LXR linux/arch/x86/kernel/io

   1/*
   2 * I/O delay strategies for inb_p/outb_p
   3 *
   4 * Allow for a DMI based override of port 0x80, needed for certain HP laptops
   5 * and possibly other systems. Also allow for the gradual elimination of
   6 * outb_p/inb_p API uses.
   7 */
   8#include <linux/kernel.h>
   9#include <linux/module.h>
  10#include <linux/delay.h>
  11#include <linux/init.h>
  12#include <linux/dmi.h>
  13#include <linux/io.h>
  14
  15int io_delay_type __read_mostly = CONFIG_DEFAULT_IO_DELAY_TYPE;
  16
  17static int __initdata io_delay_override;
  18
  19/*
  20 * Paravirt wants native_io_delay to be a constant.
  21 */
  22void native_io_delay(void)
  23{
  24        switch (io_delay_type) {
  25        default:
  26        case CONFIG_IO_DELAY_TYPE_0X80:
  27                asm volatile ("outb %al, $0x80");
  28                break;
  29        case CONFIG_IO_DELAY_TYPE_0XED:
  30                asm volatile ("outb %al, $0xed");
  31                break;
  32        case CONFIG_IO_DELAY_TYPE_UDELAY:
  33                /*
  34                 * 2 usecs is an upper-bound for the outb delay but
  35                 * note that udelay doesn't have the bus-level
  36                 * side-effects that outb does, nor does udelay() have
  37                 * precise timings during very early bootup (the delays
  38                 * are shorter until calibrated):
  39                 */
  40                udelay(2);
  41        case CONFIG_IO_DELAY_TYPE_NONE:
  42                break;
  43        }
  44}
  45EXPORT_SYMBOL(native_io_delay);
  46
  47static int __init dmi_io_delay_0xed_port(const struct dmi_system_id *id)
  48{
  49        if (io_delay_type == CONFIG_IO_DELAY_TYPE_0X80) {
  50                pr_notice("%s: using 0xed I/O delay port\n", id->ident);
  51                io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
  52        }
  53
  54        return 0;
  55}
  56
  57/*
  58 * Quirk table for systems that misbehave (lock up, etc.) if port
  59 * 0x80 is used:
  60 */
  61static struct dmi_system_id __initdata io_delay_0xed_port_dmi_table[] = {
  62        {
  63                .callback       = dmi_io_delay_0xed_port,
  64                .ident          = "Compaq Presario V6000",
  65                .matches        = {
  66                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
  67                        DMI_MATCH(DMI_BOARD_NAME,       "30B7")
  68                }
  69        },
  70        {
  71                .callback       = dmi_io_delay_0xed_port,
  72                .ident          = "HP Pavilion dv9000z",
  73                .matches        = {
  74                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
  75                        DMI_MATCH(DMI_BOARD_NAME,       "30B9")
  76                }
  77        },
  78        {
  79                .callback       = dmi_io_delay_0xed_port,
  80                .ident          = "HP Pavilion dv6000",
  81                .matches        = {
  82                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
  83                        DMI_MATCH(DMI_BOARD_NAME,       "30B8")
  84                }
  85        },
  86        {
  87                .callback       = dmi_io_delay_0xed_port,
  88                .ident          = "HP Pavilion tx1000",
  89                .matches        = {
  90                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
  91                        DMI_MATCH(DMI_BOARD_NAME,       "30BF")
  92                }
  93        },
  94        {
  95                .callback       = dmi_io_delay_0xed_port,
  96                .ident          = "Presario F700",
  97                .matches        = {
  98                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
  99                        DMI_MATCH(DMI_BOARD_NAME,       "30D3")
 100                }
 101        },
 102        { }
 103};
 104
 105void __init io_delay_init(void)
 106{
 107        if (!io_delay_override)
 108                dmi_check_system(io_delay_0xed_port_dmi_table);
 109}
 110
 111static int __init io_delay_param(char *s)
 112{
 113        if (!s)
 114                return -EINVAL;
 115
 116        if (!strcmp(s, "0x80"))
 117                io_delay_type = CONFIG_IO_DELAY_TYPE_0X80;
 118        else if (!strcmp(s, "0xed"))
 119                io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
 120        else if (!strcmp(s, "udelay"))
 121                io_delay_type = CONFIG_IO_DELAY_TYPE_UDELAY;
 122        else if (!strcmp(s, "none"))
 123                io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
 124        else
 125                return -EINVAL;
 126
 127        io_delay_override = 1;
 128        return 0;
 129}
 130
 131early_param("io_delay", io_delay_param);
 132