Linux-2.6.12-rc2
[linux-2.6.git] / 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 atomic_t rtc_inc = ATOMIC_INIT(0);
64 static rtc_task_t rtc_task;
65
66
67 static int
68 rtctimer_open(snd_timer_t *t)
69 {
70         int err;
71
72         err = rtc_register(&rtc_task);
73         if (err < 0)
74                 return err;
75         t->private_data = &rtc_task;
76         return 0;
77 }
78
79 static int
80 rtctimer_close(snd_timer_t *t)
81 {
82         rtc_task_t *rtc = t->private_data;
83         if (rtc) {
84                 rtc_unregister(rtc);
85                 t->private_data = NULL;
86         }
87         return 0;
88 }
89
90 static int
91 rtctimer_start(snd_timer_t *timer)
92 {
93         rtc_task_t *rtc = timer->private_data;
94         snd_assert(rtc != NULL, return -EINVAL);
95         rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
96         rtc_control(rtc, RTC_PIE_ON, 0);
97         atomic_set(&rtc_inc, 0);
98         return 0;
99 }
100
101 static int
102 rtctimer_stop(snd_timer_t *timer)
103 {
104         rtc_task_t *rtc = timer->private_data;
105         snd_assert(rtc != NULL, return -EINVAL);
106         rtc_control(rtc, RTC_PIE_OFF, 0);
107         return 0;
108 }
109
110 /*
111  * interrupt
112  */
113 static void rtctimer_interrupt(void *private_data)
114 {
115         int ticks;
116
117         atomic_inc(&rtc_inc);
118         ticks = atomic_read(&rtc_inc);
119         snd_timer_interrupt((snd_timer_t*)private_data, ticks);
120         atomic_sub(ticks, &rtc_inc);
121 }
122
123
124 /*
125  *  ENTRY functions
126  */
127 static int __init rtctimer_init(void)
128 {
129         int order, err;
130         snd_timer_t *timer;
131
132         if (rtctimer_freq < 2 || rtctimer_freq > 8192) {
133                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n", rtctimer_freq);
134                 return -EINVAL;
135         }
136         for (order = 1; rtctimer_freq > order; order <<= 1)
137                 ;
138         if (rtctimer_freq != order) {
139                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n", rtctimer_freq);
140                 return -EINVAL;
141         }
142
143         /* Create a new timer and set up the fields */
144         err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
145         if (err < 0)
146                 return err;
147
148         strcpy(timer->name, "RTC timer");
149         timer->hw = rtc_hw;
150         timer->hw.resolution = NANO_SEC / rtctimer_freq;
151
152         /* set up RTC callback */
153         rtc_task.func = rtctimer_interrupt;
154         rtc_task.private_data = timer;
155
156         err = snd_timer_global_register(timer);
157         if (err < 0) {
158                 snd_timer_global_free(timer);
159                 return err;
160         }
161         rtctimer = timer; /* remember this */
162
163         return 0;
164 }
165
166 static void __exit rtctimer_exit(void)
167 {
168         if (rtctimer) {
169                 snd_timer_global_unregister(rtctimer);
170                 rtctimer = NULL;
171         }
172 }
173
174
175 /*
176  * exported stuff
177  */
178 module_init(rtctimer_init)
179 module_exit(rtctimer_exit)
180
181 module_param(rtctimer_freq, int, 0444);
182 MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
183
184 MODULE_LICENSE("GPL");
185
186 MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
187
188 #endif /* CONFIG_RTC || CONFIG_RTC_MODULE */