xref: /openbmc/linux/arch/x86/kernel/io_delay.c (revision c2d64c7e)
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 #define IO_DELAY_TYPE_0X80	0
17 #define IO_DELAY_TYPE_0XED	1
18 #define IO_DELAY_TYPE_UDELAY	2
19 #define IO_DELAY_TYPE_NONE	3
20 
21 #if defined(CONFIG_IO_DELAY_0X80)
22 #define DEFAULT_IO_DELAY_TYPE	IO_DELAY_TYPE_0X80
23 #elif defined(CONFIG_IO_DELAY_0XED)
24 #define DEFAULT_IO_DELAY_TYPE	IO_DELAY_TYPE_0XED
25 #elif defined(CONFIG_IO_DELAY_UDELAY)
26 #define DEFAULT_IO_DELAY_TYPE	IO_DELAY_TYPE_UDELAY
27 #elif defined(CONFIG_IO_DELAY_NONE)
28 #define DEFAULT_IO_DELAY_TYPE	IO_DELAY_TYPE_NONE
29 #endif
30 
31 int io_delay_type __read_mostly = DEFAULT_IO_DELAY_TYPE;
32 
33 static int __initdata io_delay_override;
34 
35 /*
36  * Paravirt wants native_io_delay to be a constant.
37  */
native_io_delay(void)38 void native_io_delay(void)
39 {
40 	switch (io_delay_type) {
41 	default:
42 	case IO_DELAY_TYPE_0X80:
43 		asm volatile ("outb %al, $0x80");
44 		break;
45 	case IO_DELAY_TYPE_0XED:
46 		asm volatile ("outb %al, $0xed");
47 		break;
48 	case IO_DELAY_TYPE_UDELAY:
49 		/*
50 		 * 2 usecs is an upper-bound for the outb delay but
51 		 * note that udelay doesn't have the bus-level
52 		 * side-effects that outb does, nor does udelay() have
53 		 * precise timings during very early bootup (the delays
54 		 * are shorter until calibrated):
55 		 */
56 		udelay(2);
57 		break;
58 	case IO_DELAY_TYPE_NONE:
59 		break;
60 	}
61 }
62 EXPORT_SYMBOL(native_io_delay);
63 
dmi_io_delay_0xed_port(const struct dmi_system_id * id)64 static int __init dmi_io_delay_0xed_port(const struct dmi_system_id *id)
65 {
66 	if (io_delay_type == IO_DELAY_TYPE_0X80) {
67 		pr_notice("%s: using 0xed I/O delay port\n", id->ident);
68 		io_delay_type = IO_DELAY_TYPE_0XED;
69 	}
70 
71 	return 0;
72 }
73 
74 /*
75  * Quirk table for systems that misbehave (lock up, etc.) if port
76  * 0x80 is used:
77  */
78 static const struct dmi_system_id io_delay_0xed_port_dmi_table[] __initconst = {
79 	{
80 		.callback	= dmi_io_delay_0xed_port,
81 		.ident		= "Compaq Presario V6000",
82 		.matches	= {
83 			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),
84 			DMI_MATCH(DMI_BOARD_NAME,	"30B7")
85 		}
86 	},
87 	{
88 		.callback	= dmi_io_delay_0xed_port,
89 		.ident		= "HP Pavilion dv9000z",
90 		.matches	= {
91 			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),
92 			DMI_MATCH(DMI_BOARD_NAME,	"30B9")
93 		}
94 	},
95 	{
96 		.callback	= dmi_io_delay_0xed_port,
97 		.ident		= "HP Pavilion dv6000",
98 		.matches	= {
99 			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),
100 			DMI_MATCH(DMI_BOARD_NAME,	"30B8")
101 		}
102 	},
103 	{
104 		.callback	= dmi_io_delay_0xed_port,
105 		.ident		= "HP Pavilion tx1000",
106 		.matches	= {
107 			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),
108 			DMI_MATCH(DMI_BOARD_NAME,	"30BF")
109 		}
110 	},
111 	{
112 		.callback	= dmi_io_delay_0xed_port,
113 		.ident		= "Presario F700",
114 		.matches	= {
115 			DMI_MATCH(DMI_BOARD_VENDOR,	"Quanta"),
116 			DMI_MATCH(DMI_BOARD_NAME,	"30D3")
117 		}
118 	},
119 	{ }
120 };
121 
io_delay_init(void)122 void __init io_delay_init(void)
123 {
124 	if (!io_delay_override)
125 		dmi_check_system(io_delay_0xed_port_dmi_table);
126 }
127 
io_delay_param(char * s)128 static int __init io_delay_param(char *s)
129 {
130 	if (!s)
131 		return -EINVAL;
132 
133 	if (!strcmp(s, "0x80"))
134 		io_delay_type = IO_DELAY_TYPE_0X80;
135 	else if (!strcmp(s, "0xed"))
136 		io_delay_type = IO_DELAY_TYPE_0XED;
137 	else if (!strcmp(s, "udelay"))
138 		io_delay_type = IO_DELAY_TYPE_UDELAY;
139 	else if (!strcmp(s, "none"))
140 		io_delay_type = IO_DELAY_TYPE_NONE;
141 	else
142 		return -EINVAL;
143 
144 	io_delay_override = 1;
145 	return 0;
146 }
147 
148 early_param("io_delay", io_delay_param);
149