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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/arm/kernel/dma.c
4 *
5 * Copyright (C) 1995-2000 Russell King
6 *
7 * Front-end to the DMA handling. This handles the allocation/freeing
8 * of DMA channels, and provides a unified interface to the machines
9 * DMA facilities.
10 */
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/spinlock.h>
14#include <linux/errno.h>
15#include <linux/scatterlist.h>
16#include <linux/seq_file.h>
17#include <linux/proc_fs.h>
18
19#include <asm/dma.h>
20
21#include <asm/mach/dma.h>
22
23DEFINE_RAW_SPINLOCK(dma_spin_lock);
24EXPORT_SYMBOL(dma_spin_lock);
25
26static dma_t *dma_chan[MAX_DMA_CHANNELS];
27
28static inline dma_t *dma_channel(unsigned int chan)
29{
30 if (chan >= MAX_DMA_CHANNELS)
31 return NULL;
32
33 return dma_chan[chan];
34}
35
36int __init isa_dma_add(unsigned int chan, dma_t *dma)
37{
38 if (!dma->d_ops)
39 return -EINVAL;
40
41 sg_init_table(&dma->buf, 1);
42
43 if (dma_chan[chan])
44 return -EBUSY;
45 dma_chan[chan] = dma;
46 return 0;
47}
48
49/*
50 * Request DMA channel
51 *
52 * On certain platforms, we have to allocate an interrupt as well...
53 */
54int request_dma(unsigned int chan, const char *device_id)
55{
56 dma_t *dma = dma_channel(chan);
57 int ret;
58
59 if (!dma)
60 goto bad_dma;
61
62 if (xchg(&dma->lock, 1) != 0)
63 goto busy;
64
65 dma->device_id = device_id;
66 dma->active = 0;
67 dma->invalid = 1;
68
69 ret = 0;
70 if (dma->d_ops->request)
71 ret = dma->d_ops->request(chan, dma);
72
73 if (ret)
74 xchg(&dma->lock, 0);
75
76 return ret;
77
78bad_dma:
79 pr_err("dma: trying to allocate DMA%d\n", chan);
80 return -EINVAL;
81
82busy:
83 return -EBUSY;
84}
85EXPORT_SYMBOL(request_dma);
86
87/*
88 * Free DMA channel
89 *
90 * On certain platforms, we have to free interrupt as well...
91 */
92void free_dma(unsigned int chan)
93{
94 dma_t *dma = dma_channel(chan);
95
96 if (!dma)
97 goto bad_dma;
98
99 if (dma->active) {
100 pr_err("dma%d: freeing active DMA\n", chan);
101 dma->d_ops->disable(chan, dma);
102 dma->active = 0;
103 }
104
105 if (xchg(&dma->lock, 0) != 0) {
106 if (dma->d_ops->free)
107 dma->d_ops->free(chan, dma);
108 return;
109 }
110
111 pr_err("dma%d: trying to free free DMA\n", chan);
112 return;
113
114bad_dma:
115 pr_err("dma: trying to free DMA%d\n", chan);
116}
117EXPORT_SYMBOL(free_dma);
118
119/* Set DMA Scatter-Gather list
120 */
121void set_dma_sg (unsigned int chan, struct scatterlist *sg, int nr_sg)
122{
123 dma_t *dma = dma_channel(chan);
124
125 if (dma->active)
126 pr_err("dma%d: altering DMA SG while DMA active\n", chan);
127
128 dma->sg = sg;
129 dma->sgcount = nr_sg;
130 dma->invalid = 1;
131}
132EXPORT_SYMBOL(set_dma_sg);
133
134/* Set DMA address
135 *
136 * Copy address to the structure, and set the invalid bit
137 */
138void __set_dma_addr (unsigned int chan, void *addr)
139{
140 dma_t *dma = dma_channel(chan);
141
142 if (dma->active)
143 pr_err("dma%d: altering DMA address while DMA active\n", chan);
144
145 dma->sg = NULL;
146 dma->addr = addr;
147 dma->invalid = 1;
148}
149EXPORT_SYMBOL(__set_dma_addr);
150
151/* Set DMA byte count
152 *
153 * Copy address to the structure, and set the invalid bit
154 */
155void set_dma_count (unsigned int chan, unsigned long count)
156{
157 dma_t *dma = dma_channel(chan);
158
159 if (dma->active)
160 pr_err("dma%d: altering DMA count while DMA active\n", chan);
161
162 dma->sg = NULL;
163 dma->count = count;
164 dma->invalid = 1;
165}
166EXPORT_SYMBOL(set_dma_count);
167
168/* Set DMA direction mode
169 */
170void set_dma_mode (unsigned int chan, unsigned int mode)
171{
172 dma_t *dma = dma_channel(chan);
173
174 if (dma->active)
175 pr_err("dma%d: altering DMA mode while DMA active\n", chan);
176
177 dma->dma_mode = mode;
178 dma->invalid = 1;
179}
180EXPORT_SYMBOL(set_dma_mode);
181
182/* Enable DMA channel
183 */
184void enable_dma (unsigned int chan)
185{
186 dma_t *dma = dma_channel(chan);
187
188 if (!dma->lock)
189 goto free_dma;
190
191 if (dma->active == 0) {
192 dma->active = 1;
193 dma->d_ops->enable(chan, dma);
194 }
195 return;
196
197free_dma:
198 pr_err("dma%d: trying to enable free DMA\n", chan);
199 BUG();
200}
201EXPORT_SYMBOL(enable_dma);
202
203/* Disable DMA channel
204 */
205void disable_dma (unsigned int chan)
206{
207 dma_t *dma = dma_channel(chan);
208
209 if (!dma->lock)
210 goto free_dma;
211
212 if (dma->active == 1) {
213 dma->active = 0;
214 dma->d_ops->disable(chan, dma);
215 }
216 return;
217
218free_dma:
219 pr_err("dma%d: trying to disable free DMA\n", chan);
220 BUG();
221}
222EXPORT_SYMBOL(disable_dma);
223
224/*
225 * Is the specified DMA channel active?
226 */
227int dma_channel_active(unsigned int chan)
228{
229 dma_t *dma = dma_channel(chan);
230 return dma->active;
231}
232EXPORT_SYMBOL(dma_channel_active);
233
234void set_dma_page(unsigned int chan, char pagenr)
235{
236 pr_err("dma%d: trying to set_dma_page\n", chan);
237}
238EXPORT_SYMBOL(set_dma_page);
239
240void set_dma_speed(unsigned int chan, int cycle_ns)
241{
242 dma_t *dma = dma_channel(chan);
243 int ret = 0;
244
245 if (dma->d_ops->setspeed)
246 ret = dma->d_ops->setspeed(chan, dma, cycle_ns);
247 dma->speed = ret;
248}
249EXPORT_SYMBOL(set_dma_speed);
250
251int get_dma_residue(unsigned int chan)
252{
253 dma_t *dma = dma_channel(chan);
254 int ret = 0;
255
256 if (dma->d_ops->residue)
257 ret = dma->d_ops->residue(chan, dma);
258
259 return ret;
260}
261EXPORT_SYMBOL(get_dma_residue);
262
263#ifdef CONFIG_PROC_FS
264static int proc_dma_show(struct seq_file *m, void *v)
265{
266 int i;
267
268 for (i = 0 ; i < MAX_DMA_CHANNELS ; i++) {
269 dma_t *dma = dma_channel(i);
270 if (dma && dma->lock)
271 seq_printf(m, "%2d: %s\n", i, dma->device_id);
272 }
273 return 0;
274}
275
276static int __init proc_dma_init(void)
277{
278 proc_create_single("dma", 0, NULL, proc_dma_show);
279 return 0;
280}
281
282__initcall(proc_dma_init);
283#endif