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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 | ||
37bdfbbf SS |
54 | /* |
55 | * Macros for declaration and initialization of the kfifo datatype | |
56 | */ | |
57 | ||
58 | /* helper macro */ | |
59 | #define __kfifo_initializer(s, b) \ | |
60 | (struct kfifo) { \ | |
61 | .size = s, \ | |
62 | .in = 0, \ | |
63 | .out = 0, \ | |
64 | .buffer = b \ | |
65 | } | |
66 | ||
67 | /** | |
68 | * DECLARE_KFIFO - macro to declare a kfifo and the associated buffer | |
69 | * @name: name of the declared kfifo datatype | |
70 | * @size: size of the fifo buffer | |
71 | * | |
72 | * Note: the macro can be used inside struct or union declaration | |
73 | * Note: the macro creates two objects: | |
74 | * A kfifo object with the given name and a buffer for the kfifo | |
75 | * object named name##kfifo_buffer | |
76 | */ | |
77 | #define DECLARE_KFIFO(name, size) \ | |
78 | union { \ | |
79 | struct kfifo name; \ | |
80 | unsigned char name##kfifo_buffer[size + sizeof(struct kfifo)]; \ | |
81 | } | |
82 | ||
83 | /** | |
84 | * INIT_KFIFO - Initialize a kfifo declared by DECLARED_KFIFO | |
85 | * @name: name of the declared kfifo datatype | |
86 | * @size: size of the fifo buffer | |
87 | */ | |
88 | #define INIT_KFIFO(name) \ | |
89 | name = __kfifo_initializer(sizeof(name##kfifo_buffer) - \ | |
90 | sizeof(struct kfifo), name##kfifo_buffer) | |
91 | ||
92 | /** | |
93 | * DEFINE_KFIFO - macro to define and initialize a kfifo | |
94 | * @name: name of the declared kfifo datatype | |
95 | * @size: size of the fifo buffer | |
96 | * | |
97 | * Note: the macro can be used for global and local kfifo data type variables | |
98 | * Note: the macro creates two objects: | |
99 | * A kfifo object with the given name and a buffer for the kfifo | |
100 | * object named name##kfifo_buffer | |
101 | */ | |
102 | #define DEFINE_KFIFO(name, size) \ | |
103 | unsigned char name##kfifo_buffer[size]; \ | |
104 | struct kfifo name = __kfifo_initializer(size, name##kfifo_buffer) | |
105 | ||
106 | #undef __kfifo_initializer | |
107 | ||
45465487 | 108 | extern void kfifo_init(struct kfifo *fifo, unsigned char *buffer, |
c1e13f25 | 109 | unsigned int size); |
45465487 | 110 | extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size, |
c1e13f25 | 111 | gfp_t gfp_mask); |
1da177e4 | 112 | extern void kfifo_free(struct kfifo *fifo); |
9842c38e | 113 | extern unsigned int kfifo_in(struct kfifo *fifo, |
7acd72eb SS |
114 | const unsigned char *from, unsigned int len); |
115 | extern __must_check unsigned int kfifo_out(struct kfifo *fifo, | |
116 | unsigned char *to, unsigned int len); | |
1da177e4 | 117 | |
1da177e4 LT |
118 | /** |
119 | * kfifo_reset - removes the entire FIFO contents | |
120 | * @fifo: the fifo to be emptied. | |
121 | */ | |
122 | static inline void kfifo_reset(struct kfifo *fifo) | |
123 | { | |
e64c026d | 124 | fifo->in = fifo->out = 0; |
c1e13f25 SS |
125 | } |
126 | ||
37bdfbbf SS |
127 | /** |
128 | * kfifo_size - returns the size of the fifo in bytes | |
129 | * @fifo: the fifo to be used. | |
130 | */ | |
131 | static inline __must_check unsigned int kfifo_size(struct kfifo *fifo) | |
132 | { | |
133 | return fifo->size; | |
134 | } | |
135 | ||
c1e13f25 | 136 | /** |
e64c026d | 137 | * kfifo_len - returns the number of used bytes in the FIFO |
c1e13f25 SS |
138 | * @fifo: the fifo to be used. |
139 | */ | |
e64c026d | 140 | static inline unsigned int kfifo_len(struct kfifo *fifo) |
c1e13f25 SS |
141 | { |
142 | register unsigned int out; | |
1da177e4 | 143 | |
c1e13f25 SS |
144 | out = fifo->out; |
145 | smp_rmb(); | |
146 | return fifo->in - out; | |
1da177e4 LT |
147 | } |
148 | ||
37bdfbbf SS |
149 | /** |
150 | * kfifo_is_empty - returns true if the fifo is empty | |
151 | * @fifo: the fifo to be used. | |
152 | */ | |
153 | static inline __must_check int kfifo_is_empty(struct kfifo *fifo) | |
154 | { | |
155 | return fifo->in == fifo->out; | |
156 | } | |
157 | ||
158 | /** | |
159 | * kfifo_is_full - returns true if the fifo is full | |
160 | * @fifo: the fifo to be used. | |
161 | */ | |
162 | static inline __must_check int kfifo_is_full(struct kfifo *fifo) | |
163 | { | |
164 | return kfifo_len(fifo) == kfifo_size(fifo); | |
165 | } | |
166 | ||
167 | /** | |
168 | * kfifo_avail - returns the number of bytes available in the FIFO | |
169 | * @fifo: the fifo to be used. | |
170 | */ | |
171 | static inline __must_check unsigned int kfifo_avail(struct kfifo *fifo) | |
172 | { | |
173 | return kfifo_size(fifo) - kfifo_len(fifo); | |
174 | } | |
175 | ||
1da177e4 | 176 | /** |
7acd72eb | 177 | * kfifo_in_locked - puts some data into the FIFO using a spinlock for locking |
1da177e4 | 178 | * @fifo: the fifo to be used. |
c1e13f25 SS |
179 | * @from: the data to be added. |
180 | * @n: the length of the data to be added. | |
181 | * @lock: pointer to the spinlock to use for locking. | |
1da177e4 | 182 | * |
c1e13f25 | 183 | * This function copies at most @len bytes from the @from buffer into |
1da177e4 LT |
184 | * the FIFO depending on the free space, and returns the number of |
185 | * bytes copied. | |
186 | */ | |
9842c38e | 187 | static inline unsigned int kfifo_in_locked(struct kfifo *fifo, |
c1e13f25 | 188 | const unsigned char *from, unsigned int n, spinlock_t *lock) |
1da177e4 LT |
189 | { |
190 | unsigned long flags; | |
191 | unsigned int ret; | |
192 | ||
c1e13f25 | 193 | spin_lock_irqsave(lock, flags); |
1da177e4 | 194 | |
7acd72eb | 195 | ret = kfifo_in(fifo, from, n); |
1da177e4 | 196 | |
c1e13f25 | 197 | spin_unlock_irqrestore(lock, flags); |
1da177e4 LT |
198 | |
199 | return ret; | |
200 | } | |
201 | ||
202 | /** | |
7acd72eb | 203 | * kfifo_out_locked - gets some data from the FIFO using a spinlock for locking |
1da177e4 | 204 | * @fifo: the fifo to be used. |
c1e13f25 SS |
205 | * @to: where the data must be copied. |
206 | * @n: the size of the destination buffer. | |
207 | * @lock: pointer to the spinlock to use for locking. | |
1da177e4 | 208 | * |
72fd4a35 | 209 | * This function copies at most @len bytes from the FIFO into the |
c1e13f25 | 210 | * @to buffer and returns the number of copied bytes. |
1da177e4 | 211 | */ |
7acd72eb | 212 | static inline __must_check unsigned int kfifo_out_locked(struct kfifo *fifo, |
c1e13f25 | 213 | unsigned char *to, unsigned int n, spinlock_t *lock) |
1da177e4 LT |
214 | { |
215 | unsigned long flags; | |
216 | unsigned int ret; | |
217 | ||
c1e13f25 | 218 | spin_lock_irqsave(lock, flags); |
1da177e4 | 219 | |
7acd72eb | 220 | ret = kfifo_out(fifo, to, n); |
1da177e4 LT |
221 | |
222 | /* | |
223 | * optimization: if the FIFO is empty, set the indices to 0 | |
224 | * so we don't wrap the next time | |
225 | */ | |
37bdfbbf SS |
226 | if (kfifo_is_empty(fifo)) |
227 | kfifo_reset(fifo); | |
1da177e4 | 228 | |
c1e13f25 | 229 | spin_unlock_irqrestore(lock, flags); |
1da177e4 LT |
230 | |
231 | return ret; | |
232 | } | |
233 | ||
1da177e4 | 234 | #endif |