hp accelerometer: add freefall detection
[linux-2.6.git] / Documentation / hwmon / hpfall.c
1 /* Disk protection for HP machines.
2  *
3  * Copyright 2008 Eric Piel
4  * Copyright 2009 Pavel Machek <pavel@suse.cz>
5  *
6  * GPLv2.
7  */
8
9 #include <stdio.h>
10 #include <stdlib.h>
11 #include <unistd.h>
12 #include <fcntl.h>
13 #include <sys/stat.h>
14 #include <sys/types.h>
15 #include <string.h>
16 #include <stdint.h>
17 #include <errno.h>
18 #include <signal.h>
19
20 void write_int(char *path, int i)
21 {
22         char buf[1024];
23         int fd = open(path, O_RDWR);
24         if (fd < 0) {
25                 perror("open");
26                 exit(1);
27         }
28         sprintf(buf, "%d", i);
29         if (write(fd, buf, strlen(buf)) != strlen(buf)) {
30                 perror("write");
31                 exit(1);
32         }
33         close(fd);
34 }
35
36 void set_led(int on)
37 {
38         write_int("/sys/class/leds/hp::hddprotect/brightness", on);
39 }
40
41 void protect(int seconds)
42 {
43         write_int("/sys/block/sda/device/unload_heads", seconds*1000);
44 }
45
46 int on_ac(void)
47 {
48 //      /sys/class/power_supply/AC0/online
49 }
50
51 int lid_open(void)
52 {
53 //      /proc/acpi/button/lid/LID/state
54 }
55
56 void ignore_me(void)
57 {
58         protect(0);
59         set_led(0);
60
61 }
62
63 int main(int argc, char* argv[])
64 {
65        int fd, ret;
66
67        fd = open("/dev/freefall", O_RDONLY);
68        if (fd < 0) {
69                perror("open");
70                return EXIT_FAILURE;
71        }
72
73         signal(SIGALRM, ignore_me);
74
75        for (;;) {
76                unsigned char count;
77
78                ret = read(fd, &count, sizeof(count));
79                alarm(0);
80                if ((ret == -1) && (errno == EINTR)) {
81                        /* Alarm expired, time to unpark the heads */
82                        continue;
83                }
84
85                if (ret != sizeof(count)) {
86                        perror("read");
87                        break;
88                }
89
90                protect(21);
91                set_led(1);
92                if (1 || on_ac() || lid_open()) {
93                        alarm(2);
94                } else {
95                        alarm(20);
96                }
97        }
98
99        close(fd);
100        return EXIT_SUCCESS;
101 }