1// SPDX-License-Identifier: GPL-2.0
2/*
3 * PCIe Native PME support
4 *
5 * Copyright (C) 2007 - 2009 Intel Corp
6 * Copyright (C) 2007 - 2009 Shaohua Li <shaohua.li@intel.com>
7 * Copyright (C) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
8 */
9
10#define dev_fmt(fmt) "PME: " fmt
11
12#include <linux/bitfield.h>
13#include <linux/pci.h>
14#include <linux/kernel.h>
15#include <linux/errno.h>
16#include <linux/slab.h>
17#include <linux/init.h>
18#include <linux/interrupt.h>
19#include <linux/device.h>
20#include <linux/pm_runtime.h>
21
22#include "../pci.h"
23#include "portdrv.h"
24
25/*
26 * If this switch is set, MSI will not be used for PCIe PME signaling.  This
27 * causes the PCIe port driver to use INTx interrupts only, but it turns out
28 * that using MSI for PCIe PME signaling doesn't play well with PCIe PME-based
29 * wake-up from system sleep states.
30 */
31bool pcie_pme_msi_disabled;
32
33static int __init pcie_pme_setup(char *str)
34{
35	if (!strncmp(str, "nomsi", 5))
36		pcie_pme_msi_disabled = true;
37
38	return 1;
39}
40__setup("pcie_pme=", pcie_pme_setup);
41
42struct pcie_pme_service_data {
43	spinlock_t lock;
44	struct pcie_device *srv;
45	struct work_struct work;
46	bool noirq; /* If set, keep the PME interrupt disabled. */
47};
48
49/**
50 * pcie_pme_interrupt_enable - Enable/disable PCIe PME interrupt generation.
51 * @dev: PCIe root port or event collector.
52 * @enable: Enable or disable the interrupt.
53 */
54void pcie_pme_interrupt_enable(struct pci_dev *dev, bool enable)
55{
56	if (enable)
57		pcie_capability_set_word(dev, PCI_EXP_RTCTL,
58					 PCI_EXP_RTCTL_PMEIE);
59	else
60		pcie_capability_clear_word(dev, PCI_EXP_RTCTL,
61					   PCI_EXP_RTCTL_PMEIE);
62}
63
64/**
65 * pcie_pme_walk_bus - Scan a PCI bus for devices asserting PME#.
66 * @bus: PCI bus to scan.
67 *
68 * Scan given PCI bus and all buses under it for devices asserting PME#.
69 */
70static bool pcie_pme_walk_bus(struct pci_bus *bus)
71{
72	struct pci_dev *dev;
73	bool ret = false;
74
75	list_for_each_entry(dev, &bus->devices, bus_list) {
76		/* Skip PCIe devices in case we started from a root port. */
77		if (!pci_is_pcie(dev) && pci_check_pme_status(dev)) {
78			if (dev->pme_poll)
79				dev->pme_poll = false;
80
81			pci_wakeup_event(dev);
82			pm_request_resume(&dev->dev);
83			ret = true;
84		}
85
86		if (dev->subordinate && pcie_pme_walk_bus(dev->subordinate))
87			ret = true;
88	}
89
90	return ret;
91}
92
93/**
94 * pcie_pme_from_pci_bridge - Check if PCIe-PCI bridge generated a PME.
95 * @bus: Secondary bus of the bridge.
96 * @devfn: Device/function number to check.
97 *
98 * PME from PCI devices under a PCIe-PCI bridge may be converted to an in-band
99 * PCIe PME message.  In such that case the bridge should use the Requester ID
100 * of device/function number 0 on its secondary bus.
101 */
102static bool pcie_pme_from_pci_bridge(struct pci_bus *bus, u8 devfn)
103{
104	struct pci_dev *dev;
105	bool found = false;
106
107	if (devfn)
108		return false;
109
110	dev = pci_dev_get(bus->self);
111	if (!dev)
112		return false;
113
114	if (pci_is_pcie(dev) && pci_pcie_type(dev) == PCI_EXP_TYPE_PCI_BRIDGE) {
115		down_read(&pci_bus_sem);
116		if (pcie_pme_walk_bus(bus))
117			found = true;
118		up_read(&pci_bus_sem);
119	}
120
121	pci_dev_put(dev);
122	return found;
123}
124
125/**
126 * pcie_pme_handle_request - Find device that generated PME and handle it.
127 * @port: Root port or event collector that generated the PME interrupt.
128 * @req_id: PCIe Requester ID of the device that generated the PME.
129 */
130static void pcie_pme_handle_request(struct pci_dev *port, u16 req_id)
131{
132	u8 busnr = req_id >> 8, devfn = req_id & 0xff;
133	struct pci_bus *bus;
134	struct pci_dev *dev;
135	bool found = false;
136
137	/* First, check if the PME is from the root port itself. */
138	if (port->devfn == devfn && port->bus->number == busnr) {
139		if (port->pme_poll)
140			port->pme_poll = false;
141
142		if (pci_check_pme_status(port)) {
143			pm_request_resume(&port->dev);
144			found = true;
145		} else {
146			/*
147			 * Apparently, the root port generated the PME on behalf
148			 * of a non-PCIe device downstream.  If this is done by
149			 * a root port, the Requester ID field in its status
150			 * register may contain either the root port's, or the
151			 * source device's information (PCI Express Base
152			 * Specification, Rev. 2.0, Section 6.1.9).
153			 */
154			down_read(&pci_bus_sem);
155			found = pcie_pme_walk_bus(port->subordinate);
156			up_read(&pci_bus_sem);
157		}
158		goto out;
159	}
160
161	/* Second, find the bus the source device is on. */
162	bus = pci_find_bus(pci_domain_nr(port->bus), busnr);
163	if (!bus)
164		goto out;
165
166	/* Next, check if the PME is from a PCIe-PCI bridge. */
167	found = pcie_pme_from_pci_bridge(bus, devfn);
168	if (found)
169		goto out;
170
171	/* Finally, try to find the PME source on the bus. */
172	down_read(&pci_bus_sem);
173	list_for_each_entry(dev, &bus->devices, bus_list) {
174		pci_dev_get(dev);
175		if (dev->devfn == devfn) {
176			found = true;
177			break;
178		}
179		pci_dev_put(dev);
180	}
181	up_read(&pci_bus_sem);
182
183	if (found) {
184		/* The device is there, but we have to check its PME status. */
185		found = pci_check_pme_status(dev);
186		if (found) {
187			if (dev->pme_poll)
188				dev->pme_poll = false;
189
190			pci_wakeup_event(dev);
191			pm_request_resume(&dev->dev);
192		}
193		pci_dev_put(dev);
194	} else if (devfn) {
195		/*
196		 * The device is not there, but we can still try to recover by
197		 * assuming that the PME was reported by a PCIe-PCI bridge that
198		 * used devfn different from zero.
199		 */
200		pci_info(port, "interrupt generated for non-existent device %02x:%02x.%d\n",
201			 busnr, PCI_SLOT(devfn), PCI_FUNC(devfn));
202		found = pcie_pme_from_pci_bridge(bus, 0);
203	}
204
205 out:
206	if (!found)
207		pci_info(port, "Spurious native interrupt!\n");
208}
209
210/**
211 * pcie_pme_work_fn - Work handler for PCIe PME interrupt.
212 * @work: Work structure giving access to service data.
213 */
214static void pcie_pme_work_fn(struct work_struct *work)
215{
216	struct pcie_pme_service_data *data =
217			container_of(work, struct pcie_pme_service_data, work);
218	struct pci_dev *port = data->srv->port;
219	u32 rtsta;
220
221	spin_lock_irq(&data->lock);
222
223	for (;;) {
224		if (data->noirq)
225			break;
226
227		pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta);
228		if (PCI_POSSIBLE_ERROR(rtsta))
229			break;
230
231		if (rtsta & PCI_EXP_RTSTA_PME) {
232			/*
233			 * Clear PME status of the port.  If there are other
234			 * pending PMEs, the status will be set again.
235			 */
236			pcie_clear_root_pme_status(port);
237
238			spin_unlock_irq(&data->lock);
239			pcie_pme_handle_request(port,
240				    FIELD_GET(PCI_EXP_RTSTA_PME_RQ_ID, rtsta));
241			spin_lock_irq(&data->lock);
242
243			continue;
244		}
245
246		/* No need to loop if there are no more PMEs pending. */
247		if (!(rtsta & PCI_EXP_RTSTA_PENDING))
248			break;
249
250		spin_unlock_irq(&data->lock);
251		cpu_relax();
252		spin_lock_irq(&data->lock);
253	}
254
255	if (!data->noirq)
256		pcie_pme_interrupt_enable(port, true);
257
258	spin_unlock_irq(&data->lock);
259}
260
261/**
262 * pcie_pme_irq - Interrupt handler for PCIe root port PME interrupt.
263 * @irq: Interrupt vector.
264 * @context: Interrupt context pointer.
265 */
266static irqreturn_t pcie_pme_irq(int irq, void *context)
267{
268	struct pci_dev *port;
269	struct pcie_pme_service_data *data;
270	u32 rtsta;
271	unsigned long flags;
272
273	port = ((struct pcie_device *)context)->port;
274	data = get_service_data((struct pcie_device *)context);
275
276	spin_lock_irqsave(&data->lock, flags);
277	pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta);
278
279	if (PCI_POSSIBLE_ERROR(rtsta) || !(rtsta & PCI_EXP_RTSTA_PME)) {
280		spin_unlock_irqrestore(&data->lock, flags);
281		return IRQ_NONE;
282	}
283
284	pcie_pme_interrupt_enable(port, false);
285	spin_unlock_irqrestore(&data->lock, flags);
286
287	/* We don't use pm_wq, because it's freezable. */
288	schedule_work(&data->work);
289
290	return IRQ_HANDLED;
291}
292
293/**
294 * pcie_pme_can_wakeup - Set the wakeup capability flag.
295 * @dev: PCI device to handle.
296 * @ign: Ignored.
297 */
298static int pcie_pme_can_wakeup(struct pci_dev *dev, void *ign)
299{
300	device_set_wakeup_capable(&dev->dev, true);
301	return 0;
302}
303
304/**
305 * pcie_pme_mark_devices - Set the wakeup flag for devices below a port.
306 * @port: PCIe root port or event collector to handle.
307 *
308 * For each device below given root port, including the port itself (or for each
309 * root complex integrated endpoint if @port is a root complex event collector)
310 * set the flag indicating that it can signal run-time wake-up events.
311 */
312static void pcie_pme_mark_devices(struct pci_dev *port)
313{
314	pcie_pme_can_wakeup(port, NULL);
315
316	if (pci_pcie_type(port) == PCI_EXP_TYPE_RC_EC)
317		pcie_walk_rcec(port, pcie_pme_can_wakeup, NULL);
318	else if (port->subordinate)
319		pci_walk_bus(port->subordinate, pcie_pme_can_wakeup, NULL);
320}
321
322/**
323 * pcie_pme_probe - Initialize PCIe PME service for given root port.
324 * @srv: PCIe service to initialize.
325 */
326static int pcie_pme_probe(struct pcie_device *srv)
327{
328	struct pci_dev *port = srv->port;
329	struct pcie_pme_service_data *data;
330	int type = pci_pcie_type(port);
331	int ret;
332
333	/* Limit to Root Ports or Root Complex Event Collectors */
334	if (type != PCI_EXP_TYPE_RC_EC &&
335	    type != PCI_EXP_TYPE_ROOT_PORT)
336		return -ENODEV;
337
338	data = kzalloc(sizeof(*data), GFP_KERNEL);
339	if (!data)
340		return -ENOMEM;
341
342	spin_lock_init(&data->lock);
343	INIT_WORK(&data->work, pcie_pme_work_fn);
344	data->srv = srv;
345	set_service_data(srv, data);
346
347	pcie_pme_interrupt_enable(port, false);
348	pcie_clear_root_pme_status(port);
349
350	ret = request_irq(srv->irq, pcie_pme_irq, IRQF_SHARED, "PCIe PME", srv);
351	if (ret) {
352		kfree(data);
353		return ret;
354	}
355
356	pci_info(port, "Signaling with IRQ %d\n", srv->irq);
357
358	pcie_pme_mark_devices(port);
359	pcie_pme_interrupt_enable(port, true);
360	return 0;
361}
362
363static bool pcie_pme_check_wakeup(struct pci_bus *bus)
364{
365	struct pci_dev *dev;
366
367	if (!bus)
368		return false;
369
370	list_for_each_entry(dev, &bus->devices, bus_list)
371		if (device_may_wakeup(&dev->dev)
372		    || pcie_pme_check_wakeup(dev->subordinate))
373			return true;
374
375	return false;
376}
377
378static void pcie_pme_disable_interrupt(struct pci_dev *port,
379				       struct pcie_pme_service_data *data)
380{
381	spin_lock_irq(&data->lock);
382	pcie_pme_interrupt_enable(port, false);
383	pcie_clear_root_pme_status(port);
384	data->noirq = true;
385	spin_unlock_irq(&data->lock);
386}
387
388/**
389 * pcie_pme_suspend - Suspend PCIe PME service device.
390 * @srv: PCIe service device to suspend.
391 */
392static int pcie_pme_suspend(struct pcie_device *srv)
393{
394	struct pcie_pme_service_data *data = get_service_data(srv);
395	struct pci_dev *port = srv->port;
396	bool wakeup;
397	int ret;
398
399	if (device_may_wakeup(&port->dev)) {
400		wakeup = true;
401	} else {
402		down_read(&pci_bus_sem);
403		wakeup = pcie_pme_check_wakeup(port->subordinate);
404		up_read(&pci_bus_sem);
405	}
406	if (wakeup) {
407		ret = enable_irq_wake(srv->irq);
408		if (!ret)
409			return 0;
410	}
411
412	pcie_pme_disable_interrupt(port, data);
413
414	synchronize_irq(srv->irq);
415
416	return 0;
417}
418
419/**
420 * pcie_pme_resume - Resume PCIe PME service device.
421 * @srv: PCIe service device to resume.
422 */
423static int pcie_pme_resume(struct pcie_device *srv)
424{
425	struct pcie_pme_service_data *data = get_service_data(srv);
426
427	spin_lock_irq(&data->lock);
428	if (data->noirq) {
429		struct pci_dev *port = srv->port;
430
431		pcie_clear_root_pme_status(port);
432		pcie_pme_interrupt_enable(port, true);
433		data->noirq = false;
434	} else {
435		disable_irq_wake(srv->irq);
436	}
437	spin_unlock_irq(&data->lock);
438
439	return 0;
440}
441
442/**
443 * pcie_pme_remove - Prepare PCIe PME service device for removal.
444 * @srv: PCIe service device to remove.
445 */
446static void pcie_pme_remove(struct pcie_device *srv)
447{
448	struct pcie_pme_service_data *data = get_service_data(srv);
449
450	pcie_pme_disable_interrupt(srv->port, data);
451	free_irq(srv->irq, srv);
452	cancel_work_sync(&data->work);
453	kfree(data);
454}
455
456static struct pcie_port_service_driver pcie_pme_driver = {
457	.name		= "pcie_pme",
458	.port_type	= PCIE_ANY_PORT,
459	.service	= PCIE_PORT_SERVICE_PME,
460
461	.probe		= pcie_pme_probe,
462	.suspend	= pcie_pme_suspend,
463	.resume		= pcie_pme_resume,
464	.remove		= pcie_pme_remove,
465};
466
467/**
468 * pcie_pme_init - Register the PCIe PME service driver.
469 */
470int __init pcie_pme_init(void)
471{
472	return pcie_port_service_register(&pcie_pme_driver);
473}
474