1 files changed, 106 insertions, 0 deletions
diff --git a/arch/x86/kernel/io_delay.c b/arch/x86/kernel/io_delay.c
new file mode 100644
index 00000000000..4d955e74b97
--- /dev/null
+++ b/arch/x86/kernel/io_delay.c
@@ -0,0 +1,106 @@
+/*
+ * I/O delay strategies for inb_p/outb_p
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/dmi.h>
+#include <asm/io.h>
+
+/*
+ * Allow for a DMI based override of port 0x80 needed for certain HP laptops
+ */
+#define IO_DELAY_PORT_STD 0x80
+#define IO_DELAY_PORT_ALT 0xed
+
+static void standard_io_delay(void)
+{
+	asm volatile ("outb %%al, %0" : : "N" (IO_DELAY_PORT_STD));
+}
+
+static void alternate_io_delay(void)
+{
+	asm volatile ("outb %%al, %0" : : "N" (IO_DELAY_PORT_ALT));
+}
+
+/*
+ * 2 usecs is an upper-bound for the outb delay but note that udelay doesn't
+ * have the bus-level side-effects that outb does
+ */
+#define IO_DELAY_USECS 2
+
+/*
+ * High on a hill was a lonely goatherd
+ */
+static void udelay_io_delay(void)
+{
+	udelay(IO_DELAY_USECS);
+}
+
+#ifndef CONFIG_UDELAY_IO_DELAY
+static void (*io_delay)(void) = standard_io_delay;
+#else
+static void (*io_delay)(void) = udelay_io_delay;
+#endif
+
+/*
+ * Paravirt wants native_io_delay to be a constant.
+ */
+void native_io_delay(void)
+{
+	io_delay();
+}
+EXPORT_SYMBOL(native_io_delay);
+
+#ifndef CONFIG_UDELAY_IO_DELAY
+static int __init dmi_alternate_io_delay_port(const struct dmi_system_id *id)
+{
+	printk(KERN_NOTICE "%s: using alternate I/O delay port\n", id->ident);
+	io_delay = alternate_io_delay;
+	return 0;
+}
+
+static struct dmi_system_id __initdata alternate_io_delay_port_dmi_table[] = {
+	{
+		.callback	= dmi_alternate_io_delay_port,
+		.ident		= "HP Pavilion dv9000z",
+		.matches	= {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
+			DMI_MATCH(DMI_BOARD_NAME, "30B9")
+		}
+	},
+	{
+	}
+};
+
+static int __initdata io_delay_override;
+
+void __init io_delay_init(void)
+{
+	if (!io_delay_override)
+		dmi_check_system(alternate_io_delay_port_dmi_table);
+}
+#endif
+
+static int __init io_delay_param(char *s)
+{
+	if (!s)
+		return -EINVAL;
+
+	if (!strcmp(s, "standard"))
+		io_delay = standard_io_delay;
+	else if (!strcmp(s, "alternate"))
+		io_delay = alternate_io_delay;
+	else if (!strcmp(s, "udelay"))
+		io_delay = udelay_io_delay;
+	else
+		return -EINVAL;
+
+#ifndef CONFIG_UDELAY_IO_DELAY
+	io_delay_override = 1;
+#endif
+	return 0;
+}
+
+early_param("io_delay", io_delay_param);