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;
56 static int __init pcie_pme_setup(char *str)
58 if (!strcmp(str, "off"))
59 pcie_pme_disabled = true;
60 else if (!strcmp(str, "force"))
61 pcie_pme_force_enable = true;
64 __setup("pcie_pme=", pcie_pme_setup);
67 * pcie_pme_platform_setup - Ensure that the kernel controls the PCIe PME.
68 * @srv: PCIe PME root port service to use for carrying out the check.
70 * Notify the platform that the native PCIe PME is going to be used and return
71 * 'true' if the control of the PCIe PME registers has been acquired from the
74 static bool pcie_pme_platform_setup(struct pcie_device *srv)
76 return !pcie_pme_platform_notify(srv) || pcie_pme_force_enable;
79 struct pcie_pme_service_data {
81 struct pcie_device *srv;
82 struct work_struct work;
83 bool noirq; /* Don't enable the PME interrupt used by this service. */
87 * pcie_pme_interrupt_enable - Enable/disable PCIe PME interrupt generation.
88 * @dev: PCIe root port or event collector.
89 * @enable: Enable or disable the interrupt.
91 static void pcie_pme_interrupt_enable(struct pci_dev *dev, bool enable)
96 rtctl_pos = pci_find_capability(dev, PCI_CAP_ID_EXP) + PCI_EXP_RTCTL;
98 pci_read_config_word(dev, rtctl_pos, &rtctl);
100 rtctl |= PCI_EXP_RTCTL_PMEIE;
102 rtctl &= ~PCI_EXP_RTCTL_PMEIE;
103 pci_write_config_word(dev, rtctl_pos, rtctl);
107 * pcie_pme_clear_status - Clear root port PME interrupt status.
108 * @dev: PCIe root port or event collector.
110 static void pcie_pme_clear_status(struct pci_dev *dev)
115 rtsta_pos = pci_find_capability(dev, PCI_CAP_ID_EXP) + PCI_EXP_RTSTA;
117 pci_read_config_dword(dev, rtsta_pos, &rtsta);
118 rtsta |= PCI_EXP_RTSTA_PME;
119 pci_write_config_dword(dev, rtsta_pos, rtsta);
123 * pcie_pme_walk_bus - Scan a PCI bus for devices asserting PME#.
124 * @bus: PCI bus to scan.
126 * Scan given PCI bus and all buses under it for devices asserting PME#.
128 static bool pcie_pme_walk_bus(struct pci_bus *bus)
133 list_for_each_entry(dev, &bus->devices, bus_list) {
134 /* Skip PCIe devices in case we started from a root port. */
135 if (!dev->is_pcie && pci_check_pme_status(dev)) {
136 pm_request_resume(&dev->dev);
140 if (dev->subordinate && pcie_pme_walk_bus(dev->subordinate))
148 * pcie_pme_from_pci_bridge - Check if PCIe-PCI bridge generated a PME.
149 * @bus: Secondary bus of the bridge.
150 * @devfn: Device/function number to check.
152 * PME from PCI devices under a PCIe-PCI bridge may be converted to an in-band
153 * PCIe PME message. In such that case the bridge should use the Requester ID
154 * of device/function number 0 on its secondary bus.
156 static bool pcie_pme_from_pci_bridge(struct pci_bus *bus, u8 devfn)
164 dev = pci_dev_get(bus->self);
168 if (dev->is_pcie && dev->pcie_type == PCI_EXP_TYPE_PCI_BRIDGE) {
169 down_read(&pci_bus_sem);
170 if (pcie_pme_walk_bus(bus))
172 up_read(&pci_bus_sem);
180 * pcie_pme_handle_request - Find device that generated PME and handle it.
181 * @port: Root port or event collector that generated the PME interrupt.
182 * @req_id: PCIe Requester ID of the device that generated the PME.
184 static void pcie_pme_handle_request(struct pci_dev *port, u16 req_id)
186 u8 busnr = req_id >> 8, devfn = req_id & 0xff;
191 /* First, check if the PME is from the root port itself. */
192 if (port->devfn == devfn && port->bus->number == busnr) {
193 if (pci_check_pme_status(port)) {
194 pm_request_resume(&port->dev);
198 * Apparently, the root port generated the PME on behalf
199 * of a non-PCIe device downstream. If this is done by
200 * a root port, the Requester ID field in its status
201 * register may contain either the root port's, or the
202 * source device's information (PCI Express Base
203 * Specification, Rev. 2.0, Section 6.1.9).
205 down_read(&pci_bus_sem);
206 found = pcie_pme_walk_bus(port->subordinate);
207 up_read(&pci_bus_sem);
212 /* Second, find the bus the source device is on. */
213 bus = pci_find_bus(pci_domain_nr(port->bus), busnr);
217 /* Next, check if the PME is from a PCIe-PCI bridge. */
218 found = pcie_pme_from_pci_bridge(bus, devfn);
222 /* Finally, try to find the PME source on the bus. */
223 down_read(&pci_bus_sem);
224 list_for_each_entry(dev, &bus->devices, bus_list) {
226 if (dev->devfn == devfn) {
232 up_read(&pci_bus_sem);
235 /* The device is there, but we have to check its PME status. */
236 found = pci_check_pme_status(dev);
238 pm_request_resume(&dev->dev);
242 * The device is not there, but we can still try to recover by
243 * assuming that the PME was reported by a PCIe-PCI bridge that
244 * used devfn different from zero.
246 dev_dbg(&port->dev, "PME interrupt generated for "
247 "non-existent device %02x:%02x.%d\n",
248 busnr, PCI_SLOT(devfn), PCI_FUNC(devfn));
249 found = pcie_pme_from_pci_bridge(bus, 0);
254 dev_dbg(&port->dev, "Spurious native PME interrupt!\n");
258 * pcie_pme_work_fn - Work handler for PCIe PME interrupt.
259 * @work: Work structure giving access to service data.
261 static void pcie_pme_work_fn(struct work_struct *work)
263 struct pcie_pme_service_data *data =
264 container_of(work, struct pcie_pme_service_data, work);
265 struct pci_dev *port = data->srv->port;
269 rtsta_pos = pci_find_capability(port, PCI_CAP_ID_EXP) + PCI_EXP_RTSTA;
271 spin_lock_irq(&data->lock);
277 pci_read_config_dword(port, rtsta_pos, &rtsta);
278 if (rtsta & PCI_EXP_RTSTA_PME) {
280 * Clear PME status of the port. If there are other
281 * pending PMEs, the status will be set again.
283 pcie_pme_clear_status(port);
285 spin_unlock_irq(&data->lock);
286 pcie_pme_handle_request(port, rtsta & 0xffff);
287 spin_lock_irq(&data->lock);
292 /* No need to loop if there are no more PMEs pending. */
293 if (!(rtsta & PCI_EXP_RTSTA_PENDING))
296 spin_unlock_irq(&data->lock);
298 spin_lock_irq(&data->lock);
302 pcie_pme_interrupt_enable(port, true);
304 spin_unlock_irq(&data->lock);
308 * pcie_pme_irq - Interrupt handler for PCIe root port PME interrupt.
309 * @irq: Interrupt vector.
310 * @context: Interrupt context pointer.
312 static irqreturn_t pcie_pme_irq(int irq, void *context)
314 struct pci_dev *port;
315 struct pcie_pme_service_data *data;
320 port = ((struct pcie_device *)context)->port;
321 data = get_service_data((struct pcie_device *)context);
323 rtsta_pos = pci_find_capability(port, PCI_CAP_ID_EXP) + PCI_EXP_RTSTA;
325 spin_lock_irqsave(&data->lock, flags);
326 pci_read_config_dword(port, rtsta_pos, &rtsta);
328 if (!(rtsta & PCI_EXP_RTSTA_PME)) {
329 spin_unlock_irqrestore(&data->lock, flags);
333 pcie_pme_interrupt_enable(port, false);
334 spin_unlock_irqrestore(&data->lock, flags);
336 /* We don't use pm_wq, because it's freezable. */
337 schedule_work(&data->work);
343 * pcie_pme_set_native - Set the PME interrupt flag for given device.
344 * @dev: PCI device to handle.
347 static int pcie_pme_set_native(struct pci_dev *dev, void *ign)
349 dev_info(&dev->dev, "Signaling PME through PCIe PME interrupt\n");
351 device_set_run_wake(&dev->dev, true);
352 dev->pme_interrupt = true;
357 * pcie_pme_mark_devices - Set the PME interrupt flag for devices below a port.
358 * @port: PCIe root port or event collector to handle.
360 * For each device below given root port, including the port itself (or for each
361 * root complex integrated endpoint if @port is a root complex event collector)
362 * set the flag indicating that it can signal run-time wake-up events via PCIe
365 static void pcie_pme_mark_devices(struct pci_dev *port)
367 pcie_pme_set_native(port, NULL);
368 if (port->subordinate) {
369 pci_walk_bus(port->subordinate, pcie_pme_set_native, NULL);
371 struct pci_bus *bus = port->bus;
374 /* Check if this is a root port event collector. */
375 if (port->pcie_type != PCI_EXP_TYPE_RC_EC || !bus)
378 down_read(&pci_bus_sem);
379 list_for_each_entry(dev, &bus->devices, bus_list)
381 && dev->pcie_type == PCI_EXP_TYPE_RC_END)
382 pcie_pme_set_native(dev, NULL);
383 up_read(&pci_bus_sem);
388 * pcie_pme_probe - Initialize PCIe PME service for given root port.
389 * @srv: PCIe service to initialize.
391 static int pcie_pme_probe(struct pcie_device *srv)
393 struct pci_dev *port;
394 struct pcie_pme_service_data *data;
397 if (!pcie_pme_platform_setup(srv))
400 data = kzalloc(sizeof(*data), GFP_KERNEL);
404 spin_lock_init(&data->lock);
405 INIT_WORK(&data->work, pcie_pme_work_fn);
407 set_service_data(srv, data);
410 pcie_pme_interrupt_enable(port, false);
411 pcie_pme_clear_status(port);
413 ret = request_irq(srv->irq, pcie_pme_irq, IRQF_SHARED, "PCIe PME", srv);
417 pcie_pme_mark_devices(port);
418 pcie_pme_interrupt_enable(port, true);
425 * pcie_pme_suspend - Suspend PCIe PME service device.
426 * @srv: PCIe service device to suspend.
428 static int pcie_pme_suspend(struct pcie_device *srv)
430 struct pcie_pme_service_data *data = get_service_data(srv);
431 struct pci_dev *port = srv->port;
433 spin_lock_irq(&data->lock);
434 pcie_pme_interrupt_enable(port, false);
435 pcie_pme_clear_status(port);
437 spin_unlock_irq(&data->lock);
439 synchronize_irq(srv->irq);
445 * pcie_pme_resume - Resume PCIe PME service device.
446 * @srv - PCIe service device to resume.
448 static int pcie_pme_resume(struct pcie_device *srv)
450 struct pcie_pme_service_data *data = get_service_data(srv);
451 struct pci_dev *port = srv->port;
453 spin_lock_irq(&data->lock);
455 pcie_pme_clear_status(port);
456 pcie_pme_interrupt_enable(port, true);
457 spin_unlock_irq(&data->lock);
463 * pcie_pme_remove - Prepare PCIe PME service device for removal.
464 * @srv - PCIe service device to resume.
466 static void pcie_pme_remove(struct pcie_device *srv)
468 pcie_pme_suspend(srv);
469 free_irq(srv->irq, srv);
470 kfree(get_service_data(srv));
473 static struct pcie_port_service_driver pcie_pme_driver = {
475 .port_type = PCI_EXP_TYPE_ROOT_PORT,
476 .service = PCIE_PORT_SERVICE_PME,
478 .probe = pcie_pme_probe,
479 .suspend = pcie_pme_suspend,
480 .resume = pcie_pme_resume,
481 .remove = pcie_pme_remove,
485 * pcie_pme_service_init - Register the PCIe PME service driver.
487 static int __init pcie_pme_service_init(void)
489 return pcie_pme_disabled ?
490 -ENODEV : pcie_port_service_register(&pcie_pme_driver);
493 module_init(pcie_pme_service_init);