xref: /openbmc/linux/drivers/pci/pcie/pme.c (revision 4cff79e9)
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 #include <linux/pci.h>
11 #include <linux/kernel.h>
12 #include <linux/errno.h>
13 #include <linux/slab.h>
14 #include <linux/init.h>
15 #include <linux/interrupt.h>
16 #include <linux/device.h>
17 #include <linux/pm_runtime.h>
18 
19 #include "../pci.h"
20 #include "portdrv.h"
21 
22 /*
23  * If this switch is set, MSI will not be used for PCIe PME signaling.  This
24  * causes the PCIe port driver to use INTx interrupts only, but it turns out
25  * that using MSI for PCIe PME signaling doesn't play well with PCIe PME-based
26  * wake-up from system sleep states.
27  */
28 bool pcie_pme_msi_disabled;
29 
30 static int __init pcie_pme_setup(char *str)
31 {
32 	if (!strncmp(str, "nomsi", 5))
33 		pcie_pme_msi_disabled = true;
34 
35 	return 1;
36 }
37 __setup("pcie_pme=", pcie_pme_setup);
38 
39 struct pcie_pme_service_data {
40 	spinlock_t lock;
41 	struct pcie_device *srv;
42 	struct work_struct work;
43 	bool noirq; /* If set, keep the PME interrupt disabled. */
44 };
45 
46 /**
47  * pcie_pme_interrupt_enable - Enable/disable PCIe PME interrupt generation.
48  * @dev: PCIe root port or event collector.
49  * @enable: Enable or disable the interrupt.
50  */
51 void pcie_pme_interrupt_enable(struct pci_dev *dev, bool enable)
52 {
53 	if (enable)
54 		pcie_capability_set_word(dev, PCI_EXP_RTCTL,
55 					 PCI_EXP_RTCTL_PMEIE);
56 	else
57 		pcie_capability_clear_word(dev, PCI_EXP_RTCTL,
58 					   PCI_EXP_RTCTL_PMEIE);
59 }
60 
61 /**
62  * pcie_pme_walk_bus - Scan a PCI bus for devices asserting PME#.
63  * @bus: PCI bus to scan.
64  *
65  * Scan given PCI bus and all buses under it for devices asserting PME#.
66  */
67 static bool pcie_pme_walk_bus(struct pci_bus *bus)
68 {
69 	struct pci_dev *dev;
70 	bool ret = false;
71 
72 	list_for_each_entry(dev, &bus->devices, bus_list) {
73 		/* Skip PCIe devices in case we started from a root port. */
74 		if (!pci_is_pcie(dev) && pci_check_pme_status(dev)) {
75 			if (dev->pme_poll)
76 				dev->pme_poll = false;
77 
78 			pci_wakeup_event(dev);
79 			pm_request_resume(&dev->dev);
80 			ret = true;
81 		}
82 
83 		if (dev->subordinate && pcie_pme_walk_bus(dev->subordinate))
84 			ret = true;
85 	}
86 
87 	return ret;
88 }
89 
90 /**
91  * pcie_pme_from_pci_bridge - Check if PCIe-PCI bridge generated a PME.
92  * @bus: Secondary bus of the bridge.
93  * @devfn: Device/function number to check.
94  *
95  * PME from PCI devices under a PCIe-PCI bridge may be converted to an in-band
96  * PCIe PME message.  In such that case the bridge should use the Requester ID
97  * of device/function number 0 on its secondary bus.
98  */
99 static bool pcie_pme_from_pci_bridge(struct pci_bus *bus, u8 devfn)
100 {
101 	struct pci_dev *dev;
102 	bool found = false;
103 
104 	if (devfn)
105 		return false;
106 
107 	dev = pci_dev_get(bus->self);
108 	if (!dev)
109 		return false;
110 
111 	if (pci_is_pcie(dev) && pci_pcie_type(dev) == PCI_EXP_TYPE_PCI_BRIDGE) {
112 		down_read(&pci_bus_sem);
113 		if (pcie_pme_walk_bus(bus))
114 			found = true;
115 		up_read(&pci_bus_sem);
116 	}
117 
118 	pci_dev_put(dev);
119 	return found;
120 }
121 
122 /**
123  * pcie_pme_handle_request - Find device that generated PME and handle it.
124  * @port: Root port or event collector that generated the PME interrupt.
125  * @req_id: PCIe Requester ID of the device that generated the PME.
126  */
127 static void pcie_pme_handle_request(struct pci_dev *port, u16 req_id)
128 {
129 	u8 busnr = req_id >> 8, devfn = req_id & 0xff;
130 	struct pci_bus *bus;
131 	struct pci_dev *dev;
132 	bool found = false;
133 
134 	/* First, check if the PME is from the root port itself. */
135 	if (port->devfn == devfn && port->bus->number == busnr) {
136 		if (port->pme_poll)
137 			port->pme_poll = false;
138 
139 		if (pci_check_pme_status(port)) {
140 			pm_request_resume(&port->dev);
141 			found = true;
142 		} else {
143 			/*
144 			 * Apparently, the root port generated the PME on behalf
145 			 * of a non-PCIe device downstream.  If this is done by
146 			 * a root port, the Requester ID field in its status
147 			 * register may contain either the root port's, or the
148 			 * source device's information (PCI Express Base
149 			 * Specification, Rev. 2.0, Section 6.1.9).
150 			 */
151 			down_read(&pci_bus_sem);
152 			found = pcie_pme_walk_bus(port->subordinate);
153 			up_read(&pci_bus_sem);
154 		}
155 		goto out;
156 	}
157 
158 	/* Second, find the bus the source device is on. */
159 	bus = pci_find_bus(pci_domain_nr(port->bus), busnr);
160 	if (!bus)
161 		goto out;
162 
163 	/* Next, check if the PME is from a PCIe-PCI bridge. */
164 	found = pcie_pme_from_pci_bridge(bus, devfn);
165 	if (found)
166 		goto out;
167 
168 	/* Finally, try to find the PME source on the bus. */
169 	down_read(&pci_bus_sem);
170 	list_for_each_entry(dev, &bus->devices, bus_list) {
171 		pci_dev_get(dev);
172 		if (dev->devfn == devfn) {
173 			found = true;
174 			break;
175 		}
176 		pci_dev_put(dev);
177 	}
178 	up_read(&pci_bus_sem);
179 
180 	if (found) {
181 		/* The device is there, but we have to check its PME status. */
182 		found = pci_check_pme_status(dev);
183 		if (found) {
184 			if (dev->pme_poll)
185 				dev->pme_poll = false;
186 
187 			pci_wakeup_event(dev);
188 			pm_request_resume(&dev->dev);
189 		}
190 		pci_dev_put(dev);
191 	} else if (devfn) {
192 		/*
193 		 * The device is not there, but we can still try to recover by
194 		 * assuming that the PME was reported by a PCIe-PCI bridge that
195 		 * used devfn different from zero.
196 		 */
197 		pci_dbg(port, "PME interrupt generated for non-existent device %02x:%02x.%d\n",
198 			busnr, PCI_SLOT(devfn), PCI_FUNC(devfn));
199 		found = pcie_pme_from_pci_bridge(bus, 0);
200 	}
201 
202  out:
203 	if (!found)
204 		pci_dbg(port, "Spurious native PME interrupt!\n");
205 }
206 
207 /**
208  * pcie_pme_work_fn - Work handler for PCIe PME interrupt.
209  * @work: Work structure giving access to service data.
210  */
211 static void pcie_pme_work_fn(struct work_struct *work)
212 {
213 	struct pcie_pme_service_data *data =
214 			container_of(work, struct pcie_pme_service_data, work);
215 	struct pci_dev *port = data->srv->port;
216 	u32 rtsta;
217 
218 	spin_lock_irq(&data->lock);
219 
220 	for (;;) {
221 		if (data->noirq)
222 			break;
223 
224 		pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta);
225 		if (rtsta == (u32) ~0)
226 			break;
227 
228 		if (rtsta & PCI_EXP_RTSTA_PME) {
229 			/*
230 			 * Clear PME status of the port.  If there are other
231 			 * pending PMEs, the status will be set again.
232 			 */
233 			pcie_clear_root_pme_status(port);
234 
235 			spin_unlock_irq(&data->lock);
236 			pcie_pme_handle_request(port, rtsta & 0xffff);
237 			spin_lock_irq(&data->lock);
238 
239 			continue;
240 		}
241 
242 		/* No need to loop if there are no more PMEs pending. */
243 		if (!(rtsta & PCI_EXP_RTSTA_PENDING))
244 			break;
245 
246 		spin_unlock_irq(&data->lock);
247 		cpu_relax();
248 		spin_lock_irq(&data->lock);
249 	}
250 
251 	if (!data->noirq)
252 		pcie_pme_interrupt_enable(port, true);
253 
254 	spin_unlock_irq(&data->lock);
255 }
256 
257 /**
258  * pcie_pme_irq - Interrupt handler for PCIe root port PME interrupt.
259  * @irq: Interrupt vector.
260  * @context: Interrupt context pointer.
261  */
262 static irqreturn_t pcie_pme_irq(int irq, void *context)
263 {
264 	struct pci_dev *port;
265 	struct pcie_pme_service_data *data;
266 	u32 rtsta;
267 	unsigned long flags;
268 
269 	port = ((struct pcie_device *)context)->port;
270 	data = get_service_data((struct pcie_device *)context);
271 
272 	spin_lock_irqsave(&data->lock, flags);
273 	pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta);
274 
275 	if (rtsta == (u32) ~0 || !(rtsta & PCI_EXP_RTSTA_PME)) {
276 		spin_unlock_irqrestore(&data->lock, flags);
277 		return IRQ_NONE;
278 	}
279 
280 	pcie_pme_interrupt_enable(port, false);
281 	spin_unlock_irqrestore(&data->lock, flags);
282 
283 	/* We don't use pm_wq, because it's freezable. */
284 	schedule_work(&data->work);
285 
286 	return IRQ_HANDLED;
287 }
288 
289 /**
290  * pcie_pme_can_wakeup - Set the wakeup capability flag.
291  * @dev: PCI device to handle.
292  * @ign: Ignored.
293  */
294 static int pcie_pme_can_wakeup(struct pci_dev *dev, void *ign)
295 {
296 	device_set_wakeup_capable(&dev->dev, true);
297 	return 0;
298 }
299 
300 /**
301  * pcie_pme_mark_devices - Set the wakeup flag for devices below a port.
302  * @port: PCIe root port or event collector to handle.
303  *
304  * For each device below given root port, including the port itself (or for each
305  * root complex integrated endpoint if @port is a root complex event collector)
306  * set the flag indicating that it can signal run-time wake-up events.
307  */
308 static void pcie_pme_mark_devices(struct pci_dev *port)
309 {
310 	pcie_pme_can_wakeup(port, NULL);
311 	if (port->subordinate)
312 		pci_walk_bus(port->subordinate, pcie_pme_can_wakeup, NULL);
313 }
314 
315 /**
316  * pcie_pme_probe - Initialize PCIe PME service for given root port.
317  * @srv: PCIe service to initialize.
318  */
319 static int pcie_pme_probe(struct pcie_device *srv)
320 {
321 	struct pci_dev *port;
322 	struct pcie_pme_service_data *data;
323 	int ret;
324 
325 	data = kzalloc(sizeof(*data), GFP_KERNEL);
326 	if (!data)
327 		return -ENOMEM;
328 
329 	spin_lock_init(&data->lock);
330 	INIT_WORK(&data->work, pcie_pme_work_fn);
331 	data->srv = srv;
332 	set_service_data(srv, data);
333 
334 	port = srv->port;
335 	pcie_pme_interrupt_enable(port, false);
336 	pcie_clear_root_pme_status(port);
337 
338 	ret = request_irq(srv->irq, pcie_pme_irq, IRQF_SHARED, "PCIe PME", srv);
339 	if (ret) {
340 		kfree(data);
341 		return ret;
342 	}
343 
344 	pci_info(port, "Signaling PME with IRQ %d\n", srv->irq);
345 
346 	pcie_pme_mark_devices(port);
347 	pcie_pme_interrupt_enable(port, true);
348 	return 0;
349 }
350 
351 static bool pcie_pme_check_wakeup(struct pci_bus *bus)
352 {
353 	struct pci_dev *dev;
354 
355 	if (!bus)
356 		return false;
357 
358 	list_for_each_entry(dev, &bus->devices, bus_list)
359 		if (device_may_wakeup(&dev->dev)
360 		    || pcie_pme_check_wakeup(dev->subordinate))
361 			return true;
362 
363 	return false;
364 }
365 
366 /**
367  * pcie_pme_suspend - Suspend PCIe PME service device.
368  * @srv: PCIe service device to suspend.
369  */
370 static int pcie_pme_suspend(struct pcie_device *srv)
371 {
372 	struct pcie_pme_service_data *data = get_service_data(srv);
373 	struct pci_dev *port = srv->port;
374 	bool wakeup;
375 	int ret;
376 
377 	if (device_may_wakeup(&port->dev)) {
378 		wakeup = true;
379 	} else {
380 		down_read(&pci_bus_sem);
381 		wakeup = pcie_pme_check_wakeup(port->subordinate);
382 		up_read(&pci_bus_sem);
383 	}
384 	if (wakeup) {
385 		ret = enable_irq_wake(srv->irq);
386 		if (!ret)
387 			return 0;
388 	}
389 
390 	spin_lock_irq(&data->lock);
391 	pcie_pme_interrupt_enable(port, false);
392 	pcie_clear_root_pme_status(port);
393 	data->noirq = true;
394 	spin_unlock_irq(&data->lock);
395 
396 	synchronize_irq(srv->irq);
397 
398 	return 0;
399 }
400 
401 /**
402  * pcie_pme_resume - Resume PCIe PME service device.
403  * @srv - PCIe service device to resume.
404  */
405 static int pcie_pme_resume(struct pcie_device *srv)
406 {
407 	struct pcie_pme_service_data *data = get_service_data(srv);
408 
409 	spin_lock_irq(&data->lock);
410 	if (data->noirq) {
411 		struct pci_dev *port = srv->port;
412 
413 		pcie_clear_root_pme_status(port);
414 		pcie_pme_interrupt_enable(port, true);
415 		data->noirq = false;
416 	} else {
417 		disable_irq_wake(srv->irq);
418 	}
419 	spin_unlock_irq(&data->lock);
420 
421 	return 0;
422 }
423 
424 /**
425  * pcie_pme_remove - Prepare PCIe PME service device for removal.
426  * @srv - PCIe service device to remove.
427  */
428 static void pcie_pme_remove(struct pcie_device *srv)
429 {
430 	pcie_pme_suspend(srv);
431 	free_irq(srv->irq, srv);
432 	kfree(get_service_data(srv));
433 }
434 
435 static struct pcie_port_service_driver pcie_pme_driver = {
436 	.name		= "pcie_pme",
437 	.port_type	= PCI_EXP_TYPE_ROOT_PORT,
438 	.service	= PCIE_PORT_SERVICE_PME,
439 
440 	.probe		= pcie_pme_probe,
441 	.suspend	= pcie_pme_suspend,
442 	.resume		= pcie_pme_resume,
443 	.remove		= pcie_pme_remove,
444 };
445 
446 /**
447  * pcie_pme_service_init - Register the PCIe PME service driver.
448  */
449 static int __init pcie_pme_service_init(void)
450 {
451 	return pcie_port_service_register(&pcie_pme_driver);
452 }
453 device_initcall(pcie_pme_service_init);
454