drivers/staging/comedi/drivers/comedi_isadma.c

   1 /*
   2  * COMEDI ISA DMA support functions
   3  * Copyright (c) 2014 H Hartley Sweeten <hsweeten@visionengravers.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/slab.h>
  18 #include <linux/delay.h>
  19 #include <linux/dma-mapping.h>
  20 #include <asm/dma.h>
  21
  22 #include "../comedidev.h"
  23
  24 #include "comedi_isadma.h"
  25
  26 /**
  27  * comedi_isadma_program - program and enable an ISA DMA transfer
  28  * @desc:       the ISA DMA cookie to program and enable
  29  */
  30 void comedi_isadma_program(struct comedi_isadma_desc *desc)
  31 {
  32         unsigned long flags;
  33
  34         flags = claim_dma_lock();
  35         clear_dma_ff(desc->chan);
  36         set_dma_mode(desc->chan, desc->mode);
  37         set_dma_addr(desc->chan, desc->hw_addr);
  38         set_dma_count(desc->chan, desc->size);
  39         enable_dma(desc->chan);
  40         release_dma_lock(flags);
  41 }
  42 EXPORT_SYMBOL_GPL(comedi_isadma_program);
  43
  44 /**
  45  * comedi_isadma_disable - disable the ISA DMA channel
  46  * @dma_chan:   the DMA channel to disable
  47  *
  48  * Returns the residue (remaining bytes) left in the DMA transfer.
  49  */
  50 unsigned int comedi_isadma_disable(unsigned int dma_chan)
  51 {
  52         unsigned long flags;
  53         unsigned int residue;
  54
  55         flags = claim_dma_lock();
  56         disable_dma(dma_chan);
  57         residue = get_dma_residue(dma_chan);
  58         release_dma_lock(flags);
  59
  60         return residue;
  61 }
  62 EXPORT_SYMBOL_GPL(comedi_isadma_disable);
  63
  64 /**
  65  * comedi_isadma_disable_on_sample - disable the ISA DMA channel
  66  * @dma_chan:   the DMA channel to disable
  67  * @size:       the sample size (in bytes)
  68  *
  69  * Returns the residue (remaining bytes) left in the DMA transfer.
  70  */
  71 unsigned int comedi_isadma_disable_on_sample(unsigned int dma_chan,
  72                                              unsigned int size)
  73 {
  74         int stalled = 0;
  75         unsigned long flags;
  76         unsigned int residue;
  77         unsigned int new_residue;
  78
  79         residue = comedi_isadma_disable(dma_chan);
  80         while (residue % size) {
  81                 /* residue is a partial sample, enable DMA to allow more data */
  82                 flags = claim_dma_lock();
  83                 enable_dma(dma_chan);
  84                 release_dma_lock(flags);
  85
  86                 udelay(2);
  87                 new_residue = comedi_isadma_disable(dma_chan);
  88
  89                 /* is DMA stalled? */
  90                 if (new_residue == residue) {
  91                         stalled++;
  92                         if (stalled > 10)
  93                                 break;
  94                 }
  95                 residue = new_residue;
  96                 stalled = 0;
  97         }
  98         return residue;
  99 }
 100 EXPORT_SYMBOL_GPL(comedi_isadma_disable_on_sample);
 101
 102 /**
 103  * comedi_isadma_poll - poll the current DMA transfer
 104  * @dma:        the ISA DMA to poll
 105  *
 106  * Returns the position (in bytes) of the current DMA transfer.
 107  */
 108 unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
 109 {
 110         struct comedi_isadma_desc *desc = &dma->desc[dma->cur_dma];
 111         unsigned long flags;
 112         unsigned int result;
 113         unsigned int result1;
 114
 115         flags = claim_dma_lock();
 116         clear_dma_ff(desc->chan);
 117         if (!isa_dma_bridge_buggy)
 118                 disable_dma(desc->chan);
 119         result = get_dma_residue(desc->chan);
 120         /*
 121          * Read the counter again and choose higher value in order to
 122          * avoid reading during counter lower byte roll over if the
 123          * isa_dma_bridge_buggy is set.
 124          */
 125         result1 = get_dma_residue(desc->chan);
 126         if (!isa_dma_bridge_buggy)
 127                 enable_dma(desc->chan);
 128         release_dma_lock(flags);
 129
 130         if (result < result1)
 131                 result = result1;
 132         if (result >= desc->size || result == 0)
 133                 return 0;
 134         else
 135                 return desc->size - result;
 136 }
 137 EXPORT_SYMBOL_GPL(comedi_isadma_poll);
 138
 139 /**
 140  * comedi_isadma_set_mode - set the ISA DMA transfer direction
 141  * @desc:       the ISA DMA cookie to set
 142  * @dma_dir:    the DMA direction
 143  */
 144 void comedi_isadma_set_mode(struct comedi_isadma_desc *desc, char dma_dir)
 145 {
 146         desc->mode = (dma_dir == COMEDI_ISADMA_READ) ? DMA_MODE_READ
 147                                                      : DMA_MODE_WRITE;
 148 }
 149 EXPORT_SYMBOL_GPL(comedi_isadma_set_mode);
 150
 151 /**
 152  * comedi_isadma_alloc - allocate and initialize the ISA DMA
 153  * @dev:        comedi_device struct
 154  * @n_desc:     the number of cookies to allocate
 155  * @dma_chan:   DMA channel for the first cookie
 156  * @dma_chan2:  DMA channel for the second cookie
 157  * @maxsize:    the size of the buffer to allocate for each cookie
 158  * @dma_dir:    the DMA direction
 159  *
 160  * Returns the allocated and initialized ISA DMA or NULL if anything fails.
 161  */
 162 struct comedi_isadma *comedi_isadma_alloc(struct comedi_device *dev,
 163                                           int n_desc, unsigned int dma_chan1,
 164                                           unsigned int dma_chan2,
 165                                           unsigned int maxsize, char dma_dir)
 166 {
 167         struct comedi_isadma *dma = NULL;
 168         struct comedi_isadma_desc *desc;
 169         unsigned int dma_chans[2];
 170         int i;
 171
 172         if (n_desc < 1 || n_desc > 2)
 173                 goto no_dma;
 174
 175         dma = kzalloc(sizeof(*dma), GFP_KERNEL);
 176         if (!dma)
 177                 goto no_dma;
 178
 179         desc = kcalloc(n_desc, sizeof(*desc), GFP_KERNEL);
 180         if (!desc)
 181                 goto no_dma;
 182         dma->desc = desc;
 183         dma->n_desc = n_desc;
 184
 185         dma_chans[0] = dma_chan1;
 186         if (dma_chan2 == 0 || dma_chan2 == dma_chan1)
 187                 dma_chans[1] = dma_chan1;
 188         else
 189                 dma_chans[1] = dma_chan2;
 190
 191         if (request_dma(dma_chans[0], dev->board_name))
 192                 goto no_dma;
 193         dma->chan = dma_chans[0];
 194         if (dma_chans[1] != dma_chans[0]) {
 195                 if (request_dma(dma_chans[1], dev->board_name))
 196                         goto no_dma;
 197         }
 198         dma->chan2 = dma_chans[1];
 199
 200         for (i = 0; i < n_desc; i++) {
 201                 desc = &dma->desc[i];
 202                 desc->chan = dma_chans[i];
 203                 desc->maxsize = maxsize;
 204                 desc->virt_addr = dma_alloc_coherent(NULL, desc->maxsize,
 205                                                      &desc->hw_addr,
 206                                                      GFP_KERNEL);
 207                 if (!desc->virt_addr)
 208                         goto no_dma;
 209                 comedi_isadma_set_mode(desc, dma_dir);
 210         }
 211
 212         return dma;
 213
 214 no_dma:
 215         comedi_isadma_free(dma);
 216         return NULL;
 217 }
 218 EXPORT_SYMBOL_GPL(comedi_isadma_alloc);
 219
 220 /**
 221  * comedi_isadma_free - free the ISA DMA
 222  * @dma:        the ISA DMA to free
 223  */
 224 void comedi_isadma_free(struct comedi_isadma *dma)
 225 {
 226         struct comedi_isadma_desc *desc;
 227         int i;
 228
 229         if (!dma)
 230                 return;
 231
 232         if (dma->desc) {
 233                 for (i = 0; i < dma->n_desc; i++) {
 234                         desc = &dma->desc[i];
 235                         if (desc->virt_addr)
 236                                 dma_free_coherent(NULL, desc->maxsize,
 237                                                 desc->virt_addr, desc->hw_addr);
 238                 }
 239                 kfree(dma->desc);
 240         }
 241         if (dma->chan2 && dma->chan2 != dma->chan)
 242                 free_dma(dma->chan2);
 243         if (dma->chan)
 244                 free_dma(dma->chan);
 245         kfree(dma);
 246 }
 247 EXPORT_SYMBOL_GPL(comedi_isadma_free);
 248
 249 static int __init comedi_isadma_init(void)
 250 {
 251         return 0;
 252 }
 253 module_init(comedi_isadma_init);
 254
 255 static void __exit comedi_isadma_exit(void)
 256 {
 257 }
 258 module_exit(comedi_isadma_exit);
 259
 260 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 261 MODULE_DESCRIPTION("Comedi ISA DMA support");
 262 MODULE_LICENSE("GPL");