[PATCH 2/2] ISA DMA suspend for x86_64

Pierre Ossman
2005-06-30T18:09:33Z

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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>

Word of warning, I haven't tested this platform since I don't have any
x86_64 hardware. But it shouldn't differ from i386.

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Index: linux-wbsd/arch/x86_64/kernel/i8237.c
===================================================================
--- linux-wbsd/arch/x86_64/kernel/i8237.c (revision 0)
+++ linux-wbsd/arch/x86_64/kernel/i8237.c (revision 0)
@@ -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);
Index: linux-wbsd/arch/x86_64/kernel/Makefile
===================================================================
--- linux-wbsd/arch/x86_64/kernel/Makefile (revision 153)
+++ linux-wbsd/arch/x86_64/kernel/Makefile (working copy)
@@ -7,7 +7,7 @@
obj-y := process.o semaphore.o signal.o entry.o traps.o irq.o \
ptrace.o time.o ioport.o ldt.o setup.o i8259.o sys_x86_64.o \
x8664_ksyms.o i387.o syscall.o vsyscall.o \
- setup64.o bootflag.o e820.o reboot.o quirks.o
+ setup64.o bootflag.o e820.o reboot.o quirks.o i8237.o

obj-$(CONFIG_X86_MCE) += mce.o
obj-$(CONFIG_X86_MCE_INTEL) += mce_intel.o