2 * PCIe Native PME support
4 * Copyright (C) 2007 - 2009 Intel Corp
5 * Copyright (C) 2007 - 2009 Shaohua Li <shaohua.li@intel.com>
6 * Copyright (C) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
8 * This file is subject to the terms and conditions of the GNU General Public
9 * License V2. See the file "COPYING" in the main directory of this archive
13 #include <linux/module.h>
14 #include <linux/pci.h>
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/init.h>
18 #include <linux/interrupt.h>
19 #include <linux/device.h>
20 #include <linux/pcieport_if.h>
21 #include <linux/acpi.h>
22 #include <linux/pci-acpi.h>
23 #include <linux/pm_runtime.h>
25 #include "../../pci.h"
28 #define PCI_EXP_RTSTA_PME 0x10000 /* PME status */
29 #define PCI_EXP_RTSTA_PENDING 0x20000 /* PME pending */
32 * If set, this switch will prevent the PCIe root port PME service driver from
33 * being registered. Consequently, the interrupt-based PCIe PME signaling will
34 * not be used by any PCIe root ports in that case.
36 static bool pcie_pme_disabled;
39 * The PCI Express Base Specification 2.0, Section 6.1.8, states the following:
40 * "In order to maintain compatibility with non-PCI Express-aware system
41 * software, system power management logic must be configured by firmware to use
42 * the legacy mechanism of signaling PME by default. PCI Express-aware system
43 * software must notify the firmware prior to enabling native, interrupt-based
44 * PME signaling." However, if the platform doesn't provide us with a suitable
45 * notification mechanism or the notification fails, it is not clear whether or
46 * not we are supposed to use the interrupt-based PCIe PME signaling. The
47 * switch below can be used to indicate the desired behaviour. When set, it
48 * will make the kernel use the interrupt-based PCIe PME signaling regardless of
49 * the platform notification status, although the kernel will attempt to notify
50 * the platform anyway. When unset, it will prevent the kernel from using the
51 * the interrupt-based PCIe PME signaling if the platform notification fails,
52 * which is the default.
54 static bool pcie_pme_force_enable;
57 * If this switch is set, MSI will not be used for PCIe PME signaling. This
58 * causes the PCIe port driver to use INTx interrupts only, but it turns out
59 * that using MSI for PCIe PME signaling doesn't play well with PCIe PME-based
60 * wake-up from system sleep states.
62 bool pcie_pme_msi_disabled;
64 static int __init pcie_pme_setup(char *str)
66 if (!strcmp(str, "off"))
67 pcie_pme_disabled = true;
68 else if (!strcmp(str, "force"))
69 pcie_pme_force_enable = true;
70 else if (!strcmp(str, "nomsi"))
71 pcie_pme_msi_disabled = true;
74 __setup("pcie_pme=", pcie_pme_setup);
77 * pcie_pme_platform_setup - Ensure that the kernel controls the PCIe PME.
78 * @srv: PCIe PME root port service to use for carrying out the check.
80 * Notify the platform that the native PCIe PME is going to be used and return
81 * 'true' if the control of the PCIe PME registers has been acquired from the
84 static bool pcie_pme_platform_setup(struct pcie_device *srv)
86 if (!pcie_pme_platform_notify(srv))
88 return pcie_pme_force_enable;
91 struct pcie_pme_service_data {
93 struct pcie_device *srv;
94 struct work_struct work;
95 bool noirq; /* Don't enable the PME interrupt used by this service. */
99 * pcie_pme_interrupt_enable - Enable/disable PCIe PME interrupt generation.
100 * @dev: PCIe root port or event collector.
101 * @enable: Enable or disable the interrupt.
103 static void pcie_pme_interrupt_enable(struct pci_dev *dev, bool enable)
108 rtctl_pos = pci_find_capability(dev, PCI_CAP_ID_EXP) + PCI_EXP_RTCTL;
110 pci_read_config_word(dev, rtctl_pos, &rtctl);
112 rtctl |= PCI_EXP_RTCTL_PMEIE;
114 rtctl &= ~PCI_EXP_RTCTL_PMEIE;
115 pci_write_config_word(dev, rtctl_pos, rtctl);
119 * pcie_pme_clear_status - Clear root port PME interrupt status.
120 * @dev: PCIe root port or event collector.
122 static void pcie_pme_clear_status(struct pci_dev *dev)
127 rtsta_pos = pci_find_capability(dev, PCI_CAP_ID_EXP) + PCI_EXP_RTSTA;
129 pci_read_config_dword(dev, rtsta_pos, &rtsta);
130 rtsta |= PCI_EXP_RTSTA_PME;
131 pci_write_config_dword(dev, rtsta_pos, rtsta);
135 * pcie_pme_walk_bus - Scan a PCI bus for devices asserting PME#.
136 * @bus: PCI bus to scan.
138 * Scan given PCI bus and all buses under it for devices asserting PME#.
140 static bool pcie_pme_walk_bus(struct pci_bus *bus)
145 list_for_each_entry(dev, &bus->devices, bus_list) {
146 /* Skip PCIe devices in case we started from a root port. */
147 if (!dev->is_pcie && pci_check_pme_status(dev)) {
148 pm_request_resume(&dev->dev);
152 if (dev->subordinate && pcie_pme_walk_bus(dev->subordinate))
160 * pcie_pme_from_pci_bridge - Check if PCIe-PCI bridge generated a PME.
161 * @bus: Secondary bus of the bridge.
162 * @devfn: Device/function number to check.
164 * PME from PCI devices under a PCIe-PCI bridge may be converted to an in-band
165 * PCIe PME message. In such that case the bridge should use the Requester ID
166 * of device/function number 0 on its secondary bus.
168 static bool pcie_pme_from_pci_bridge(struct pci_bus *bus, u8 devfn)
176 dev = pci_dev_get(bus->self);
180 if (dev->is_pcie && dev->pcie_type == PCI_EXP_TYPE_PCI_BRIDGE) {
181 down_read(&pci_bus_sem);
182 if (pcie_pme_walk_bus(bus))
184 up_read(&pci_bus_sem);
192 * pcie_pme_handle_request - Find device that generated PME and handle it.
193 * @port: Root port or event collector that generated the PME interrupt.
194 * @req_id: PCIe Requester ID of the device that generated the PME.
196 static void pcie_pme_handle_request(struct pci_dev *port, u16 req_id)
198 u8 busnr = req_id >> 8, devfn = req_id & 0xff;
203 /* First, check if the PME is from the root port itself. */
204 if (port->devfn == devfn && port->bus->number == busnr) {
205 if (pci_check_pme_status(port)) {
206 pm_request_resume(&port->dev);
210 * Apparently, the root port generated the PME on behalf
211 * of a non-PCIe device downstream. If this is done by
212 * a root port, the Requester ID field in its status
213 * register may contain either the root port's, or the
214 * source device's information (PCI Express Base
215 * Specification, Rev. 2.0, Section 6.1.9).
217 down_read(&pci_bus_sem);
218 found = pcie_pme_walk_bus(port->subordinate);
219 up_read(&pci_bus_sem);
224 /* Second, find the bus the source device is on. */
225 bus = pci_find_bus(pci_domain_nr(port->bus), busnr);
229 /* Next, check if the PME is from a PCIe-PCI bridge. */
230 found = pcie_pme_from_pci_bridge(bus, devfn);
234 /* Finally, try to find the PME source on the bus. */
235 down_read(&pci_bus_sem);
236 list_for_each_entry(dev, &bus->devices, bus_list) {
238 if (dev->devfn == devfn) {
244 up_read(&pci_bus_sem);
247 /* The device is there, but we have to check its PME status. */
248 found = pci_check_pme_status(dev);
250 pm_request_resume(&dev->dev);
254 * The device is not there, but we can still try to recover by
255 * assuming that the PME was reported by a PCIe-PCI bridge that
256 * used devfn different from zero.
258 dev_dbg(&port->dev, "PME interrupt generated for "
259 "non-existent device %02x:%02x.%d\n",
260 busnr, PCI_SLOT(devfn), PCI_FUNC(devfn));
261 found = pcie_pme_from_pci_bridge(bus, 0);
266 dev_dbg(&port->dev, "Spurious native PME interrupt!\n");
270 * pcie_pme_work_fn - Work handler for PCIe PME interrupt.
271 * @work: Work structure giving access to service data.
273 static void pcie_pme_work_fn(struct work_struct *work)
275 struct pcie_pme_service_data *data =
276 container_of(work, struct pcie_pme_service_data, work);
277 struct pci_dev *port = data->srv->port;
281 rtsta_pos = pci_find_capability(port, PCI_CAP_ID_EXP) + PCI_EXP_RTSTA;
283 spin_lock_irq(&data->lock);
289 pci_read_config_dword(port, rtsta_pos, &rtsta);
290 if (rtsta & PCI_EXP_RTSTA_PME) {
292 * Clear PME status of the port. If there are other
293 * pending PMEs, the status will be set again.
295 pcie_pme_clear_status(port);
297 spin_unlock_irq(&data->lock);
298 pcie_pme_handle_request(port, rtsta & 0xffff);
299 spin_lock_irq(&data->lock);
304 /* No need to loop if there are no more PMEs pending. */
305 if (!(rtsta & PCI_EXP_RTSTA_PENDING))
308 spin_unlock_irq(&data->lock);
310 spin_lock_irq(&data->lock);
314 pcie_pme_interrupt_enable(port, true);
316 spin_unlock_irq(&data->lock);
320 * pcie_pme_irq - Interrupt handler for PCIe root port PME interrupt.
321 * @irq: Interrupt vector.
322 * @context: Interrupt context pointer.
324 static irqreturn_t pcie_pme_irq(int irq, void *context)
326 struct pci_dev *port;
327 struct pcie_pme_service_data *data;
332 port = ((struct pcie_device *)context)->port;
333 data = get_service_data((struct pcie_device *)context);
335 rtsta_pos = pci_find_capability(port, PCI_CAP_ID_EXP) + PCI_EXP_RTSTA;
337 spin_lock_irqsave(&data->lock, flags);
338 pci_read_config_dword(port, rtsta_pos, &rtsta);
340 if (!(rtsta & PCI_EXP_RTSTA_PME)) {
341 spin_unlock_irqrestore(&data->lock, flags);
345 pcie_pme_interrupt_enable(port, false);
346 spin_unlock_irqrestore(&data->lock, flags);
348 /* We don't use pm_wq, because it's freezable. */
349 schedule_work(&data->work);
355 * pcie_pme_set_native - Set the PME interrupt flag for given device.
356 * @dev: PCI device to handle.
359 static int pcie_pme_set_native(struct pci_dev *dev, void *ign)
361 dev_info(&dev->dev, "Signaling PME through PCIe PME interrupt\n");
363 device_set_run_wake(&dev->dev, true);
364 dev->pme_interrupt = true;
369 * pcie_pme_mark_devices - Set the PME interrupt flag for devices below a port.
370 * @port: PCIe root port or event collector to handle.
372 * For each device below given root port, including the port itself (or for each
373 * root complex integrated endpoint if @port is a root complex event collector)
374 * set the flag indicating that it can signal run-time wake-up events via PCIe
377 static void pcie_pme_mark_devices(struct pci_dev *port)
379 pcie_pme_set_native(port, NULL);
380 if (port->subordinate) {
381 pci_walk_bus(port->subordinate, pcie_pme_set_native, NULL);
383 struct pci_bus *bus = port->bus;
386 /* Check if this is a root port event collector. */
387 if (port->pcie_type != PCI_EXP_TYPE_RC_EC || !bus)
390 down_read(&pci_bus_sem);
391 list_for_each_entry(dev, &bus->devices, bus_list)
393 && dev->pcie_type == PCI_EXP_TYPE_RC_END)
394 pcie_pme_set_native(dev, NULL);
395 up_read(&pci_bus_sem);
400 * pcie_pme_probe - Initialize PCIe PME service for given root port.
401 * @srv: PCIe service to initialize.
403 static int pcie_pme_probe(struct pcie_device *srv)
405 struct pci_dev *port;
406 struct pcie_pme_service_data *data;
409 if (!pcie_pme_platform_setup(srv))
412 data = kzalloc(sizeof(*data), GFP_KERNEL);
416 spin_lock_init(&data->lock);
417 INIT_WORK(&data->work, pcie_pme_work_fn);
419 set_service_data(srv, data);
422 pcie_pme_interrupt_enable(port, false);
423 pcie_pme_clear_status(port);
425 ret = request_irq(srv->irq, pcie_pme_irq, IRQF_SHARED, "PCIe PME", srv);
429 pcie_pme_mark_devices(port);
430 pcie_pme_interrupt_enable(port, true);
437 * pcie_pme_suspend - Suspend PCIe PME service device.
438 * @srv: PCIe service device to suspend.
440 static int pcie_pme_suspend(struct pcie_device *srv)
442 struct pcie_pme_service_data *data = get_service_data(srv);
443 struct pci_dev *port = srv->port;
445 spin_lock_irq(&data->lock);
446 pcie_pme_interrupt_enable(port, false);
447 pcie_pme_clear_status(port);
449 spin_unlock_irq(&data->lock);
451 synchronize_irq(srv->irq);
457 * pcie_pme_resume - Resume PCIe PME service device.
458 * @srv - PCIe service device to resume.
460 static int pcie_pme_resume(struct pcie_device *srv)
462 struct pcie_pme_service_data *data = get_service_data(srv);
463 struct pci_dev *port = srv->port;
465 spin_lock_irq(&data->lock);
467 pcie_pme_clear_status(port);
468 pcie_pme_interrupt_enable(port, true);
469 spin_unlock_irq(&data->lock);
475 * pcie_pme_remove - Prepare PCIe PME service device for removal.
476 * @srv - PCIe service device to resume.
478 static void pcie_pme_remove(struct pcie_device *srv)
480 pcie_pme_suspend(srv);
481 free_irq(srv->irq, srv);
482 kfree(get_service_data(srv));
485 static struct pcie_port_service_driver pcie_pme_driver = {
487 .port_type = PCI_EXP_TYPE_ROOT_PORT,
488 .service = PCIE_PORT_SERVICE_PME,
490 .probe = pcie_pme_probe,
491 .suspend = pcie_pme_suspend,
492 .resume = pcie_pme_resume,
493 .remove = pcie_pme_remove,
497 * pcie_pme_service_init - Register the PCIe PME service driver.
499 static int __init pcie_pme_service_init(void)
501 return pcie_pme_disabled ?
502 -ENODEV : pcie_port_service_register(&pcie_pme_driver);
505 module_init(pcie_pme_service_init);