[PATCH 0/2] iio: adc: ti-ads1298 & Kconfig

[PATCH 0/2] iio: adc: ti-ads1298 & Kconfig

[Arthur-Prince]

These patches improve the ti-ads1298 driver in two ways:

1- Safe usage guarantee for device communication
  Wrap calls to ads1298_reg_access() and ads1298_write_raw()
  with iio_device_claim_direct() / iio_device_release_direct()
  so that configuration operations cannot interrupt an ongoing
  buffered capture.

2- Add kfifo dependency for module compilation 
  The driver now selects CONFIG_IIO_KFIFO_BUFFER in its Kconfig,
  just like other IIO ADC drivers, to ensure the kfifo buffer
  API is available when building ti-ads1298 as a module.

Arthur-Prince (2):
  iio: adc: ti-ads1298
  iio: adc: Kconfig

 drivers/iio/adc/Kconfig      |  1 +
 drivers/iio/adc/ti-ads1298.c | 25 +++++++++++++++++++++----
 2 files changed, 22 insertions(+), 4 deletions(-)

-- 
2.45.2

[PATCH 1/2] iio: adc: ti-ads1298: Add safe usage guarantee for device communication

[Arthur-Prince]

Add safe usage guarantee for device communication in 
ads1298_reg_access/ ads1298_write_raw (ti-ads1298) that 
prevent simultaneous read/write operations.

Signed-off-by: Arthur-Prince <r2.arthur.prince@gmail.com>
Co-developed-by: Mariana Valério <mariana.valerio2@hotmail.com>
Signed-off-by: Mariana Valério <mariana.valerio2@hotmail.com>
---
 drivers/iio/adc/ti-ads1298.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/adc/ti-ads1298.c b/drivers/iio/adc/ti-ads1298.c
index 03f762415fa5..438bcc3c74da 100644
--- a/drivers/iio/adc/ti-ads1298.c
+++ b/drivers/iio/adc/ti-ads1298.c
@@ -355,9 +355,19 @@ static int ads1298_write_raw(struct iio_dev *indio_dev,
 {
 	struct ads1298_private *priv = iio_priv(indio_dev);
 
+	int ret;
+
 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
-		return ads1298_set_samp_freq(priv, val);
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		ret = ads1298_set_samp_freq(priv, val);
+
+		iio_device_release_direct_mode(indio_dev);
+
+		return ret;
 	default:
 		return -EINVAL;
 	}
@@ -417,10 +427,17 @@ static int ads1298_reg_access(struct iio_dev *indio_dev, unsigned int reg,
 {
 	struct ads1298_private *priv = iio_priv(indio_dev);
 
+	int ret;
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
 	if (readval)
-		return regmap_read(priv->regmap, reg, readval);
-
-	return regmap_write(priv->regmap, reg, writeval);
+		ret = regmap_read(priv->regmap, reg, readval);
+	else
+		ret = regmap_write(priv->regmap, reg, writeval);
+	
+	iio_device_release_direct_mode(indio_dev);
+	return ret;
 }
 
 static void ads1298_rdata_unmark_busy(struct ads1298_private *priv)
-- 
2.45.2

Re: [PATCH 1/2] iio: adc: ti-ads1298: Add safe usage guarantee for device communication

[Jonathan Cameron]

On Wed, 23 Apr 2025 15:46:25 -0300
Arthur-Prince <r2.arthur.prince@gmail.com> wrote:

> Add safe usage guarantee for device communication in 
> ads1298_reg_access/ ads1298_write_raw (ti-ads1298) that 
> prevent simultaneous read/write operations.
> 
> Signed-off-by: Arthur-Prince <r2.arthur.prince@gmail.com>
> Co-developed-by: Mariana Valério <mariana.valerio2@hotmail.com>
> Signed-off-by: Mariana Valério <mariana.valerio2@hotmail.com>
Two different things seem to be going on in here...

> ---
>  drivers/iio/adc/ti-ads1298.c | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/ti-ads1298.c b/drivers/iio/adc/ti-ads1298.c
> index 03f762415fa5..438bcc3c74da 100644
> --- a/drivers/iio/adc/ti-ads1298.c
> +++ b/drivers/iio/adc/ti-ads1298.c
> @@ -355,9 +355,19 @@ static int ads1298_write_raw(struct iio_dev *indio_dev,
>  {
>  	struct ads1298_private *priv = iio_priv(indio_dev);
>  
> +	int ret;
> +
>  	switch (mask) {
>  	case IIO_CHAN_INFO_SAMP_FREQ:
> -		return ads1298_set_samp_freq(priv, val);
> +		ret = iio_device_claim_direct_mode(indio_dev);
> +		if (ret)
> +			return ret;
> +
> +		ret = ads1298_set_samp_freq(priv, val);
> +
> +		iio_device_release_direct_mode(indio_dev);
This prevents changing the sampling frequency.  Some drivers prevent this
whilst in buffered mode, but why is that necessary here?

> +
> +		return ret;
>  	default:
>  		return -EINVAL;
>  	}
> @@ -417,10 +427,17 @@ static int ads1298_reg_access(struct iio_dev *indio_dev, unsigned int reg,
>  {
>  	struct ads1298_private *priv = iio_priv(indio_dev);
>  
> +	int ret;
> +	ret = iio_device_claim_direct_mode(indio_dev);
For this one it's a debug interface. If the issue is people shooting themselves in the
foot then we don't normally prevent that for these.

If there is something fundamental about regmap implementation
that makes these accesses have side effects unconnected to what is being
written then that needs calling out.

> +	if (ret)
> +		return ret;
>  	if (readval)
> -		return regmap_read(priv->regmap, reg, readval);
> -
> -	return regmap_write(priv->regmap, reg, writeval);
> +		ret = regmap_read(priv->regmap, reg, readval);
> +	else
> +		ret = regmap_write(priv->regmap, reg, writeval);
> +	
> +	iio_device_release_direct_mode(indio_dev);
> +	return ret;
>  }
>  
>  static void ads1298_rdata_unmark_busy(struct ads1298_private *priv)

[PATCH 2/2] iio: adc: Kconfig: add kfifo dependency to fix module build

[Arthur-Prince]

Add dependency to Kconfig’s ti-ads1298 because compiling it as a module
failed with an undefined kfifo symbol. Building the full kernel passed
since kfifo was enabled globally. Selecting IIO_KFIFO_BUFFER in 
ti-ads1298’s Kconfig, as done by other IIO ADC drivers, now ensures kfifo
buffer support is included for module builds.

Signed-off-by: Arthur-Prince <r2.arthur.prince@gmail.com>
Co-developed-by: Mariana Valério <mariana.valerio2@hotmail.com>
Signed-off-by: Mariana Valério <mariana.valerio2@hotmail.com>
---
 drivers/iio/adc/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 849c90203071..513f2238fdee 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1492,6 +1492,7 @@ config TI_ADS1298
 	tristate "Texas Instruments ADS1298"
 	depends on SPI
 	select IIO_BUFFER
+	select IIO_KFIFO_BUF
 	help
 	  If you say yes here you get support for Texas Instruments ADS1298
 	  medical ADC chips
-- 
2.45.2

Re: [PATCH 2/2] iio: adc: Kconfig: add kfifo dependency to fix module build

[Jonathan Cameron]

On Wed, 23 Apr 2025 15:46:26 -0300
Arthur-Prince <r2.arthur.prince@gmail.com> wrote:

> Add dependency to Kconfig’s ti-ads1298 because compiling it as a module
> failed with an undefined kfifo symbol. Building the full kernel passed
> since kfifo was enabled globally. Selecting IIO_KFIFO_BUFFER in 
> ti-ads1298’s Kconfig, as done by other IIO ADC drivers, now ensures kfifo
> buffer support is included for module builds.
> 
> Signed-off-by: Arthur-Prince <r2.arthur.prince@gmail.com>
> Co-developed-by: Mariana Valério <mariana.valerio2@hotmail.com>
> Signed-off-by: Mariana Valério <mariana.valerio2@hotmail.com>
Fixes tag?
Otherwise looks good.

> ---
>  drivers/iio/adc/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 849c90203071..513f2238fdee 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -1492,6 +1492,7 @@ config TI_ADS1298
>  	tristate "Texas Instruments ADS1298"
>  	depends on SPI
>  	select IIO_BUFFER
> +	select IIO_KFIFO_BUF
>  	help
>  	  If you say yes here you get support for Texas Instruments ADS1298
>  	  medical ADC chips