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i8237.c

/*
 * 8237A DMA controller suspend functions.
 *
 * Written by Pierre Ossman, 2005.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 */

#include <linux/init.h>
#include <linux/sysdev.h>

#include <asm/dma.h>

/*
 * This module just handles suspend/resume issues with the
 * 8237A DMA controller (used for ISA and LPC).
 * Allocation is handled in kernel/dma.c and normal usage is
 * in asm/dma.h.
 */

static int i8237A_resume(struct sys_device *dev)
{
      unsigned long flags;
      int i;

      flags = claim_dma_lock();

      dma_outb(DMA1_RESET_REG, 0);
      dma_outb(DMA2_RESET_REG, 0);

      for (i = 0;i < 8;i++) {
            set_dma_addr(i, 0x000000);
            /* DMA count is a bit weird so this is not 0 */
            set_dma_count(i, 1);
      }

      /* Enable cascade DMA or channel 0-3 won't work */
      enable_dma(4);

      release_dma_lock(flags);

      return 0;
}

static int i8237A_suspend(struct sys_device *dev, pm_message_t state)
{
      return 0;
}

static struct sysdev_class i8237_sysdev_class = {
      set_kset_name("i8237"),
      .suspend = i8237A_suspend,
      .resume = i8237A_resume,
};

static struct sys_device device_i8237A = {
      .id   = 0,
      .cls  = &i8237_sysdev_class,
};

static int __init i8237A_init_sysfs(void)
{
      int error = sysdev_class_register(&i8237_sysdev_class);
      if (!error)
            error = sysdev_register(&device_i8237A);
      return error;
}

device_initcall(i8237A_init_sysfs);

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