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 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
100 static int
101 rtctimer_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
109 static void rtctimer_tasklet(unsigned long data)
110 {
111 snd_timer_interrupt((struct snd_timer *)data, 1);
112 }
113
114 /*
115 * interrupt
116 */
117 static void rtctimer_interrupt(void *private_data)
118 {
119 tasklet_hi_schedule(private_data);
120 }
121
122
123 /*
124 * ENTRY functions
125 */
126 static int __init rtctimer_init(void)
127 {
128 int err;
129 struct snd_timer *timer;
130
131 if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
132 !is_power_of_2(rtctimer_freq)) {
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
164 static 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 */
176 module_init(rtctimer_init)
177 module_exit(rtctimer_exit)
178
179 module_param(rtctimer_freq, int, 0444);
180 MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
181
182 MODULE_LICENSE("GPL");
183
184 MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
185
186 #endif /* CONFIG_RTC || CONFIG_RTC_MODULE */
187
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