Re: [PATCH 1/3] iio: ak8975 : Add AK8963 compatibility mode support

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On 03/12/2014 03:07 AM, Lars-Peter Clausen wrote:
> On 03/11/2014 10:15 PM, Srinivas Pandruvada wrote:
>> AK8963 and AK8975 use same register definitions, except the range
>> of X,Y,Z values. Added support of 8963 based on i2c_device_id.
>> Unfortunately there is no way to detect the type via registers,
>> both device registers return 0x48 as id of chipset.
>>
>> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
>
> Hi,
>
> a few small comments.
>

Thanks. I will take care in the next version.

-Srinivas

>> ---
>>   drivers/iio/magnetometer/Kconfig  |  3 ++-
>>   drivers/iio/magnetometer/ak8975.c | 40 
>> +++++++++++++++++++++++++++++++++++----
>>   2 files changed, 38 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/iio/magnetometer/Kconfig 
>> b/drivers/iio/magnetometer/Kconfig
>> index d86d226..05a364c54 100644
>> --- a/drivers/iio/magnetometer/Kconfig
>> +++ b/drivers/iio/magnetometer/Kconfig
>> @@ -11,7 +11,8 @@ config AK8975
>>       depends on GPIOLIB
>>       help
>>         Say yes here to build support for Asahi Kasei AK8975 3-Axis
>> -      Magnetometer.
>> +      Magnetometer. This driver can also support AK8963, if i2c
>> +      device name is identified as ak8963.
>>
>>         To compile this driver as a module, choose M here: the module
>>         will be called ak8975.
>> diff --git a/drivers/iio/magnetometer/ak8975.c 
>> b/drivers/iio/magnetometer/ak8975.c
>> index 0542354..a55c94f 100644
>> --- a/drivers/iio/magnetometer/ak8975.c
>> +++ b/drivers/iio/magnetometer/ak8975.c
>> @@ -85,7 +85,15 @@
>>   #define AK8975_MAX_CONVERSION_TIMEOUT    500
>>   #define AK8975_CONVERSION_DONE_POLL_TIME 10
>>   #define AK8975_DATA_READY_TIMEOUT    ((100*HZ)/1000)
>> -#define RAW_TO_GAUSS(asa) ((((asa) + 128) * 3000) / 256)
>> +#define RAW_TO_GAUSS_8975(asa) ((((asa) + 128) * 3000) / 256)
>> +#define RAW_TO_GAUSS_8963(asa) ((((asa) + 128) * 6000) / 256)
>> +
>> +/* Compatible Asahi Kasei Compass parts */
>> +enum asahi_compass_chipset {
>> +    AK8975,
>> +    AK8963,
>> +    AK_INVALID,
>
> Not sure if you need AK_INVALID, it is never used.
>
>> +};
>>
>>   /*
>>    * Per-instance context data for the device.
>> @@ -101,6 +109,7 @@ struct ak8975_data {
>>       int            eoc_irq;
>>       wait_queue_head_t    data_ready_queue;
>>       unsigned long        flags;
>> +    int            chipset;
>
> enum asahi_compass_chipset ...
>
>>   };
>>
>>   static const int ak8975_index_to_reg[] = {
>> @@ -272,9 +281,21 @@ static int ak8975_setup(struct i2c_client *client)
>>    * Since ASA doesn't change, we cache the resultant scale factor 
>> into the
>>    * device context in ak8975_setup().
>>    */
>> -    data->raw_to_gauss[0] = RAW_TO_GAUSS(data->asa[0]);
>> -    data->raw_to_gauss[1] = RAW_TO_GAUSS(data->asa[1]);
>> -    data->raw_to_gauss[2] = RAW_TO_GAUSS(data->asa[2]);
>> +    if (data->chipset == AK8963) {
>> +        /*
>> +         * H range is +-8190 and magnetometer range is +-4912.
>> +         * So HuT using the above explanation for 8975,
>> +         * 4912/8190 = ~ 6/10.
>> +         * So the Hadj should use 6/10 instead of 3/10.
>> +         */
>> +        data->raw_to_gauss[0] = RAW_TO_GAUSS_8963(data->asa[0]);
>> +        data->raw_to_gauss[1] = RAW_TO_GAUSS_8963(data->asa[1]);
>> +        data->raw_to_gauss[2] = RAW_TO_GAUSS_8963(data->asa[2]);
>> +    } else {
>> +        data->raw_to_gauss[0] = RAW_TO_GAUSS_8975(data->asa[0]);
>> +        data->raw_to_gauss[1] = RAW_TO_GAUSS_8975(data->asa[1]);
>> +        data->raw_to_gauss[2] = RAW_TO_GAUSS_8975(data->asa[2]);
>> +    }
>>
>>       return 0;
>>   }
>> @@ -499,6 +520,16 @@ static int ak8975_probe(struct i2c_client *client,
>>       data->eoc_gpio = eoc_gpio;
>>       data->eoc_irq = 0;
>>
>> +    if (id) {
>
> id will never be NULL.
>
>> +        data->chipset = (int)(id->driver_data);
>> +        if (data->chipset == AK8963)
>> +            dev_dbg(&client->dev,
>> +                "AK8975 driver is running in AK8963 mode\n");
>> +        else
>> +            dev_dbg(&client->dev,
>> +                "AK8975 driver is running in normal mode\n");
>
> How about printing just id->name, this way you do not have to add a 
> new else branch when a new part is supported.
>
>> +    }
>> +
>>       /* Perform some basic start-of-day setup of the device. */
>>       err = ak8975_setup(client);
>>       if (err < 0) {
>> @@ -552,6 +583,7 @@ static int ak8975_remove(struct i2c_client *client)
>>
>>   static const struct i2c_device_id ak8975_id[] = {
>>       {"ak8975", 0},
>
> Should change the 0 to AK8975
>
>> +    {"ak8963", AK8963},
>>       {}
>>   };
>>
>>
>
>