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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/interrupt.h>
25#include <linux/moduleparam.h>
vignesh babu62e96a12007-02-22 13:23:01 +010026#include <linux/log2.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <sound/core.h>
28#include <sound/timer.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
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 */
Takashi Iwai53d2f742005-11-17 13:56:05 +010040static int rtctimer_open(struct snd_timer *t);
41static int rtctimer_close(struct snd_timer *t);
42static int rtctimer_start(struct snd_timer *t);
43static int rtctimer_stop(struct snd_timer *t);
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
45
46/*
47 * The hardware dependent description for this timer.
48 */
Takashi Iwai53d2f742005-11-17 13:56:05 +010049static struct snd_timer_hardware rtc_hw = {
Clemens Ladischac5d1a72006-10-27 10:45:00 +020050 .flags = SNDRV_TIMER_HW_AUTO |
51 SNDRV_TIMER_HW_FIRST |
52 SNDRV_TIMER_HW_TASKLET,
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 .ticks = 100000000L, /* FIXME: XXX */
54 .open = rtctimer_open,
55 .close = rtctimer_close,
56 .start = rtctimer_start,
57 .stop = rtctimer_stop,
58};
59
60static int rtctimer_freq = RTC_FREQ; /* frequency */
Takashi Iwai53d2f742005-11-17 13:56:05 +010061static struct snd_timer *rtctimer;
Clemens Ladischac5d1a72006-10-27 10:45:00 +020062static struct tasklet_struct rtc_tasklet;
Linus Torvalds1da177e2005-04-16 15:20:36 -070063static rtc_task_t rtc_task;
64
65
66static int
Takashi Iwai53d2f742005-11-17 13:56:05 +010067rtctimer_open(struct snd_timer *t)
Linus Torvalds1da177e2005-04-16 15:20:36 -070068{
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
78static int
Takashi Iwai53d2f742005-11-17 13:56:05 +010079rtctimer_close(struct snd_timer *t)
Linus Torvalds1da177e2005-04-16 15:20:36 -070080{
81 rtc_task_t *rtc = t->private_data;
82 if (rtc) {
83 rtc_unregister(rtc);
Clemens Ladischac5d1a72006-10-27 10:45:00 +020084 tasklet_kill(&rtc_tasklet);
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 t->private_data = NULL;
86 }
87 return 0;
88}
89
90static int
Takashi Iwai53d2f742005-11-17 13:56:05 +010091rtctimer_start(struct snd_timer *timer)
Linus Torvalds1da177e2005-04-16 15:20:36 -070092{
93 rtc_task_t *rtc = timer->private_data;
Takashi Iwai7eaa9432008-08-08 17:09:09 +020094 if (snd_BUG_ON(!rtc))
95 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
97 rtc_control(rtc, RTC_PIE_ON, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 return 0;
99}
100
101static int
Takashi Iwai53d2f742005-11-17 13:56:05 +0100102rtctimer_stop(struct snd_timer *timer)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103{
104 rtc_task_t *rtc = timer->private_data;
Takashi Iwai7eaa9432008-08-08 17:09:09 +0200105 if (snd_BUG_ON(!rtc))
106 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 rtc_control(rtc, RTC_PIE_OFF, 0);
108 return 0;
109}
110
Clemens Ladischac5d1a72006-10-27 10:45:00 +0200111static void rtctimer_tasklet(unsigned long data)
112{
113 snd_timer_interrupt((struct snd_timer *)data, 1);
114}
115
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116/*
117 * interrupt
118 */
119static void rtctimer_interrupt(void *private_data)
120{
Clemens Ladischac5d1a72006-10-27 10:45:00 +0200121 tasklet_hi_schedule(private_data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122}
123
124
125/*
126 * ENTRY functions
127 */
128static int __init rtctimer_init(void)
129{
Clemens Ladischd9ad1bd2005-09-27 15:57:24 +0200130 int err;
Takashi Iwai53d2f742005-11-17 13:56:05 +0100131 struct snd_timer *timer;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
Clemens Ladischd9ad1bd2005-09-27 15:57:24 +0200133 if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
vignesh babu62e96a12007-02-22 13:23:01 +0100134 !is_power_of_2(rtctimer_freq)) {
Clemens Ladischde242142005-10-12 17:12:31 +0200135 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
136 rtctimer_freq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 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
Clemens Ladischde242142005-10-12 17:12:31 +0200145 timer->module = THIS_MODULE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 strcpy(timer->name, "RTC timer");
147 timer->hw = rtc_hw;
148 timer->hw.resolution = NANO_SEC / rtctimer_freq;
149
Clemens Ladischac5d1a72006-10-27 10:45:00 +0200150 tasklet_init(&rtc_tasklet, rtctimer_tasklet, (unsigned long)timer);
151
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 /* set up RTC callback */
153 rtc_task.func = rtctimer_interrupt;
Clemens Ladischac5d1a72006-10-27 10:45:00 +0200154 rtc_task.private_data = &rtc_tasklet;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155
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
166static void __exit rtctimer_exit(void)
167{
168 if (rtctimer) {
Takashi Iwaic4614822006-06-23 14:38:23 +0200169 snd_timer_global_free(rtctimer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 rtctimer = NULL;
171 }
172}
173
174
175/*
176 * exported stuff
177 */
178module_init(rtctimer_init)
179module_exit(rtctimer_exit)
180
181module_param(rtctimer_freq, int, 0444);
182MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
183
184MODULE_LICENSE("GPL");
185
186MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
187
188#endif /* CONFIG_RTC || CONFIG_RTC_MODULE */