arch/x86/kernel/io_delay.c

   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
  15 int io_delay_type __read_mostly = CONFIG_DEFAULT_IO_DELAY_TYPE;
  16
  17 static int __initdata io_delay_override;
  18
  19 /*
  20  * Paravirt wants native_io_delay to be a constant.
  21  */
  22 void 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 }
  45 EXPORT_SYMBOL(native_io_delay);
  46
  47 static 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  */
  61 static 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
 105 void __init io_delay_init(void)
 106 {
 107         if (!io_delay_override)
 108                 dmi_check_system(io_delay_0xed_port_dmi_table);
 109 }
 110
 111 static 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
 131 early_param("io_delay", io_delay_param);