Re: [PATCH v5 2/2] iio: accel: Add sampling rate support for STK8312

[Jonathan Cameron <jic23@kernel.org>]

On 24/06/15 15:01, Tiberiu Breana wrote:
> Added support for setting the STK8312 accelerometer's
> sampling rate.
> 
> Signed-off-by: Tiberiu Breana <tiberiu.a.breana@intel.com>
Applied
> ---
> v5: no new changes
> v4: no new changes
> v3: no new changes
> v2: replaced stk8312_samp_freq_table with a struct for better readability
> ---
>  drivers/iio/accel/stk8312.c | 96 ++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 82 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/iio/accel/stk8312.c b/drivers/iio/accel/stk8312.c
> index be58d66..c2bd144 100644
> --- a/drivers/iio/accel/stk8312.c
> +++ b/drivers/iio/accel/stk8312.c
> @@ -29,6 +29,7 @@
>  #define STK8312_REG_ZOUT		0x02
>  #define STK8312_REG_INTSU		0x06
>  #define STK8312_REG_MODE		0x07
> +#define STK8312_REG_SR			0x08
>  #define STK8312_REG_STH			0x13
>  #define STK8312_REG_RESET		0x20
>  #define STK8312_REG_AFECTRL		0x24
> @@ -41,6 +42,8 @@
>  #define STK8312_DREADY_BIT		0x10
>  #define STK8312_INT_MODE		0xC0
>  #define STK8312_RNG_MASK		0xC0
> +#define STK8312_SR_MASK			0x07
> +#define STK8312_SR_400HZ_IDX		0
>  #define STK8312_RNG_SHIFT		6
>  #define STK8312_READ_RETRIES		16
>  #define STK8312_ALL_CHANNEL_MASK	7
> @@ -65,20 +68,29 @@ static const int stk8312_scale_table[][2] = {
>  	{0, 461600}, {1, 231100}
>  };
>  
> -#define STK8312_ACCEL_CHANNEL(index, 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),	\
> -	.scan_index = index,					\
> -	.scan_type = {						\
> -		.sign = 's',					\
> -		.realbits = 8,					\
> -		.storagebits = 8,				\
> -		.endianness = IIO_CPU,				\
> -	},							\
> +static const struct {
> +	u16 val;
> +	u32 val2;
> +} stk8312_samp_freq_table[] = {
> +	{400, 0}, {200, 0}, {100, 0}, {50, 0}, {25, 0},
> +	{12, 500000}, {6, 250000}, {3, 125000}
> +};
> +
> +#define STK8312_ACCEL_CHANNEL(index, 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),	\
> +	.scan_index = index,						\
> +	.scan_type = {							\
> +		.sign = 's',						\
> +		.realbits = 8,						\
> +		.storagebits = 8,					\
> +		.endianness = IIO_CPU,					\
> +	},								\
>  }
>  
>  static const struct iio_chan_spec stk8312_channels[] = {
> @@ -92,6 +104,7 @@ struct stk8312_data {
>  	struct i2c_client *client;
>  	struct mutex lock;
>  	int range;
> +	u8 sample_rate_idx;
>  	u8 mode;
>  	struct iio_trigger *dready_trig;
>  	bool dready_trigger_on;
> @@ -100,8 +113,11 @@ struct stk8312_data {
>  
>  static IIO_CONST_ATTR(in_accel_scale_available, STK8312_SCALE_AVAIL);
>  
> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("3.125 6.25 12.5 25 50 100 200 400");
> +
>  static struct attribute *stk8312_attributes[] = {
>  	&iio_const_attr_in_accel_scale_available.dev_attr.attr,
> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
>  	NULL,
>  };
>  
> @@ -220,6 +236,39 @@ static const struct iio_trigger_ops stk8312_trigger_ops = {
>  	.owner = THIS_MODULE,
>  };
>  
> +static int stk8312_set_sample_rate(struct stk8312_data *data, int rate)
> +{
> +	int ret;
> +	u8 masked_reg;
> +	u8 mode;
> +	struct i2c_client *client = data->client;
> +
> +	if (rate == data->sample_rate_idx)
> +		return 0;
> +
> +	mode = data->mode;
> +	/* We need to go in standby mode to modify registers */
> +	ret = stk8312_set_mode(data, STK8312_MODE_STANDBY);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, STK8312_REG_SR);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "failed to set sampling rate\n");
> +		return ret;
> +	}
> +
> +	masked_reg = (ret & (~STK8312_SR_MASK)) | rate;
> +
> +	ret = i2c_smbus_write_byte_data(client, STK8312_REG_SR, masked_reg);
> +	if (ret < 0)
> +		dev_err(&client->dev, "failed to set sampling rate\n");
> +	else
> +		data->sample_rate_idx = rate;
> +
> +	return stk8312_set_mode(data, mode);
> +}
> +
>  static int stk8312_set_range(struct stk8312_data *data, u8 range)
>  {
>  	int ret;
> @@ -303,6 +352,10 @@ static int stk8312_read_raw(struct iio_dev *indio_dev,
>  		*val = stk8312_scale_table[data->range - 1][0];
>  		*val2 = stk8312_scale_table[data->range - 1][1];
>  		return IIO_VAL_INT_PLUS_MICRO;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*val = stk8312_samp_freq_table[data->sample_rate_idx].val;
> +		*val2 = stk8312_samp_freq_table[data->sample_rate_idx].val2;
> +		return IIO_VAL_INT_PLUS_MICRO;
>  	}
>  
>  	return -EINVAL;
> @@ -333,6 +386,20 @@ static int stk8312_write_raw(struct iio_dev *indio_dev,
>  		mutex_unlock(&data->lock);
>  
>  		return ret;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		for (i = 0; i < ARRAY_SIZE(stk8312_samp_freq_table); i++)
> +			if (val == stk8312_samp_freq_table[i].val &&
> +			    val2 == stk8312_samp_freq_table[i].val2) {
> +				index = i;
> +				break;
> +			}
> +		if (index < 0)
> +			return -EINVAL;
> +		mutex_lock(&data->lock);
> +		ret = stk8312_set_sample_rate(data, index);
> +		mutex_unlock(&data->lock);
> +
> +		return ret;
>  	}
>  
>  	return -EINVAL;
> @@ -479,6 +546,7 @@ static int stk8312_probe(struct i2c_client *client,
>  		dev_err(&client->dev, "failed to reset sensor\n");
>  		return ret;
>  	}
> +	data->sample_rate_idx = STK8312_SR_400HZ_IDX;
>  	ret = stk8312_set_range(data, 1);
>  	if (ret < 0)
>  		return ret;
>