LXR linux/arch/x86/kernel/io

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * I/O delay strategies for inb_p/outb_p
   4 *
   5 * Allow for a DMI based override of port 0x80, needed for certain HP laptops
   6 * and possibly other systems. Also allow for the gradual elimination of
   7 * outb_p/inb_p API uses.
   8 */
   9#include <linux/kernel.h>
  10#include <linux/export.h>
  11#include <linux/delay.h>
  12#include <linux/init.h>
  13#include <linux/dmi.h>
  14#include <linux/io.h>
  15
  16#define IO_DELAY_TYPE_0X80      0
  17#define IO_DELAY_TYPE_0XED      1
  18#define IO_DELAY_TYPE_UDELAY    2
  19#define IO_DELAY_TYPE_NONE      3
  20
  21#if defined(CONFIG_IO_DELAY_0X80)
  22#define DEFAULT_IO_DELAY_TYPE   IO_DELAY_TYPE_0X80
  23#elif defined(CONFIG_IO_DELAY_0XED)
  24#define DEFAULT_IO_DELAY_TYPE   IO_DELAY_TYPE_0XED
  25#elif defined(CONFIG_IO_DELAY_UDELAY)
  26#define DEFAULT_IO_DELAY_TYPE   IO_DELAY_TYPE_UDELAY
  27#elif defined(CONFIG_IO_DELAY_NONE)
  28#define DEFAULT_IO_DELAY_TYPE   IO_DELAY_TYPE_NONE
  29#endif
  30
  31int io_delay_type __read_mostly = DEFAULT_IO_DELAY_TYPE;
  32
  33static int __initdata io_delay_override;
  34
  35/*
  36 * Paravirt wants native_io_delay to be a constant.
  37 */
  38void native_io_delay(void)
  39{
  40        switch (io_delay_type) {
  41        default:
  42        case IO_DELAY_TYPE_0X80:
  43                asm volatile ("outb %al, $0x80");
  44                break;
  45        case IO_DELAY_TYPE_0XED:
  46                asm volatile ("outb %al, $0xed");
  47                break;
  48        case IO_DELAY_TYPE_UDELAY:
  49                /*
  50                 * 2 usecs is an upper-bound for the outb delay but
  51                 * note that udelay doesn't have the bus-level
  52                 * side-effects that outb does, nor does udelay() have
  53                 * precise timings during very early bootup (the delays
  54                 * are shorter until calibrated):
  55                 */
  56                udelay(2);
  57                break;
  58        case IO_DELAY_TYPE_NONE:
  59                break;
  60        }
  61}
  62EXPORT_SYMBOL(native_io_delay);
  63
  64static int __init dmi_io_delay_0xed_port(const struct dmi_system_id *id)
  65{
  66        if (io_delay_type == IO_DELAY_TYPE_0X80) {
  67                pr_notice("%s: using 0xed I/O delay port\n", id->ident);
  68                io_delay_type = IO_DELAY_TYPE_0XED;
  69        }
  70
  71        return 0;
  72}
  73
  74/*
  75 * Quirk table for systems that misbehave (lock up, etc.) if port
  76 * 0x80 is used:
  77 */
  78static const struct dmi_system_id io_delay_0xed_port_dmi_table[] __initconst = {
  79        {
  80                .callback       = dmi_io_delay_0xed_port,
  81                .ident          = "Compaq Presario V6000",
  82                .matches        = {
  83                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
  84                        DMI_MATCH(DMI_BOARD_NAME,       "30B7")
  85                }
  86        },
  87        {
  88                .callback       = dmi_io_delay_0xed_port,
  89                .ident          = "HP Pavilion dv9000z",
  90                .matches        = {
  91                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
  92                        DMI_MATCH(DMI_BOARD_NAME,       "30B9")
  93                }
  94        },
  95        {
  96                .callback       = dmi_io_delay_0xed_port,
  97                .ident          = "HP Pavilion dv6000",
  98                .matches        = {
  99                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
 100                        DMI_MATCH(DMI_BOARD_NAME,       "30B8")
 101                }
 102        },
 103        {
 104                .callback       = dmi_io_delay_0xed_port,
 105                .ident          = "HP Pavilion tx1000",
 106                .matches        = {
 107                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
 108                        DMI_MATCH(DMI_BOARD_NAME,       "30BF")
 109                }
 110        },
 111        {
 112                .callback       = dmi_io_delay_0xed_port,
 113                .ident          = "Presario F700",
 114                .matches        = {
 115                        DMI_MATCH(DMI_BOARD_VENDOR,     "Quanta"),
 116                        DMI_MATCH(DMI_BOARD_NAME,       "30D3")
 117                }
 118        },
 119        { }
 120};
 121
 122void __init io_delay_init(void)
 123{
 124        if (!io_delay_override)
 125                dmi_check_system(io_delay_0xed_port_dmi_table);
 126}
 127
 128static int __init io_delay_param(char *s)
 129{
 130        if (!s)
 131                return -EINVAL;
 132
 133        if (!strcmp(s, "0x80"))
 134                io_delay_type = IO_DELAY_TYPE_0X80;
 135        else if (!strcmp(s, "0xed"))
 136                io_delay_type = IO_DELAY_TYPE_0XED;
 137        else if (!strcmp(s, "udelay"))
 138                io_delay_type = IO_DELAY_TYPE_UDELAY;
 139        else if (!strcmp(s, "none"))
 140                io_delay_type = IO_DELAY_TYPE_NONE;
 141        else
 142                return -EINVAL;
 143
 144        io_delay_override = 1;
 145        return 0;
 146}
 147
 148early_param("io_delay", io_delay_param);
 149