Re: [PATCH 2/5] platform/x86: msi-ec: Add fw version and release date attributes

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Tue, 10 Oct 2023, Nikita Kravets wrote:

> Create a root attribute group and add the first platform device
> attributes: firmware version and firmware release date. Firmware
> version attribute uses an already present ec_get_firmware_version()
> function. Both features are present on all supported laptops.
> 
> Cc: Aakash Singh <mail@singhaakash.dev>
> Cc: Jose Angel Pastrana <japp0005@red.ujaen.es>
> Signed-off-by: Nikita Kravets <teackot@gmail.com>
> ---
>  drivers/platform/x86/msi-ec.c | 67 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 66 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/msi-ec.c b/drivers/platform/x86/msi-ec.c
> index 12c559c9eac4..772b230fb47e 100644
> --- a/drivers/platform/x86/msi-ec.c
> +++ b/drivers/platform/x86/msi-ec.c
> @@ -818,17 +818,82 @@ static struct acpi_battery_hook battery_hook = {
>  	.name = MSI_EC_DRIVER_NAME,
>  };
>  
> +/*
> + * Sysfs platform device attributes
> + */
> +
> +static ssize_t fw_version_show(struct device *device,
> +			       struct device_attribute *attr, char *buf)
> +{
> +	u8 rdata[MSI_EC_FW_VERSION_LENGTH + 1];
> +	int result;
> +
> +	result = ec_get_firmware_version(rdata);
> +	if (result < 0)
> +		return result;
> +
> +	return sysfs_emit(buf, "%s\n", rdata);
> +}
> +
> +static ssize_t fw_release_date_show(struct device *device,
> +				    struct device_attribute *attr, char *buf)
> +{
> +	u8 rdate[MSI_EC_FW_DATE_LENGTH + 1];
> +	u8 rtime[MSI_EC_FW_TIME_LENGTH + 1];
> +	int result;
> +	int year, month, day, hour, minute, second;
> +
> +	memset(rdate, 0, MSI_EC_FW_DATE_LENGTH + 1);

sizeof(*rdate) is safer so please use it.

> +	result = ec_read_seq(MSI_EC_FW_DATE_ADDRESS,
> +			     rdate,
> +			     MSI_EC_FW_DATE_LENGTH);
> +	if (result < 0)
> +		return result;
> +
> +	result = sscanf(rdate, "%02d%02d%04d", &month, &day, &year);

There fields would naturally be %u and unsigned but see the other comment 
below before doing this change.

> +	if (result != 3)
> +		return -EINVAL;

EINVAL should be returned if the input was invalid but here the data 
itself is not okay so some other errno would be better.

> +	memset(rtime, 0, MSI_EC_FW_TIME_LENGTH + 1);

sizeof() like above.

> +	result = ec_read_seq(MSI_EC_FW_TIME_ADDRESS,
> +			     rtime,
> +			     MSI_EC_FW_TIME_LENGTH);
> +	if (result < 0)
> +		return result;
> +
> +	result = sscanf(rtime, "%02d:%02d:%02d", &hour, &minute, &second);
> +	if (result != 3)
> +		return -EINVAL;

Ditto.

> +
> +	return sysfs_emit(buf, "%04d/%02d/%02d %02d:%02d:%02d\n", year, month, day,
> +			  hour, minute, second);

It would be kind of nice to use %pt formatting here instead of custom
datetime format, however, it would either require converting to time64_t 
or using struct rtc_time. The latter would naturally have the right fields 
but they're not unsigned so my comment above about %u is not going to work 
well with it.

I'm also a bit unsure whether it's appropriate to use that struct outside 
of rtc realm. vsprintf.c seems to convert time64_t into rtc_time before 
printing though.

Hans, do you have any idea about the struct rtc_time?

> +}
> +
> +static DEVICE_ATTR_RO(fw_version);
> +static DEVICE_ATTR_RO(fw_release_date);
> +
> +static struct attribute *msi_root_attrs[] = {
> +	&dev_attr_fw_version.attr,
> +	&dev_attr_fw_release_date.attr,
> +	NULL
> +};
> +
> +static struct attribute_group msi_root_group = {
> +	.attrs = msi_root_attrs,
> +};
> +
>  /*
>   * Sysfs platform driver
>   */
>  
>  static int msi_platform_probe(struct platform_device *pdev)
>  {
> -	return 0;
> +	return sysfs_create_group(&pdev->dev.kobj, &msi_root_group);
>  }
>  
>  static int msi_platform_remove(struct platform_device *pdev)
>  {
> +	sysfs_remove_group(&pdev->dev.kobj, &msi_root_group);
>  	return 0;
>  }

Don't handle add/remove but put the attribute group pointer into the 
platform_driver.driver instead.

-- 
 i.