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 #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_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         printk(KERN_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                 printk(KERN_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         printk(KERN_ERR "dma%d: trying to free free DMA\n", chan);
 115         return;
 116
 117 bad_dma:
 118         printk(KERN_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                 printk(KERN_ERR "dma%d: altering DMA SG while "
 130                        "DMA active\n", chan);
 131
 132         dma->sg = sg;
 133         dma->sgcount = nr_sg;
 134         dma->invalid = 1;
 135 }
 136 EXPORT_SYMBOL(set_dma_sg);
 137
 138 /* Set DMA address
 139  *
 140  * Copy address to the structure, and set the invalid bit
 141  */
 142 void __set_dma_addr (unsigned int chan, void *addr)
 143 {
 144         dma_t *dma = dma_channel(chan);
 145
 146         if (dma->active)
 147                 printk(KERN_ERR "dma%d: altering DMA address while "
 148                        "DMA active\n", chan);
 149
 150         dma->sg = NULL;
 151         dma->addr = addr;
 152         dma->invalid = 1;
 153 }
 154 EXPORT_SYMBOL(__set_dma_addr);
 155
 156 /* Set DMA byte count
 157  *
 158  * Copy address to the structure, and set the invalid bit
 159  */
 160 void set_dma_count (unsigned int chan, unsigned long count)
 161 {
 162         dma_t *dma = dma_channel(chan);
 163
 164         if (dma->active)
 165                 printk(KERN_ERR "dma%d: altering DMA count while "
 166                        "DMA active\n", chan);
 167
 168         dma->sg = NULL;
 169         dma->count = count;
 170         dma->invalid = 1;
 171 }
 172 EXPORT_SYMBOL(set_dma_count);
 173
 174 /* Set DMA direction mode
 175  */
 176 void set_dma_mode (unsigned int chan, unsigned int mode)
 177 {
 178         dma_t *dma = dma_channel(chan);
 179
 180         if (dma->active)
 181                 printk(KERN_ERR "dma%d: altering DMA mode while "
 182                        "DMA active\n", chan);
 183
 184         dma->dma_mode = mode;
 185         dma->invalid = 1;
 186 }
 187 EXPORT_SYMBOL(set_dma_mode);
 188
 189 /* Enable DMA channel
 190  */
 191 void enable_dma (unsigned int chan)
 192 {
 193         dma_t *dma = dma_channel(chan);
 194
 195         if (!dma->lock)
 196                 goto free_dma;
 197
 198         if (dma->active == 0) {
 199                 dma->active = 1;
 200                 dma->d_ops->enable(chan, dma);
 201         }
 202         return;
 203
 204 free_dma:
 205         printk(KERN_ERR "dma%d: trying to enable free DMA\n", chan);
 206         BUG();
 207 }
 208 EXPORT_SYMBOL(enable_dma);
 209
 210 /* Disable DMA channel
 211  */
 212 void disable_dma (unsigned int chan)
 213 {
 214         dma_t *dma = dma_channel(chan);
 215
 216         if (!dma->lock)
 217                 goto free_dma;
 218
 219         if (dma->active == 1) {
 220                 dma->active = 0;
 221                 dma->d_ops->disable(chan, dma);
 222         }
 223         return;
 224
 225 free_dma:
 226         printk(KERN_ERR "dma%d: trying to disable free DMA\n", chan);
 227         BUG();
 228 }
 229 EXPORT_SYMBOL(disable_dma);
 230
 231 /*
 232  * Is the specified DMA channel active?
 233  */
 234 int dma_channel_active(unsigned int chan)
 235 {
 236         dma_t *dma = dma_channel(chan);
 237         return dma->active;
 238 }
 239 EXPORT_SYMBOL(dma_channel_active);
 240
 241 void set_dma_page(unsigned int chan, char pagenr)
 242 {
 243         printk(KERN_ERR "dma%d: trying to set_dma_page\n", chan);
 244 }
 245 EXPORT_SYMBOL(set_dma_page);
 246
 247 void set_dma_speed(unsigned int chan, int cycle_ns)
 248 {
 249         dma_t *dma = dma_channel(chan);
 250         int ret = 0;
 251
 252         if (dma->d_ops->setspeed)
 253                 ret = dma->d_ops->setspeed(chan, dma, cycle_ns);
 254         dma->speed = ret;
 255 }
 256 EXPORT_SYMBOL(set_dma_speed);
 257
 258 int get_dma_residue(unsigned int chan)
 259 {
 260         dma_t *dma = dma_channel(chan);
 261         int ret = 0;
 262
 263         if (dma->d_ops->residue)
 264                 ret = dma->d_ops->residue(chan, dma);
 265
 266         return ret;
 267 }
 268 EXPORT_SYMBOL(get_dma_residue);
 269
 270 #ifdef CONFIG_PROC_FS
 271 static int proc_dma_show(struct seq_file *m, void *v)
 272 {
 273         int i;
 274
 275         for (i = 0 ; i < MAX_DMA_CHANNELS ; i++) {
 276                 dma_t *dma = dma_channel(i);
 277                 if (dma && dma->lock)
 278                         seq_printf(m, "%2d: %s\n", i, dma->device_id);
 279         }
 280         return 0;
 281 }
 282
 283 static int proc_dma_open(struct inode *inode, struct file *file)
 284 {
 285         return single_open(file, proc_dma_show, NULL);
 286 }
 287
 288 static const struct file_operations proc_dma_operations = {
 289         .open           = proc_dma_open,
 290         .read           = seq_read,
 291         .llseek         = seq_lseek,
 292         .release        = single_release,
 293 };
 294
 295 static int __init proc_dma_init(void)
 296 {
 297         proc_create("dma", 0, NULL, &proc_dma_operations);
 298         return 0;
 299 }
 300
 301 __initcall(proc_dma_init);
 302 #endif