Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
[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/interrupt.h>
26 #include <linux/moduleparam.h>
27 #include <linux/log2.h>
28 #include <sound/core.h>
29 #include <sound/timer.h>
30
31 #if defined(CONFIG_RTC) || defined(CONFIG_RTC_MODULE)
32
33 #include <linux/mc146818rtc.h>
34
35 #define RTC_FREQ        1024            /* default frequency */
36 #define NANO_SEC        1000000000L     /* 10^9 in sec */
37
38 /*
39  * prototypes
40  */
41 static int rtctimer_open(struct snd_timer *t);
42 static int rtctimer_close(struct snd_timer *t);
43 static int rtctimer_start(struct snd_timer *t);
44 static int rtctimer_stop(struct snd_timer *t);
45
46
47 /*
48  * The hardware dependent description for this timer.
49  */
50 static struct snd_timer_hardware rtc_hw = {
51         .flags =        SNDRV_TIMER_HW_AUTO |
52                         SNDRV_TIMER_HW_FIRST |
53                         SNDRV_TIMER_HW_TASKLET,
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 struct snd_timer *rtctimer;
63 static struct tasklet_struct rtc_tasklet;
64 static rtc_task_t rtc_task;
65
66
67 static int
68 rtctimer_open(struct snd_timer *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(struct snd_timer *t)
81 {
82         rtc_task_t *rtc = t->private_data;
83         if (rtc) {
84                 rtc_unregister(rtc);
85                 tasklet_kill(&rtc_tasklet);
86                 t->private_data = NULL;
87         }
88         return 0;
89 }
90
91 static int
92 rtctimer_start(struct snd_timer *timer)
93 {
94         rtc_task_t *rtc = timer->private_data;
95         snd_assert(rtc != NULL, 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         snd_assert(rtc != NULL, return -EINVAL);
106         rtc_control(rtc, RTC_PIE_OFF, 0);
107         return 0;
108 }
109
110 static void rtctimer_tasklet(unsigned long data)
111 {
112         snd_timer_interrupt((struct snd_timer *)data, 1);
113 }
114
115 /*
116  * interrupt
117  */
118 static void rtctimer_interrupt(void *private_data)
119 {
120         tasklet_hi_schedule(private_data);
121 }
122
123
124 /*
125  *  ENTRY functions
126  */
127 static int __init rtctimer_init(void)
128 {
129         int err;
130         struct snd_timer *timer;
131
132         if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
133             !is_power_of_2(rtctimer_freq)) {
134                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
135                            rtctimer_freq);
136                 return -EINVAL;
137         }
138
139         /* Create a new timer and set up the fields */
140         err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
141         if (err < 0)
142                 return err;
143
144         timer->module = THIS_MODULE;
145         strcpy(timer->name, "RTC timer");
146         timer->hw = rtc_hw;
147         timer->hw.resolution = NANO_SEC / rtctimer_freq;
148
149         tasklet_init(&rtc_tasklet, rtctimer_tasklet, (unsigned long)timer);
150
151         /* set up RTC callback */
152         rtc_task.func = rtctimer_interrupt;
153         rtc_task.private_data = &rtc_tasklet;
154
155         err = snd_timer_global_register(timer);
156         if (err < 0) {
157                 snd_timer_global_free(timer);
158                 return err;
159         }
160         rtctimer = timer; /* remember this */
161
162         return 0;
163 }
164
165 static void __exit rtctimer_exit(void)
166 {
167         if (rtctimer) {
168                 snd_timer_global_free(rtctimer);
169                 rtctimer = NULL;
170         }
171 }
172
173
174 /*
175  * exported stuff
176  */
177 module_init(rtctimer_init)
178 module_exit(rtctimer_exit)
179
180 module_param(rtctimer_freq, int, 0444);
181 MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
182
183 MODULE_LICENSE("GPL");
184
185 MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
186
187 #endif /* CONFIG_RTC || CONFIG_RTC_MODULE */