drivers/pci/pcie/aer/ecrc.c

   1 /*
   2  *    Enables/disables PCIe ECRC checking.
   3  *
   4  *    (C) Copyright 2009 Hewlett-Packard Development Company, L.P.
   5  *    Andrew Patterson <andrew.patterson@hp.com>
   6  *
   7  *    This program is free software; you can redistribute it and/or modify
   8  *    it under the terms of the GNU General Public License as published by
   9  *    the Free Software Foundation; version 2 of the License.
  10  *
  11  *    This program is distributed in the hope that it will be useful,
  12  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *    MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14  *    General Public License for more details.
  15  *
  16  *    You should have received a copy of the GNU General Public License
  17  *    along with this program; if not, write to the Free Software
  18  *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19  *    02111-1307, USA.
  20  *
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/moduleparam.h>
  26 #include <linux/pci.h>
  27 #include <linux/pci_regs.h>
  28 #include <linux/errno.h>
  29 #include "../../pci.h"
  30
  31 #define ECRC_POLICY_DEFAULT 0           /* ECRC set by BIOS */
  32 #define ECRC_POLICY_OFF     1           /* ECRC off for performance */
  33 #define ECRC_POLICY_ON      2           /* ECRC on for data integrity */
  34
  35 static int ecrc_policy = ECRC_POLICY_DEFAULT;
  36
  37 static const char *ecrc_policy_str[] = {
  38         [ECRC_POLICY_DEFAULT] = "bios",
  39         [ECRC_POLICY_OFF] = "off",
  40         [ECRC_POLICY_ON] = "on"
  41 };
  42
  43 /**
  44  * enable_ercr_checking - enable PCIe ECRC checking for a device
  45  * @dev: the PCI device
  46  *
  47  * Returns 0 on success, or negative on failure.
  48  */
  49 static int enable_ecrc_checking(struct pci_dev *dev)
  50 {
  51         int pos;
  52         u32 reg32;
  53
  54         if (!pci_is_pcie(dev))
  55                 return -ENODEV;
  56
  57         pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
  58         if (!pos)
  59                 return -ENODEV;
  60
  61         pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
  62         if (reg32 & PCI_ERR_CAP_ECRC_GENC)
  63                 reg32 |= PCI_ERR_CAP_ECRC_GENE;
  64         if (reg32 & PCI_ERR_CAP_ECRC_CHKC)
  65                 reg32 |= PCI_ERR_CAP_ECRC_CHKE;
  66         pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);
  67
  68         return 0;
  69 }
  70
  71 /**
  72  * disable_ercr_checking - disables PCIe ECRC checking for a device
  73  * @dev: the PCI device
  74  *
  75  * Returns 0 on success, or negative on failure.
  76  */
  77 static int disable_ecrc_checking(struct pci_dev *dev)
  78 {
  79         int pos;
  80         u32 reg32;
  81
  82         if (!pci_is_pcie(dev))
  83                 return -ENODEV;
  84
  85         pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
  86         if (!pos)
  87                 return -ENODEV;
  88
  89         pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
  90         reg32 &= ~(PCI_ERR_CAP_ECRC_GENE | PCI_ERR_CAP_ECRC_CHKE);
  91         pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);
  92
  93         return 0;
  94 }
  95
  96 /**
  97  * pcie_set_ecrc_checking - set/unset PCIe ECRC checking for a device based on global policy
  98  * @dev: the PCI device
  99  */
 100 void pcie_set_ecrc_checking(struct pci_dev *dev)
 101 {
 102         switch (ecrc_policy) {
 103         case ECRC_POLICY_DEFAULT:
 104                 return;
 105         case ECRC_POLICY_OFF:
 106                 disable_ecrc_checking(dev);
 107                 break;
 108         case ECRC_POLICY_ON:
 109                 enable_ecrc_checking(dev);
 110                 break;
 111         default:
 112                 return;
 113         }
 114 }
 115
 116 /**
 117  * pcie_ecrc_get_policy - parse kernel command-line ecrc option
 118  */
 119 void pcie_ecrc_get_policy(char *str)
 120 {
 121         int i;
 122
 123         for (i = 0; i < ARRAY_SIZE(ecrc_policy_str); i++)
 124                 if (!strncmp(str, ecrc_policy_str[i],
 125                              strlen(ecrc_policy_str[i])))
 126                         break;
 127         if (i >= ARRAY_SIZE(ecrc_policy_str))
 128                 return;
 129
 130         ecrc_policy = i;
 131 }