1 #include <linux/pci.h>
2 #include <linux/module.h>
3 #include <linux/sched.h>
4 #include <linux/ioport.h>
5 #include <linux/wait.h>
6
7 #include "pci.h"
8
9 /*
10 * This interrupt-safe spinlock protects all accesses to PCI
11 * configuration space.
12 */
13
14 static DEFINE_SPINLOCK(pci_lock);
15
16 /*
17 * Wrappers for all PCI configuration access functions. They just check
18 * alignment, do locking and call the low-level functions pointed to
19 * by pci_dev->ops.
20 */
21
22 #define PCI_byte_BAD 0
23 #define PCI_word_BAD (pos & 1)
24 #define PCI_dword_BAD (pos & 3)
25
26 #define PCI_OP_READ(size,type,len) \
27 int pci_bus_read_config_##size \
28 (struct pci_bus *bus, unsigned int devfn, int pos, type *value) \
29 { \
30 int res; \
31 unsigned long flags; \
32 u32 data = 0; \
33 if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
34 spin_lock_irqsave(&pci_lock, flags); \
35 res = bus->ops->read(bus, devfn, pos, len, &data); \
36 *value = (type)data; \
37 spin_unlock_irqrestore(&pci_lock, flags); \
38 return res; \
39 }
40
41 #define PCI_OP_WRITE(size,type,len) \
42 int pci_bus_write_config_##size \
43 (struct pci_bus *bus, unsigned int devfn, int pos, type value) \
44 { \
45 int res; \
46 unsigned long flags; \
47 if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
48 spin_lock_irqsave(&pci_lock, flags); \
49 res = bus->ops->write(bus, devfn, pos, len, value); \
50 spin_unlock_irqrestore(&pci_lock, flags); \
51 return res; \
52 }
53
54 PCI_OP_READ(byte, u8, 1)
55 PCI_OP_READ(word, u16, 2)
56 PCI_OP_READ(dword, u32, 4)
57 PCI_OP_WRITE(byte, u8, 1)
58 PCI_OP_WRITE(word, u16, 2)
59 PCI_OP_WRITE(dword, u32, 4)
60
61 EXPORT_SYMBOL(pci_bus_read_config_byte);
62 EXPORT_SYMBOL(pci_bus_read_config_word);
63 EXPORT_SYMBOL(pci_bus_read_config_dword);
64 EXPORT_SYMBOL(pci_bus_write_config_byte);
65 EXPORT_SYMBOL(pci_bus_write_config_word);
66 EXPORT_SYMBOL(pci_bus_write_config_dword);
67
68 /*
69 * The following routines are to prevent the user from accessing PCI config
70 * space when it's unsafe to do so. Some devices require this during BIST and
71 * we're required to prevent it during D-state transitions.
72 *
73 * We have a bit per device to indicate it's blocked and a global wait queue
74 * for callers to sleep on until devices are unblocked.
75 */
76 static DECLARE_WAIT_QUEUE_HEAD(pci_ucfg_wait);
77
78 static noinline void pci_wait_ucfg(struct pci_dev *dev)
79 {
80 DECLARE_WAITQUEUE(wait, current);
81
82 __add_wait_queue(&pci_ucfg_wait, &wait);
83 do {
84 set_current_state(TASK_UNINTERRUPTIBLE);
85 spin_unlock_irq(&pci_lock);
86 schedule();
87 spin_lock_irq(&pci_lock);
88 } while (dev->block_ucfg_access);
89 __remove_wait_queue(&pci_ucfg_wait, &wait);
90 }
91
92 #define PCI_USER_READ_CONFIG(size,type) \
93 int pci_user_read_config_##size \
94 (struct pci_dev *dev, int pos, type *val) \
95 { \
96 int ret = 0; \
97 u32 data = -1; \
98 if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
99 spin_lock_irq(&pci_lock); \
100 if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev); \
101 ret = dev->bus->ops->read(dev->bus, dev->devfn, \
102 pos, sizeof(type), &data); \
103 spin_unlock_irq(&pci_lock); \
104 *val = (type)data; \
105 return ret; \
106 }
107
108 #define PCI_USER_WRITE_CONFIG(size,type) \
109 int pci_user_write_config_##size \
110 (struct pci_dev *dev, int pos, type val) \
111 { \
112 int ret = -EIO; \
113 if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
114 spin_lock_irq(&pci_lock); \
115 if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev); \
116 ret = dev->bus->ops->write(dev->bus, dev->devfn, \
117 pos, sizeof(type), val); \
118 spin_unlock_irq(&pci_lock); \
119 return ret; \
120 }
121
122 PCI_USER_READ_CONFIG(byte, u8)
123 PCI_USER_READ_CONFIG(word, u16)
124 PCI_USER_READ_CONFIG(dword, u32)
125 PCI_USER_WRITE_CONFIG(byte, u8)
126 PCI_USER_WRITE_CONFIG(word, u16)
127 PCI_USER_WRITE_CONFIG(dword, u32)
128
129 /**
130 * pci_block_user_cfg_access - Block userspace PCI config reads/writes
131 * @dev: pci device struct
132 *
133 * When user access is blocked, any reads or writes to config space will
134 * sleep until access is unblocked again. We don't allow nesting of
135 * block/unblock calls.
136 */
137 void pci_block_user_cfg_access(struct pci_dev *dev)
138 {
139 unsigned long flags;
140 int was_blocked;
141
142 spin_lock_irqsave(&pci_lock, flags);
143 was_blocked = dev->block_ucfg_access;
144 dev->block_ucfg_access = 1;
145 spin_unlock_irqrestore(&pci_lock, flags);
146
147 /* If we BUG() inside the pci_lock, we're guaranteed to hose
148 * the machine */
149 BUG_ON(was_blocked);
150 }
151 EXPORT_SYMBOL_GPL(pci_block_user_cfg_access);
152
153 /**
154 * pci_unblock_user_cfg_access - Unblock userspace PCI config reads/writes
155 * @dev: pci device struct
156 *
157 * This function allows userspace PCI config accesses to resume.
158 */
159 void pci_unblock_user_cfg_access(struct pci_dev *dev)
160 {
161 unsigned long flags;
162
163 spin_lock_irqsave(&pci_lock, flags);
164
165 /* This indicates a problem in the caller, but we don't need
166 * to kill them, unlike a double-block above. */
167 WARN_ON(!dev->block_ucfg_access);
168
169 dev->block_ucfg_access = 0;
170 wake_up_all(&pci_ucfg_wait);
171 spin_unlock_irqrestore(&pci_lock, flags);
172 }
173 EXPORT_SYMBOL_GPL(pci_unblock_user_cfg_access);
174
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