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Message-ID: <f4106f92-0011-a10d-653d-e315334d9472@axentia.se>
Date: Sun, 30 Oct 2016 22:12:32 +0100
From: Peter Rosin <peda@...ntia.se>
To: Peter Meerwald-Stadler <pmeerw@...erw.net>,
Jonathan Cameron <jic23@...nel.org>
CC: <linux-kernel@...r.kernel.org>, Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
Rob Herring <robh+dt@...nel.org>,
"Mark Rutland" <mark.rutland@....com>, <linux-iio@...r.kernel.org>,
<devicetree@...r.kernel.org>
Subject: Re: [PATCH v3 2/8] iio: inkern: add helpers to query available values
from channels
On 2016-10-30 16:23, Peter Meerwald-Stadler wrote:
>
>> On 23/10/16 23:39, Peter Rosin wrote:
>>> Specifically a helper for reading the available maximum raw value of a
>>> channel and a helper for forwarding read_avail requests for raw values
>>> from one iio driver to an iio channel that is consumed.
>>>
>>> These rather specific helpers are in turn built with generic helpers
>>> making it easy to build more helpers for available values as needed.
>>>
>>> Signed-off-by: Peter Rosin <peda@...ntia.se>
>> Looks good to me. Just what I was after.
>
> some comments below
>
>> Jonathan
>>> ---
>>> drivers/iio/inkern.c | 97 ++++++++++++++++++++++++++++++++++++++++++++
>>> include/linux/iio/consumer.h | 29 +++++++++++++
>>> include/linux/iio/iio.h | 17 ++++++++
>>> 3 files changed, 143 insertions(+)
>>>
>>> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
>>> index c4757e6367e7..74808f8a187a 100644
>>> --- a/drivers/iio/inkern.c
>>> +++ b/drivers/iio/inkern.c
>>> @@ -703,6 +703,103 @@ int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
>>> }
>>> EXPORT_SYMBOL_GPL(iio_read_channel_scale);
>>>
>>> +static int iio_channel_read_avail(struct iio_channel *chan,
>>> + const int **vals, int *type, int *length,
>>> + enum iio_chan_info_enum info)
>>> +{
>>> + if (!iio_channel_has_available(chan->channel, info))
>>> + return -EINVAL;
>>> +
>>> + return chan->indio_dev->info->read_avail(chan->indio_dev, chan->channel,
>>> + vals, type, length, info);
>>> +}
>>> +
>>> +int iio_read_avail_channel_raw(struct iio_channel *chan,
>>> + const int **vals, int *type, int *length)
>>> +{
>>> + int ret;
>>> +
>>> + mutex_lock(&chan->indio_dev->info_exist_lock);
>>> + if (!chan->indio_dev->info) {
>>> + ret = -ENODEV;
>>> + goto err_unlock;
>>> + }
>>> +
>>> + ret = iio_channel_read_avail(chan,
>>> + vals, type, length, IIO_CHAN_INFO_RAW);
>>> +err_unlock:
>>> + mutex_unlock(&chan->indio_dev->info_exist_lock);
>>> +
>>> + return ret;
>>> +}
>>> +EXPORT_SYMBOL_GPL(iio_read_avail_channel_raw);
>>> +
>>> +static int iio_channel_read_max(struct iio_channel *chan,
>>> + int *val, int *val2, int *type,
>>> + enum iio_chan_info_enum info)
>>> +{
>>> + int unused;
>>> + const int *vals;
>>> + int length;
>>> + int ret;
>>> +
>>> + if (!val2)
>>> + val2 = &unused;
>>> +
>>> + ret = iio_channel_read_avail(chan, &vals, type, &length, info);
>>> + switch (ret) {
>>> + case IIO_AVAIL_RANGE:
>>> + switch (*type) {
>>> + case IIO_VAL_INT:
>>> + *val = vals[2];
>>> + break;
>>> + default:
>>> + *val = vals[4];
>>> + *val2 = vals[5];
>>> + }
>>> + return 0;
>>> +
>>> + case IIO_AVAIL_LIST:
>>> + if (length <= 0)
>>> + return -EINVAL;
>>> + switch (*type) {
>>> + case IIO_VAL_INT:
>>> + *val = vals[--length];
>>> + while (length) {
>>> + if (vals[--length] > *val)
>>> + *val = vals[length];
>>> + }
>>> + break;
>>> + default:
>>> + /* FIXME: learn about max for other iio values */
>>> + return -EINVAL;
>>> + }
>>> + return 0;
>>> +
>>> + default:
>>> + return ret;
>>> + }
>>> +}
>>> +
>>> +int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
>>> +{
>>> + int ret;
>>> + int type;
>>> +
>>> + mutex_lock(&chan->indio_dev->info_exist_lock);
>>> + if (!chan->indio_dev->info) {
>>> + ret = -ENODEV;
>>> + goto err_unlock;
>>> + }
>>> +
>>> + ret = iio_channel_read_max(chan, val, NULL, &type, IIO_CHAN_INFO_RAW);
>>> +err_unlock:
>>> + mutex_unlock(&chan->indio_dev->info_exist_lock);
>>> +
>>> + return ret;
>>> +}
>>> +EXPORT_SYMBOL_GPL(iio_read_max_channel_raw);
>>> +
>>> int iio_get_channel_type(struct iio_channel *chan, enum iio_chan_type *type)
>>> {
>>> int ret = 0;
>>> diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
>>> index 9edccfba1ffb..baab5e45734f 100644
>>> --- a/include/linux/iio/consumer.h
>>> +++ b/include/linux/iio/consumer.h
>>> @@ -226,6 +226,35 @@ int iio_read_channel_processed(struct iio_channel *chan, int *val);
>>> int iio_write_channel_raw(struct iio_channel *chan, int val);
>>>
>>> /**
>>> + * iio_read_max_channel_raw() - read maximum available raw value from a given
>>> + * channel
>>> + * @chan: The channel being queried.
>>> + * @val: Value read back.
>>> + *
>>> + * Note raw reads from iio channels are in adc counts and hence
>
> "Note: raw reads..." would be easier...
> here and below
All other function comments lack the colon after that Note, so I was just
following that lead. I suggest that this can be fixed up later with one
patch for all comments, if needed?
> why is there no val2 here?
Everything else in inkern.c that handles the raw channel assumes it
is of type IIO_VAL_INT. Again, just following the lead.
> just reading the documentation ("maximum available raw value") I am not
> sure what the function does: does it return the maximum value possible? or
> the maximum value in some internal buffer? maximum value ever seen?
Maximum possible, that's what the available attribute is all
about; possible values. How about:
* iio_read_max_channel_raw() - read maximum available raw value from a given
* channel, i.e. the maximum possible value.
>>> + * scale will need to be applied if standard units are required.
>>> + */
>>> +int iio_read_max_channel_raw(struct iio_channel *chan, int *val);
>>> +
>>> +/**
>>> + * iio_read_avail_channel_raw() - read available raw values from a given channel
>>> + * @chan: The channel being queried.
>>> + * @vals: Available values read back.
>
> no vals2?
Same raw channel assumption about IIO_VAL_INT.
>>> + * @type: Type of available values in vals.
>
> it is not clear what type is
Same as in the iio_channel_has_info function right above which has
the same kind of explanation. Again, just following the lead.
>>> + * @length: Number of entries in vals.
>>> + *
>>> + * Returns an error code, IIO_AVAIL_RANGE or IIO_AVAIL_LIST.
>>> + *
>>> + * For ranges, three vals are always returned; min, step and max.
>>> + * For lists, all the possible values are enumerated.
>>> + *
>>> + * Note raw available values from iio channels are in adc counts and
>>> + * hence scale will need to be applied if standard units are required.
>>> + */
>>> +int iio_read_avail_channel_raw(struct iio_channel *chan,
>>> + const int **vals, int *type, int *length);
>>> +
>>> +/**
>>> * iio_get_channel_type() - get the type of a channel
>>> * @channel: The channel being queried.
>>> * @type: The type of the channel.
>>> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
>>> index 45b781084a4b..e565701d13ce 100644
>>> --- a/include/linux/iio/iio.h
>>> +++ b/include/linux/iio/iio.h
>>> @@ -315,6 +315,23 @@ static inline bool iio_channel_has_info(const struct iio_chan_spec *chan,
>>> (chan->info_mask_shared_by_all & BIT(type));
>>> }
>>>
>>> +/**
>>> + * iio_channel_has_available() - Checks if a channel has an available attribute
>>> + * @chan: The channel to be queried
>>> + * @type: Type of the available attribute to be checked
>>> + *
>>> + * Returns true if the channels supports reporting available values for the
>
> channel
I'll fix that.
Sigh, I guess there's enough small changes that I'll need to do a v4.
I'll hold off on that for a couple of days though since there is
nothing badly wrong...
Cheers,
Peter
>>> + * given attribute type, false otherwise.
>>> + */
>>> +static inline bool iio_channel_has_available(const struct iio_chan_spec *chan,
>>> + enum iio_chan_info_enum type)
>>> +{
>>> + return (chan->info_mask_separate_available & BIT(type)) |
>>> + (chan->info_mask_shared_by_type_available & BIT(type)) |
>>> + (chan->info_mask_shared_by_dir_available & BIT(type)) |
>>> + (chan->info_mask_shared_by_all_available & BIT(type));
>>> +}
>>> +
>>> #define IIO_CHAN_SOFT_TIMESTAMP(_si) { \
>>> .type = IIO_TIMESTAMP, \
>>> .channel = -1, \
>>>
>>
>
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