xref: /openbmc/linux/arch/x86/kernel/io_delay.c (revision 22246614)
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 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 };
97 
98 void __init io_delay_init(void)
99 {
100 	if (!io_delay_override)
101 		dmi_check_system(io_delay_0xed_port_dmi_table);
102 }
103 
104 static int __init io_delay_param(char *s)
105 {
106 	if (!strcmp(s, "0x80"))
107 		io_delay_type = CONFIG_IO_DELAY_TYPE_0X80;
108 	else if (!strcmp(s, "0xed"))
109 		io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
110 	else if (!strcmp(s, "udelay"))
111 		io_delay_type = CONFIG_IO_DELAY_TYPE_UDELAY;
112 	else if (!strcmp(s, "none"))
113 		io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
114 	else
115 		return -EINVAL;
116 
117 	io_delay_override = 1;
118 	return 0;
119 }
120 
121 early_param("io_delay", io_delay_param);
122