Merge master.kernel.org:/pub/scm/linux/kernel/git/davej/cpufreq
[linux-2.6] / sound / core / rtctimer.c
1 /*
2  *  RTC based high-frequency timer
3  *
4  *  Copyright (C) 2000 Takashi Iwai
5  *      based on rtctimer.c by Steve Ratcliffe
6  *
7  *   This program is free software; you can redistribute it and/or modify
8  *   it under the terms of the GNU General Public License as published by
9  *   the Free Software Foundation; either version 2 of the License, or
10  *   (at your option) any later version.
11  *
12  *   This program is distributed in the hope that it will be useful,
13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  *   GNU General Public License for more details.
16  *
17  *   You should have received a copy of the GNU General Public License
18  *   along with this program; if not, write to the Free Software
19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
20  *
21  */
22
23 #include <sound/driver.h>
24 #include <linux/init.h>
25 #include <linux/time.h>
26 #include <linux/threads.h>
27 #include <linux/interrupt.h>
28 #include <linux/moduleparam.h>
29 #include <sound/core.h>
30 #include <sound/timer.h>
31 #include <sound/info.h>
32
33 #if defined(CONFIG_RTC) || defined(CONFIG_RTC_MODULE)
34
35 #include <linux/mc146818rtc.h>
36
37 #define RTC_FREQ        1024            /* default frequency */
38 #define NANO_SEC        1000000000L     /* 10^9 in sec */
39
40 /*
41  * prototypes
42  */
43 static int rtctimer_open(snd_timer_t *t);
44 static int rtctimer_close(snd_timer_t *t);
45 static int rtctimer_start(snd_timer_t *t);
46 static int rtctimer_stop(snd_timer_t *t);
47
48
49 /*
50  * The hardware dependent description for this timer.
51  */
52 static struct _snd_timer_hardware rtc_hw = {
53         .flags =        SNDRV_TIMER_HW_FIRST|SNDRV_TIMER_HW_AUTO,
54         .ticks =        100000000L,             /* FIXME: XXX */
55         .open =         rtctimer_open,
56         .close =        rtctimer_close,
57         .start =        rtctimer_start,
58         .stop =         rtctimer_stop,
59 };
60
61 static int rtctimer_freq = RTC_FREQ;            /* frequency */
62 static snd_timer_t *rtctimer;
63 static rtc_task_t rtc_task;
64
65
66 static int
67 rtctimer_open(snd_timer_t *t)
68 {
69         int err;
70
71         err = rtc_register(&rtc_task);
72         if (err < 0)
73                 return err;
74         t->private_data = &rtc_task;
75         return 0;
76 }
77
78 static int
79 rtctimer_close(snd_timer_t *t)
80 {
81         rtc_task_t *rtc = t->private_data;
82         if (rtc) {
83                 rtc_unregister(rtc);
84                 t->private_data = NULL;
85         }
86         return 0;
87 }
88
89 static int
90 rtctimer_start(snd_timer_t *timer)
91 {
92         rtc_task_t *rtc = timer->private_data;
93         snd_assert(rtc != NULL, return -EINVAL);
94         rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
95         rtc_control(rtc, RTC_PIE_ON, 0);
96         return 0;
97 }
98
99 static int
100 rtctimer_stop(snd_timer_t *timer)
101 {
102         rtc_task_t *rtc = timer->private_data;
103         snd_assert(rtc != NULL, return -EINVAL);
104         rtc_control(rtc, RTC_PIE_OFF, 0);
105         return 0;
106 }
107
108 /*
109  * interrupt
110  */
111 static void rtctimer_interrupt(void *private_data)
112 {
113         snd_timer_interrupt(private_data, 1);
114 }
115
116
117 /*
118  *  ENTRY functions
119  */
120 static int __init rtctimer_init(void)
121 {
122         int err;
123         snd_timer_t *timer;
124
125         if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
126             (rtctimer_freq & (rtctimer_freq - 1)) != 0) {
127                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
128                            rtctimer_freq);
129                 return -EINVAL;
130         }
131
132         /* Create a new timer and set up the fields */
133         err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
134         if (err < 0)
135                 return err;
136
137         timer->module = THIS_MODULE;
138         strcpy(timer->name, "RTC timer");
139         timer->hw = rtc_hw;
140         timer->hw.resolution = NANO_SEC / rtctimer_freq;
141
142         /* set up RTC callback */
143         rtc_task.func = rtctimer_interrupt;
144         rtc_task.private_data = timer;
145
146         err = snd_timer_global_register(timer);
147         if (err < 0) {
148                 snd_timer_global_free(timer);
149                 return err;
150         }
151         rtctimer = timer; /* remember this */
152
153         return 0;
154 }
155
156 static void __exit rtctimer_exit(void)
157 {
158         if (rtctimer) {
159                 snd_timer_global_unregister(rtctimer);
160                 rtctimer = NULL;
161         }
162 }
163
164
165 /*
166  * exported stuff
167  */
168 module_init(rtctimer_init)
169 module_exit(rtctimer_exit)
170
171 module_param(rtctimer_freq, int, 0444);
172 MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
173
174 MODULE_LICENSE("GPL");
175
176 MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
177
178 #endif /* CONFIG_RTC || CONFIG_RTC_MODULE */