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/*
* 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);
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