xref: /linux/arch/x86/kernel/io_delay.c (revision e5c86679d5e864947a52fb31e45a425dea3e7fa9)
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/export.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);
132