GNU Linux-libre 4.14.266-gnu1
[releases.git] / 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);