drivers/pci/pcie/pcie-dpc.c

   1 /*
   2  * PCI Express Downstream Port Containment services driver
   3  * Author: Keith Busch <keith.busch@intel.com>
   4  *
   5  * Copyright (C) 2016 Intel Corp.
   6  *
   7  * This file is subject to the terms and conditions of the GNU General Public
   8  * License.  See the file "COPYING" in the main directory of this archive
   9  * for more details.
  10  */
  11
  12 #include <linux/delay.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/init.h>
  15 #include <linux/pci.h>
  16 #include <linux/pcieport_if.h>
  17
  18 struct dpc_dev {
  19         struct pcie_device      *dev;
  20         struct work_struct      work;
  21         int                     cap_pos;
  22 };
  23
  24 static void dpc_wait_link_inactive(struct pci_dev *pdev)
  25 {
  26         unsigned long timeout = jiffies + HZ;
  27         u16 lnk_status;
  28
  29         pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
  30         while (lnk_status & PCI_EXP_LNKSTA_DLLLA &&
  31                                         !time_after(jiffies, timeout)) {
  32                 msleep(10);
  33                 pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
  34         }
  35         if (lnk_status & PCI_EXP_LNKSTA_DLLLA)
  36                 dev_warn(&pdev->dev, "Link state not disabled for DPC event");
  37 }
  38
  39 static void interrupt_event_handler(struct work_struct *work)
  40 {
  41         struct dpc_dev *dpc = container_of(work, struct dpc_dev, work);
  42         struct pci_dev *dev, *temp, *pdev = dpc->dev->port;
  43         struct pci_bus *parent = pdev->subordinate;
  44
  45         pci_lock_rescan_remove();
  46         list_for_each_entry_safe_reverse(dev, temp, &parent->devices,
  47                                          bus_list) {
  48                 pci_dev_get(dev);
  49                 pci_stop_and_remove_bus_device(dev);
  50                 pci_dev_put(dev);
  51         }
  52         pci_unlock_rescan_remove();
  53
  54         dpc_wait_link_inactive(pdev);
  55         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,
  56                 PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT);
  57 }
  58
  59 static irqreturn_t dpc_irq(int irq, void *context)
  60 {
  61         struct dpc_dev *dpc = (struct dpc_dev *)context;
  62         struct pci_dev *pdev = dpc->dev->port;
  63         u16 status, source;
  64
  65         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS, &status);
  66         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_SOURCE_ID,
  67                              &source);
  68         if (!status)
  69                 return IRQ_NONE;
  70
  71         dev_info(&dpc->dev->device, "DPC containment event, status:%#06x source:%#06x\n",
  72                 status, source);
  73
  74         if (status & PCI_EXP_DPC_STATUS_TRIGGER) {
  75                 u16 reason = (status >> 1) & 0x3;
  76
  77                 dev_warn(&dpc->dev->device, "DPC %s triggered, remove downstream devices\n",
  78                          (reason == 0) ? "unmasked uncorrectable error" :
  79                          (reason == 1) ? "ERR_NONFATAL" :
  80                          (reason == 2) ? "ERR_FATAL" : "extended error");
  81                 schedule_work(&dpc->work);
  82         }
  83         return IRQ_HANDLED;
  84 }
  85
  86 #define FLAG(x, y) (((x) & (y)) ? '+' : '-')
  87 static int dpc_probe(struct pcie_device *dev)
  88 {
  89         struct dpc_dev *dpc;
  90         struct pci_dev *pdev = dev->port;
  91         int status;
  92         u16 ctl, cap;
  93
  94         dpc = devm_kzalloc(&dev->device, sizeof(*dpc), GFP_KERNEL);
  95         if (!dpc)
  96                 return -ENOMEM;
  97
  98         dpc->cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
  99         dpc->dev = dev;
 100         INIT_WORK(&dpc->work, interrupt_event_handler);
 101         set_service_data(dev, dpc);
 102
 103         status = devm_request_irq(&dev->device, dev->irq, dpc_irq, IRQF_SHARED,
 104                                   "pcie-dpc", dpc);
 105         if (status) {
 106                 dev_warn(&dev->device, "request IRQ%d failed: %d\n", dev->irq,
 107                          status);
 108                 return status;
 109         }
 110
 111         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CAP, &cap);
 112         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
 113
 114         ctl |= PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN;
 115         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
 116
 117         dev_info(&dev->device, "DPC error containment capabilities: Int Msg #%d, RPExt%c PoisonedTLP%c SwTrigger%c RP PIO Log %d, DL_ActiveErr%c\n",
 118                 cap & 0xf, FLAG(cap, PCI_EXP_DPC_CAP_RP_EXT),
 119                 FLAG(cap, PCI_EXP_DPC_CAP_POISONED_TLP),
 120                 FLAG(cap, PCI_EXP_DPC_CAP_SW_TRIGGER), (cap >> 8) & 0xf,
 121                 FLAG(cap, PCI_EXP_DPC_CAP_DL_ACTIVE));
 122         return status;
 123 }
 124
 125 static void dpc_remove(struct pcie_device *dev)
 126 {
 127         struct dpc_dev *dpc = get_service_data(dev);
 128         struct pci_dev *pdev = dev->port;
 129         u16 ctl;
 130
 131         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
 132         ctl &= ~(PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN);
 133         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
 134 }
 135
 136 static struct pcie_port_service_driver dpcdriver = {
 137         .name           = "dpc",
 138         .port_type      = PCIE_ANY_PORT,
 139         .service        = PCIE_PORT_SERVICE_DPC,
 140         .probe          = dpc_probe,
 141         .remove         = dpc_remove,
 142 };
 143
 144 static int __init dpc_service_init(void)
 145 {
 146         return pcie_port_service_register(&dpcdriver);
 147 }
 148 device_initcall(dpc_service_init);