linux-kernel - Re: [PATCH v2 4/5] rtc-rv8803: extend sysfs to trigger internal ts-event

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Message-ID: <Z7YFk_SqDaucs092@mt.com>
Date: Wed, 19 Feb 2025 17:23:47 +0100
From: Manuel Traut <manuel.traut@...com>
To: Markus Burri <markus.burri@...com>
Cc: linux-kernel@...r.kernel.org,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Marek Vasut <marex@...x.de>,
	linux-rtc@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 4/5] rtc-rv8803: extend sysfs to trigger internal
 ts-event

On Thu, Jan 16, 2025 at 02:15:31PM +0100, Markus Burri wrote:
> Extend sysfs to trigger an internal time-stamp event.
> 
> The trigger function can be used from an application to trigger an
> internal time-stamp event.
> 
> Signed-off-by: Markus Burri <markus.burri@...com>
Reviewed-by: Manuel Traut <manuel.traut@...com>

> ---
>  .../ABI/testing/sysfs-class-rtc-tamper        |  7 ++++
>  drivers/rtc/rtc-rv8803.c                      | 33 +++++++++++++++++++
>  2 files changed, 40 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-rtc-tamper b/Documentation/ABI/testing/sysfs-class-rtc-tamper
> index f035d0fa5..2fd6578a6 100644
> --- a/Documentation/ABI/testing/sysfs-class-rtc-tamper
> +++ b/Documentation/ABI/testing/sysfs-class-rtc-tamper
> @@ -18,4 +18,11 @@ Description:	(RO) Attribute to read the stored timestamps form buffer FIFO.
>  		- "1234.567 EVIN1=1" for a trigger from EVIN1 changed from low to high
>  		- "1234.567 EVIN1=0 EVIN2=1 for a simultaneous trigger of EVIN1 changed to low and
>  		  EVIN2 changed to high.
> +		- "1234.567 CMD=0" for a internal trigger
>  
> +What:		/sys/class/rtc/rtcX/tamper/trigger
> +Date:		January 2025
> +KernelVersion:	6.13
> +Contact:	Markus Burri <markus.burri@...com>
> +Description:	(WO) Attribute to trigger an internal timestamp event
> +		Write a '1' to trigger an internal event and store a timestamp.
> diff --git a/drivers/rtc/rtc-rv8803.c b/drivers/rtc/rtc-rv8803.c
> index 764e654c2..ca3a19162 100644
> --- a/drivers/rtc/rtc-rv8803.c
> +++ b/drivers/rtc/rtc-rv8803.c
> @@ -904,12 +904,45 @@ static ssize_t read_show(struct device *dev, struct device_attribute *attr, char
>  	return offset;
>  }
>  
> +static ssize_t trigger_store(struct device *dev, struct device_attribute *attr, const char *buf,
> +			     size_t count)
> +{
> +	struct rv8803_data *rv8803 = dev_get_drvdata(dev->parent);
> +	struct i2c_client *client = rv8803->client;
> +	int ret;
> +	unsigned long tmo;
> +
> +	guard(mutex)(&rv8803->flags_lock);
> +
> +	/* CMDTRGEN */
> +	ret = rv8803_write_reg(client, RX8901_WRCMD_CFG, BIT(0));
> +	if (ret < 0)
> +		return ret;
> +	ret = rv8803_write_reg(client, RX8901_WRCMD_TRG, 0xFF);
> +	if (ret < 0)
> +		return ret;
> +
> +	tmo = jiffies + msecs_to_jiffies(100); /* timeout 100ms */
> +	do {
> +		usleep_range(10, 2000);
> +		ret = rv8803_read_reg(client, RX8901_WRCMD_TRG);
> +		if (ret < 0)
> +			return ret;
> +		if (time_after(jiffies, tmo))
> +			return -EBUSY;
> +	} while (ret);
> +
> +	return count;
> +}
> +
>  static DEVICE_ATTR_WO(enable);
>  static DEVICE_ATTR_RO(read);
> +static DEVICE_ATTR_WO(trigger);
>  
>  static struct attribute *rv8803_rtc_event_attrs[] = {
>  	&dev_attr_enable.attr,
>  	&dev_attr_read.attr,
> +	&dev_attr_trigger.attr,
>  	NULL
>  };
>  
> -- 
> 2.39.5
>