Re: [PATCH 4/6] iio: accel: kxcjk-1013: Set adjustable range

[Jonathan Cameron <jic23@kernel.org>]

On 17/07/14 01:42, Srinivas Pandruvada wrote:
> This chip can support 3 different ranges. Allowing range specification.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
A few minor suggestions.  Basically fine though.
> ---
>   drivers/iio/accel/kxcjk-1013.c | 80 +++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 79 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/accel/kxcjk-1013.c b/drivers/iio/accel/kxcjk-1013.c
> index 4912143..975f8a6 100644
> --- a/drivers/iio/accel/kxcjk-1013.c
> +++ b/drivers/iio/accel/kxcjk-1013.c
> @@ -70,6 +70,10 @@
>   #define KXCJK1013_REG_INT_REG1_BIT_IEA	BIT(4)
>   #define KXCJK1013_REG_INT_REG1_BIT_IEN	BIT(5)
>
> +#define KXCJK1013_RANGE_2G		0x00
> +#define KXCJK1013_RANGE_4G		0x01
> +#define KXCJK1013_RANGE_8G		0x02
These are effectively used as an enum?  Hence I'd make them one.

> +
>   #define KXCJK1013_DATA_MASK_12_BIT	0x0FFF
>   #define KXCJK1013_MAX_STARTUP_TIME_US	100000
>
> @@ -86,6 +90,7 @@ struct kxcjk1013_data {
>   	struct mutex mutex;
>   	s16 buffer[8];
>   	u8 odr_bits;
> +	u8 range;
with an enum above this becomes a little more obvious too.
>   	bool active_high_intr;
>   	bool trigger_on;
>   };
> @@ -120,6 +125,14 @@ static const struct {
>   			   {0x02, 21000}, {0x03, 11000}, {0x04, 6400},
>   			   {0x05, 3900}, {0x06, 2700}, {0x07, 2100} };
>
> +static const struct {
> +	u16 scale;
> +	u8 gsel_0;
> +	u8 gsel_1;
Could use a bitfield to make it clear these are single bits..
> +} KXCJK1013_scale_table[] = { {9582, 0, 0},
> +			      {19163, 0, 1},
> +			      {38326, 1, 0} };
> +
Once the _4G etc defines are an enum, you can explicitly set the values
in the table using [KXCJK1013_RANGE_2G] = etc
  
>   static int kxcjk1013_set_mode(struct kxcjk1013_data *data,
>   			      enum kxcjk1013_mode mode)
>   {
> @@ -190,6 +203,7 @@ static int kxcjk1013_chip_init(struct kxcjk1013_data *data)
>   	/* Setting range to 4G */
>   	ret |= KXCJK1013_REG_CTRL1_BIT_GSEL0;
>   	ret &= ~KXCJK1013_REG_CTRL1_BIT_GSEL1;
> +	data->range = KXCJK1013_RANGE_4G;
I'd almost be tempted to call the set function here instead of hand coding
this case.  I know it will involve more hardware writes, but it will give
slightly more obviously correct code (one path to set it rather than two).
>
>   	/* Set 12 bit mode */
>   	ret |= KXCJK1013_REG_CTRL1_BIT_RES;
> @@ -422,6 +436,59 @@ static int kxcjk1013_get_startup_times(struct kxcjk1013_data *data)
>   	return KXCJK1013_MAX_STARTUP_TIME_US;
>   }
>
> +static int kxcjk1013_set_scale(struct kxcjk1013_data *data, int val)
> +{
> +	int ret, i;
> +	enum kxcjk1013_mode store_mode;
> +
> +
> +	for (i = 0; i < ARRAY_SIZE(KXCJK1013_scale_table); ++i) {
> +		if (KXCJK1013_scale_table[i].scale == val) {
> +
> +			ret = kxcjk1013_get_mode(data, &store_mode);
> +			if (ret < 0)
> +				return ret;
> +
> +			ret = kxcjk1013_set_mode(data, STANDBY);
> +			if (ret < 0)
> +				return ret;
> +
> +			ret = i2c_smbus_read_byte_data(data->client,
> +						       KXCJK1013_REG_CTRL1);
> +			if (ret < 0) {
> +				dev_err(&data->client->dev,
> +						"Error reading reg_ctrl1\n");
> +				return ret;
> +			}
> +
> +			ret |= (KXCJK1013_scale_table[i].gsel_0 << 3);
> +			ret |= (KXCJK1013_scale_table[i].gsel_1 << 4);
> +
> +			ret = i2c_smbus_write_byte_data(data->client,
> +							KXCJK1013_REG_CTRL1,
> +							ret);
> +			if (ret < 0) {
> +				dev_err(&data->client->dev,
> +					"Error writing reg_ctrl1\n");
> +				return ret;
> +			}
> +
> +			data->range = i;
> +			dev_dbg(&data->client->dev, "New Scale range %d\n", i);
> +
> +			if (store_mode == OPERATION) {
> +				ret = kxcjk1013_set_mode(data, OPERATION);
> +				if (ret)
> +					return ret;
> +			}
> +
> +			return 0;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
>   static int kxcjk1013_read_raw(struct iio_dev *indio_dev,
>   			      struct iio_chan_spec const *chan, int *val,
>   			      int *val2, long mask)
> @@ -458,7 +525,7 @@ static int kxcjk1013_read_raw(struct iio_dev *indio_dev,
>
>   	case IIO_CHAN_INFO_SCALE:
>   		*val = 0;
> -		*val2 = 19163; /* range +-4g (4/2047*9.806650) */
> +		*val2 = KXCJK1013_scale_table[data->range].scale;
>   		return IIO_VAL_INT_PLUS_MICRO;
>
>   	case IIO_CHAN_INFO_SAMP_FREQ:
> @@ -485,6 +552,14 @@ static int kxcjk1013_write_raw(struct iio_dev *indio_dev,
>   		ret = kxcjk1013_set_odr(data, val, val2);
>   		mutex_unlock(&data->mutex);
>   		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		if (val)
> +			return -EINVAL;
> +
> +		mutex_lock(&data->mutex);
> +		ret = kxcjk1013_set_scale(data, val2);
> +		mutex_unlock(&data->mutex);
> +		break;
>   	default:
>   		ret = -EINVAL;
>   	}
> @@ -506,8 +581,11 @@ static int kxcjk1013_validate_trigger(struct iio_dev *indio_dev,
>   static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
>   	"0.781000 1.563000 3.125000 6.250000 12.500000 25 50 100 200 400 800 1600");
>
> +static IIO_CONST_ATTR(in_accel_scale_available, "0.009582 0.019163 0.038326");
> +
>   static struct attribute *kxcjk1013_attributes[] = {
>   	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
> +	&iio_const_attr_in_accel_scale_available.dev_attr.attr,
>   	NULL,
>   };
>
>