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-rw-r--r--drivers/rtc/Kconfig12
-rw-r--r--drivers/rtc/rtc-dev.c104
-rw-r--r--include/linux/rtc.h14
3 files changed, 130 insertions, 0 deletions
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index cdd97192dc69..4941cade319f 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -97,6 +97,18 @@ config RTC_INTF_DEV
97 97
98 If unsure, say Y. 98 If unsure, say Y.
99 99
100config RTC_INTF_DEV_UIE_EMUL
101 bool "RTC UIE emulation on dev interface"
102 depends on RTC_INTF_DEV
103 help
104 Provides an emulation for RTC_UIE if the underlying rtc chip
105 driver does not expose RTC_UIE ioctls. Those requests generate
106 once-per-second update interrupts, used for synchronization.
107
108 The emulation code will read the time from the hardware
109 clock several times per second, please enable this option
110 only if you know that you really need it.
111
100config RTC_DRV_TEST 112config RTC_DRV_TEST
101 tristate "Test driver/device" 113 tristate "Test driver/device"
102 help 114 help
diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
index 37c3cc1b3dd5..dfa72c9c2687 100644
--- a/drivers/rtc/rtc-dev.c
+++ b/drivers/rtc/rtc-dev.c
@@ -46,6 +46,105 @@ static int rtc_dev_open(struct inode *inode, struct file *file)
46 return err; 46 return err;
47} 47}
48 48
49#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
50/*
51 * Routine to poll RTC seconds field for change as often as possible,
52 * after first RTC_UIE use timer to reduce polling
53 */
54static void rtc_uie_task(struct work_struct *work)
55{
56 struct rtc_device *rtc =
57 container_of(work, struct rtc_device, uie_task);
58 struct rtc_time tm;
59 int num = 0;
60 int err;
61
62 err = rtc_read_time(rtc, &tm);
63
64 spin_lock_irq(&rtc->irq_lock);
65 if (rtc->stop_uie_polling || err) {
66 rtc->uie_task_active = 0;
67 } else if (rtc->oldsecs != tm.tm_sec) {
68 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
69 rtc->oldsecs = tm.tm_sec;
70 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
71 rtc->uie_timer_active = 1;
72 rtc->uie_task_active = 0;
73 add_timer(&rtc->uie_timer);
74 } else if (schedule_work(&rtc->uie_task) == 0) {
75 rtc->uie_task_active = 0;
76 }
77 spin_unlock_irq(&rtc->irq_lock);
78 if (num)
79 rtc_update_irq(rtc, num, RTC_UF | RTC_IRQF);
80}
81static void rtc_uie_timer(unsigned long data)
82{
83 struct rtc_device *rtc = (struct rtc_device *)data;
84 unsigned long flags;
85
86 spin_lock_irqsave(&rtc->irq_lock, flags);
87 rtc->uie_timer_active = 0;
88 rtc->uie_task_active = 1;
89 if ((schedule_work(&rtc->uie_task) == 0))
90 rtc->uie_task_active = 0;
91 spin_unlock_irqrestore(&rtc->irq_lock, flags);
92}
93
94static int clear_uie(struct rtc_device *rtc)
95{
96 spin_lock_irq(&rtc->irq_lock);
97 if (rtc->uie_irq_active) {
98 rtc->stop_uie_polling = 1;
99 if (rtc->uie_timer_active) {
100 spin_unlock_irq(&rtc->irq_lock);
101 del_timer_sync(&rtc->uie_timer);
102 spin_lock_irq(&rtc->irq_lock);
103 rtc->uie_timer_active = 0;
104 }
105 if (rtc->uie_task_active) {
106 spin_unlock_irq(&rtc->irq_lock);
107 flush_scheduled_work();
108 spin_lock_irq(&rtc->irq_lock);
109 }
110 rtc->uie_irq_active = 0;
111 }
112 spin_unlock_irq(&rtc->irq_lock);
113 return 0;
114}
115
116static int set_uie(struct rtc_device *rtc)
117{
118 struct rtc_time tm;
119 int err;
120
121 err = rtc_read_time(rtc, &tm);
122 if (err)
123 return err;
124 spin_lock_irq(&rtc->irq_lock);
125 if (!rtc->uie_irq_active) {
126 rtc->uie_irq_active = 1;
127 rtc->stop_uie_polling = 0;
128 rtc->oldsecs = tm.tm_sec;
129 rtc->uie_task_active = 1;
130 if (schedule_work(&rtc->uie_task) == 0)
131 rtc->uie_task_active = 0;
132 }
133 rtc->irq_data = 0;
134 spin_unlock_irq(&rtc->irq_lock);
135 return 0;
136}
137
138int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
139{
140 if (enabled)
141 return set_uie(rtc);
142 else
143 return clear_uie(rtc);
144}
145EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
146
147#endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
49 148
50static ssize_t 149static ssize_t
51rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) 150rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
@@ -387,6 +486,11 @@ void rtc_dev_prepare(struct rtc_device *rtc)
387 486
388 rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id); 487 rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
389 488
489#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
490 INIT_WORK(&rtc->uie_task, rtc_uie_task);
491 setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
492#endif
493
390 cdev_init(&rtc->char_dev, &rtc_dev_fops); 494 cdev_init(&rtc->char_dev, &rtc_dev_fops);
391 rtc->char_dev.owner = rtc->owner; 495 rtc->char_dev.owner = rtc->owner;
392} 496}
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index a0b639f8e805..80408e711bed 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -203,6 +203,18 @@ struct rtc_device
203 struct hrtimer pie_timer; /* sub second exp, so needs hrtimer */ 203 struct hrtimer pie_timer; /* sub second exp, so needs hrtimer */
204 int pie_enabled; 204 int pie_enabled;
205 struct work_struct irqwork; 205 struct work_struct irqwork;
206
207
208#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
209 struct work_struct uie_task;
210 struct timer_list uie_timer;
211 /* Those fields are protected by rtc->irq_lock */
212 unsigned int oldsecs;
213 unsigned int uie_irq_active:1;
214 unsigned int stop_uie_polling:1;
215 unsigned int uie_task_active:1;
216 unsigned int uie_timer_active:1;
217#endif
206}; 218};
207#define to_rtc_device(d) container_of(d, struct rtc_device, dev) 219#define to_rtc_device(d) container_of(d, struct rtc_device, dev)
208 220
@@ -235,6 +247,8 @@ extern int rtc_irq_set_freq(struct rtc_device *rtc,
235 struct rtc_task *task, int freq); 247 struct rtc_task *task, int freq);
236extern int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled); 248extern int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled);
237extern int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled); 249extern int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled);
250extern int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc,
251 unsigned int enabled);
238 252
239void rtc_aie_update_irq(void *private); 253void rtc_aie_update_irq(void *private);
240void rtc_uie_update_irq(void *private); 254void rtc_uie_update_irq(void *private);