Re: [PATCH v1 1/5] IIO: core: Introduce read_raw_multi

[Jonathan Cameron <jic23@kernel.org>]

On 04/04/14 22:38, Srinivas Pandruvada wrote:
> On 03/29/2014 04:15 AM, Jonathan Cameron wrote:
>> On 23/02/14 19:50, Srinivas Pandruvada wrote:
>>> This callback is introduced to overcome some limitations of existing
>>> read_raw callback. The functionality of both existing read_raw and
>>> read_raw_multi is similar, both are used to request values from the
>>> device. The current read_raw callback allows only two return values.
>>> The new read_raw_multi allows returning multiple values. Instead of
>>> passing just address of val and val2, it passes length and pointer
>>> to values. Depending on the type and length of passed buffer, iio
>>> client drivers can return multiple values.
>>>
>>> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
>> Hi Srinivas.
>>
>> Whilst it wasn't the most in depth of discussions, I think the outcome
>> of the 'how to handle quaternion sysfs naming' element of the
>> thread.
>> [RFC] IIO: New interfaces for 'interesting' channel types.
>>
>> was that we should do them as a modifier instead of a new channel type.
>> e.g.
>>
>> in_rot_quaternion_raw
>> etc.
>>
>> Could you convert this driver over and repost?
>>
>> If you disagree, then feel free to contribute to that discussion and
>> we'll continue from there.
>>
>> Sorry this took so long to sort out, I was hoping for a few more inputs
>> but there we are...
>>
> Hi Jonathan,
>
> I have resubmitted with the modifier for quaternion dropping this patch.
> I only allow buffered mode as without this patch representing in raw mode
> all four component is not possible. Current applications only is using buffer mode.
> So I can wait for core support something similar to this patch.
>
> Thanks,
> Srinivas
Hi Srinivas,

I'm a bit lost on this.  I was quite happy with this patch and can't immediately
see why the change to using a modifier requires dropping it?

It just makes for slightly different handling in the read_raw_multi call inside
the driver itself...

or am I missing something...

Jonathan
>
>
>
>
>> Jonathan
>>> ---
>>>   drivers/iio/iio_core.h           |  2 +-
>>>   drivers/iio/industrialio-core.c  | 51 +++++++++++++++++++++++-----------------
>>>   drivers/iio/industrialio-event.c |  6 +++--
>>>   drivers/iio/inkern.c             | 15 ++++++++++--
>>>   include/linux/iio/iio.h          | 16 +++++++++++++
>>>   5 files changed, 63 insertions(+), 27 deletions(-)
>>>
>>> diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
>>> index f6db6af..4172f22 100644
>>> --- a/drivers/iio/iio_core.h
>>> +++ b/drivers/iio/iio_core.h
>>> @@ -35,7 +35,7 @@ int __iio_add_chan_devattr(const char *postfix,
>>>                  struct list_head *attr_list);
>>>   void iio_free_chan_devattr_list(struct list_head *attr_list);
>>>
>>> -ssize_t iio_format_value(char *buf, unsigned int type, int val, int val2);
>>> +ssize_t iio_format_value(char *buf, unsigned int type, int *val);
>>>
>>>   /* Event interface flags */
>>>   #define IIO_BUSY_BIT_POS 1
>>> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
>>> index acc911a..b1225a4 100644
>>> --- a/drivers/iio/industrialio-core.c
>>> +++ b/drivers/iio/industrialio-core.c
>>> @@ -373,41 +373,42 @@ EXPORT_SYMBOL_GPL(iio_enum_write);
>>>    * @buf: The buffer to which the formated value gets written
>>>    * @type: One of the IIO_VAL_... constants. This decides how the val and val2
>>>    *        parameters are formatted.
>>> - * @val: First part of the value, exact meaning depends on the type parameter.
>>> - * @val2: Second part of the value, exact meaning depends on the type parameter.
>>> + * @vals: pointer to the values, exact meaning depends on the type parameter.
>>>    */
>>> -ssize_t iio_format_value(char *buf, unsigned int type, int val, int val2)
>>> +ssize_t iio_format_value(char *buf, unsigned int type, int *vals)
>>>   {
>>>       unsigned long long tmp;
>>>       bool scale_db = false;
>>>
>>>       switch (type) {
>>>       case IIO_VAL_INT:
>>> -        return sprintf(buf, "%d\n", val);
>>> +        return sprintf(buf, "%d\n", vals[0]);
>>>       case IIO_VAL_INT_PLUS_MICRO_DB:
>>>           scale_db = true;
>>>       case IIO_VAL_INT_PLUS_MICRO:
>>> -        if (val2 < 0)
>>> -            return sprintf(buf, "-%ld.%06u%s\n", abs(val), -val2,
>>> +        if (vals[1] < 0)
>>> +            return sprintf(buf, "-%ld.%06u%s\n", abs(vals[0]),
>>> +                    -vals[1],
>>>                   scale_db ? " dB" : "");
>>>           else
>>> -            return sprintf(buf, "%d.%06u%s\n", val, val2,
>>> +            return sprintf(buf, "%d.%06u%s\n", vals[0], vals[1],
>>>                   scale_db ? " dB" : "");
>>>       case IIO_VAL_INT_PLUS_NANO:
>>> -        if (val2 < 0)
>>> -            return sprintf(buf, "-%ld.%09u\n", abs(val), -val2);
>>> +        if (vals[1] < 0)
>>> +            return sprintf(buf, "-%ld.%09u\n", abs(vals[0]),
>>> +                    -vals[1]);
>>>           else
>>> -            return sprintf(buf, "%d.%09u\n", val, val2);
>>> +            return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
>>>       case IIO_VAL_FRACTIONAL:
>>> -        tmp = div_s64((s64)val * 1000000000LL, val2);
>>> -        val2 = do_div(tmp, 1000000000LL);
>>> -        val = tmp;
>>> -        return sprintf(buf, "%d.%09u\n", val, val2);
>>> +        tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]);
>>> +        vals[1] = do_div(tmp, 1000000000LL);
>>> +        vals[0] = tmp;
>>> +        return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
>>>       case IIO_VAL_FRACTIONAL_LOG2:
>>> -        tmp = (s64)val * 1000000000LL >> val2;
>>> -        val2 = do_div(tmp, 1000000000LL);
>>> -        val = tmp;
>>> -        return sprintf(buf, "%d.%09u\n", val, val2);
>>> +        tmp = (s64)vals[0] * 1000000000LL >> vals[1];
>>> +        vals[1] = do_div(tmp, 1000000000LL);
>>> +        vals[0] = tmp;
>>> +        return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
>>>       default:
>>>           return 0;
>>>       }
>>> @@ -419,14 +420,20 @@ static ssize_t iio_read_channel_info(struct device *dev,
>>>   {
>>>       struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>       struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
>>> -    int val, val2;
>>> -    int ret = indio_dev->info->read_raw(indio_dev, this_attr->c,
>>> -                        &val, &val2, this_attr->address);
>>> +    int vals[INDIO_MAX_RAW_ELEMENTS];
>>> +    int ret;
>>> +
>>> +    if (indio_dev->info->read_raw_multi)
>>> +        ret = indio_dev->info->read_raw_multi(indio_dev, this_attr->c,
>>> +                INDIO_MAX_RAW_ELEMENTS, vals, this_attr->address);
>>> +    else
>>> +        ret = indio_dev->info->read_raw(indio_dev, this_attr->c,
>>> +                    &vals[0], &vals[1], this_attr->address);
>>>
>>>       if (ret < 0)
>>>           return ret;
>>>
>>> -    return iio_format_value(buf, ret, val, val2);
>>> +    return iio_format_value(buf, ret, vals);
>>>   }
>>>
>>>   /**
>>> diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
>>> index c9c1419..0f7f78e 100644
>>> --- a/drivers/iio/industrialio-event.c
>>> +++ b/drivers/iio/industrialio-event.c
>>> @@ -272,7 +272,7 @@ static ssize_t iio_ev_value_show(struct device *dev,
>>>   {
>>>       struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>       struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
>>> -    int val, val2;
>>> +    int val, val2, val_arr[2];
>>>       int ret;
>>>
>>>       ret = indio_dev->info->read_event_value(indio_dev,
>>> @@ -281,7 +281,9 @@ static ssize_t iio_ev_value_show(struct device *dev,
>>>           &val, &val2);
>>>       if (ret < 0)
>>>           return ret;
>>> -    return iio_format_value(buf, ret, val, val2);
>>> +    val_arr[0] = val;
>>> +    val_arr[1] = val2;
>>> +    return iio_format_value(buf, ret, val_arr);
>>>   }
>>>
>>>   static ssize_t iio_ev_value_store(struct device *dev,
>>> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
>>> index 0cf5f8e..6a93d57 100644
>>> --- a/drivers/iio/inkern.c
>>> +++ b/drivers/iio/inkern.c
>>> @@ -417,12 +417,23 @@ static int iio_channel_read(struct iio_channel *chan, int *val, int *val2,
>>>       enum iio_chan_info_enum info)
>>>   {
>>>       int unused;
>>> +    int vals[INDIO_MAX_RAW_ELEMENTS];
>>> +    int ret;
>>>
>>>       if (val2 == NULL)
>>>           val2 = &unused;
>>>
>>> -    return chan->indio_dev->info->read_raw(chan->indio_dev, chan->channel,
>>> -                        val, val2, info);
>>> +    if (chan->indio_dev->info->read_raw_multi) {
>>> +        ret = chan->indio_dev->info->read_raw_multi(chan->indio_dev,
>>> +                    chan->channel, INDIO_MAX_RAW_ELEMENTS,
>>> +                    vals, info);
>>> +        *val = vals[0];
>>> +        *val2 = vals[1];
>>> +    } else
>>> +        ret = chan->indio_dev->info->read_raw(chan->indio_dev,
>>> +                    chan->channel, val, val2, info);
>>> +
>>> +    return ret;
>>>   }
>>>
>>>   int iio_read_channel_raw(struct iio_channel *chan, int *val)
>>> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
>>> index 75a8a20..ddf9f60 100644
>>> --- a/include/linux/iio/iio.h
>>> +++ b/include/linux/iio/iio.h
>>> @@ -284,6 +284,8 @@ static inline s64 iio_get_time_ns(void)
>>>   #define INDIO_ALL_BUFFER_MODES                    \
>>>       (INDIO_BUFFER_TRIGGERED | INDIO_BUFFER_HARDWARE)
>>>
>>> +#define INDIO_MAX_RAW_ELEMENTS        4
>>> +
>>>   struct iio_trigger; /* forward declaration */
>>>   struct iio_dev;
>>>
>>> @@ -298,6 +300,14 @@ struct iio_dev;
>>>    *            the channel in question.  Return value will specify the
>>>    *            type of value returned by the device. val and val2 will
>>>    *            contain the elements making up the returned value.
>>> + * @read_raw_multi:    function to return values from the device.
>>> + *            mask specifies which value. Note 0 means a reading of
>>> + *            the channel in question.  Return value will specify the
>>> + *            type of value returned by the device. vals pointer
>>> + *            contain the elements making up the returned value.
>>> + *            val_len specifies maximum number of elements
>>> + *            vals pointer can contain. In contrast to to read_raw
>>> + *            device can return multiple values not just two.
>>>    * @write_raw:        function to write a value to the device.
>>>    *            Parameters are the same as for read_raw.
>>>    * @write_raw_get_fmt:    callback function to query the expected
>>> @@ -324,6 +334,12 @@ struct iio_info {
>>>               int *val2,
>>>               long mask);
>>>
>>> +    int (*read_raw_multi)(struct iio_dev *indio_dev,
>>> +            struct iio_chan_spec const *chan,
>>> +            int val_len,
>>> +            int *vals,
>>> +            long mask);
>>> +
>>>       int (*write_raw)(struct iio_dev *indio_dev,
>>>                struct iio_chan_spec const *chan,
>>>                int val,
>>>
>>
>>
>
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