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