root/arch/x86/kernel/io_delay.c

DEFINITIONS

1. native_io_delay
2. dmi_io_delay_0xed_port
3. io_delay_init
4. io_delay_param

/*
 * I/O delay strategies for inb_p/outb_p
 *
 * Allow for a DMI based override of port 0x80, needed for certain HP laptops
 * and possibly other systems. Also allow for the gradual elimination of
 * outb_p/inb_p API uses.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/dmi.h>
#include <asm/io.h>

int io_delay_type __read_mostly = CONFIG_DEFAULT_IO_DELAY_TYPE;

static int __initdata io_delay_override;

/*
 * Paravirt wants native_io_delay to be a constant.
 */
void native_io_delay(void)
{
        switch (io_delay_type) {
        default:
        case CONFIG_IO_DELAY_TYPE_0X80:
                asm volatile ("outb %al, $0x80");
                break;
        case CONFIG_IO_DELAY_TYPE_0XED:
                asm volatile ("outb %al, $0xed");
                break;
        case CONFIG_IO_DELAY_TYPE_UDELAY:
                /*
                 * 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, nor does udelay() have
                 * precise timings during very early bootup (the delays
                 * are shorter until calibrated):
                 */
                udelay(2);
        case CONFIG_IO_DELAY_TYPE_NONE:
                break;
        }
}
EXPORT_SYMBOL(native_io_delay);

static int __init dmi_io_delay_0xed_port(const struct dmi_system_id *id)
{
        if (io_delay_type == CONFIG_IO_DELAY_TYPE_0X80) {
                printk(KERN_NOTICE "%s: using 0xed I/O delay port\n",
                        id->ident);
                io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
        }

        return 0;
}

/*
 * Quirk table for systems that misbehave (lock up, etc.) if port
 * 0x80 is used:
 */
static struct dmi_system_id __initdata io_delay_0xed_port_dmi_table[] = {
        {
                .callback       = dmi_io_delay_0xed_port,
                .ident          = "Compaq Presario V6000",
                .matches        = {
                        DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
                        DMI_MATCH(DMI_BOARD_NAME, "30B7")
                }
        },
        {
                .callback       = dmi_io_delay_0xed_port,
                .ident          = "HP Pavilion dv9000z",
                .matches        = {
                        DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
                        DMI_MATCH(DMI_BOARD_NAME, "30B9")
                }
        },
        {
                .callback       = dmi_io_delay_0xed_port,
                .ident          = "HP Pavilion dv6000",
                .matches        = {
                        DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
                        DMI_MATCH(DMI_BOARD_NAME, "30B8")
                }
        },
        {
                .callback       = dmi_io_delay_0xed_port,
                .ident          = "HP Pavilion tx1000",
                .matches        = {
                        DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
                        DMI_MATCH(DMI_BOARD_NAME, "30BF")
                }
        },
        {
                .callback       = dmi_io_delay_0xed_port,
                .ident          = "Presario F700",
                .matches        = {
                        DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
                        DMI_MATCH(DMI_BOARD_NAME, "30D3")
                }
        },
        { }
};

void __init io_delay_init(void)
{
        if (!io_delay_override)
                dmi_check_system(io_delay_0xed_port_dmi_table);
}

static int __init io_delay_param(char *s)
{
        if (!s)
                return -EINVAL;

        if (!strcmp(s, "0x80"))
                io_delay_type = CONFIG_IO_DELAY_TYPE_0X80;
        else if (!strcmp(s, "0xed"))
                io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
        else if (!strcmp(s, "udelay"))
                io_delay_type = CONFIG_IO_DELAY_TYPE_UDELAY;
        else if (!strcmp(s, "none"))
                io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
        else
                return -EINVAL;

        io_delay_override = 1;
        return 0;
}

early_param("io_delay", io_delay_param);