diff mbox

[1/3] rtc: omap: Unlock and Lock rtc registers before and after register writes

Message ID 1427867698-1326-2-git-send-email-lokeshvutla@ti.com (mailing list archive)
State New, archived
Headers show

Commit Message

Lokesh Vutla April 1, 2015, 5:54 a.m. UTC 
RTC module contains a kicker mechanism to prevent any spurious writes
from changing the register values. This mechanism requires two MMR
writes to the KICK0 and KICK1 registers with exact data values
before the kicker lock mechanism is released.

Currently the driver release the lock in the probe and leaves it enabled
until the rtc driver removal. This eliminates the idea of preventing
spurious writes when RTC driver is loaded.
So implement rtc lock and unlock functions before and after register writes.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
---
- This is as advised by Paul to implement lock and unlock functions in
  the driver and not to unlock and leave it in probe.
  The same discussion can be seen here:
  http://www.mail-archive.com/linux-omap%40vger.kernel.org/msg111588.html

 drivers/rtc/rtc-omap.c | 46 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 38 insertions(+), 8 deletions(-)

Comments

Alexandre Belloni April 1, 2015, 3:52 p.m. UTC | #1 
Hi,

On 01/04/2015 at 11:24:56 +0530, Lokesh Vutla wrote :
> RTC module contains a kicker mechanism to prevent any spurious writes
> from changing the register values. This mechanism requires two MMR
> writes to the KICK0 and KICK1 registers with exact data values
> before the kicker lock mechanism is released.
> 
> Currently the driver release the lock in the probe and leaves it enabled
> until the rtc driver removal. This eliminates the idea of preventing
> spurious writes when RTC driver is loaded.
> So implement rtc lock and unlock functions before and after register writes.
> 
> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
> ---
> - This is as advised by Paul to implement lock and unlock functions in
>   the driver and not to unlock and leave it in probe.
>   The same discussion can be seen here:
>   http://www.mail-archive.com/linux-omap%40vger.kernel.org/msg111588.html
> 
>  drivers/rtc/rtc-omap.c | 46 ++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 38 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 8e5851a..96cc613 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -156,6 +156,22 @@ static inline void rtc_writel(struct omap_rtc *rtc, unsigned int reg, u32 val)
>  	writel(val, rtc->base + reg);
>  }
>  
> +static void rtc_unlock(struct omap_rtc *rtc)
> +{
> +	if (rtc->type->has_kicker) {

Instead of testing for has_kicker each time, I would add .lock and
.unlock to omap_rtc_device_type and directly use rtc->type->lock and
rtc->type->unlock.

> +		rtc_writel(rtc, OMAP_RTC_KICK0_REG, KICK0_VALUE);
> +		rtc_writel(rtc, OMAP_RTC_KICK1_REG, KICK1_VALUE);
> +	}
> +}
> +
Lokesh Vutla April 2, 2015, 11:12 a.m. UTC | #2 
Hi,

On Wednesday 01 April 2015 09:22 PM, Alexandre Belloni wrote:
> Hi,
> 
> On 01/04/2015 at 11:24:56 +0530, Lokesh Vutla wrote :
>> RTC module contains a kicker mechanism to prevent any spurious writes
>> from changing the register values. This mechanism requires two MMR
>> writes to the KICK0 and KICK1 registers with exact data values
>> before the kicker lock mechanism is released.
>>
>> Currently the driver release the lock in the probe and leaves it enabled
>> until the rtc driver removal. This eliminates the idea of preventing
>> spurious writes when RTC driver is loaded.
>> So implement rtc lock and unlock functions before and after register writes.
>>
>> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
>> ---
>> - This is as advised by Paul to implement lock and unlock functions in
>>   the driver and not to unlock and leave it in probe.
>>   The same discussion can be seen here:
>>   http://www.mail-archive.com/linux-omap%40vger.kernel.org/msg111588.html
>>
>>  drivers/rtc/rtc-omap.c | 46 ++++++++++++++++++++++++++++++++++++++--------
>>  1 file changed, 38 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
>> index 8e5851a..96cc613 100644
>> --- a/drivers/rtc/rtc-omap.c
>> +++ b/drivers/rtc/rtc-omap.c
>> @@ -156,6 +156,22 @@ static inline void rtc_writel(struct omap_rtc *rtc, unsigned int reg, u32 val)
>>  	writel(val, rtc->base + reg);
>>  }
>>  
>> +static void rtc_unlock(struct omap_rtc *rtc)
>> +{
>> +	if (rtc->type->has_kicker) {
> 
> Instead of testing for has_kicker each time, I would add .lock and
> .unlock to omap_rtc_device_type and directly use rtc->type->lock and
> rtc->type->unlock.
Makes sense. I have posted v2 of my series updating this.

Thanks and regards,
Lokesh
> 
>> +		rtc_writel(rtc, OMAP_RTC_KICK0_REG, KICK0_VALUE);
>> +		rtc_writel(rtc, OMAP_RTC_KICK1_REG, KICK1_VALUE);
>> +	}
>> +}
>> +

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diff mbox

Patch

diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index 8e5851a..96cc613 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -156,6 +156,22 @@  static inline void rtc_writel(struct omap_rtc *rtc, unsigned int reg, u32 val)
 	writel(val, rtc->base + reg);
 }
 
+static void rtc_unlock(struct omap_rtc *rtc)
+{
+	if (rtc->type->has_kicker) {
+		rtc_writel(rtc, OMAP_RTC_KICK0_REG, KICK0_VALUE);
+		rtc_writel(rtc, OMAP_RTC_KICK1_REG, KICK1_VALUE);
+	}
+}
+
+static void rtc_lock(struct omap_rtc *rtc)
+{
+	if (rtc->type->has_kicker) {
+		rtc_writel(rtc, OMAP_RTC_KICK0_REG, 0);
+		rtc_writel(rtc, OMAP_RTC_KICK1_REG, 0);
+	}
+}
+
 /*
  * We rely on the rtc framework to handle locking (rtc->ops_lock),
  * so the only other requirement is that register accesses which
@@ -186,7 +202,9 @@  static irqreturn_t rtc_irq(int irq, void *dev_id)
 
 	/* alarm irq? */
 	if (irq_data & OMAP_RTC_STATUS_ALARM) {
+		rtc_unlock(rtc);
 		rtc_write(rtc, OMAP_RTC_STATUS_REG, OMAP_RTC_STATUS_ALARM);
+		rtc_lock(rtc);
 		events |= RTC_IRQF | RTC_AF;
 	}
 
@@ -218,9 +236,11 @@  static int omap_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 		irqwake_reg &= ~OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN;
 	}
 	rtc_wait_not_busy(rtc);
+	rtc_unlock(rtc);
 	rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, reg);
 	if (rtc->type->has_irqwakeen)
 		rtc_write(rtc, OMAP_RTC_IRQWAKEEN, irqwake_reg);
+	rtc_lock(rtc);
 	local_irq_enable();
 
 	return 0;
@@ -293,12 +313,14 @@  static int omap_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	local_irq_disable();
 	rtc_wait_not_busy(rtc);
 
+	rtc_unlock(rtc);
 	rtc_write(rtc, OMAP_RTC_YEARS_REG, tm->tm_year);
 	rtc_write(rtc, OMAP_RTC_MONTHS_REG, tm->tm_mon);
 	rtc_write(rtc, OMAP_RTC_DAYS_REG, tm->tm_mday);
 	rtc_write(rtc, OMAP_RTC_HOURS_REG, tm->tm_hour);
 	rtc_write(rtc, OMAP_RTC_MINUTES_REG, tm->tm_min);
 	rtc_write(rtc, OMAP_RTC_SECONDS_REG, tm->tm_sec);
+	rtc_lock(rtc);
 
 	local_irq_enable();
 
@@ -341,6 +363,7 @@  static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 	local_irq_disable();
 	rtc_wait_not_busy(rtc);
 
+	rtc_unlock(rtc);
 	rtc_write(rtc, OMAP_RTC_ALARM_YEARS_REG, alm->time.tm_year);
 	rtc_write(rtc, OMAP_RTC_ALARM_MONTHS_REG, alm->time.tm_mon);
 	rtc_write(rtc, OMAP_RTC_ALARM_DAYS_REG, alm->time.tm_mday);
@@ -362,6 +385,7 @@  static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 	rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, reg);
 	if (rtc->type->has_irqwakeen)
 		rtc_write(rtc, OMAP_RTC_IRQWAKEEN, irqwake_reg);
+	rtc_lock(rtc);
 
 	local_irq_enable();
 
@@ -391,6 +415,7 @@  static void omap_rtc_power_off(void)
 	unsigned long now;
 	u32 val;
 
+	rtc_unlock(rtc);
 	/* enable pmic_power_en control */
 	val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
 	rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);
@@ -423,6 +448,7 @@  static void omap_rtc_power_off(void)
 	val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
 	rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
 			val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
+	rtc_lock(rtc);
 
 	/*
 	 * Wait for alarm to trigger (within two seconds) and external PMIC to
@@ -527,10 +553,7 @@  static int __init omap_rtc_probe(struct platform_device *pdev)
 	pm_runtime_enable(&pdev->dev);
 	pm_runtime_get_sync(&pdev->dev);
 
-	if (rtc->type->has_kicker) {
-		rtc_writel(rtc, OMAP_RTC_KICK0_REG, KICK0_VALUE);
-		rtc_writel(rtc, OMAP_RTC_KICK1_REG, KICK1_VALUE);
-	}
+	rtc_unlock(rtc);
 
 	/*
 	 * disable interrupts
@@ -593,6 +616,8 @@  static int __init omap_rtc_probe(struct platform_device *pdev)
 	if (reg != new_ctrl)
 		rtc_write(rtc, OMAP_RTC_CTRL_REG, new_ctrl);
 
+	rtc_lock(rtc);
+
 	device_init_wakeup(&pdev->dev, true);
 
 	rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
@@ -626,8 +651,7 @@  static int __init omap_rtc_probe(struct platform_device *pdev)
 
 err:
 	device_init_wakeup(&pdev->dev, false);
-	if (rtc->type->has_kicker)
-		rtc_writel(rtc, OMAP_RTC_KICK0_REG, 0);
+	rtc_lock(rtc);
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
@@ -646,11 +670,11 @@  static int __exit omap_rtc_remove(struct platform_device *pdev)
 
 	device_init_wakeup(&pdev->dev, 0);
 
+	rtc_unlock(rtc);
 	/* leave rtc running, but disable irqs */
 	rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, 0);
 
-	if (rtc->type->has_kicker)
-		rtc_writel(rtc, OMAP_RTC_KICK0_REG, 0);
+	rtc_lock(rtc);
 
 	/* Disable the clock/module */
 	pm_runtime_put_sync(&pdev->dev);
@@ -666,6 +690,7 @@  static int omap_rtc_suspend(struct device *dev)
 
 	rtc->interrupts_reg = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
 
+	rtc_unlock(rtc);
 	/*
 	 * FIXME: the RTC alarm is not currently acting as a wakeup event
 	 * source on some platforms, and in fact this enable() call is just
@@ -675,6 +700,7 @@  static int omap_rtc_suspend(struct device *dev)
 		enable_irq_wake(rtc->irq_alarm);
 	else
 		rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, 0);
+	rtc_lock(rtc);
 
 	/* Disable the clock/module */
 	pm_runtime_put_sync(dev);
@@ -689,10 +715,12 @@  static int omap_rtc_resume(struct device *dev)
 	/* Enable the clock/module so that we can access the registers */
 	pm_runtime_get_sync(dev);
 
+	rtc_unlock(rtc);
 	if (device_may_wakeup(dev))
 		disable_irq_wake(rtc->irq_alarm);
 	else
 		rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, rtc->interrupts_reg);
+	rtc_lock(rtc);
 
 	return 0;
 }
@@ -709,9 +737,11 @@  static void omap_rtc_shutdown(struct platform_device *pdev)
 	 * Keep the ALARM interrupt enabled to allow the system to power up on
 	 * alarm events.
 	 */
+	rtc_unlock(rtc);
 	mask = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
 	mask &= OMAP_RTC_INTERRUPTS_IT_ALARM;
 	rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, mask);
+	rtc_lock(rtc);
 }
 
 static struct platform_driver omap_rtc_driver = {