root/drivers/pci/pcie/pme.c

DEFINITIONS

1. pcie_pme_setup
2. pcie_pme_interrupt_enable
3. pcie_pme_walk_bus
4. pcie_pme_from_pci_bridge
5. pcie_pme_handle_request
6. pcie_pme_work_fn
7. pcie_pme_irq
8. pcie_pme_can_wakeup
9. pcie_pme_mark_devices
10. pcie_pme_probe
11. pcie_pme_check_wakeup
12. pcie_pme_disable_interrupt
13. pcie_pme_suspend
14. pcie_pme_resume
15. pcie_pme_remove
16. pcie_pme_init

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