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 (!dev->is_pcie)
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, ®32);
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 (!dev->is_pcie)
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, ®32);
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 }
132
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