drivers/pci/pcie/pcie-dpc.c

   1 /*
   2  * PCI Express Downstream Port Containment services driver
   3  * Copyright (C) 2016 Intel Corp.
   4  *
   5  * This file is subject to the terms and conditions of the GNU General Public
   6  * License.  See the file "COPYING" in the main directory of this archive
   7  * for more details.
   8  */
   9
  10 #include <linux/delay.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/module.h>
  13 #include <linux/pci.h>
  14 #include <linux/pcieport_if.h>
  15
  16 struct dpc_dev {
  17         struct pcie_device      *dev;
  18         struct work_struct      work;
  19         int                     cap_pos;
  20 };
  21
  22 static void dpc_wait_link_inactive(struct pci_dev *pdev)
  23 {
  24         unsigned long timeout = jiffies + HZ;
  25         u16 lnk_status;
  26
  27         pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
  28         while (lnk_status & PCI_EXP_LNKSTA_DLLLA &&
  29                                         !time_after(jiffies, timeout)) {
  30                 msleep(10);
  31                 pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
  32         }
  33         if (lnk_status & PCI_EXP_LNKSTA_DLLLA)
  34                 dev_warn(&pdev->dev, "Link state not disabled for DPC event");
  35 }
  36
  37 static void interrupt_event_handler(struct work_struct *work)
  38 {
  39         struct dpc_dev *dpc = container_of(work, struct dpc_dev, work);
  40         struct pci_dev *dev, *temp, *pdev = dpc->dev->port;
  41         struct pci_bus *parent = pdev->subordinate;
  42
  43         pci_lock_rescan_remove();
  44         list_for_each_entry_safe_reverse(dev, temp, &parent->devices,
  45                                          bus_list) {
  46                 pci_dev_get(dev);
  47                 pci_stop_and_remove_bus_device(dev);
  48                 pci_dev_put(dev);
  49         }
  50         pci_unlock_rescan_remove();
  51
  52         dpc_wait_link_inactive(pdev);
  53         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,
  54                 PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT);
  55 }
  56
  57 static irqreturn_t dpc_irq(int irq, void *context)
  58 {
  59         struct dpc_dev *dpc = (struct dpc_dev *)context;
  60         struct pci_dev *pdev = dpc->dev->port;
  61         u16 status, source;
  62
  63         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS, &status);
  64         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_SOURCE_ID,
  65                              &source);
  66         if (!status)
  67                 return IRQ_NONE;
  68
  69         dev_info(&dpc->dev->device, "DPC containment event, status:%#06x source:%#06x\n",
  70                 status, source);
  71
  72         if (status & PCI_EXP_DPC_STATUS_TRIGGER) {
  73                 u16 reason = (status >> 1) & 0x3;
  74
  75                 dev_warn(&dpc->dev->device, "DPC %s triggered, remove downstream devices\n",
  76                          (reason == 0) ? "unmasked uncorrectable error" :
  77                          (reason == 1) ? "ERR_NONFATAL" :
  78                          (reason == 2) ? "ERR_FATAL" : "extended error");
  79                 schedule_work(&dpc->work);
  80         }
  81         return IRQ_HANDLED;
  82 }
  83
  84 #define FLAG(x, y) (((x) & (y)) ? '+' : '-')
  85 static int dpc_probe(struct pcie_device *dev)
  86 {
  87         struct dpc_dev *dpc;
  88         struct pci_dev *pdev = dev->port;
  89         int status;
  90         u16 ctl, cap;
  91
  92         dpc = devm_kzalloc(&dev->device, sizeof(*dpc), GFP_KERNEL);
  93         if (!dpc)
  94                 return -ENOMEM;
  95
  96         dpc->cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
  97         dpc->dev = dev;
  98         INIT_WORK(&dpc->work, interrupt_event_handler);
  99         set_service_data(dev, dpc);
 100
 101         status = devm_request_irq(&dev->device, dev->irq, dpc_irq, IRQF_SHARED,
 102                                   "pcie-dpc", dpc);
 103         if (status) {
 104                 dev_warn(&dev->device, "request IRQ%d failed: %d\n", dev->irq,
 105                          status);
 106                 return status;
 107         }
 108
 109         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CAP, &cap);
 110         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
 111
 112         ctl |= PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN;
 113         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
 114
 115         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",
 116                 cap & 0xf, FLAG(cap, PCI_EXP_DPC_CAP_RP_EXT),
 117                 FLAG(cap, PCI_EXP_DPC_CAP_POISONED_TLP),
 118                 FLAG(cap, PCI_EXP_DPC_CAP_SW_TRIGGER), (cap >> 8) & 0xf,
 119                 FLAG(cap, PCI_EXP_DPC_CAP_DL_ACTIVE));
 120         return status;
 121 }
 122
 123 static void dpc_remove(struct pcie_device *dev)
 124 {
 125         struct dpc_dev *dpc = get_service_data(dev);
 126         struct pci_dev *pdev = dev->port;
 127         u16 ctl;
 128
 129         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
 130         ctl &= ~(PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN);
 131         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
 132 }
 133
 134 static struct pcie_port_service_driver dpcdriver = {
 135         .name           = "dpc",
 136         .port_type      = PCI_EXP_TYPE_ROOT_PORT | PCI_EXP_TYPE_DOWNSTREAM,
 137         .service        = PCIE_PORT_SERVICE_DPC,
 138         .probe          = dpc_probe,
 139         .remove         = dpc_remove,
 140 };
 141
 142 static int __init dpc_service_init(void)
 143 {
 144         return pcie_port_service_register(&dpcdriver);
 145 }
 146
 147 static void __exit dpc_service_exit(void)
 148 {
 149         pcie_port_service_unregister(&dpcdriver);
 150 }
 151
 152 MODULE_DESCRIPTION("PCI Express Downstream Port Containment driver");
 153 MODULE_AUTHOR("Keith Busch <keith.busch@intel.com>");
 154 MODULE_LICENSE("GPL");
 155 MODULE_VERSION("0.1");
 156
 157 module_init(dpc_service_init);
 158 module_exit(dpc_service_exit);