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
  24 static 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
  48 static int i8237A_suspend(struct sys_device *dev, pm_message_t state)
  49 {
  50         return 0;
  51 }
  52
  53 static struct sysdev_class i8237_sysdev_class = {
  54         set_kset_name("i8237"),
  55         .suspend = i8237A_suspend,
  56         .resume = i8237A_resume,
  57 };
  58
  59 static struct sys_device device_i8237A = {
  60         .id     = 0,
  61         .cls    = &i8237_sysdev_class,
  62 };
  63
  64 static 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
  72 device_initcall(i8237A_init_sysfs);