1 files changed, 38 insertions, 0 deletions

diff --git a/arch/alpha/kernel/ns87312.c b/arch/alpha/kernel/ns87312.c
new file mode 100644
index 000000000000..342b56d24c20
--- /dev/null
+++ b/arch/alpha/kernel/ns87312.c
@@ -0,0 +1,38 @@
+/*
+ *      linux/arch/alpha/kernel/ns87312.c
+ */
+
+#include <linux/init.h>
+#include <asm/io.h>
+#include "proto.h"
+
+
+/*
+ * The SRM console *disables* the IDE interface, this code ensures it's
+ * enabled.
+ *
+ * This code bangs on a control register of the 87312 Super I/O chip
+ * that implements parallel port/serial ports/IDE/FDI.  Depending on
+ * the motherboard, the Super I/O chip can be configured through a
+ * pair of registers that are located either at I/O ports 0x26e/0x26f
+ * or 0x398/0x399.  Unfortunately, autodetecting which base address is
+ * in use works only once (right after a reset).  The Super I/O chip
+ * has the additional quirk that configuration register data must be
+ * written twice (I believe this is a safety feature to prevent
+ * accidental modification---fun, isn't it?).
+ */
+
+void __init
+ns87312_enable_ide(long ide_base)
+{
+        int data;
+        unsigned long flags;
+
+        local_irq_save(flags);
+        outb(0, ide_base);              /* set the index register for reg #0 */
+        data = inb(ide_base+1);         /* read the current contents */
+        outb(0, ide_base);              /* set the index register for reg #0 */
+        outb(data | 0x40, ide_base+1);  /* turn on IDE */
+        outb(data | 0x40, ide_base+1);  /* turn on IDE, really! */
+        local_irq_restore(flags);
+}