arch/arm26/kernel/dma.c

   1 /*
   2  *  linux/arch/arm26/kernel/dma.c
   3  *
   4  *  Copyright (C) 1995-2000 Russell King
   5  *                2003      Ian Molton
   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 version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  *  Front-end to the DMA handling.  This handles the allocation/freeing
  12  *  of DMA channels, and provides a unified interface to the machines
  13  *  DMA facilities.
  14  */
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/sched.h>
  18 #include <linux/mman.h>
  19 #include <linux/init.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/errno.h>
  22
  23 #include <asm/dma.h>
  24
  25 DEFINE_SPINLOCK(dma_spin_lock);
  26
  27 static dma_t dma_chan[MAX_DMA_CHANNELS];
  28
  29 /*
  30  * Get dma list for /proc/dma
  31  */
  32 int get_dma_list(char *buf)
  33 {
  34         dma_t *dma;
  35         char *p = buf;
  36         int i;
  37
  38         for (i = 0, dma = dma_chan; i < MAX_DMA_CHANNELS; i++, dma++)
  39                 if (dma->lock)
  40                         p += sprintf(p, "%2d: %14s %s\n", i,
  41                                      dma->d_ops->type, dma->device_id);
  42
  43         return p - buf;
  44 }
  45
  46 /*
  47  * Request DMA channel
  48  *
  49  * On certain platforms, we have to allocate an interrupt as well...
  50  */
  51 int request_dma(dmach_t channel, const char *device_id)
  52 {
  53         dma_t *dma = dma_chan + channel;
  54         int ret;
  55
  56         if (channel >= MAX_DMA_CHANNELS || !dma->d_ops)
  57                 goto bad_dma;
  58
  59         if (xchg(&dma->lock, 1) != 0)
  60                 goto busy;
  61
  62         dma->device_id = device_id;
  63         dma->active    = 0;
  64         dma->invalid   = 1;
  65
  66         ret = 0;
  67         if (dma->d_ops->request)
  68                 ret = dma->d_ops->request(channel, dma);
  69
  70         if (ret)
  71                 xchg(&dma->lock, 0);
  72
  73         return ret;
  74
  75 bad_dma:
  76         printk(KERN_ERR "dma: trying to allocate DMA%d\n", channel);
  77         return -EINVAL;
  78
  79 busy:
  80         return -EBUSY;
  81 }
  82
  83 /*
  84  * Free DMA channel
  85  *
  86  * On certain platforms, we have to free interrupt as well...
  87  */
  88 void free_dma(dmach_t channel)
  89 {
  90         dma_t *dma = dma_chan + channel;
  91
  92         if (channel >= MAX_DMA_CHANNELS || !dma->d_ops)
  93                 goto bad_dma;
  94
  95         if (dma->active) {
  96                 printk(KERN_ERR "dma%d: freeing active DMA\n", channel);
  97                 dma->d_ops->disable(channel, dma);
  98                 dma->active = 0;
  99         }
 100
 101         if (xchg(&dma->lock, 0) != 0) {
 102                 if (dma->d_ops->free)
 103                         dma->d_ops->free(channel, dma);
 104                 return;
 105         }
 106
 107         printk(KERN_ERR "dma%d: trying to free free DMA\n", channel);
 108         return;
 109
 110 bad_dma:
 111         printk(KERN_ERR "dma: trying to free DMA%d\n", channel);
 112 }
 113
 114 /* Set DMA Scatter-Gather list
 115  */
 116 void set_dma_sg (dmach_t channel, struct scatterlist *sg, int nr_sg)
 117 {
 118         dma_t *dma = dma_chan + channel;
 119
 120         if (dma->active)
 121                 printk(KERN_ERR "dma%d: altering DMA SG while "
 122                        "DMA active\n", channel);
 123
 124         dma->sg = sg;
 125         dma->sgcount = nr_sg;
 126         dma->using_sg = 1;
 127         dma->invalid = 1;
 128 }
 129
 130 /* Set DMA address
 131  *
 132  * Copy address to the structure, and set the invalid bit
 133  */
 134 void set_dma_addr (dmach_t channel, unsigned long physaddr)
 135 {
 136         dma_t *dma = dma_chan + channel;
 137
 138         if (dma->active)
 139                 printk(KERN_ERR "dma%d: altering DMA address while "
 140                        "DMA active\n", channel);
 141
 142         dma->sg = &dma->buf;
 143         dma->sgcount = 1;
 144         dma->buf.__address = (char *)physaddr;//FIXME - not pretty
 145         dma->using_sg = 0;
 146         dma->invalid = 1;
 147 }
 148
 149 /* Set DMA byte count
 150  *
 151  * Copy address to the structure, and set the invalid bit
 152  */
 153 void set_dma_count (dmach_t channel, unsigned long count)
 154 {
 155         dma_t *dma = dma_chan + channel;
 156
 157         if (dma->active)
 158                 printk(KERN_ERR "dma%d: altering DMA count while "
 159                        "DMA active\n", channel);
 160
 161         dma->sg = &dma->buf;
 162         dma->sgcount = 1;
 163         dma->buf.length = count;
 164         dma->using_sg = 0;
 165         dma->invalid = 1;
 166 }
 167
 168 /* Set DMA direction mode
 169  */
 170 void set_dma_mode (dmach_t channel, dmamode_t mode)
 171 {
 172         dma_t *dma = dma_chan + channel;
 173
 174         if (dma->active)
 175                 printk(KERN_ERR "dma%d: altering DMA mode while "
 176                        "DMA active\n", channel);
 177
 178         dma->dma_mode = mode;
 179         dma->invalid = 1;
 180 }
 181
 182 /* Enable DMA channel
 183  */
 184 void enable_dma (dmach_t channel)
 185 {
 186         dma_t *dma = dma_chan + channel;
 187
 188         if (!dma->lock)
 189                 goto free_dma;
 190
 191         if (dma->active == 0) {
 192                 dma->active = 1;
 193                 dma->d_ops->enable(channel, dma);
 194         }
 195         return;
 196
 197 free_dma:
 198         printk(KERN_ERR "dma%d: trying to enable free DMA\n", channel);
 199         BUG();
 200 }
 201
 202 /* Disable DMA channel
 203  */
 204 void disable_dma (dmach_t channel)
 205 {
 206         dma_t *dma = dma_chan + channel;
 207
 208         if (!dma->lock)
 209                 goto free_dma;
 210
 211         if (dma->active == 1) {
 212                 dma->active = 0;
 213                 dma->d_ops->disable(channel, dma);
 214         }
 215         return;
 216
 217 free_dma:
 218         printk(KERN_ERR "dma%d: trying to disable free DMA\n", channel);
 219         BUG();
 220 }
 221
 222 /*
 223  * Is the specified DMA channel active?
 224  */
 225 int dma_channel_active(dmach_t channel)
 226 {
 227         return dma_chan[channel].active;
 228 }
 229
 230 void set_dma_page(dmach_t channel, char pagenr)
 231 {
 232         printk(KERN_ERR "dma%d: trying to set_dma_page\n", channel);
 233 }
 234
 235 void set_dma_speed(dmach_t channel, int cycle_ns)
 236 {
 237         dma_t *dma = dma_chan + channel;
 238         int ret = 0;
 239
 240         if (dma->d_ops->setspeed)
 241                 ret = dma->d_ops->setspeed(channel, dma, cycle_ns);
 242         dma->speed = ret;
 243 }
 244
 245 int get_dma_residue(dmach_t channel)
 246 {
 247         dma_t *dma = dma_chan + channel;
 248         int ret = 0;
 249
 250         if (dma->d_ops->residue)
 251                 ret = dma->d_ops->residue(channel, dma);
 252
 253         return ret;
 254 }
 255
 256 void __init init_dma(void)
 257 {
 258         arch_dma_init(dma_chan);
 259 }
 260
 261 EXPORT_SYMBOL(request_dma);
 262 EXPORT_SYMBOL(free_dma);
 263 EXPORT_SYMBOL(enable_dma);
 264 EXPORT_SYMBOL(disable_dma);
 265 EXPORT_SYMBOL(set_dma_addr);
 266 EXPORT_SYMBOL(set_dma_count);
 267 EXPORT_SYMBOL(set_dma_mode);
 268 EXPORT_SYMBOL(set_dma_page);
 269 EXPORT_SYMBOL(get_dma_residue);
 270 EXPORT_SYMBOL(set_dma_sg);
 271 EXPORT_SYMBOL(set_dma_speed);
 272
 273 EXPORT_SYMBOL(dma_spin_lock);