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/init.h>
  11 #include <linux/delay.h>
  12 #include <linux/dmi.h>
  13 #include <asm/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                 printk(KERN_NOTICE "%s: using 0xed I/O delay port\n",
  51                         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 struct dmi_system_id __initdata io_delay_0xed_port_dmi_table[] = {
  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 tx1000",
  82                 .matches        = {
  83                         DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
  84                         DMI_MATCH(DMI_BOARD_NAME, "30BF")
  85                 }
  86         },
  87         { }
  88 };
  89
  90 void __init io_delay_init(void)
  91 {
  92         if (!io_delay_override)
  93                 dmi_check_system(io_delay_0xed_port_dmi_table);
  94 }
  95
  96 static int __init io_delay_param(char *s)
  97 {
  98         if (!strcmp(s, "0x80"))
  99                 io_delay_type = CONFIG_IO_DELAY_TYPE_0X80;
 100         else if (!strcmp(s, "0xed"))
 101                 io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
 102         else if (!strcmp(s, "udelay"))
 103                 io_delay_type = CONFIG_IO_DELAY_TYPE_UDELAY;
 104         else if (!strcmp(s, "none"))
 105                 io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
 106         else
 107                 return -EINVAL;
 108
 109         io_delay_override = 1;
 110         return 0;
 111 }
 112
 113 early_param("io_delay", io_delay_param);