795312e763
Reset the ISA DMA controller into a known state after a suspend. Primary concern was reenabling the cascading DMA channel (4). Signed-off-by: Pierre Ossman <drzeus@drzeus.cx> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
68 lines
1.3 KiB
C
68 lines
1.3 KiB
C
/*
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* i8237.c: 8237A DMA controller suspend functions.
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*
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* Written by Pierre Ossman, 2005.
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*/
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#include <linux/init.h>
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#include <linux/sysdev.h>
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#include <asm/dma.h>
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/*
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* This module just handles suspend/resume issues with the
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* 8237A DMA controller (used for ISA and LPC).
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* Allocation is handled in kernel/dma.c and normal usage is
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* in asm/dma.h.
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*/
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static int i8237A_resume(struct sys_device *dev)
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{
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unsigned long flags;
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int i;
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flags = claim_dma_lock();
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dma_outb(DMA1_RESET_REG, 0);
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dma_outb(DMA2_RESET_REG, 0);
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for (i = 0;i < 8;i++) {
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set_dma_addr(i, 0x000000);
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/* DMA count is a bit weird so this is not 0 */
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set_dma_count(i, 1);
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}
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/* Enable cascade DMA or channel 0-3 won't work */
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enable_dma(4);
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release_dma_lock(flags);
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return 0;
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}
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static int i8237A_suspend(struct sys_device *dev, pm_message_t state)
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{
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return 0;
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}
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static struct sysdev_class i8237_sysdev_class = {
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set_kset_name("i8237"),
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.suspend = i8237A_suspend,
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.resume = i8237A_resume,
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};
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static struct sys_device device_i8237A = {
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.id = 0,
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.cls = &i8237_sysdev_class,
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};
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static int __init i8237A_init_sysfs(void)
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{
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int error = sysdev_class_register(&i8237_sysdev_class);
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if (!error)
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error = sysdev_register(&device_i8237A);
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return error;
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}
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device_initcall(i8237A_init_sysfs);
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