linux-kernel - Re: [PATCH v5 1/4] iio: ad_sigma_delta: Allow to provide custom data register address

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Date:   Sat, 17 Nov 2018 16:30:54 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Stefan Popa <stefan.popa@...log.com>
Cc:     <Michael.Hennerich@...log.com>, <knaack.h@....de>,
        <lars@...afoo.de>, <pmeerw@...erw.net>,
        <gregkh@...uxfoundation.org>, <linux-kernel@...r.kernel.org>,
        <linux-iio@...r.kernel.org>
Subject: Re: [PATCH v5 1/4] iio: ad_sigma_delta: Allow to provide custom
 data register address

On Tue, 13 Nov 2018 13:20:24 +0200
Stefan Popa <stefan.popa@...log.com> wrote:

> From: Lars-Peter Clausen <lars@...afoo.de>
> 
> Some newer devices from the Sigma-Delta ADC family do have their data
> register at a different address than the current default address. Add a
> parameter to the ad_sigma_delta_info struct which allows to override the
> default address.
> 
> Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
> Signed-off-by: Stefan Popa <stefan.popa@...log.com>
Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.

Thanks,

Jonathan

> ---
> Changes in v2:
> 	- Added this commit.
> Changes in v3:
> 	- Nothing changed.
> Changes in v4:
> 	- Nothing changed.
> Changes in v5:
> 	- Nothing changed.
> 
>  drivers/iio/adc/ad_sigma_delta.c       | 22 +++++++++++++++++-----
>  include/linux/iio/adc/ad_sigma_delta.h |  3 +++
>  2 files changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
> index fc95107..ff5f2da 100644
> --- a/drivers/iio/adc/ad_sigma_delta.c
> +++ b/drivers/iio/adc/ad_sigma_delta.c
> @@ -278,6 +278,7 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
>  {
>  	struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
>  	unsigned int sample, raw_sample;
> +	unsigned int data_reg;
>  	int ret = 0;
>  
>  	if (iio_buffer_enabled(indio_dev))
> @@ -305,7 +306,12 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
>  	if (ret < 0)
>  		goto out;
>  
> -	ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_DATA,
> +	if (sigma_delta->info->data_reg != 0)
> +		data_reg = sigma_delta->info->data_reg;
> +	else
> +		data_reg = AD_SD_REG_DATA;
> +
> +	ret = ad_sd_read_reg(sigma_delta, data_reg,
>  		DIV_ROUND_UP(chan->scan_type.realbits + chan->scan_type.shift, 8),
>  		&raw_sample);
>  
> @@ -392,6 +398,7 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
>  	struct iio_dev *indio_dev = pf->indio_dev;
>  	struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
>  	unsigned int reg_size;
> +	unsigned int data_reg;
>  	uint8_t data[16];
>  	int ret;
>  
> @@ -401,18 +408,23 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
>  			indio_dev->channels[0].scan_type.shift;
>  	reg_size = DIV_ROUND_UP(reg_size, 8);
>  
> +	if (sigma_delta->info->data_reg != 0)
> +		data_reg = sigma_delta->info->data_reg;
> +	else
> +		data_reg = AD_SD_REG_DATA;
> +
>  	switch (reg_size) {
>  	case 4:
>  	case 2:
>  	case 1:
> -		ret = ad_sd_read_reg_raw(sigma_delta, AD_SD_REG_DATA,
> -			reg_size, &data[0]);
> +		ret = ad_sd_read_reg_raw(sigma_delta, data_reg, reg_size,
> +			&data[0]);
>  		break;
>  	case 3:
>  		/* We store 24 bit samples in a 32 bit word. Keep the upper
>  		 * byte set to zero. */
> -		ret = ad_sd_read_reg_raw(sigma_delta, AD_SD_REG_DATA,
> -			reg_size, &data[1]);
> +		ret = ad_sd_read_reg_raw(sigma_delta, data_reg, reg_size,
> +			&data[1]);
>  		break;
>  	}
>  
> diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h
> index 730ead1..7e84351 100644
> --- a/include/linux/iio/adc/ad_sigma_delta.h
> +++ b/include/linux/iio/adc/ad_sigma_delta.h
> @@ -39,6 +39,8 @@ struct iio_dev;
>   *		if there is just one read-only sample data shift register.
>   * @addr_shift: Shift of the register address in the communications register.
>   * @read_mask: Mask for the communications register having the read bit set.
> + * @data_reg: Address of the data register, if 0 the default address of 0x3 will
> + *   be used.
>   */
>  struct ad_sigma_delta_info {
>  	int (*set_channel)(struct ad_sigma_delta *, unsigned int channel);
> @@ -47,6 +49,7 @@ struct ad_sigma_delta_info {
>  	bool has_registers;
>  	unsigned int addr_shift;
>  	unsigned int read_mask;
> +	unsigned int data_reg;
>  };
>  
>  /**