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Linux/arch/arm/kernel/dma.c

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  1 /*
  2  *  linux/arch/arm/kernel/dma.c
  3  *
  4  *  Copyright (C) 1995-2000 Russell King
  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 version 2 as
  8  * published by the Free Software Foundation.
  9  *
 10  *  Front-end to the DMA handling.  This handles the allocation/freeing
 11  *  of DMA channels, and provides a unified interface to the machines
 12  *  DMA facilities.
 13  */
 14 #include <linux/module.h>
 15 #include <linux/init.h>
 16 #include <linux/spinlock.h>
 17 #include <linux/errno.h>
 18 #include <linux/scatterlist.h>
 19 #include <linux/seq_file.h>
 20 #include <linux/proc_fs.h>
 21 
 22 #include <asm/dma.h>
 23 
 24 #include <asm/mach/dma.h>
 25 
 26 DEFINE_RAW_SPINLOCK(dma_spin_lock);
 27 EXPORT_SYMBOL(dma_spin_lock);
 28 
 29 static dma_t *dma_chan[MAX_DMA_CHANNELS];
 30 
 31 static inline dma_t *dma_channel(unsigned int chan)
 32 {
 33         if (chan >= MAX_DMA_CHANNELS)
 34                 return NULL;
 35 
 36         return dma_chan[chan];
 37 }
 38 
 39 int __init isa_dma_add(unsigned int chan, dma_t *dma)
 40 {
 41         if (!dma->d_ops)
 42                 return -EINVAL;
 43 
 44         sg_init_table(&dma->buf, 1);
 45 
 46         if (dma_chan[chan])
 47                 return -EBUSY;
 48         dma_chan[chan] = dma;
 49         return 0;
 50 }
 51 
 52 /*
 53  * Request DMA channel
 54  *
 55  * On certain platforms, we have to allocate an interrupt as well...
 56  */
 57 int request_dma(unsigned int chan, const char *device_id)
 58 {
 59         dma_t *dma = dma_channel(chan);
 60         int ret;
 61 
 62         if (!dma)
 63                 goto bad_dma;
 64 
 65         if (xchg(&dma->lock, 1) != 0)
 66                 goto busy;
 67 
 68         dma->device_id = device_id;
 69         dma->active    = 0;
 70         dma->invalid   = 1;
 71 
 72         ret = 0;
 73         if (dma->d_ops->request)
 74                 ret = dma->d_ops->request(chan, dma);
 75 
 76         if (ret)
 77                 xchg(&dma->lock, 0);
 78 
 79         return ret;
 80 
 81 bad_dma:
 82         pr_err("dma: trying to allocate DMA%d\n", chan);
 83         return -EINVAL;
 84 
 85 busy:
 86         return -EBUSY;
 87 }
 88 EXPORT_SYMBOL(request_dma);
 89 
 90 /*
 91  * Free DMA channel
 92  *
 93  * On certain platforms, we have to free interrupt as well...
 94  */
 95 void free_dma(unsigned int chan)
 96 {
 97         dma_t *dma = dma_channel(chan);
 98 
 99         if (!dma)
100                 goto bad_dma;
101 
102         if (dma->active) {
103                 pr_err("dma%d: freeing active DMA\n", chan);
104                 dma->d_ops->disable(chan, dma);
105                 dma->active = 0;
106         }
107 
108         if (xchg(&dma->lock, 0) != 0) {
109                 if (dma->d_ops->free)
110                         dma->d_ops->free(chan, dma);
111                 return;
112         }
113 
114         pr_err("dma%d: trying to free free DMA\n", chan);
115         return;
116 
117 bad_dma:
118         pr_err("dma: trying to free DMA%d\n", chan);
119 }
120 EXPORT_SYMBOL(free_dma);
121 
122 /* Set DMA Scatter-Gather list
123  */
124 void set_dma_sg (unsigned int chan, struct scatterlist *sg, int nr_sg)
125 {
126         dma_t *dma = dma_channel(chan);
127 
128         if (dma->active)
129                 pr_err("dma%d: altering DMA SG while DMA active\n", chan);
130 
131         dma->sg = sg;
132         dma->sgcount = nr_sg;
133         dma->invalid = 1;
134 }
135 EXPORT_SYMBOL(set_dma_sg);
136 
137 /* Set DMA address
138  *
139  * Copy address to the structure, and set the invalid bit
140  */
141 void __set_dma_addr (unsigned int chan, void *addr)
142 {
143         dma_t *dma = dma_channel(chan);
144 
145         if (dma->active)
146                 pr_err("dma%d: altering DMA address while DMA active\n", chan);
147 
148         dma->sg = NULL;
149         dma->addr = addr;
150         dma->invalid = 1;
151 }
152 EXPORT_SYMBOL(__set_dma_addr);
153 
154 /* Set DMA byte count
155  *
156  * Copy address to the structure, and set the invalid bit
157  */
158 void set_dma_count (unsigned int chan, unsigned long count)
159 {
160         dma_t *dma = dma_channel(chan);
161 
162         if (dma->active)
163                 pr_err("dma%d: altering DMA count while DMA active\n", chan);
164 
165         dma->sg = NULL;
166         dma->count = count;
167         dma->invalid = 1;
168 }
169 EXPORT_SYMBOL(set_dma_count);
170 
171 /* Set DMA direction mode
172  */
173 void set_dma_mode (unsigned int chan, unsigned int mode)
174 {
175         dma_t *dma = dma_channel(chan);
176 
177         if (dma->active)
178                 pr_err("dma%d: altering DMA mode while DMA active\n", chan);
179 
180         dma->dma_mode = mode;
181         dma->invalid = 1;
182 }
183 EXPORT_SYMBOL(set_dma_mode);
184 
185 /* Enable DMA channel
186  */
187 void enable_dma (unsigned int chan)
188 {
189         dma_t *dma = dma_channel(chan);
190 
191         if (!dma->lock)
192                 goto free_dma;
193 
194         if (dma->active == 0) {
195                 dma->active = 1;
196                 dma->d_ops->enable(chan, dma);
197         }
198         return;
199 
200 free_dma:
201         pr_err("dma%d: trying to enable free DMA\n", chan);
202         BUG();
203 }
204 EXPORT_SYMBOL(enable_dma);
205 
206 /* Disable DMA channel
207  */
208 void disable_dma (unsigned int chan)
209 {
210         dma_t *dma = dma_channel(chan);
211 
212         if (!dma->lock)
213                 goto free_dma;
214 
215         if (dma->active == 1) {
216                 dma->active = 0;
217                 dma->d_ops->disable(chan, dma);
218         }
219         return;
220 
221 free_dma:
222         pr_err("dma%d: trying to disable free DMA\n", chan);
223         BUG();
224 }
225 EXPORT_SYMBOL(disable_dma);
226 
227 /*
228  * Is the specified DMA channel active?
229  */
230 int dma_channel_active(unsigned int chan)
231 {
232         dma_t *dma = dma_channel(chan);
233         return dma->active;
234 }
235 EXPORT_SYMBOL(dma_channel_active);
236 
237 void set_dma_page(unsigned int chan, char pagenr)
238 {
239         pr_err("dma%d: trying to set_dma_page\n", chan);
240 }
241 EXPORT_SYMBOL(set_dma_page);
242 
243 void set_dma_speed(unsigned int chan, int cycle_ns)
244 {
245         dma_t *dma = dma_channel(chan);
246         int ret = 0;
247 
248         if (dma->d_ops->setspeed)
249                 ret = dma->d_ops->setspeed(chan, dma, cycle_ns);
250         dma->speed = ret;
251 }
252 EXPORT_SYMBOL(set_dma_speed);
253 
254 int get_dma_residue(unsigned int chan)
255 {
256         dma_t *dma = dma_channel(chan);
257         int ret = 0;
258 
259         if (dma->d_ops->residue)
260                 ret = dma->d_ops->residue(chan, dma);
261 
262         return ret;
263 }
264 EXPORT_SYMBOL(get_dma_residue);
265 
266 #ifdef CONFIG_PROC_FS
267 static int proc_dma_show(struct seq_file *m, void *v)
268 {
269         int i;
270 
271         for (i = 0 ; i < MAX_DMA_CHANNELS ; i++) {
272                 dma_t *dma = dma_channel(i);
273                 if (dma && dma->lock)
274                         seq_printf(m, "%2d: %s\n", i, dma->device_id);
275         }
276         return 0;
277 }
278 
279 static int proc_dma_open(struct inode *inode, struct file *file)
280 {
281         return single_open(file, proc_dma_show, NULL);
282 }
283 
284 static const struct file_operations proc_dma_operations = {
285         .open           = proc_dma_open,
286         .read           = seq_read,
287         .llseek         = seq_lseek,
288         .release        = single_release,
289 };
290 
291 static int __init proc_dma_init(void)
292 {
293         proc_create("dma", 0, NULL, &proc_dma_operations);
294         return 0;
295 }
296 
297 __initcall(proc_dma_init);
298 #endif
299 

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