x86/kernel/io_delay.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * I/O delay strategies for inb_p/outb_p
0004  *
0005  * Allow for a DMI based override of port 0x80, needed for certain HP laptops
0006  * and possibly other systems. Also allow for the gradual elimination of
0007  * outb_p/inb_p API uses.
0008  */
0009 #include <linux/kernel.h>
0010 #include <linux/export.h>
0011 #include <linux/delay.h>
0012 #include <linux/init.h>
0013 #include <linux/dmi.h>
0014 #include <linux/io.h>
0015
0016 #define IO_DELAY_TYPE_0X80  0
0017 #define IO_DELAY_TYPE_0XED  1
0018 #define IO_DELAY_TYPE_UDELAY    2
0019 #define IO_DELAY_TYPE_NONE  3
0020
0021 #if defined(CONFIG_IO_DELAY_0X80)
0022 #define DEFAULT_IO_DELAY_TYPE   IO_DELAY_TYPE_0X80
0023 #elif defined(CONFIG_IO_DELAY_0XED)
0024 #define DEFAULT_IO_DELAY_TYPE   IO_DELAY_TYPE_0XED
0025 #elif defined(CONFIG_IO_DELAY_UDELAY)
0026 #define DEFAULT_IO_DELAY_TYPE   IO_DELAY_TYPE_UDELAY
0027 #elif defined(CONFIG_IO_DELAY_NONE)
0028 #define DEFAULT_IO_DELAY_TYPE   IO_DELAY_TYPE_NONE
0029 #endif
0030
0031 int io_delay_type __read_mostly = DEFAULT_IO_DELAY_TYPE;
0032
0033 static int __initdata io_delay_override;
0034
0035 /*
0036  * Paravirt wants native_io_delay to be a constant.
0037  */
0038 void native_io_delay(void)
0039 {
0040     switch (io_delay_type) {
0041     default:
0042     case IO_DELAY_TYPE_0X80:
0043         asm volatile ("outb %al, $0x80");
0044         break;
0045     case IO_DELAY_TYPE_0XED:
0046         asm volatile ("outb %al, $0xed");
0047         break;
0048     case IO_DELAY_TYPE_UDELAY:
0049         /*
0050          * 2 usecs is an upper-bound for the outb delay but
0051          * note that udelay doesn't have the bus-level
0052          * side-effects that outb does, nor does udelay() have
0053          * precise timings during very early bootup (the delays
0054          * are shorter until calibrated):
0055          */
0056         udelay(2);
0057         break;
0058     case IO_DELAY_TYPE_NONE:
0059         break;
0060     }
0061 }
0062 EXPORT_SYMBOL(native_io_delay);
0063
0064 static int __init dmi_io_delay_0xed_port(const struct dmi_system_id *id)
0065 {
0066     if (io_delay_type == IO_DELAY_TYPE_0X80) {
0067         pr_notice("%s: using 0xed I/O delay port\n", id->ident);
0068         io_delay_type = IO_DELAY_TYPE_0XED;
0069     }
0070
0071     return 0;
0072 }
0073
0074 /*
0075  * Quirk table for systems that misbehave (lock up, etc.) if port
0076  * 0x80 is used:
0077  */
0078 static const struct dmi_system_id io_delay_0xed_port_dmi_table[] __initconst = {
0079     {
0080         .callback   = dmi_io_delay_0xed_port,
0081         .ident      = "Compaq Presario V6000",
0082         .matches    = {
0083             DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
0084             DMI_MATCH(DMI_BOARD_NAME,   "30B7")
0085         }
0086     },
0087     {
0088         .callback   = dmi_io_delay_0xed_port,
0089         .ident      = "HP Pavilion dv9000z",
0090         .matches    = {
0091             DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
0092             DMI_MATCH(DMI_BOARD_NAME,   "30B9")
0093         }
0094     },
0095     {
0096         .callback   = dmi_io_delay_0xed_port,
0097         .ident      = "HP Pavilion dv6000",
0098         .matches    = {
0099             DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
0100             DMI_MATCH(DMI_BOARD_NAME,   "30B8")
0101         }
0102     },
0103     {
0104         .callback   = dmi_io_delay_0xed_port,
0105         .ident      = "HP Pavilion tx1000",
0106         .matches    = {
0107             DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
0108             DMI_MATCH(DMI_BOARD_NAME,   "30BF")
0109         }
0110     },
0111     {
0112         .callback   = dmi_io_delay_0xed_port,
0113         .ident      = "Presario F700",
0114         .matches    = {
0115             DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
0116             DMI_MATCH(DMI_BOARD_NAME,   "30D3")
0117         }
0118     },
0119     { }
0120 };
0121
0122 void __init io_delay_init(void)
0123 {
0124     if (!io_delay_override)
0125         dmi_check_system(io_delay_0xed_port_dmi_table);
0126 }
0127
0128 static int __init io_delay_param(char *s)
0129 {
0130     if (!s)
0131         return -EINVAL;
0132
0133     if (!strcmp(s, "0x80"))
0134         io_delay_type = IO_DELAY_TYPE_0X80;
0135     else if (!strcmp(s, "0xed"))
0136         io_delay_type = IO_DELAY_TYPE_0XED;
0137     else if (!strcmp(s, "udelay"))
0138         io_delay_type = IO_DELAY_TYPE_UDELAY;
0139     else if (!strcmp(s, "none"))
0140         io_delay_type = IO_DELAY_TYPE_NONE;
0141     else
0142         return -EINVAL;
0143
0144     io_delay_override = 1;
0145     return 0;
0146 }
0147
0148 early_param("io_delay", io_delay_param);