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
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 */
native_io_delay(void)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
dmi_io_delay_0xed_port(const struct dmi_system_id * id)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
io_delay_init(void)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
io_delay_param(char * s)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