arch/x86/kernel/i8237.c

   1 /*
   2  * 8237A DMA controller suspend functions.
   3  *
   4  * Written by Pierre Ossman, 2005.
   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 as published by
   8  * the Free Software Foundation; either version 2 of the License, or (at
   9  * your option) any later version.
  10  */
  11
  12 #include <linux/init.h>
  13 #include <linux/syscore_ops.h>
  14
  15 #include <asm/dma.h>
  16
  17 /*
  18  * This module just handles suspend/resume issues with the
  19  * 8237A DMA controller (used for ISA and LPC).
  20  * Allocation is handled in kernel/dma.c and normal usage is
  21  * in asm/dma.h.
  22  */
  23
  24 static void i8237A_resume(void)
  25 {
  26         unsigned long flags;
  27         int i;
  28
  29         flags = claim_dma_lock();
  30
  31         dma_outb(0, DMA1_RESET_REG);
  32         dma_outb(0, DMA2_RESET_REG);
  33
  34         for (i = 0; i < 8; i++) {
  35                 set_dma_addr(i, 0x000000);
  36                 /* DMA count is a bit weird so this is not 0 */
  37                 set_dma_count(i, 1);
  38         }
  39
  40         /* Enable cascade DMA or channel 0-3 won't work */
  41         enable_dma(4);
  42
  43         release_dma_lock(flags);
  44 }
  45
  46 static struct syscore_ops i8237_syscore_ops = {
  47         .resume         = i8237A_resume,
  48 };
  49
  50 static int __init i8237A_init_ops(void)
  51 {
  52         register_syscore_ops(&i8237_syscore_ops);
  53         return 0;
  54 }
  55 device_initcall(i8237A_init_ops);