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

[Jonathan Cameron <jic23@kernel.org>]

On 25/07/14 00:04, Srinivas Pandruvada wrote:
>
> On 07/20/2014 08:45 AM, Jonathan Cameron wrote:
>> 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..
> I thought bit fields is not recommended for portability concerns in kernel.
> Hence avoided using bit fields.
I believe that is more about anything that might be exposed to userspace rather
than there being any issues using them internally.  Still, it's not something
I feel strongly about either way!

J
>
> Thanks,
> Srinivas
>
>>> +} 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,
>>>   };
>>>
>>>
>>
>>
>