations it's GPIO pin 6 of the Intel PCH.
525  * The GPE merely signals that an interrupt occurred, the actual type of event
526  * is identified by reading a gmux register.
527  */
528 
529 static inline void gmux_disable_interrupts(struct apple_gmux_data *gmux_data)
530 {
531 	gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_ENABLE,
532 		    GMUX_INTERRUPT_DISABLE);
533 }
534 
535 static inline void gmux_enable_interrupts(struct apple_gmux_data *gmux_data)
536 {
537 	gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_ENABLE,
538 		    GMUX_INTERRUPT_ENABLE);
539 }
540 
541 static inline u8 gmux_interrupt_get_status(struct apple_gmux_data *gmux_data)
542 {
543 	return gmux_read8(gmux_data, GMUX_PORT_INTERRUPT_STATUS);
544 }
545 
546 static void gmux_clear_interrupts(struct apple_gmux_data *gmux_data)
547 {
548 	u8 status;
549 
550 	/* to clear interrupts write back current status */
551 	status = gmux_interrupt_get_status(gmux_data);
552 	gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_STATUS, status);
553 }
554 
555 static void gmux_notify_handler(acpi_handle device, u32 value, void *context)
556 {
557 	u8 status;
558 	struct pnp_dev *pnp = (struct pnp_dev *)context;
559 	struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
560 
561 	status = gmux_interrupt_get_status(gmux_data);
562 	gmux_disable_interrupts(gmux_data);
563 	pr_debug("Notify handler called: status %d\n", status);
564 
565 	gmux_clear_interrupts(gmux_data);
566 	gmux_enable_interrupts(gmux_data);
567 
568 	if (status & GMUX_INTERRUPT_STATUS_POWER)
569 		complete(&gmux_data->powerchange_done);
570 }
571 
572 static int gmux_suspend(struct device *dev)
573 {
574 	struct pnp_dev *pnp = to_pnp_dev(dev);
575 	struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
576 
577 	gmux_disable_interrupts(gmux_data);
578 	return 0;
579 }
580 
581 static int gmux_resume(struct device *dev)
582 {
583 	struct pnp_dev *pnp = to_pnp_dev(dev);
584 	struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
585 
586 	gmux_enable_interrupts(gmux_data);
587 	gmux_write_switch_state(gmux_data);
588 	if (gmux_data->power_state == VGA_SWITCHEROO_OFF)
589 		gmux_set_discrete_state(gmux_data, gmux_data->power_state);
590 	return 0;
591 }
592 
593 static int is_thunderbolt(struct device *dev, void *data)
594 {
595 	return to_pci_dev(dev)->is_thunderbolt;
596 }
597 
598 static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
599 {
600 	struct apple_gmux_data *gmux_data;
601 	struct resource *res;
602 	struct backlight_properties props;
603 	struct backlight_device *bdev;
604 	u8 ver_major, ver_minor, ver_release;
605 	int ret = -ENXIO;
606 	acpi_status status;
607 	unsigned long long gpe;
608 
609 	if (apple_gmux_data)
610 		return -EBUSY;
611 
612 	gmux_data = kzalloc(sizeof(*gmux_data), GFP_KERNEL);
613 	if (!gmux_data)
614 		return -ENOMEM;
615 	pnp_set_drvdata(pnp, gmux_data);
616 
617 	res = pnp_get_resource(pnp, IORESOURCE_IO, 0);
618 	if (!res) {
619 		pr_err("Failed to find gmux I/O resource\n");
620 		goto err_free;
621 	}
622 
623 	gmux_data->iostart = res->start;
624 	gmux_data->iolen = resource_size(res);
625 
626 	if (gmux_data->iolen < GMUX_MIN_IO_LEN) {
627 		pr_err("gmux I/O region too small (%lu < %u)\n",
628 		       gmux_data->iolen, GMUX_MIN_IO_LEN);
629 		goto err_free;
630 	}
631 
632 	if (!request_region(gmux_data->iostart, gmux_data->iolen,
633 			    "Apple gmux")) {
634 		pr_err("gmux I/O already in use\n");
635 		goto err_free;
636 	}
637 
638 	/*
639 	 * Invalid version information may indicate either that the gmux
640 	 * device isn't present or that it's a new one that uses indexed
641 	 * io
642 	 */
643 
644 	ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
645 	ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
646 	ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
647 	if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
648 		if (gmux_is_indexed(gmux_data)) {
649 			u32 version;
650 			mutex_init(&gmux_data->index_lock);
651 			gmux_data->indexed = true;
652 			version = gmux_read32(gmux_data,
653 				GMUX_PORT_VERSION_MAJOR);
654 			ver_major = (version >> 24) & 0xff;
655 			ver_minor = (version >> 16) & 0xff;
656 			ver_release = (version >> 8) & 0xff;
657 		} else {
658 			pr_info("gmux device not present\n");
659 			ret = -ENODEV;
660 			goto err_release;
661 		}
662 	}
663 	pr_info("Found gmux version %d.%d.%d [%s]\n", ver_major, ver_minor,
664 		ver_release, (gmux_data->indexed ? "indexed" : "classic"));
665 
666 	memset(&props, 0, sizeof(props));
667 	props.type = BACKLIGHT_PLATFORM;
668 	props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS);
669 
670 	/*
671 	 * Currently it's assumed that the maximum brightness is less than
672 	 * 2^24 for compatibility with old gmux versions. Cap the max
673 	 * brightness at this value, but print a warning if the hardware
674 	 * reports something higher so that it can be fixed.
675 	 */
676 	if (WARN_ON(props.max_brightness > GMUX_MAX_BRIGHTNESS))
677 		props.max_brightness = GMUX_MAX_BRIGHTNESS;
678 
679 	bdev = backlight_device_register("gmux_backlight", &pnp->dev,
680 					 gmux_data, &gmux_bl_ops, &props);
681 	if (IS_ERR(bdev)) {
682 		ret = PTR_ERR(bdev);
683 		goto err_release;
684 	}
685 
686 	gmux_data->bdev = bdev;
687 	bdev->props.brightness = gmux_get_brightness(bdev);
688 	backlight_update_status(bdev);
689 
690 	/*
691 	 * The backlight situation on Macs is complicated. If the gmux is
692 	 * present it's the best choice, because it always works for
693 	 * backlight control and supports more levels than other options.
694 	 * Disable the other backlight choices.
695 	 */
696 	apple_bl_unregister();
697 
698 	gmux_data->power_state = VGA_SWITCHEROO_ON;
699 
700 	gmux_data->dhandle = ACPI_HANDLE(&pnp->dev);
701 	if (!gmux_data->dhandle) {
702 		pr_err("Cannot find acpi handle for pnp device %s\n",
703 		       dev_name(&pnp->dev));
704 		ret = -ENODEV;
705 		goto err_notify;
706 	}
707 
708 	status = acpi_evaluate_integer(gmux_data->dhandle, "GMGP", NULL, &gpe);
709 	if (ACPI_SUCCESS(status)) {
710 		gmux_data->gpe = (int)gpe;
711 
712 		status = acpi_install_notify_handler(gmux_data->dhandle,
713 						     ACPI_DEVICE_NOTIFY,
714 						     &gmux_notify_handler, pnp);
715 		if (ACPI_FAILURE(status)) {
716 			pr_err("Install notify handler failed: %s\n",
717 			       acpi_format_exception(status));
718 			ret = -ENODEV;
719 			goto err_notify;
720 		}
721 
722 		status = acpi_enable_gpe(NULL, gmux_data->gpe);
723 		if (ACPI_FAILURE(status)) {
724 			pr_err("Cannot enable gpe: %s\n",
725 			       acpi_format_exception(status));
726 			goto err_enable_gpe;
727 		}
728 	} else {
729 		pr_warn("No GPE found for gmux\n");
730 		gmux_data->gpe = -1;
731 	}
732 
733 	/*
734 	 * If Thunderbolt is present, the external DP port is not fully
735 	 * switchable. Force its AUX channel to the discrete GPU.
736 	 */
737 	gmux_data->external_switchable =
738 		!bus_for_each_dev(&pci_bus_type, NULL, NULL, is_thunderbolt);
739 	if (!gmux_data->external_switchable)
740 		gmux_write8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 3);
741 
742 	apple_gmux_data = gmux_data;
743 	init_completion(&gmux_data->powerchange_done);
744 	gmux_enable_interrupts(gmux_data);
745 	gmux_read_switch_state(gmux_data);
746 
747 	/*
748 	 * Retina MacBook Pros cannot switch the panel's AUX separately
749 	 * and need eDP pre-calibration. They are distinguishable from
750 	 * pre-retinas by having an "indexed" gmux.
751 	 *
752 	 * Pre-retina MacBook Pros can switch the panel's DDC separately.
753 	 */
754 	if (gmux_data->indexed)
755 		ret = vga_switcheroo_register_handler(&gmux_handler_indexed,
756 					      VGA_SWITCHEROO_NEEDS_EDP_CONFIG);
757 	else
758 		ret = vga_switcheroo_register_handler(&gmux_handler_classic,
759 					      VGA_SWITCHEROO_CAN_SWITCH_DDC);
760 	if (ret) {
761 		pr_err("Failed to register vga_switcheroo handler\n");
762 		goto err_register_handler;
763 	}
764 
765 	return 0;
766 
767 err_register_handler:
768 	gmux_disable_interrupts(gmux_data);
769 	apple_gmux_data = NULL;
770 	if (gmux_data->gpe >= 0)
771 		acpi_disable_gpe(NULL, gmux_data->gpe);
772 err_enable_gpe:
773 	if (gmux_data->gpe >= 0)
774 		acpi_remove_notify_handler(gmux_data->dhandle,
775 					   ACPI_DEVICE_NOTIFY,
776 					   &gmux_notify_handler);
777 err_notify:
778 	backlight_device_unregister(bdev);
779 err_release:
780 	release_region(gmux_data->iostart, gmux_data->iolen);
781 err_free:
782 	kfree(gmux_data);
783 	return ret;
784 }
785 
786 static void gmux_remove(struct pnp_dev *pnp)
787 {
788 	struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
789 
790 	vga_switcheroo_unregister_handler();
791 	gmux_disable_interrupts(gmux_data);
792 	if (gmux_data->gpe >= 0) {
793 		acpi_disable_gpe(NULL, gmux_data->gpe);
794 		acpi_remove_notify_handler(gmux_data->dhandle,
795 					   ACPI_DEVICE_NOTIFY,
796 					   &gmux_notify_handler);
797 	}
798 
799 	backlight_device_unregister(gmux_data->bdev);
800 
801 	release_region(gmux_data->iostart, gmux_data->iolen);
802 	apple_gmux_data = NULL;
803 	kfree(gmux_data);
804 
805 	apple_bl_register();
806 }
807 
808 static const struct pnp_device_id gmux_device_ids[] = {
809 	{GMUX_ACPI_HID, 0},
810 	{"", 0}
811 };
812 
813 static const struct dev_pm_ops gmux_dev_pm_ops = {
814 	.suspend = gmux_suspend,
815 	.resume = gmux_resume,
816 };
817 
818 static struct pnp_driver gmux_pnp_driver = {
819 	.name		= "apple-gmux",
820 	.probe		= gmux_probe,
821 	.remove		= gmux_remove,
822 	.id_table	= gmux_device_ids,
823 	.driver		= {
824 			.pm = &gmux_dev_pm_ops,
825 	},
826 };
827 
828 module_pnp_driver(gmux_pnp_driver);
829 MODULE_AUTHOR("Seth Forshee <seth.forshee@canonical.com>");
830 MODULE_DESCRIPTION("Apple Gmux Driver");
831 MODULE_LICENSE("GPL");
832 MODULE_DEVICE_TABLE(pnp, gmux_device_ids);
833