Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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 <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 */
40static 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);
44
45
46/*
47 * The hardware dependent description for this timer.
48 */
49static 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
60static int rtctimer_freq = RTC_FREQ; /* frequency */
61static struct snd_timer *rtctimer;
62static struct tasklet_struct rtc_tasklet;
63static rtc_task_t rtc_task;
64
65
66static int
67rtctimer_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
78static int
79rtctimer_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
90static int
91rtctimer_start(struct snd_timer *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 return 0;
98}
99
100static int
101rtctimer_stop(struct snd_timer *timer)
102{
103 rtc_task_t *rtc = timer->private_data;
104 snd_assert(rtc != NULL, return -EINVAL);
105 rtc_control(rtc, RTC_PIE_OFF, 0);
106 return 0;
107}
108
109static void rtctimer_tasklet(unsigned long data)
110{
111 snd_timer_interrupt((struct snd_timer *)data, 1);
112}
113
114/*
115 * interrupt
116 */
117static void rtctimer_interrupt(void *private_data)
118{
119 tasklet_hi_schedule(private_data);
120}
121
122
123/*
124 * ENTRY functions
125 */
126static int __init rtctimer_init(void)
127{
128 int err;
129 struct snd_timer *timer;
130
131 if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
132 (rtctimer_freq & (rtctimer_freq - 1)) != 0) {
133 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
134 rtctimer_freq);
135 return -EINVAL;
136 }
137
138 /* Create a new timer and set up the fields */
139 err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
140 if (err < 0)
141 return err;
142
143 timer->module = THIS_MODULE;
144 strcpy(timer->name, "RTC timer");
145 timer->hw = rtc_hw;
146 timer->hw.resolution = NANO_SEC / rtctimer_freq;
147
148 tasklet_init(&rtc_tasklet, rtctimer_tasklet, (unsigned long)timer);
149
150 /* set up RTC callback */
151 rtc_task.func = rtctimer_interrupt;
152 rtc_task.private_data = &rtc_tasklet;
153
154 err = snd_timer_global_register(timer);
155 if (err < 0) {
156 snd_timer_global_free(timer);
157 return err;
158 }
159 rtctimer = timer; /* remember this */
160
161 return 0;
162}
163
164static void __exit rtctimer_exit(void)
165{
166 if (rtctimer) {
167 snd_timer_global_free(rtctimer);
168 rtctimer = NULL;
169 }
170}
171
172
173/*
174 * exported stuff
175 */
176module_init(rtctimer_init)
177module_exit(rtctimer_exit)
178
179module_param(rtctimer_freq, int, 0444);
180MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
181
182MODULE_LICENSE("GPL");
183
184MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
185
186#endif /* CONFIG_RTC || CONFIG_RTC_MODULE */