[v2] rtc: pcf2127: handle timestamp interrupts

commit 03623b4b041c ("rtc: pcf2127: add tamper detection support")
added support for timestamp interrupts. However they are not being
handled in the irq handler. If a timestamp interrupt occurs it
results in kernel disabling the interrupt and displaying the call
trace:

[  121.145580] irq 78: nobody cared (try booting with the "irqpoll" option)
...
[  121.238087] [<00000000c4d69393>] irq_default_primary_handler threaded [<000000000a90d25b>] pcf2127_rtc_irq [rtc_pcf2127]
[  121.248971] Disabling IRQ #78

Handle timestamp interrupts in pcf2127_rtc_irq(). Set a flag to mark
the timestamp as valid and only report to sysfs if the flag is set.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
history:
v2: -Add a flag to mark the occurrence of timestamp interrupt
    -Add Biwen Li in Cc

 drivers/rtc/rtc-pcf2127.c | 53 +++++++++++++++++++++------------------
 1 file changed, 28 insertions(+), 25 deletions(-)

On Fri, Apr 30, 2021 at 11:18:52AM +0200, Mian Yousaf Kaukab wrote:
> commit 03623b4b041c ("rtc: pcf2127: add tamper detection support")
> added support for timestamp interrupts. However they are not being
> handled in the irq handler. If a timestamp interrupt occurs it
> results in kernel disabling the interrupt and displaying the call
> trace:
> 
> [  121.145580] irq 78: nobody cared (try booting with the "irqpoll" option)
> ...
> [  121.238087] [<00000000c4d69393>] irq_default_primary_handler threaded [<000000000a90d25b>] pcf2127_rtc_irq [rtc_pcf2127]
> [  121.248971] Disabling IRQ #78
> 
> Handle timestamp interrupts in pcf2127_rtc_irq(). Set a flag to mark
> the timestamp as valid and only report to sysfs if the flag is set.
> 
> Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
> ---
> history:
> v2: -Add a flag to mark the occurrence of timestamp interrupt
>     -Add Biwen Li in Cc
> 
>  drivers/rtc/rtc-pcf2127.c | 53 +++++++++++++++++++++------------------
>  1 file changed, 28 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
> index d13c20a2adf7..0e2333ea1243 100644
> --- a/drivers/rtc/rtc-pcf2127.c
> +++ b/drivers/rtc/rtc-pcf2127.c
> @@ -94,10 +94,18 @@
>  #define PCF2127_WD_VAL_MAX		255
>  #define PCF2127_WD_VAL_DEFAULT		60
>  
> +/* Mask for currently enabled interrupts */
> +#define PCF2127_CTRL1_IRQ_MASK (PCF2127_BIT_CTRL1_TSF1)
> +#define PCF2127_CTRL2_IRQ_MASK ( \
> +		PCF2127_BIT_CTRL2_AF | \
> +		PCF2127_BIT_CTRL2_WDTF | \
> +		PCF2127_BIT_CTRL2_TSF2)
> +
>  struct pcf2127 {
>  	struct rtc_device *rtc;
>  	struct watchdog_device wdd;
>  	struct regmap *regmap;
> +	bool timestamp_valid;
>  };
>  
>  /*
> @@ -437,20 +445,33 @@ static int pcf2127_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
>  static irqreturn_t pcf2127_rtc_irq(int irq, void *dev)
>  {
>  	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
> -	unsigned int ctrl2 = 0;
> +	unsigned int ctrl1, ctrl2;
>  	int ret = 0;
>  
> +	ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL1, &ctrl1);
> +	if (ret)
> +		return IRQ_NONE;
> +
>  	ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL2, &ctrl2);
>  	if (ret)
>  		return IRQ_NONE;
>  
> -	if (!(ctrl2 & PCF2127_BIT_CTRL2_AF))
> +	if (!(ctrl1 & PCF2127_CTRL1_IRQ_MASK || ctrl2 & PCF2127_CTRL2_IRQ_MASK))
>  		return IRQ_NONE;
>  
> -	regmap_write(pcf2127->regmap, PCF2127_REG_CTRL2,
> -		     ctrl2 & ~(PCF2127_BIT_CTRL2_AF | PCF2127_BIT_CTRL2_WDTF));
> +	if (ctrl1 & PCF2127_CTRL1_IRQ_MASK)
> +		regmap_write(pcf2127->regmap, PCF2127_REG_CTRL1,
> +			ctrl1 & ~PCF2127_CTRL1_IRQ_MASK);
> +
> +	if (ctrl2 & PCF2127_CTRL2_IRQ_MASK)
> +		regmap_write(pcf2127->regmap, PCF2127_REG_CTRL2,
> +			ctrl2 & ~PCF2127_CTRL2_IRQ_MASK);
>  
> -	rtc_update_irq(pcf2127->rtc, 1, RTC_IRQF | RTC_AF);
> +	if (ctrl1 & PCF2127_BIT_CTRL1_TSF1 || ctrl2 & PCF2127_BIT_CTRL2_TSF2)
> +		pcf2127->timestamp_valid = true;
> +
> +	if (ctrl2 & PCF2127_BIT_CTRL2_AF)
> +		rtc_update_irq(pcf2127->rtc, 1, RTC_IRQF | RTC_AF);
>  
>  	pcf2127_wdt_active_ping(&pcf2127->wdd);
>  
> @@ -473,25 +494,8 @@ static ssize_t timestamp0_store(struct device *dev,
>  				const char *buf, size_t count)
>  {
>  	struct pcf2127 *pcf2127 = dev_get_drvdata(dev->parent);
> -	int ret;
>  
> -	ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL1,
> -				 PCF2127_BIT_CTRL1_TSF1, 0);
> -	if (ret) {
> -		dev_err(dev, "%s: update ctrl1 ret=%d\n", __func__, ret);
> -		return ret;
> -	}
> -
> -	ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL2,
> -				 PCF2127_BIT_CTRL2_TSF2, 0);
> -	if (ret) {
> -		dev_err(dev, "%s: update ctrl2 ret=%d\n", __func__, ret);
> -		return ret;
> -	}
> -
> -	ret = pcf2127_wdt_active_ping(&pcf2127->wdd);
This call was removed by mistake. v3 already sent to restore it.

> -	if (ret)
> -		return ret;
> +	pcf2127->timestamp_valid = false;
>  
>  	return count;
>  };
> @@ -524,8 +528,7 @@ static ssize_t timestamp0_show(struct device *dev,
>  	if (ret)
>  		return ret;
>  
> -	if (!(data[PCF2127_REG_CTRL1] & PCF2127_BIT_CTRL1_TSF1) &&
> -	    !(data[PCF2127_REG_CTRL2] & PCF2127_BIT_CTRL2_TSF2))
> +	if (!pcf2127->timestamp_valid)
>  		return 0;
>  
>  	tm.tm_sec = bcd2bin(data[PCF2127_REG_TS_SC] & 0x7F);
> -- 
> 2.26.2

BR,
Yousaf