io_delay.c

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/*
 * 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/delay.h>
#include <linux/init.h>
#include <linux/dmi.h>
#include <linux/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) {
        pr_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);