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 */
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 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 .callback = dmi_io_delay_0xed_port,
97 .ident = "Presario F700",
98 .matches = {
99 DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
100 DMI_MATCH(DMI_BOARD_NAME, "30D3")
101 }
102 },
103 { }
104 };
105
io_delay_init(void)106 void __init io_delay_init(void)
107 {
108 if (!io_delay_override)
109 dmi_check_system(io_delay_0xed_port_dmi_table);
110 }
111
io_delay_param(char * s)112 static int __init io_delay_param(char *s)
113 {
114 if (!s)
115 return -EINVAL;
116
117 if (!strcmp(s, "0x80"))
118 io_delay_type = CONFIG_IO_DELAY_TYPE_0X80;
119 else if (!strcmp(s, "0xed"))
120 io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
121 else if (!strcmp(s, "udelay"))
122 io_delay_type = CONFIG_IO_DELAY_TYPE_UDELAY;
123 else if (!strcmp(s, "none"))
124 io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
125 else
126 return -EINVAL;
127
128 io_delay_override = 1;
129 return 0;
130 }
131
132 early_param("io_delay", io_delay_param);
133