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/delay.h>
11#include <linux/init.h>
12#include <linux/dmi.h>
13#include <linux/io.h>
14
15int io_delay_type __read_mostly = CONFIG_DEFAULT_IO_DELAY_TYPE;
16
17static int __initdata io_delay_override;
18
19/*
20 * Paravirt wants native_io_delay to be a constant.
21 */
22void 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}
45EXPORT_SYMBOL(native_io_delay);
46
47static 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 */
61static 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
105void __init io_delay_init(void)
106{
107	if (!io_delay_override)
108		dmi_check_system(io_delay_0xed_port_dmi_table);
109}
110
111static 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
131early_param("io_delay", io_delay_param);
132