git.oblomov.eu Git - linux-2.6/blob - 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  * Request DMA channel
  30  *
  31  * On certain platforms, we have to allocate an interrupt as well...
  32  */
  33 int request_dma(dmach_t channel, const char *device_id)
  34 {
  35         dma_t *dma = dma_chan + channel;
  36         int ret;
  37
  38         if (channel >= MAX_DMA_CHANNELS || !dma->d_ops)
  39                 goto bad_dma;
  40
  41         if (xchg(&dma->lock, 1) != 0)
  42                 goto busy;
  43
  44         dma->device_id = device_id;
  45         dma->active    = 0;
  46         dma->invalid   = 1;
  47
  48         ret = 0;
  49         if (dma->d_ops->request)
  50                 ret = dma->d_ops->request(channel, dma);
  51
  52         if (ret)
  53                 xchg(&dma->lock, 0);
  54
  55         return ret;
  56
  57 bad_dma:
  58         printk(KERN_ERR "dma: trying to allocate DMA%d\n", channel);
  59         return -EINVAL;
  60
  61 busy:
  62         return -EBUSY;
  63 }
  64 EXPORT_SYMBOL(request_dma);
  65
  66 /*
  67  * Free DMA channel
  68  *
  69  * On certain platforms, we have to free interrupt as well...
  70  */
  71 void free_dma(dmach_t channel)
  72 {
  73         dma_t *dma = dma_chan + channel;
  74
  75         if (channel >= MAX_DMA_CHANNELS || !dma->d_ops)
  76                 goto bad_dma;
  77
  78         if (dma->active) {
  79                 printk(KERN_ERR "dma%d: freeing active DMA\n", channel);
  80                 dma->d_ops->disable(channel, dma);
  81                 dma->active = 0;
  82         }
  83
  84         if (xchg(&dma->lock, 0) != 0) {
  85                 if (dma->d_ops->free)
  86                         dma->d_ops->free(channel, dma);
  87                 return;
  88         }
  89
  90         printk(KERN_ERR "dma%d: trying to free free DMA\n", channel);
  91         return;
  92
  93 bad_dma:
  94         printk(KERN_ERR "dma: trying to free DMA%d\n", channel);
  95 }
  96 EXPORT_SYMBOL(free_dma);
  97
  98 /* Set DMA Scatter-Gather list
  99  */
 100 void set_dma_sg (dmach_t channel, struct scatterlist *sg, int nr_sg)
 101 {
 102         dma_t *dma = dma_chan + channel;
 103
 104         if (dma->active)
 105                 printk(KERN_ERR "dma%d: altering DMA SG while "
 106                        "DMA active\n", channel);
 107
 108         dma->sg = sg;
 109         dma->sgcount = nr_sg;
 110         dma->invalid = 1;
 111 }
 112 EXPORT_SYMBOL(set_dma_sg);
 113
 114 /* Set DMA address
 115  *
 116  * Copy address to the structure, and set the invalid bit
 117  */
 118 void __set_dma_addr (dmach_t channel, void *addr)
 119 {
 120         dma_t *dma = dma_chan + channel;
 121
 122         if (dma->active)
 123                 printk(KERN_ERR "dma%d: altering DMA address while "
 124                        "DMA active\n", channel);
 125
 126         dma->sg = NULL;
 127         dma->addr = addr;
 128         dma->invalid = 1;
 129 }
 130 EXPORT_SYMBOL(__set_dma_addr);
 131
 132 /* Set DMA byte count
 133  *
 134  * Copy address to the structure, and set the invalid bit
 135  */
 136 void set_dma_count (dmach_t channel, unsigned long count)
 137 {
 138         dma_t *dma = dma_chan + channel;
 139
 140         if (dma->active)
 141                 printk(KERN_ERR "dma%d: altering DMA count while "
 142                        "DMA active\n", channel);
 143
 144         dma->sg = NULL;
 145         dma->count = count;
 146         dma->invalid = 1;
 147 }
 148 EXPORT_SYMBOL(set_dma_count);
 149
 150 /* Set DMA direction mode
 151  */
 152 void set_dma_mode (dmach_t channel, dmamode_t mode)
 153 {
 154         dma_t *dma = dma_chan + channel;
 155
 156         if (dma->active)
 157                 printk(KERN_ERR "dma%d: altering DMA mode while "
 158                        "DMA active\n", channel);
 159
 160         dma->dma_mode = mode;
 161         dma->invalid = 1;
 162 }
 163 EXPORT_SYMBOL(set_dma_mode);
 164
 165 /* Enable DMA channel
 166  */
 167 void enable_dma (dmach_t channel)
 168 {
 169         dma_t *dma = dma_chan + channel;
 170
 171         if (!dma->lock)
 172                 goto free_dma;
 173
 174         if (dma->active == 0) {
 175                 dma->active = 1;
 176                 dma->d_ops->enable(channel, dma);
 177         }
 178         return;
 179
 180 free_dma:
 181         printk(KERN_ERR "dma%d: trying to enable free DMA\n", channel);
 182         BUG();
 183 }
 184 EXPORT_SYMBOL(enable_dma);
 185
 186 /* Disable DMA channel
 187  */
 188 void disable_dma (dmach_t channel)
 189 {
 190         dma_t *dma = dma_chan + channel;
 191
 192         if (!dma->lock)
 193                 goto free_dma;
 194
 195         if (dma->active == 1) {
 196                 dma->active = 0;
 197                 dma->d_ops->disable(channel, dma);
 198         }
 199         return;
 200
 201 free_dma:
 202         printk(KERN_ERR "dma%d: trying to disable free DMA\n", channel);
 203         BUG();
 204 }
 205 EXPORT_SYMBOL(disable_dma);
 206
 207 /*
 208  * Is the specified DMA channel active?
 209  */
 210 int dma_channel_active(dmach_t channel)
 211 {
 212         return dma_chan[channel].active;
 213 }
 214 EXPORT_SYMBOL(dma_channel_active);
 215
 216 void set_dma_page(dmach_t channel, char pagenr)
 217 {
 218         printk(KERN_ERR "dma%d: trying to set_dma_page\n", channel);
 219 }
 220 EXPORT_SYMBOL(set_dma_page);
 221
 222 void set_dma_speed(dmach_t channel, int cycle_ns)
 223 {
 224         dma_t *dma = dma_chan + channel;
 225         int ret = 0;
 226
 227         if (dma->d_ops->setspeed)
 228                 ret = dma->d_ops->setspeed(channel, dma, cycle_ns);
 229         dma->speed = ret;
 230 }
 231 EXPORT_SYMBOL(set_dma_speed);
 232
 233 int get_dma_residue(dmach_t channel)
 234 {
 235         dma_t *dma = dma_chan + channel;
 236         int ret = 0;
 237
 238         if (dma->d_ops->residue)
 239                 ret = dma->d_ops->residue(channel, dma);
 240
 241         return ret;
 242 }
 243 EXPORT_SYMBOL(get_dma_residue);
 244
 245 static int __init init_dma(void)
 246 {
 247         arch_dma_init(dma_chan);
 248         return 0;
 249 }
 250
 251 core_initcall(init_dma);