s2io: Fixes in updating skb->truesize and code cleanup.
[linux-2.6] / drivers / pci / access.c
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);