linux/arch/x86/kernel/i8237.c
Rafael J. Wysocki f3c6ea1b06 x86: Use syscore_ops instead of sysdev classes and sysdevs
Some subsystems in the x86 tree need to carry out suspend/resume and
shutdown operations with one CPU on-line and interrupts disabled and
they define sysdev classes and sysdevs or sysdev drivers for this
purpose.  This leads to unnecessarily complicated code and excessive
memory usage, so switch them to using struct syscore_ops objects for
this purpose instead.

Generally, there are three categories of subsystems that use
sysdevs for implementing PM operations: (1) subsystems whose
suspend/resume callbacks ignore their arguments entirely (the
majority), (2) subsystems whose suspend/resume callbacks use their
struct sys_device argument, but don't really need to do that,
because they can be implemented differently in an arguably simpler
way (io_apic.c), and (3) subsystems whose suspend/resume callbacks
use their struct sys_device argument, but the value of that argument
is always the same and could be ignored (microcode_core.c).  In all
of these cases the subsystems in question may be readily converted to
using struct syscore_ops objects for power management and shutdown.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
2011-03-23 22:15:54 +01:00

55 lines
1.2 KiB
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/syscore_ops.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 void i8237A_resume(void)
{
unsigned long flags;
int i;
flags = claim_dma_lock();
dma_outb(0, DMA1_RESET_REG);
dma_outb(0, DMA2_RESET_REG);
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);
}
static struct syscore_ops i8237_syscore_ops = {
.resume = i8237A_resume,
};
static int __init i8237A_init_ops(void)
{
register_syscore_ops(&i8237_syscore_ops);
return 0;
}
device_initcall(i8237A_init_ops);