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 #include "../pci.h"
  18
  19 struct dpc_dev {
  20         struct pcie_device      *dev;
  21         struct work_struct      work;
  22         int                     cap_pos;
  23         bool                    rp;
  24 };
  25
  26 static int dpc_wait_rp_inactive(struct dpc_dev *dpc)
  27 {
  28         unsigned long timeout = jiffies + HZ;
  29         struct pci_dev *pdev = dpc->dev->port;
  30         u16 status;
  31
  32         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS, &status);
  33         while (status & PCI_EXP_DPC_RP_BUSY &&
  34                                         !time_after(jiffies, timeout)) {
  35                 msleep(10);
  36                 pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS, &status);
  37         }
  38         if (status & PCI_EXP_DPC_RP_BUSY) {
  39                 dev_warn(&pdev->dev, "DPC root port still busy\n");
  40                 return -EBUSY;
  41         }
  42         return 0;
  43 }
  44
  45 static void dpc_wait_link_inactive(struct pci_dev *pdev)
  46 {
  47         unsigned long timeout = jiffies + HZ;
  48         u16 lnk_status;
  49
  50         pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
  51         while (lnk_status & PCI_EXP_LNKSTA_DLLLA &&
  52                                         !time_after(jiffies, timeout)) {
  53                 msleep(10);
  54                 pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
  55         }
  56         if (lnk_status & PCI_EXP_LNKSTA_DLLLA)
  57                 dev_warn(&pdev->dev, "Link state not disabled for DPC event\n");
  58 }
  59
  60 static void interrupt_event_handler(struct work_struct *work)
  61 {
  62         struct dpc_dev *dpc = container_of(work, struct dpc_dev, work);
  63         struct pci_dev *dev, *temp, *pdev = dpc->dev->port;
  64         struct pci_bus *parent = pdev->subordinate;
  65
  66         pci_lock_rescan_remove();
  67         list_for_each_entry_safe_reverse(dev, temp, &parent->devices,
  68                                          bus_list) {
  69                 pci_dev_get(dev);
  70                 pci_dev_set_disconnected(dev, NULL);
  71                 if (pci_has_subordinate(dev))
  72                         pci_walk_bus(dev->subordinate,
  73                                      pci_dev_set_disconnected, NULL);
  74                 pci_stop_and_remove_bus_device(dev);
  75                 pci_dev_put(dev);
  76         }
  77         pci_unlock_rescan_remove();
  78
  79         dpc_wait_link_inactive(pdev);
  80         if (dpc->rp && dpc_wait_rp_inactive(dpc))
  81                 return;
  82         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,
  83                 PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT);
  84 }
  85
  86 static irqreturn_t dpc_irq(int irq, void *context)
  87 {
  88         struct dpc_dev *dpc = (struct dpc_dev *)context;
  89         struct pci_dev *pdev = dpc->dev->port;
  90         u16 status, source;
  91
  92         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS, &status);
  93         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_SOURCE_ID,
  94                              &source);
  95         if (!status)
  96                 return IRQ_NONE;
  97
  98         dev_info(&dpc->dev->device, "DPC containment event, status:%#06x source:%#06x\n",
  99                 status, source);
 100
 101         if (status & PCI_EXP_DPC_STATUS_TRIGGER) {
 102                 u16 reason = (status >> 1) & 0x3;
 103                 u16 ext_reason = (status >> 5) & 0x3;
 104
 105                 dev_warn(&dpc->dev->device, "DPC %s detected, remove downstream devices\n",
 106                          (reason == 0) ? "unmasked uncorrectable error" :
 107                          (reason == 1) ? "ERR_NONFATAL" :
 108                          (reason == 2) ? "ERR_FATAL" :
 109                          (ext_reason == 0) ? "RP PIO error" :
 110                          (ext_reason == 1) ? "software trigger" :
 111                                              "reserved error");
 112                 schedule_work(&dpc->work);
 113         }
 114         return IRQ_HANDLED;
 115 }
 116
 117 #define FLAG(x, y) (((x) & (y)) ? '+' : '-')
 118 static int dpc_probe(struct pcie_device *dev)
 119 {
 120         struct dpc_dev *dpc;
 121         struct pci_dev *pdev = dev->port;
 122         int status;
 123         u16 ctl, cap;
 124
 125         dpc = devm_kzalloc(&dev->device, sizeof(*dpc), GFP_KERNEL);
 126         if (!dpc)
 127                 return -ENOMEM;
 128
 129         dpc->cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
 130         dpc->dev = dev;
 131         INIT_WORK(&dpc->work, interrupt_event_handler);
 132         set_service_data(dev, dpc);
 133
 134         status = devm_request_irq(&dev->device, dev->irq, dpc_irq, IRQF_SHARED,
 135                                   "pcie-dpc", dpc);
 136         if (status) {
 137                 dev_warn(&dev->device, "request IRQ%d failed: %d\n", dev->irq,
 138                          status);
 139                 return status;
 140         }
 141
 142         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CAP, &cap);
 143         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
 144
 145         dpc->rp = (cap & PCI_EXP_DPC_CAP_RP_EXT);
 146
 147         ctl |= PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN;
 148         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
 149
 150         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",
 151                 cap & 0xf, FLAG(cap, PCI_EXP_DPC_CAP_RP_EXT),
 152                 FLAG(cap, PCI_EXP_DPC_CAP_POISONED_TLP),
 153                 FLAG(cap, PCI_EXP_DPC_CAP_SW_TRIGGER), (cap >> 8) & 0xf,
 154                 FLAG(cap, PCI_EXP_DPC_CAP_DL_ACTIVE));
 155         return status;
 156 }
 157
 158 static void dpc_remove(struct pcie_device *dev)
 159 {
 160         struct dpc_dev *dpc = get_service_data(dev);
 161         struct pci_dev *pdev = dev->port;
 162         u16 ctl;
 163
 164         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
 165         ctl &= ~(PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN);
 166         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
 167 }
 168
 169 static struct pcie_port_service_driver dpcdriver = {
 170         .name           = "dpc",
 171         .port_type      = PCIE_ANY_PORT,
 172         .service        = PCIE_PORT_SERVICE_DPC,
 173         .probe          = dpc_probe,
 174         .remove         = dpc_remove,
 175 };
 176
 177 static int __init dpc_service_init(void)
 178 {
 179         return pcie_port_service_register(&dpcdriver);
 180 }
 181 device_initcall(dpc_service_init);