LXR linux/arch/i386/kernel/i8237.c

   1/*
   2 * i8237.c: 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/sysdev.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 int i8237A_resume(struct sys_device *dev)
  25{
  26        unsigned long flags;
  27        int i;
  28
  29        flags = claim_dma_lock();
  30
  31        dma_outb(DMA1_RESET_REG, 0);
  32        dma_outb(DMA2_RESET_REG, 0);
  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        return 0;
  46}
  47
  48static int i8237A_suspend(struct sys_device *dev, pm_message_t state)
  49{
  50        return 0;
  51}
  52
  53static struct sysdev_class i8237_sysdev_class = {
  54        set_kset_name("i8237"),
  55        .suspend = i8237A_suspend,
  56        .resume = i8237A_resume,
  57};
  58
  59static struct sys_device device_i8237A = {
  60        .id     = 0,
  61        .cls    = &i8237_sysdev_class,
  62};
  63
  64static int __init i8237A_init_sysfs(void)
  65{
  66        int error = sysdev_class_register(&i8237_sysdev_class);
  67        if (!error)
  68                error = sysdev_register(&device_i8237A);
  69        return error;
  70}
  71
  72device_initcall(i8237A_init_sysfs);
  73