Merge branch 'linus' into x86/signal
[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 <linux/init.h>
24 #include <linux/interrupt.h>
25 #include <linux/moduleparam.h>
26 #include <linux/log2.h>
27 #include <sound/core.h>
28 #include <sound/timer.h>
29
30 #if defined(CONFIG_RTC) || defined(CONFIG_RTC_MODULE)
31
32 #include <linux/mc146818rtc.h>
33
34 #define RTC_FREQ        1024            /* default frequency */
35 #define NANO_SEC        1000000000L     /* 10^9 in sec */
36
37 /*
38  * prototypes
39  */
40 static int rtctimer_open(struct snd_timer *t);
41 static int rtctimer_close(struct snd_timer *t);
42 static int rtctimer_start(struct snd_timer *t);
43 static int rtctimer_stop(struct snd_timer *t);
44
45
46 /*
47  * The hardware dependent description for this timer.
48  */
49 static struct snd_timer_hardware rtc_hw = {
50         .flags =        SNDRV_TIMER_HW_AUTO |
51                         SNDRV_TIMER_HW_FIRST |
52                         SNDRV_TIMER_HW_TASKLET,
53         .ticks =        100000000L,             /* FIXME: XXX */
54         .open =         rtctimer_open,
55         .close =        rtctimer_close,
56         .start =        rtctimer_start,
57         .stop =         rtctimer_stop,
58 };
59
60 static int rtctimer_freq = RTC_FREQ;            /* frequency */
61 static struct snd_timer *rtctimer;
62 static struct tasklet_struct rtc_tasklet;
63 static rtc_task_t rtc_task;
64
65
66 static int
67 rtctimer_open(struct snd_timer *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(struct snd_timer *t)
80 {
81         rtc_task_t *rtc = t->private_data;
82         if (rtc) {
83                 rtc_unregister(rtc);
84                 tasklet_kill(&rtc_tasklet);
85                 t->private_data = NULL;
86         }
87         return 0;
88 }
89
90 static int
91 rtctimer_start(struct snd_timer *timer)
92 {
93         rtc_task_t *rtc = timer->private_data;
94         if (snd_BUG_ON(!rtc))
95                 return -EINVAL;
96         rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
97         rtc_control(rtc, RTC_PIE_ON, 0);
98         return 0;
99 }
100
101 static int
102 rtctimer_stop(struct snd_timer *timer)
103 {
104         rtc_task_t *rtc = timer->private_data;
105         if (snd_BUG_ON(!rtc))
106                 return -EINVAL;
107         rtc_control(rtc, RTC_PIE_OFF, 0);
108         return 0;
109 }
110
111 static void rtctimer_tasklet(unsigned long data)
112 {
113         snd_timer_interrupt((struct snd_timer *)data, 1);
114 }
115
116 /*
117  * interrupt
118  */
119 static void rtctimer_interrupt(void *private_data)
120 {
121         tasklet_hi_schedule(private_data);
122 }
123
124
125 /*
126  *  ENTRY functions
127  */
128 static int __init rtctimer_init(void)
129 {
130         int err;
131         struct snd_timer *timer;
132
133         if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
134             !is_power_of_2(rtctimer_freq)) {
135                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
136                            rtctimer_freq);
137                 return -EINVAL;
138         }
139
140         /* Create a new timer and set up the fields */
141         err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
142         if (err < 0)
143                 return err;
144
145         timer->module = THIS_MODULE;
146         strcpy(timer->name, "RTC timer");
147         timer->hw = rtc_hw;
148         timer->hw.resolution = NANO_SEC / rtctimer_freq;
149
150         tasklet_init(&rtc_tasklet, rtctimer_tasklet, (unsigned long)timer);
151
152         /* set up RTC callback */
153         rtc_task.func = rtctimer_interrupt;
154         rtc_task.private_data = &rtc_tasklet;
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_free(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 */