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e5711071 PH |
1 | /* |
2 | * DMA-able FIFO implementation | |
3 | * | |
4 | * Copyright (C) 2012 Peter Hurley <peter@hurleysoftware.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
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 | |
14 | * GNU 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 Foundation, | |
18 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
19 | */ | |
20 | ||
21 | #include <linux/kernel.h> | |
22 | #include <linux/slab.h> | |
23 | #include <linux/list.h> | |
24 | #include <linux/bug.h> | |
25 | ||
26 | #include "dma_fifo.h" | |
27 | ||
28 | #ifdef DEBUG_TRACING | |
29 | #define df_trace(s, args...) pr_debug(s, ##args) | |
30 | #else | |
31 | #define df_trace(s, args...) | |
32 | #endif | |
33 | ||
34 | #define FAIL(fifo, condition, format...) ({ \ | |
35 | fifo->corrupt = !!(condition); \ | |
1b94242a | 36 | WARN(fifo->corrupt, format); \ |
e5711071 PH |
37 | }) |
38 | ||
39 | /* | |
40 | * private helper fn to determine if check is in open interval (lo,hi) | |
41 | */ | |
42 | static bool addr_check(unsigned check, unsigned lo, unsigned hi) | |
43 | { | |
44 | return check - (lo + 1) < (hi - 1) - lo; | |
45 | } | |
46 | ||
47 | /** | |
48 | * dma_fifo_init: initialize the fifo to a valid but inoperative state | |
49 | * @fifo: address of in-place "struct dma_fifo" object | |
50 | */ | |
51 | void dma_fifo_init(struct dma_fifo *fifo) | |
52 | { | |
53 | memset(fifo, 0, sizeof(*fifo)); | |
54 | INIT_LIST_HEAD(&fifo->pending); | |
55 | } | |
56 | ||
57 | /** | |
58 | * dma_fifo_alloc - initialize and allocate dma_fifo | |
59 | * @fifo: address of in-place "struct dma_fifo" object | |
60 | * @size: 'apparent' size, in bytes, of fifo | |
61 | * @align: dma alignment to maintain (should be at least cpu cache alignment), | |
62 | * must be power of 2 | |
63 | * @tx_limit: maximum # of bytes transmissable per dma (rounded down to | |
64 | * multiple of alignment, but at least align size) | |
65 | * @open_limit: maximum # of outstanding dma transactions allowed | |
66 | * @gfp_mask: get_free_pages mask, passed to kmalloc() | |
67 | * | |
68 | * The 'apparent' size will be rounded up to next greater aligned size. | |
69 | * Returns 0 if no error, otherwise an error code | |
70 | */ | |
71 | int dma_fifo_alloc(struct dma_fifo *fifo, int size, unsigned align, | |
72 | int tx_limit, int open_limit, gfp_t gfp_mask) | |
73 | { | |
74 | int capacity; | |
75 | ||
76 | if (!is_power_of_2(align) || size < 0) | |
77 | return -EINVAL; | |
78 | ||
79 | size = round_up(size, align); | |
80 | capacity = size + align * open_limit + align * DMA_FIFO_GUARD; | |
81 | fifo->data = kmalloc(capacity, gfp_mask); | |
82 | if (!fifo->data) | |
83 | return -ENOMEM; | |
84 | ||
85 | fifo->in = 0; | |
86 | fifo->out = 0; | |
87 | fifo->done = 0; | |
88 | fifo->size = size; | |
89 | fifo->avail = size; | |
90 | fifo->align = align; | |
91 | fifo->tx_limit = max_t(int, round_down(tx_limit, align), align); | |
92 | fifo->open = 0; | |
93 | fifo->open_limit = open_limit; | |
94 | fifo->guard = size + align * open_limit; | |
95 | fifo->capacity = capacity; | |
96 | fifo->corrupt = 0; | |
97 | ||
98 | return 0; | |
99 | } | |
100 | ||
101 | /** | |
102 | * dma_fifo_free - frees the fifo | |
103 | * @fifo: address of in-place "struct dma_fifo" to free | |
104 | * | |
105 | * Also reinits the fifo to a valid but inoperative state. This | |
106 | * allows the fifo to be reused with a different target requiring | |
107 | * different fifo parameters. | |
108 | */ | |
109 | void dma_fifo_free(struct dma_fifo *fifo) | |
110 | { | |
111 | struct dma_pending *pending, *next; | |
112 | ||
113 | if (fifo->data == NULL) | |
114 | return; | |
115 | ||
116 | list_for_each_entry_safe(pending, next, &fifo->pending, link) | |
117 | list_del_init(&pending->link); | |
118 | kfree(fifo->data); | |
119 | fifo->data = NULL; | |
120 | } | |
121 | ||
122 | /** | |
123 | * dma_fifo_reset - dumps the fifo contents and reinits for reuse | |
124 | * @fifo: address of in-place "struct dma_fifo" to reset | |
125 | */ | |
126 | void dma_fifo_reset(struct dma_fifo *fifo) | |
127 | { | |
128 | struct dma_pending *pending, *next; | |
129 | ||
130 | if (fifo->data == NULL) | |
131 | return; | |
132 | ||
133 | list_for_each_entry_safe(pending, next, &fifo->pending, link) | |
134 | list_del_init(&pending->link); | |
135 | fifo->in = 0; | |
136 | fifo->out = 0; | |
137 | fifo->done = 0; | |
138 | fifo->avail = fifo->size; | |
139 | fifo->open = 0; | |
140 | fifo->corrupt = 0; | |
141 | } | |
142 | ||
143 | /** | |
144 | * dma_fifo_in - copies data into the fifo | |
145 | * @fifo: address of in-place "struct dma_fifo" to write to | |
146 | * @src: buffer to copy from | |
147 | * @n: # of bytes to copy | |
148 | * | |
149 | * Returns the # of bytes actually copied, which can be less than requested if | |
150 | * the fifo becomes full. If < 0, return is error code. | |
151 | */ | |
152 | int dma_fifo_in(struct dma_fifo *fifo, const void *src, int n) | |
153 | { | |
154 | int ofs, l; | |
155 | ||
156 | if (fifo->data == NULL) | |
157 | return -ENOENT; | |
158 | if (fifo->corrupt) | |
159 | return -ENXIO; | |
160 | ||
161 | if (n > fifo->avail) | |
162 | n = fifo->avail; | |
163 | if (n <= 0) | |
164 | return 0; | |
165 | ||
166 | ofs = fifo->in % fifo->capacity; | |
167 | l = min(n, fifo->capacity - ofs); | |
168 | memcpy(fifo->data + ofs, src, l); | |
169 | memcpy(fifo->data, src + l, n - l); | |
170 | ||
171 | if (FAIL(fifo, addr_check(fifo->done, fifo->in, fifo->in + n) || | |
172 | fifo->avail < n, | |
173 | "fifo corrupt: in:%u out:%u done:%u n:%d avail:%d", | |
174 | fifo->in, fifo->out, fifo->done, n, fifo->avail)) | |
175 | return -ENXIO; | |
176 | ||
177 | fifo->in += n; | |
178 | fifo->avail -= n; | |
179 | ||
180 | df_trace("in:%u out:%u done:%u n:%d avail:%d", fifo->in, fifo->out, | |
181 | fifo->done, n, fifo->avail); | |
182 | ||
183 | return n; | |
184 | } | |
185 | ||
186 | /** | |
187 | * dma_fifo_out_pend - gets address/len of next avail read and marks as pended | |
188 | * @fifo: address of in-place "struct dma_fifo" to read from | |
189 | * @pended: address of structure to fill with read address/len | |
190 | * The data/len fields will be NULL/0 if no dma is pended. | |
191 | * | |
192 | * Returns the # of used bytes remaining in fifo (ie, if > 0, more data | |
193 | * remains in the fifo that was not pended). If < 0, return is error code. | |
194 | */ | |
195 | int dma_fifo_out_pend(struct dma_fifo *fifo, struct dma_pending *pended) | |
196 | { | |
197 | unsigned len, n, ofs, l, limit; | |
198 | ||
199 | if (fifo->data == NULL) | |
200 | return -ENOENT; | |
201 | if (fifo->corrupt) | |
202 | return -ENXIO; | |
203 | ||
204 | pended->len = 0; | |
205 | pended->data = NULL; | |
206 | pended->out = fifo->out; | |
207 | ||
208 | len = fifo->in - fifo->out; | |
209 | if (!len) | |
210 | return -ENODATA; | |
211 | if (fifo->open == fifo->open_limit) | |
212 | return -EAGAIN; | |
213 | ||
214 | n = len; | |
215 | ofs = fifo->out % fifo->capacity; | |
216 | l = fifo->capacity - ofs; | |
217 | limit = min_t(unsigned, l, fifo->tx_limit); | |
218 | if (n > limit) { | |
219 | n = limit; | |
220 | fifo->out += limit; | |
221 | } else if (ofs + n > fifo->guard) { | |
222 | fifo->out += l; | |
223 | fifo->in = fifo->out; | |
224 | } else { | |
225 | fifo->out += round_up(n, fifo->align); | |
226 | fifo->in = fifo->out; | |
227 | } | |
228 | ||
229 | df_trace("in: %u out: %u done: %u n: %d len: %u avail: %d", fifo->in, | |
230 | fifo->out, fifo->done, n, len, fifo->avail); | |
231 | ||
232 | pended->len = n; | |
233 | pended->data = fifo->data + ofs; | |
234 | pended->next = fifo->out; | |
235 | list_add_tail(&pended->link, &fifo->pending); | |
236 | ++fifo->open; | |
237 | ||
238 | if (FAIL(fifo, fifo->open > fifo->open_limit, | |
239 | "past open limit:%d (limit:%d)", | |
240 | fifo->open, fifo->open_limit)) | |
241 | return -ENXIO; | |
242 | if (FAIL(fifo, fifo->out & (fifo->align - 1), | |
243 | "fifo out unaligned:%u (align:%u)", | |
244 | fifo->out, fifo->align)) | |
245 | return -ENXIO; | |
246 | ||
247 | return len - n; | |
248 | } | |
249 | ||
250 | /** | |
251 | * dma_fifo_out_complete - marks pended dma as completed | |
252 | * @fifo: address of in-place "struct dma_fifo" which was read from | |
253 | * @complete: address of structure for previously pended dma to mark completed | |
254 | */ | |
255 | int dma_fifo_out_complete(struct dma_fifo *fifo, struct dma_pending *complete) | |
256 | { | |
257 | struct dma_pending *pending, *next, *tmp; | |
258 | ||
259 | if (fifo->data == NULL) | |
260 | return -ENOENT; | |
261 | if (fifo->corrupt) | |
262 | return -ENXIO; | |
263 | if (list_empty(&fifo->pending) && fifo->open == 0) | |
264 | return -EINVAL; | |
265 | ||
266 | if (FAIL(fifo, list_empty(&fifo->pending) != (fifo->open == 0), | |
267 | "pending list disagrees with open count:%d", | |
268 | fifo->open)) | |
269 | return -ENXIO; | |
270 | ||
271 | tmp = complete->data; | |
272 | *tmp = *complete; | |
273 | list_replace(&complete->link, &tmp->link); | |
274 | dp_mark_completed(tmp); | |
275 | ||
276 | /* Only update the fifo in the original pended order */ | |
277 | list_for_each_entry_safe(pending, next, &fifo->pending, link) { | |
278 | if (!dp_is_completed(pending)) { | |
279 | df_trace("still pending: saved out: %u len: %d", | |
280 | pending->out, pending->len); | |
281 | break; | |
282 | } | |
283 | ||
284 | if (FAIL(fifo, pending->out != fifo->done || | |
285 | addr_check(fifo->in, fifo->done, pending->next), | |
286 | "in:%u out:%u done:%u saved:%u next:%u", | |
287 | fifo->in, fifo->out, fifo->done, pending->out, | |
288 | pending->next)) | |
289 | return -ENXIO; | |
290 | ||
291 | list_del_init(&pending->link); | |
292 | fifo->done = pending->next; | |
293 | fifo->avail += pending->len; | |
294 | --fifo->open; | |
295 | ||
296 | df_trace("in: %u out: %u done: %u len: %u avail: %d", fifo->in, | |
297 | fifo->out, fifo->done, pending->len, fifo->avail); | |
298 | } | |
299 | ||
300 | if (FAIL(fifo, fifo->open < 0, "open dma:%d < 0", fifo->open)) | |
301 | return -ENXIO; | |
302 | if (FAIL(fifo, fifo->avail > fifo->size, "fifo avail:%d > size:%d", | |
303 | fifo->avail, fifo->size)) | |
304 | return -ENXIO; | |
305 | ||
306 | return 0; | |
307 | } |