LXR linux/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
  24static 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
  46static struct syscore_ops i8237_syscore_ops = {
  47        .resume         = i8237A_resume,
  48};
  49
  50static int __init i8237A_init_ops(void)
  51{
  52        register_syscore_ops(&i8237_syscore_ops);
  53        return 0;
  54}
  55device_initcall(i8237A_init_ops);
  56