arch/x86/kernel/io_delay.c

   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
  31 int io_delay_type __read_mostly = DEFAULT_IO_DELAY_TYPE;
  32
  33 static int __initdata io_delay_override;
  34
  35 /*
  36  * Paravirt wants native_io_delay to be a constant.
  37  */
  38 void 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 }
  62 EXPORT_SYMBOL(native_io_delay);
  63
  64 static 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  */
  78 static 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
 122 void __init io_delay_init(void)
 123 {
 124         if (!io_delay_override)
 125                 dmi_check_system(io_delay_0xed_port_dmi_table);
 126 }
 127
 128 static 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
 148 early_param("io_delay", io_delay_param);