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43c16408 AP |
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: | |
50e5628a | 109 | enable_ecrc_checking(dev); |
43c16408 AP |
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 | } |