ARM: 6455/2: Better use of the RTC framework for sa11xx.

This patch uses the RTC framework to treat some common ioctl.

In particular, it fixes the behaviour of rtc_irq_set_freq(), which did
not work as expected because the timer was not beeing retriggered.
Signed-off-by: Marcelo Roberto Jimenez <mroberto@cpti.cetuc.puc-rio.br>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/rtc/rtc-sa1100.c

@@ -42,7 +42,7 @@
 #define RTC_DEF_DIVIDER		(32768 - 1)
 #define RTC_DEF_TRIM		0
 
-static unsigned long rtc_freq = 1024;
+static const unsigned long RTC_FREQ = 1024;
 static unsigned long timer_freq;
 static struct rtc_time rtc_alarm;
 static DEFINE_SPINLOCK(sa1100_rtc_lock);
@@ -156,8 +156,58 @@ static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static int sa1100_irq_set_freq(struct device *dev, int freq)
+{
+	if (freq < 1 || freq > timer_freq) {
+		return -EINVAL;
+	} else {
+		struct rtc_device *rtc = (struct rtc_device *)dev;
+
+		rtc->irq_freq = freq;
+
+		return 0;
+	}
+}
+
 static int rtc_timer1_count;
 
+static int sa1100_irq_set_state(struct device *dev, int enabled)
+{
+	spin_lock_irq(&sa1100_rtc_lock);
+	if (enabled) {
+		struct rtc_device *rtc = (struct rtc_device *)dev;
+
+		OSMR1 = timer_freq / rtc->irq_freq + OSCR;
+		OIER |= OIER_E1;
+		rtc_timer1_count = 1;
+	} else {
+		OIER &= ~OIER_E1;
+	}
+	spin_unlock_irq(&sa1100_rtc_lock);
+
+	return 0;
+}
+
+static inline int sa1100_timer1_retrigger(struct rtc_device *rtc)
+{
+	unsigned long diff;
+	unsigned long period = timer_freq / rtc->irq_freq;
+
+	spin_lock_irq(&sa1100_rtc_lock);
+
+	do {
+		OSMR1 += period;
+		diff = OSMR1 - OSCR;
+		/* If OSCR > OSMR1, diff is a very large number (unsigned
+		 * math). This means we have a lost interrupt. */
+	} while (diff > period);
+	OIER |= OIER_E1;
+
+	spin_unlock_irq(&sa1100_rtc_lock);
+
+	return 0;
+}
+
 static irqreturn_t timer1_interrupt(int irq, void *dev_id)
 {
 	struct platform_device *pdev = to_platform_device(dev_id);
@@ -175,7 +225,11 @@ static irqreturn_t timer1_interrupt(int irq, void *dev_id)
 	rtc_update_irq(rtc, rtc_timer1_count, RTC_PF | RTC_IRQF);
 
 	if (rtc_timer1_count == 1)
-		rtc_timer1_count = (rtc_freq * ((1 << 30) / (timer_freq >> 2)));
+		rtc_timer1_count =
+			(rtc->irq_freq * ((1 << 30) / (timer_freq >> 2)));
+
+	/* retrigger. */
+	sa1100_timer1_retrigger(rtc);
 
 	return IRQ_HANDLED;
 }
@@ -183,8 +237,10 @@ static irqreturn_t timer1_interrupt(int irq, void *dev_id)
 static int sa1100_rtc_read_callback(struct device *dev, int data)
 {
 	if (data & RTC_PF) {
+		struct rtc_device *rtc = (struct rtc_device *)dev;
+
 		/* interpolate missed periods and set match for the next */
-		unsigned long period = timer_freq / rtc_freq;
+		unsigned long period = timer_freq / rtc->irq_freq;
 		unsigned long oscr = OSCR;
 		unsigned long osmr1 = OSMR1;
 		unsigned long missed = (oscr - osmr1)/period;
@@ -207,6 +263,7 @@ static int sa1100_rtc_read_callback(struct device *dev, int data)
 static int sa1100_rtc_open(struct device *dev)
 {
 	int ret;
+	struct rtc_device *rtc = (struct rtc_device *)dev;
 
 	ret = request_irq(IRQ_RTC1Hz, sa1100_rtc_interrupt, IRQF_DISABLED,
 		"rtc 1Hz", dev);
@@ -226,6 +283,9 @@ static int sa1100_rtc_open(struct device *dev)
 		dev_err(dev, "IRQ %d already in use.\n", IRQ_OST1);
 		goto fail_pi;
 	}
+	rtc->max_user_freq = RTC_FREQ;
+	sa1100_irq_set_freq(dev, RTC_FREQ);
+
 	return 0;
 
  fail_pi:
@@ -274,25 +334,6 @@ static int sa1100_rtc_ioctl(struct device *dev, unsigned int cmd,
 		RTSR |= RTSR_HZE;
 		spin_unlock_irq(&sa1100_rtc_lock);
 		return 0;
-	case RTC_PIE_OFF:
-		spin_lock_irq(&sa1100_rtc_lock);
-		OIER &= ~OIER_E1;
-		spin_unlock_irq(&sa1100_rtc_lock);
-		return 0;
-	case RTC_PIE_ON:
-		spin_lock_irq(&sa1100_rtc_lock);
-		OSMR1 = timer_freq / rtc_freq + OSCR;
-		OIER |= OIER_E1;
-		rtc_timer1_count = 1;
-		spin_unlock_irq(&sa1100_rtc_lock);
-		return 0;
-	case RTC_IRQP_READ:
-		return put_user(rtc_freq, (unsigned long *)arg);
-	case RTC_IRQP_SET:
-		if (arg < 1 || arg > timer_freq)
-			return -EINVAL;
-		rtc_freq = arg;
-		return 0;
 	}
 	return -ENOIOCTLCMD;
 }
@@ -344,12 +385,14 @@ static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 
 static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
 {
+	struct rtc_device *rtc = (struct rtc_device *)dev;
+
 	seq_printf(seq, "trim/divider\t: 0x%08x\n", (u32) RTTR);
 	seq_printf(seq, "update_IRQ\t: %s\n",
 			(RTSR & RTSR_HZE) ? "yes" : "no");
 	seq_printf(seq, "periodic_IRQ\t: %s\n",
 			(OIER & OIER_E1) ? "yes" : "no");
-	seq_printf(seq, "periodic_freq\t: %ld\n", rtc_freq);
+	seq_printf(seq, "periodic_freq\t: %d\n", rtc->irq_freq);
 	seq_printf(seq, "RTSR\t\t: 0x%08x\n", (u32)RTSR);
 
 	return 0;
@@ -365,6 +408,8 @@ static const struct rtc_class_ops sa1100_rtc_ops = {
 	.read_alarm = sa1100_rtc_read_alarm,
 	.set_alarm = sa1100_rtc_set_alarm,
 	.proc = sa1100_rtc_proc,
+	.irq_set_freq = sa1100_irq_set_freq,
+	.irq_set_state = sa1100_irq_set_state,
 };
 
 static int sa1100_rtc_probe(struct platform_device *pdev)
@@ -391,13 +436,18 @@ static int sa1100_rtc_probe(struct platform_device *pdev)
 	device_init_wakeup(&pdev->dev, 1);
 
 	rtc = rtc_device_register(pdev->name, &pdev->dev, &sa1100_rtc_ops,
-				THIS_MODULE);
+		THIS_MODULE);
 
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);
 
 	platform_set_drvdata(pdev, rtc);
 
+	/* Set the irq_freq */
+	/*TODO: Find out who is messing with this value after we initialize
+	 * it here.*/
+	rtc->irq_freq = RTC_FREQ;
+
 	/* Fix for a nasty initialization problem the in SA11xx RTSR register.
 	 * See also the comments in sa1100_rtc_interrupt().
 	 *