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1da177e4 | 1 | /* |
45465487 | 2 | * A generic kernel FIFO implementation. |
1da177e4 | 3 | * |
45465487 | 4 | * Copyright (C) 2009 Stefani Seibold <stefani@seibold.net> |
1da177e4 LT |
5 | * Copyright (C) 2004 Stelian Pop <stelian@popies.net> |
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; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
20 | * | |
21 | */ | |
7acd72eb SS |
22 | |
23 | /* | |
24 | * Howto porting drivers to the new generic fifo API: | |
25 | * | |
26 | * - Modify the declaration of the "struct kfifo *" object into a | |
27 | * in-place "struct kfifo" object | |
28 | * - Init the in-place object with kfifo_alloc() or kfifo_init() | |
29 | * Note: The address of the in-place "struct kfifo" object must be | |
30 | * passed as the first argument to this functions | |
31 | * - Replace the use of __kfifo_put into kfifo_in and __kfifo_get | |
32 | * into kfifo_out | |
33 | * - Replace the use of kfifo_put into kfifo_in_locked and kfifo_get | |
34 | * into kfifo_out_locked | |
35 | * Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc | |
36 | * must be passed now to the kfifo_in_locked and kfifo_out_locked | |
37 | * as the last parameter. | |
38 | * - All formerly name __kfifo_* functions has been renamed into kfifo_* | |
39 | */ | |
40 | ||
1da177e4 LT |
41 | #ifndef _LINUX_KFIFO_H |
42 | #define _LINUX_KFIFO_H | |
43 | ||
1da177e4 LT |
44 | #include <linux/kernel.h> |
45 | #include <linux/spinlock.h> | |
46 | ||
47 | struct kfifo { | |
48 | unsigned char *buffer; /* the buffer holding the data */ | |
49 | unsigned int size; /* the size of the allocated buffer */ | |
50 | unsigned int in; /* data is added at offset (in % size) */ | |
51 | unsigned int out; /* data is extracted from off. (out % size) */ | |
1da177e4 LT |
52 | }; |
53 | ||
45465487 | 54 | extern void kfifo_init(struct kfifo *fifo, unsigned char *buffer, |
c1e13f25 | 55 | unsigned int size); |
45465487 | 56 | extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size, |
c1e13f25 | 57 | gfp_t gfp_mask); |
1da177e4 | 58 | extern void kfifo_free(struct kfifo *fifo); |
7acd72eb SS |
59 | extern __must_check unsigned int kfifo_in(struct kfifo *fifo, |
60 | const unsigned char *from, unsigned int len); | |
61 | extern __must_check unsigned int kfifo_out(struct kfifo *fifo, | |
62 | unsigned char *to, unsigned int len); | |
1da177e4 | 63 | |
1da177e4 LT |
64 | /** |
65 | * kfifo_reset - removes the entire FIFO contents | |
66 | * @fifo: the fifo to be emptied. | |
67 | */ | |
68 | static inline void kfifo_reset(struct kfifo *fifo) | |
69 | { | |
e64c026d | 70 | fifo->in = fifo->out = 0; |
c1e13f25 SS |
71 | } |
72 | ||
73 | /** | |
e64c026d | 74 | * kfifo_len - returns the number of used bytes in the FIFO |
c1e13f25 SS |
75 | * @fifo: the fifo to be used. |
76 | */ | |
e64c026d | 77 | static inline unsigned int kfifo_len(struct kfifo *fifo) |
c1e13f25 SS |
78 | { |
79 | register unsigned int out; | |
1da177e4 | 80 | |
c1e13f25 SS |
81 | out = fifo->out; |
82 | smp_rmb(); | |
83 | return fifo->in - out; | |
1da177e4 LT |
84 | } |
85 | ||
86 | /** | |
7acd72eb | 87 | * kfifo_in_locked - puts some data into the FIFO using a spinlock for locking |
1da177e4 | 88 | * @fifo: the fifo to be used. |
c1e13f25 SS |
89 | * @from: the data to be added. |
90 | * @n: the length of the data to be added. | |
91 | * @lock: pointer to the spinlock to use for locking. | |
1da177e4 | 92 | * |
c1e13f25 | 93 | * This function copies at most @len bytes from the @from buffer into |
1da177e4 LT |
94 | * the FIFO depending on the free space, and returns the number of |
95 | * bytes copied. | |
96 | */ | |
7acd72eb | 97 | static inline __must_check unsigned int kfifo_in_locked(struct kfifo *fifo, |
c1e13f25 | 98 | const unsigned char *from, unsigned int n, spinlock_t *lock) |
1da177e4 LT |
99 | { |
100 | unsigned long flags; | |
101 | unsigned int ret; | |
102 | ||
c1e13f25 | 103 | spin_lock_irqsave(lock, flags); |
1da177e4 | 104 | |
7acd72eb | 105 | ret = kfifo_in(fifo, from, n); |
1da177e4 | 106 | |
c1e13f25 | 107 | spin_unlock_irqrestore(lock, flags); |
1da177e4 LT |
108 | |
109 | return ret; | |
110 | } | |
111 | ||
112 | /** | |
7acd72eb | 113 | * kfifo_out_locked - gets some data from the FIFO using a spinlock for locking |
1da177e4 | 114 | * @fifo: the fifo to be used. |
c1e13f25 SS |
115 | * @to: where the data must be copied. |
116 | * @n: the size of the destination buffer. | |
117 | * @lock: pointer to the spinlock to use for locking. | |
1da177e4 | 118 | * |
72fd4a35 | 119 | * This function copies at most @len bytes from the FIFO into the |
c1e13f25 | 120 | * @to buffer and returns the number of copied bytes. |
1da177e4 | 121 | */ |
7acd72eb | 122 | static inline __must_check unsigned int kfifo_out_locked(struct kfifo *fifo, |
c1e13f25 | 123 | unsigned char *to, unsigned int n, spinlock_t *lock) |
1da177e4 LT |
124 | { |
125 | unsigned long flags; | |
126 | unsigned int ret; | |
127 | ||
c1e13f25 | 128 | spin_lock_irqsave(lock, flags); |
1da177e4 | 129 | |
7acd72eb | 130 | ret = kfifo_out(fifo, to, n); |
1da177e4 LT |
131 | |
132 | /* | |
133 | * optimization: if the FIFO is empty, set the indices to 0 | |
134 | * so we don't wrap the next time | |
135 | */ | |
136 | if (fifo->in == fifo->out) | |
137 | fifo->in = fifo->out = 0; | |
138 | ||
c1e13f25 | 139 | spin_unlock_irqrestore(lock, flags); |
1da177e4 LT |
140 | |
141 | return ret; | |
142 | } | |
143 | ||
1da177e4 | 144 | #endif |