arch/arm/kernel/dma.c

   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/slab.h>
  16 #include <linux/mman.h>
  17 #include <linux/init.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/errno.h>
  20
  21 #include <asm/dma.h>
  22
  23 #include <asm/mach/dma.h>
  24
  25 DEFINE_SPINLOCK(dma_spin_lock);
  26
  27 #if MAX_DMA_CHANNELS > 0
  28
  29 static dma_t dma_chan[MAX_DMA_CHANNELS];
  30
  31 /*
  32  * Get dma list for /proc/dma
  33  */
  34 int get_dma_list(char *buf)
  35 {
  36         dma_t *dma;
  37         char *p = buf;
  38         int i;
  39
  40         for (i = 0, dma = dma_chan; i < MAX_DMA_CHANNELS; i++, dma++)
  41                 if (dma->lock)
  42                         p += sprintf(p, "%2d: %14s %s\n", i,
  43                                      dma->d_ops->type, dma->device_id);
  44
  45         return p - buf;
  46 }
  47
  48 /*
  49  * Request DMA channel
  50  *
  51  * On certain platforms, we have to allocate an interrupt as well...
  52  */
  53 int request_dma(dmach_t channel, const char *device_id)
  54 {
  55         dma_t *dma = dma_chan + channel;
  56         int ret;
  57
  58         if (channel >= MAX_DMA_CHANNELS || !dma->d_ops)
  59                 goto bad_dma;
  60
  61         if (xchg(&dma->lock, 1) != 0)
  62                 goto busy;
  63
  64         dma->device_id = device_id;
  65         dma->active    = 0;
  66         dma->invalid   = 1;
  67
  68         ret = 0;
  69         if (dma->d_ops->request)
  70                 ret = dma->d_ops->request(channel, dma);
  71
  72         if (ret)
  73                 xchg(&dma->lock, 0);
  74
  75         return ret;
  76
  77 bad_dma:
  78         printk(KERN_ERR "dma: trying to allocate DMA%d\n", channel);
  79         return -EINVAL;
  80
  81 busy:
  82         return -EBUSY;
  83 }
  84
  85 /*
  86  * Free DMA channel
  87  *
  88  * On certain platforms, we have to free interrupt as well...
  89  */
  90 void free_dma(dmach_t channel)
  91 {
  92         dma_t *dma = dma_chan + channel;
  93
  94         if (channel >= MAX_DMA_CHANNELS || !dma->d_ops)
  95                 goto bad_dma;
  96
  97         if (dma->active) {
  98                 printk(KERN_ERR "dma%d: freeing active DMA\n", channel);
  99                 dma->d_ops->disable(channel, dma);
 100                 dma->active = 0;
 101         }
 102
 103         if (xchg(&dma->lock, 0) != 0) {
 104                 if (dma->d_ops->free)
 105                         dma->d_ops->free(channel, dma);
 106                 return;
 107         }
 108
 109         printk(KERN_ERR "dma%d: trying to free free DMA\n", channel);
 110         return;
 111
 112 bad_dma:
 113         printk(KERN_ERR "dma: trying to free DMA%d\n", channel);
 114 }
 115
 116 /* Set DMA Scatter-Gather list
 117  */
 118 void set_dma_sg (dmach_t channel, struct scatterlist *sg, int nr_sg)
 119 {
 120         dma_t *dma = dma_chan + channel;
 121
 122         if (dma->active)
 123                 printk(KERN_ERR "dma%d: altering DMA SG while "
 124                        "DMA active\n", channel);
 125
 126         dma->sg = sg;
 127         dma->sgcount = nr_sg;
 128         dma->using_sg = 1;
 129         dma->invalid = 1;
 130 }
 131
 132 /* Set DMA address
 133  *
 134  * Copy address to the structure, and set the invalid bit
 135  */
 136 void set_dma_addr (dmach_t channel, unsigned long physaddr)
 137 {
 138         dma_t *dma = dma_chan + channel;
 139
 140         if (dma->active)
 141                 printk(KERN_ERR "dma%d: altering DMA address while "
 142                        "DMA active\n", channel);
 143
 144         dma->sg = &dma->buf;
 145         dma->sgcount = 1;
 146         dma->buf.__address = bus_to_virt(physaddr);
 147         dma->using_sg = 0;
 148         dma->invalid = 1;
 149 }
 150
 151 /* Set DMA byte count
 152  *
 153  * Copy address to the structure, and set the invalid bit
 154  */
 155 void set_dma_count (dmach_t channel, unsigned long count)
 156 {
 157         dma_t *dma = dma_chan + channel;
 158
 159         if (dma->active)
 160                 printk(KERN_ERR "dma%d: altering DMA count while "
 161                        "DMA active\n", channel);
 162
 163         dma->sg = &dma->buf;
 164         dma->sgcount = 1;
 165         dma->buf.length = count;
 166         dma->using_sg = 0;
 167         dma->invalid = 1;
 168 }
 169
 170 /* Set DMA direction mode
 171  */
 172 void set_dma_mode (dmach_t channel, dmamode_t mode)
 173 {
 174         dma_t *dma = dma_chan + channel;
 175
 176         if (dma->active)
 177                 printk(KERN_ERR "dma%d: altering DMA mode while "
 178                        "DMA active\n", channel);
 179
 180         dma->dma_mode = mode;
 181         dma->invalid = 1;
 182 }
 183
 184 /* Enable DMA channel
 185  */
 186 void enable_dma (dmach_t channel)
 187 {
 188         dma_t *dma = dma_chan + channel;
 189
 190         if (!dma->lock)
 191                 goto free_dma;
 192
 193         if (dma->active == 0) {
 194                 dma->active = 1;
 195                 dma->d_ops->enable(channel, dma);
 196         }
 197         return;
 198
 199 free_dma:
 200         printk(KERN_ERR "dma%d: trying to enable free DMA\n", channel);
 201         BUG();
 202 }
 203
 204 /* Disable DMA channel
 205  */
 206 void disable_dma (dmach_t channel)
 207 {
 208         dma_t *dma = dma_chan + channel;
 209
 210         if (!dma->lock)
 211                 goto free_dma;
 212
 213         if (dma->active == 1) {
 214                 dma->active = 0;
 215                 dma->d_ops->disable(channel, dma);
 216         }
 217         return;
 218
 219 free_dma:
 220         printk(KERN_ERR "dma%d: trying to disable free DMA\n", channel);
 221         BUG();
 222 }
 223
 224 /*
 225  * Is the specified DMA channel active?
 226  */
 227 int dma_channel_active(dmach_t channel)
 228 {
 229         return dma_chan[channel].active;
 230 }
 231
 232 void set_dma_page(dmach_t channel, char pagenr)
 233 {
 234         printk(KERN_ERR "dma%d: trying to set_dma_page\n", channel);
 235 }
 236
 237 void set_dma_speed(dmach_t channel, int cycle_ns)
 238 {
 239         dma_t *dma = dma_chan + channel;
 240         int ret = 0;
 241
 242         if (dma->d_ops->setspeed)
 243                 ret = dma->d_ops->setspeed(channel, dma, cycle_ns);
 244         dma->speed = ret;
 245 }
 246
 247 int get_dma_residue(dmach_t channel)
 248 {
 249         dma_t *dma = dma_chan + channel;
 250         int ret = 0;
 251
 252         if (dma->d_ops->residue)
 253                 ret = dma->d_ops->residue(channel, dma);
 254
 255         return ret;
 256 }
 257
 258 void __init init_dma(void)
 259 {
 260         arch_dma_init(dma_chan);
 261 }
 262
 263 #else
 264
 265 int request_dma(dmach_t channel, const char *device_id)
 266 {
 267         return -EINVAL;
 268 }
 269
 270 int get_dma_residue(dmach_t channel)
 271 {
 272         return 0;
 273 }
 274
 275 #define GLOBAL_ALIAS(_a,_b) asm (".set " #_a "," #_b "; .globl " #_a)
 276 GLOBAL_ALIAS(disable_dma, get_dma_residue);
 277 GLOBAL_ALIAS(enable_dma, get_dma_residue);
 278 GLOBAL_ALIAS(free_dma, get_dma_residue);
 279 GLOBAL_ALIAS(get_dma_list, get_dma_residue);
 280 GLOBAL_ALIAS(set_dma_mode, get_dma_residue);
 281 GLOBAL_ALIAS(set_dma_page, get_dma_residue);
 282 GLOBAL_ALIAS(set_dma_count, get_dma_residue);
 283 GLOBAL_ALIAS(set_dma_addr, get_dma_residue);
 284 GLOBAL_ALIAS(set_dma_sg, get_dma_residue);
 285 GLOBAL_ALIAS(set_dma_speed, get_dma_residue);
 286 GLOBAL_ALIAS(init_dma, get_dma_residue);
 287
 288 #endif
 289
 290 EXPORT_SYMBOL(request_dma);
 291 EXPORT_SYMBOL(free_dma);
 292 EXPORT_SYMBOL(enable_dma);
 293 EXPORT_SYMBOL(disable_dma);
 294 EXPORT_SYMBOL(set_dma_addr);
 295 EXPORT_SYMBOL(set_dma_count);
 296 EXPORT_SYMBOL(set_dma_mode);
 297 EXPORT_SYMBOL(set_dma_page);
 298 EXPORT_SYMBOL(get_dma_residue);
 299 EXPORT_SYMBOL(set_dma_sg);
 300 EXPORT_SYMBOL(set_dma_speed);
 301
 302 EXPORT_SYMBOL(dma_spin_lock);