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/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 */
43static int rtctimer_open(struct snd_timer *t);
44static int rtctimer_close(struct snd_timer *t);
45static int rtctimer_start(struct snd_timer *t);
46static int rtctimer_stop(struct snd_timer *t);
47
48
49/*
50 * The hardware dependent description for this timer.
51 */
52static 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
61static int rtctimer_freq = RTC_FREQ; /* frequency */
62static struct snd_timer *rtctimer;
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 t->private_data = NULL;
85 }
86 return 0;
87}
88
89static int
90rtctimer_start(struct snd_timer *timer)
91{
92 rtc_task_t *rtc = timer->private_data;
93 snd_assert(rtc != NULL, return -EINVAL);
94 rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
95 rtc_control(rtc, RTC_PIE_ON, 0);
96 return 0;
97}
98
99static int
100rtctimer_stop(struct snd_timer *timer)
101{
102 rtc_task_t *rtc = timer->private_data;
103 snd_assert(rtc != NULL, return -EINVAL);
104 rtc_control(rtc, RTC_PIE_OFF, 0);
105 return 0;
106}
107
108/*
109 * interrupt
110 */
111static void rtctimer_interrupt(void *private_data)
112{
113 snd_timer_interrupt(private_data, 1);
114}
115
116
117/*
118 * ENTRY functions
119 */
120static int __init rtctimer_init(void)
121{
122 int err;
123 struct snd_timer *timer;
124
125 if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
126 (rtctimer_freq & (rtctimer_freq - 1)) != 0) {
127 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
128 rtctimer_freq);
129 return -EINVAL;
130 }
131
132 /* Create a new timer and set up the fields */
133 err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
134 if (err < 0)
135 return err;
136
137 timer->module = THIS_MODULE;
138 strcpy(timer->name, "RTC timer");
139 timer->hw = rtc_hw;
140 timer->hw.resolution = NANO_SEC / rtctimer_freq;
141
142 /* set up RTC callback */
143 rtc_task.func = rtctimer_interrupt;
144 rtc_task.private_data = timer;
145
146 err = snd_timer_global_register(timer);
147 if (err < 0) {
148 snd_timer_global_free(timer);
149 return err;
150 }
151 rtctimer = timer; /* remember this */
152
153 return 0;
154}
155
156static void __exit rtctimer_exit(void)
157{
158 if (rtctimer) {
159 snd_timer_global_unregister(rtctimer);
160 rtctimer = NULL;
161 }
162}
163
164
165/*
166 * exported stuff
167 */
168module_init(rtctimer_init)
169module_exit(rtctimer_exit)
170
171module_param(rtctimer_freq, int, 0444);
172MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
173
174MODULE_LICENSE("GPL");
175
176MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
177
178#endif /* CONFIG_RTC || CONFIG_RTC_MODULE */