Re: [PATCH] ti_tscadc: Match mfd sub devices to regmap interface

[Lars-Peter Clausen <lars@metafoo.de>]

On 10/31/2012 05:41 AM, Russ Dill wrote:
> On Wed, Oct 31, 2012 at 8:55 AM, Pantelis Antoniou
> <panto@antoniou-consulting.com> wrote:
>> The MFD parent device now uses a regmap, instead of direct
>> memory access. Use the same method in the sub devices to avoid
>> nasty surprises.
>>
>> Also rework the channel initialization of tiadc a bit.
>>
>> Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
>> ---
>>  drivers/iio/adc/ti_am335x_adc.c           | 27 +++++++++++++++++++--------
>>  drivers/input/touchscreen/ti_am335x_tsc.c | 16 +++++++++++++---
>>  drivers/mfd/ti_am335x_tscadc.c            |  7 +++++--
>>  3 files changed, 37 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
>> index d48fd79..5f325c1 100644
>> --- a/drivers/iio/adc/ti_am335x_adc.c
>> +++ b/drivers/iio/adc/ti_am335x_adc.c
>> @@ -23,7 +23,9 @@
>>  #include <linux/iio/iio.h>
>>  #include <linux/iio/machine.h>
>>  #include <linux/iio/driver.h>
>> +#include <linux/regmap.h>
>>
>> +#include <linux/io.h>
>>  #include <linux/mfd/ti_am335x_tscadc.h>
>>  #include <linux/platform_data/ti_am335x_adc.h>
>>
>> @@ -36,13 +38,17 @@ struct tiadc_device {
>>
>>  static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)
>>  {
>> -       return readl(adc->mfd_tscadc->tscadc_base + reg);
>> +       unsigned int val;
>> +
>> +       val = (unsigned int)-1;
>> +       regmap_read(adc->mfd_tscadc->regmap_tscadc, reg, &val);
>> +       return val;
>>  }
> 
> Would it be cleaner to instead do:
> 
> static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)
> {
>        unsigned int val;
> 
>        return regmap_read(adc->mfd_tscadc->regmap_tscadc, reg, &val) ? : val;
> }

In my opinion the best would be to just mimic the regmap interface here. Return
an error code or 0 and pass the value back through a pointer parameter.