c706a3061553d31f69e8904ae23b7b2b335ccfd8
[sfrench/cifs-2.6.git] / arch / x86 / kernel / io_delay.c
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 tx1000",
82                 .matches        = {
83                         DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
84                         DMI_MATCH(DMI_BOARD_NAME, "30BF")
85                 }
86         },
87         { }
88 };
89
90 void __init io_delay_init(void)
91 {
92         if (!io_delay_override)
93                 dmi_check_system(io_delay_0xed_port_dmi_table);
94 }
95
96 static int __init io_delay_param(char *s)
97 {
98         if (!strcmp(s, "0x80"))
99                 io_delay_type = CONFIG_IO_DELAY_TYPE_0X80;
100         else if (!strcmp(s, "0xed"))
101                 io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
102         else if (!strcmp(s, "udelay"))
103                 io_delay_type = CONFIG_IO_DELAY_TYPE_UDELAY;
104         else if (!strcmp(s, "none"))
105                 io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
106         else
107                 return -EINVAL;
108
109         io_delay_override = 1;
110         return 0;
111 }
112
113 early_param("io_delay", io_delay_param);