1 files changed, 127 insertions, 34 deletions

diff --git a/drivers/rtc/rtc-sa1100.c b/drivers/rtc/rtc-sa1100.c
index e4a44b641702..88ea52b8647a 100644
--- a/drivers/rtc/rtc-sa1100.c
+++ b/drivers/rtc/rtc-sa1100.c
@@ -39,10 +39,10 @@
 #include <mach/regs-ost.h>
 #endif
 
-#define RTC_DEF_DIVIDER         32768 - 1
+#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);
@@ -61,7 +61,8 @@ static inline int rtc_periodic_alarm(struct rtc_time *tm)
  * Calculate the next alarm time given the requested alarm time mask
  * and the current time.
  */
-static void rtc_next_alarm_time(struct rtc_time *next, struct rtc_time *now, struct rtc_time *alrm)
+static void rtc_next_alarm_time(struct rtc_time *next, struct rtc_time *now,
+        struct rtc_time *alrm)
 {
         unsigned long next_time;
         unsigned long now_time;
@@ -116,7 +117,23 @@ static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id)
         rtsr = RTSR;
         /* clear interrupt sources */
         RTSR = 0;
-        RTSR = (RTSR_AL | RTSR_HZ) & (rtsr >> 2);
+        /* Fix for a nasty initialization problem the in SA11xx RTSR register.
+         * See also the comments in sa1100_rtc_probe(). */
+        if (rtsr & (RTSR_ALE | RTSR_HZE)) {
+                /* This is the original code, before there was the if test
+                 * above. This code does not clear interrupts that were not
+                 * enabled. */
+                RTSR = (RTSR_AL | RTSR_HZ) & (rtsr >> 2);
+        } else {
+                /* For some reason, it is possible to enter this routine
+                 * without interruptions enabled, it has been tested with
+                 * several units (Bug in SA11xx chip?).
+                 *
+                 * This situation leads to an infinite "loop" of interrupt
+                 * routine calling and as a result the processor seems to
+                 * lock on its first call to open(). */
+                RTSR = RTSR_AL | RTSR_HZ;
+        }
 
         /* clear alarm interrupt if it has occurred */
         if (rtsr & RTSR_AL)
@@ -139,8 +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);
@@ -158,7 +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;
 }
@@ -166,8 +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;
@@ -178,7 +251,7 @@ static int sa1100_rtc_read_callback(struct device *dev, int data)
                  * Here we compare (match - OSCR) 8 instead of 0 --
                  * see comment in pxa_timer_interrupt() for explanation.
                  */
-                while( (signed long)((osmr1 = OSMR1) - OSCR) <= 8 ) {
+                while ((signed long)((osmr1 = OSMR1) - OSCR) <= 8) {
                         data += 0x100;
                         OSSR = OSSR_M1; /* clear match on timer 1 */
                         OSMR1 = osmr1 + period;
@@ -190,25 +263,29 @@ 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);
+                "rtc 1Hz", dev);
         if (ret) {
                 dev_err(dev, "IRQ %d already in use.\n", IRQ_RTC1Hz);
                 goto fail_ui;
         }
         ret = request_irq(IRQ_RTCAlrm, sa1100_rtc_interrupt, IRQF_DISABLED,
-                                "rtc Alrm", dev);
+                "rtc Alrm", dev);
         if (ret) {
                 dev_err(dev, "IRQ %d already in use.\n", IRQ_RTCAlrm);
                 goto fail_ai;
         }
         ret = request_irq(IRQ_OST1, timer1_interrupt, IRQF_DISABLED,
-                                "rtc timer", dev);
+                "rtc timer", dev);
         if (ret) {
                 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:
@@ -236,7 +313,7 @@ static void sa1100_rtc_release(struct device *dev)
 static int sa1100_rtc_ioctl(struct device *dev, unsigned int cmd,
                 unsigned long arg)
 {
-        switch(cmd) {
+        switch (cmd) {
         case RTC_AIE_OFF:
                 spin_lock_irq(&sa1100_rtc_lock);
                 RTSR &= ~RTSR_ALE;
@@ -257,25 +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;
 }
@@ -327,12 +385,15 @@ 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;
 }
@@ -347,6 +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)
@@ -364,7 +427,8 @@ static int sa1100_rtc_probe(struct platform_device *pdev)
          */
         if (RTTR == 0) {
                 RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
-                dev_warn(&pdev->dev, "warning: initializing default clock divider/trim value\n");
+                dev_warn(&pdev->dev, "warning: "
+                        "initializing default clock divider/trim value\n");
                 /* The current RTC value probably doesn't make sense either */
                 RCNR = 0;
         }
@@ -372,13 +436,42 @@ 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().
+         *
+         * Sometimes bit 1 of the RTSR (RTSR_HZ) will wake up 1, which means an
+         * interrupt pending, even though interrupts were never enabled.
+         * In this case, this bit it must be reset before enabling
+         * interruptions to avoid a nonexistent interrupt to occur.
+         *
+         * In principle, the same problem would apply to bit 0, although it has
+         * never been observed to happen.
+         *
+         * This issue is addressed both here and in sa1100_rtc_interrupt().
+         * If the issue is not addressed here, in the times when the processor
+         * wakes up with the bit set there will be one spurious interrupt.
+         *
+         * The issue is also dealt with in sa1100_rtc_interrupt() to be on the
+         * safe side, once the condition that lead to this strange
+         * initialization is unknown and could in principle happen during
+         * normal processing.
+         *
+         * Notice that clearing bit 1 and 0 is accomplished by writting ONES to
+         * the corresponding bits in RTSR. */
+        RTSR = RTSR_AL | RTSR_HZ;
+
         return 0;
 }
 
@@ -386,7 +479,7 @@ static int sa1100_rtc_remove(struct platform_device *pdev)
 {
         struct rtc_device *rtc = platform_get_drvdata(pdev);
 
-        if (rtc)
+        if (rtc)
                 rtc_device_unregister(rtc);
 
         return 0;