drivers/pci/pcie/aer/ecrc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *    Enables/disables PCIe ECRC checking.
   4  *
   5  *    (C) Copyright 2009 Hewlett-Packard Development Company, L.P.
   6  *    Andrew Patterson <andrew.patterson@hp.com>
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/pci.h>
  13 #include <linux/pci_regs.h>
  14 #include <linux/errno.h>
  15 #include "../../pci.h"
  16
  17 #define ECRC_POLICY_DEFAULT 0           /* ECRC set by BIOS */
  18 #define ECRC_POLICY_OFF     1           /* ECRC off for performance */
  19 #define ECRC_POLICY_ON      2           /* ECRC on for data integrity */
  20
  21 static int ecrc_policy = ECRC_POLICY_DEFAULT;
  22
  23 static const char *ecrc_policy_str[] = {
  24         [ECRC_POLICY_DEFAULT] = "bios",
  25         [ECRC_POLICY_OFF] = "off",
  26         [ECRC_POLICY_ON] = "on"
  27 };
  28
  29 /**
  30  * enable_ercr_checking - enable PCIe ECRC checking for a device
  31  * @dev: the PCI device
  32  *
  33  * Returns 0 on success, or negative on failure.
  34  */
  35 static int enable_ecrc_checking(struct pci_dev *dev)
  36 {
  37         int pos;
  38         u32 reg32;
  39
  40         if (!pci_is_pcie(dev))
  41                 return -ENODEV;
  42
  43         pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
  44         if (!pos)
  45                 return -ENODEV;
  46
  47         pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
  48         if (reg32 & PCI_ERR_CAP_ECRC_GENC)
  49                 reg32 |= PCI_ERR_CAP_ECRC_GENE;
  50         if (reg32 & PCI_ERR_CAP_ECRC_CHKC)
  51                 reg32 |= PCI_ERR_CAP_ECRC_CHKE;
  52         pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);
  53
  54         return 0;
  55 }
  56
  57 /**
  58  * disable_ercr_checking - disables PCIe ECRC checking for a device
  59  * @dev: the PCI device
  60  *
  61  * Returns 0 on success, or negative on failure.
  62  */
  63 static int disable_ecrc_checking(struct pci_dev *dev)
  64 {
  65         int pos;
  66         u32 reg32;
  67
  68         if (!pci_is_pcie(dev))
  69                 return -ENODEV;
  70
  71         pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
  72         if (!pos)
  73                 return -ENODEV;
  74
  75         pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
  76         reg32 &= ~(PCI_ERR_CAP_ECRC_GENE | PCI_ERR_CAP_ECRC_CHKE);
  77         pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);
  78
  79         return 0;
  80 }
  81
  82 /**
  83  * pcie_set_ecrc_checking - set/unset PCIe ECRC checking for a device based on global policy
  84  * @dev: the PCI device
  85  */
  86 void pcie_set_ecrc_checking(struct pci_dev *dev)
  87 {
  88         switch (ecrc_policy) {
  89         case ECRC_POLICY_DEFAULT:
  90                 return;
  91         case ECRC_POLICY_OFF:
  92                 disable_ecrc_checking(dev);
  93                 break;
  94         case ECRC_POLICY_ON:
  95                 enable_ecrc_checking(dev);
  96                 break;
  97         default:
  98                 return;
  99         }
 100 }
 101
 102 /**
 103  * pcie_ecrc_get_policy - parse kernel command-line ecrc option
 104  */
 105 void pcie_ecrc_get_policy(char *str)
 106 {
 107         int i;
 108
 109         for (i = 0; i < ARRAY_SIZE(ecrc_policy_str); i++)
 110                 if (!strncmp(str, ecrc_policy_str[i],
 111                              strlen(ecrc_policy_str[i])))
 112                         break;
 113         if (i >= ARRAY_SIZE(ecrc_policy_str))
 114                 return;
 115
 116         ecrc_policy = i;
 117 }