Re: [PATCH 2/2] iio: accel: Add sampling rate support for STK8BA50

[Jonathan Cameron <jic23@kernel.org>]

On 10/06/15 16:07, Tiberiu Breana wrote:
> Added support for setting the STK8BA50 accelerometer's
> sampling rate.
> 
> Signed-off-by: Tiberiu Breana <tiberiu.a.breana@intel.com>
Applied to the togreg branch of iio.git.
Initially pushed out as testing for the autobuilder to play with it.
Thanks,

Jonathan
> ---
> v2: addressed Daniel's comments
> ---
>  drivers/iio/accel/stk8ba50.c | 57 ++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 50 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iio/accel/stk8ba50.c b/drivers/iio/accel/stk8ba50.c
> index 3302a3d..92229bd 100644
> --- a/drivers/iio/accel/stk8ba50.c
> +++ b/drivers/iio/accel/stk8ba50.c
> @@ -21,6 +21,7 @@
>  #define STK8BA50_REG_YOUT			0x04
>  #define STK8BA50_REG_ZOUT			0x06
>  #define STK8BA50_REG_RANGE			0x0F
> +#define STK8BA50_REG_BWSEL			0x10
>  #define STK8BA50_REG_POWMODE			0x11
>  #define STK8BA50_REG_SWRST			0x14
>  
> @@ -29,6 +30,7 @@
>  #define STK8BA50_MODE_POWERBIT			BIT(7)
>  #define STK8BA50_DATA_SHIFT			6
>  #define STK8BA50_RESET_CMD			0xB6
> +#define STK8BA50_SR_1792HZ_IDX			7
>  
>  #define STK8BA50_DRIVER_NAME			"stk8ba50"
>  
> @@ -57,19 +59,30 @@ static const struct {
>  	{3, 38400}, {5, 76700}, {8, 153400}, {12, 306900}
>  };
>  
> +/* Sample rates are stored as { <register value>, <Hz value> } */
> +static const struct {
> +	u8 reg_val;
> +	u16 samp_freq;
> +} stk8ba50_samp_freq_table[] = {
> +	{0x08, 14},  {0x09, 25},  {0x0A, 56},  {0x0B, 112},
> +	{0x0C, 224}, {0x0D, 448}, {0x0E, 896}, {0x0F, 1792}
> +};
> +
>  struct stk8ba50_data {
>  	struct i2c_client *client;
>  	struct mutex lock;
>  	int range;
> +	u8 sample_rate_idx;
>  };
>  
> -#define STK8BA50_ACCEL_CHANNEL(reg, axis) {			\
> -	.type = IIO_ACCEL,					\
> -	.address = reg,						\
> -	.modified = 1,						\
> -	.channel2 = IIO_MOD_##axis,				\
> -	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> -	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +#define STK8BA50_ACCEL_CHANNEL(reg, axis) {				\
> +	.type = IIO_ACCEL,						\
> +	.address = reg,							\
> +	.modified = 1,							\
> +	.channel2 = IIO_MOD_##axis,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
> +				    BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
>  }
>  
>  static const struct iio_chan_spec stk8ba50_channels[] = {
> @@ -80,8 +93,11 @@ static const struct iio_chan_spec stk8ba50_channels[] = {
>  
>  static IIO_CONST_ATTR(in_accel_scale_available, STK8BA50_SCALE_AVAIL);
>  
> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("14 25 56 112 224 448 896 1792");
> +
>  static struct attribute *stk8ba50_attributes[] = {
>  	&iio_const_attr_in_accel_scale_available.dev_attr.attr,
> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
>  	NULL,
>  };
>  
> @@ -119,6 +135,11 @@ static int stk8ba50_read_raw(struct iio_dev *indio_dev,
>  		*val = 0;
>  		*val2 = stk8ba50_scale_table[data->range].scale_val;
>  		return IIO_VAL_INT_PLUS_MICRO;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*val = stk8ba50_samp_freq_table
> +				[data->sample_rate_idx].samp_freq;
> +		*val2 = 0;
> +		return IIO_VAL_INT;
>  	}
>  
>  	return -EINVAL;
> @@ -156,6 +177,25 @@ static int stk8ba50_write_raw(struct iio_dev *indio_dev,
>  			data->range = index;
>  
>  		return ret;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		for (i = 0; i < ARRAY_SIZE(stk8ba50_samp_freq_table); i++)
> +			if (val == stk8ba50_samp_freq_table[i].samp_freq) {
> +				index = i;
> +				break;
> +			}
> +		if (index < 0)
> +			return -EINVAL;
> +
> +		ret = i2c_smbus_write_byte_data(data->client,
> +				STK8BA50_REG_BWSEL,
> +				stk8ba50_samp_freq_table[index].reg_val);
> +		if (ret < 0)
> +			dev_err(&data->client->dev,
> +					"failed to set sampling rate\n");
> +		else
> +			data->sample_rate_idx = index;
> +
> +		return ret;
>  	}
>  
>  	return -EINVAL;
> @@ -231,6 +271,9 @@ static int stk8ba50_probe(struct i2c_client *client,
>  	/* The default range is +/-2g */
>  	data->range = 0;
>  
> +	/* The default sampling rate is 1792 Hz (maximum) */
> +	data->sample_rate_idx = STK8BA50_SR_1792HZ_IDX;
> +
>  	ret = iio_device_register(indio_dev);
>  	if (ret < 0) {
>  		dev_err(&client->dev, "device_register failed\n");
>