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Subject[PATCH 1/7] Blackfin RTC driver: the frequency function is in units of Hz, not units of seconds, so lock our driver down to 1 Hz
Date
From: Mike Frysinger <michael.frysinger@analog.com>

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
---
drivers/rtc/rtc-bfin.c | 24 +++++++++++++++++-------
1 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/rtc/rtc-bfin.c b/drivers/rtc/rtc-bfin.c
index 1aa709d..303ed6e 100644
--- a/drivers/rtc/rtc-bfin.c
+++ b/drivers/rtc/rtc-bfin.c
@@ -72,7 +72,7 @@ struct bfin_rtc {
#define SEC_BITS_OFF 0

/* Some helper functions to convert between the common RTC notion of time
- * and the internal Blackfin notion that is stored in 32bits.
+ * and the internal Blackfin notion that is encoded in 32bits.
*/
static inline u32 rtc_time_to_bfin(unsigned long now)
{
@@ -112,6 +112,11 @@ static inline void rtc_bfin_to_tm(u32 rtc_bfin, struct rtc_time *tm)
* If anyone can point out the obvious solution here, i'm listening :). This
* shouldn't be an issue on an SMP or preempt system as this function should
* only be called with the rtc lock held.
+ *
+ * Other options:
+ * - disable PREN so the sync happens at 32.768kHZ ... but this changes the
+ * inc rate for all RTC registers from 1HZ to 32.768kHZ ...
+ * - use the write complete IRQ
*/
static void rtc_bfin_sync_pending(void)
{
@@ -356,12 +361,18 @@ static int bfin_rtc_proc(struct device *dev, struct seq_file *seq)
return 0;
}

+/**
+ * bfin_irq_set_freq - make sure hardware supports requested freq
+ * @dev: pointer to RTC device structure
+ * @freq: requested frequency rate
+ *
+ * The Blackfin RTC can only generate periodic events at 1 per
+ * second (1 Hz), so reject any attempt at changing it.
+ */
static int bfin_irq_set_freq(struct device *dev, int freq)
{
- struct bfin_rtc *rtc = dev_get_drvdata(dev);
stampit();
- rtc->rtc_dev->irq_freq = freq;
- return 0;
+ return -ENOTTY;
}

static struct rtc_class_ops bfin_rtc_ops = {
@@ -394,14 +405,13 @@ static int __devinit bfin_rtc_probe(struct platform_device *pdev)
ret = PTR_ERR(rtc->rtc_dev);
goto err;
}
- rtc->rtc_dev->irq_freq = 0;
- rtc->rtc_dev->max_user_freq = (2 << 16); /* stopwatch is an unsigned 16 bit reg */
+ rtc->rtc_dev->irq_freq = 1;

platform_set_drvdata(pdev, rtc);

return 0;

-err:
+ err:
kfree(rtc);
return ret;
}
--
1.5.3.4
-
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