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/init.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/errno.h>
  18
  19 #include <asm/dma.h>
  20
  21 #include <asm/mach/dma.h>
  22
  23 DEFINE_SPINLOCK(dma_spin_lock);
  24 EXPORT_SYMBOL(dma_spin_lock);
  25
  26 static dma_t dma_chan[MAX_DMA_CHANNELS];
  27
  28 /*
  29  * Get dma list for /proc/dma
  30  */
  31 int get_dma_list(char *buf)
  32 {
  33         dma_t *dma;
  34         char *p = buf;
  35         int i;
  36
  37         for (i = 0, dma = dma_chan; i < MAX_DMA_CHANNELS; i++, dma++)
  38                 if (dma->lock)
  39                         p += sprintf(p, "%2d: %14s %s\n", i,
  40                                      dma->d_ops->type, dma->device_id);
  41
  42         return p - buf;
  43 }
  44
  45 /*
  46  * Request DMA channel
  47  *
  48  * On certain platforms, we have to allocate an interrupt as well...
  49  */
  50 int request_dma(dmach_t channel, const char *device_id)
  51 {
  52         dma_t *dma = dma_chan + channel;
  53         int ret;
  54
  55         if (channel >= MAX_DMA_CHANNELS || !dma->d_ops)
  56                 goto bad_dma;
  57
  58         if (xchg(&dma->lock, 1) != 0)
  59                 goto busy;
  60
  61         dma->device_id = device_id;
  62         dma->active    = 0;
  63         dma->invalid   = 1;
  64
  65         ret = 0;
  66         if (dma->d_ops->request)
  67                 ret = dma->d_ops->request(channel, dma);
  68
  69         if (ret)
  70                 xchg(&dma->lock, 0);
  71
  72         return ret;
  73
  74 bad_dma:
  75         printk(KERN_ERR "dma: trying to allocate DMA%d\n", channel);
  76         return -EINVAL;
  77
  78 busy:
  79         return -EBUSY;
  80 }
  81 EXPORT_SYMBOL(request_dma);
  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 EXPORT_SYMBOL(free_dma);
 114
 115 /* Set DMA Scatter-Gather list
 116  */
 117 void set_dma_sg (dmach_t channel, struct scatterlist *sg, int nr_sg)
 118 {
 119         dma_t *dma = dma_chan + channel;
 120
 121         if (dma->active)
 122                 printk(KERN_ERR "dma%d: altering DMA SG while "
 123                        "DMA active\n", channel);
 124
 125         dma->sg = sg;
 126         dma->sgcount = nr_sg;
 127         dma->invalid = 1;
 128 }
 129 EXPORT_SYMBOL(set_dma_sg);
 130
 131 /* Set DMA address
 132  *
 133  * Copy address to the structure, and set the invalid bit
 134  */
 135 void __set_dma_addr (dmach_t channel, void *addr)
 136 {
 137         dma_t *dma = dma_chan + channel;
 138
 139         if (dma->active)
 140                 printk(KERN_ERR "dma%d: altering DMA address while "
 141                        "DMA active\n", channel);
 142
 143         dma->sg = NULL;
 144         dma->addr = addr;
 145         dma->invalid = 1;
 146 }
 147 EXPORT_SYMBOL(__set_dma_addr);
 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 = NULL;
 162         dma->count = count;
 163         dma->invalid = 1;
 164 }
 165 EXPORT_SYMBOL(set_dma_count);
 166
 167 /* Set DMA direction mode
 168  */
 169 void set_dma_mode (dmach_t channel, dmamode_t mode)
 170 {
 171         dma_t *dma = dma_chan + channel;
 172
 173         if (dma->active)
 174                 printk(KERN_ERR "dma%d: altering DMA mode while "
 175                        "DMA active\n", channel);
 176
 177         dma->dma_mode = mode;
 178         dma->invalid = 1;
 179 }
 180 EXPORT_SYMBOL(set_dma_mode);
 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 EXPORT_SYMBOL(enable_dma);
 202
 203 /* Disable DMA channel
 204  */
 205 void disable_dma (dmach_t channel)
 206 {
 207         dma_t *dma = dma_chan + channel;
 208
 209         if (!dma->lock)
 210                 goto free_dma;
 211
 212         if (dma->active == 1) {
 213                 dma->active = 0;
 214                 dma->d_ops->disable(channel, dma);
 215         }
 216         return;
 217
 218 free_dma:
 219         printk(KERN_ERR "dma%d: trying to disable free DMA\n", channel);
 220         BUG();
 221 }
 222 EXPORT_SYMBOL(disable_dma);
 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 EXPORT_SYMBOL(set_dma_page);
 237
 238 void set_dma_speed(dmach_t channel, int cycle_ns)
 239 {
 240         dma_t *dma = dma_chan + channel;
 241         int ret = 0;
 242
 243         if (dma->d_ops->setspeed)
 244                 ret = dma->d_ops->setspeed(channel, dma, cycle_ns);
 245         dma->speed = ret;
 246 }
 247 EXPORT_SYMBOL(set_dma_speed);
 248
 249 int get_dma_residue(dmach_t channel)
 250 {
 251         dma_t *dma = dma_chan + channel;
 252         int ret = 0;
 253
 254         if (dma->d_ops->residue)
 255                 ret = dma->d_ops->residue(channel, dma);
 256
 257         return ret;
 258 }
 259 EXPORT_SYMBOL(get_dma_residue);
 260
 261 static int __init init_dma(void)
 262 {
 263         arch_dma_init(dma_chan);
 264         return 0;
 265 }
 266
 267 core_initcall(init_dma);