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authorPierre Ossman <drzeus@drzeus.cx>2005-09-03 15:56:54 -0700
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 00:06:14 -0700
commit795312e763569ce4df67e7a0ca726a9901358fa2 (patch)
treec04db2abe5b75fd8c5e40e4365aa9d267bc66b7d /arch/i386/kernel/i8237.c
parent2a23b5d1e119fd10e25b8e93464c8d549f5a5c5d (diff)
[PATCH] ISA DMA suspend for i386
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>
Diffstat (limited to 'arch/i386/kernel/i8237.c')
-rw-r--r--arch/i386/kernel/i8237.c67
1 files changed, 67 insertions, 0 deletions
diff --git a/arch/i386/kernel/i8237.c b/arch/i386/kernel/i8237.c
new file mode 100644
index 00000000000..c36d1c006c2
--- /dev/null
+++ b/arch/i386/kernel/i8237.c
@@ -0,0 +1,67 @@
+/*
+ * i8237.c: 8237A DMA controller suspend functions.
+ *
+ * Written by Pierre Ossman, 2005.
+ */
+
+#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);