[PATCH 1/3] iio: add iio_read_channel_offset() consumer api

[PATCH 1/3] iio: add iio_read_channel_offset() consumer api

[Kim, Milo]

This allows the iio consumer to get the offset of the channel.
The value of offset can be used when calculating the result such
as 'result = raw * scale + offset'.

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
---
 drivers/iio/inkern.c         |   21 +++++++++++++++++++++
 include/linux/iio/consumer.h |    9 +++++++++
 2 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index b5afc2f..bd09245 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -269,6 +269,27 @@ err_unlock:
 }
 EXPORT_SYMBOL_GPL(iio_read_channel_scale);
 
+int iio_read_channel_offset(struct iio_channel *chan, int *val)
+{
+	int val2, ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = chan->indio_dev->info->read_raw(chan->indio_dev,
+					      chan->channel,
+					      val, &val2,
+					      IIO_CHAN_INFO_OFFSET);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_offset);
+
 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 e2657e6..d9d69fa 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -93,4 +93,13 @@ int iio_get_channel_type(struct iio_channel *channel,
 int iio_read_channel_scale(struct iio_channel *chan, int *val,
 			   int *val2);
 
+/**
+ * iio_read_channel_offset() - read offset from a given channel
+ * @channel:		The channel being queried.
+ * @val:		Offset Value read back.
+ *
+ * Note offset can be used in the consumer when calculating the result
+ * such as 'result = raw * scale + offset'.
+ */
+int iio_read_channel_offset(struct iio_channel *chan, int *val);
 #endif
-- 
1.7.2.5


Best Regards,
Milo

Re: [PATCH 1/3] iio: add iio_read_channel_offset() consumer api

[Peter Meerwald]

comment below

p.

> This allows the iio consumer to get the offset of the channel.
> The value of offset can be used when calculating the result such
> as 'result = raw * scale + offset'.
> 
> Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
> ---
>  drivers/iio/inkern.c         |   21 +++++++++++++++++++++
>  include/linux/iio/consumer.h |    9 +++++++++
>  2 files changed, 30 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index b5afc2f..bd09245 100644
> --- a/drivers/iio/inkern.c
> +++ b/drivers/iio/inkern.c
> @@ -269,6 +269,27 @@ err_unlock:
>  }
>  EXPORT_SYMBOL_GPL(iio_read_channel_scale);
>  
> +int iio_read_channel_offset(struct iio_channel *chan, int *val)
> +{
> +	int val2, ret;
> +
> +	mutex_lock(&chan->indio_dev->info_exist_lock);
> +	if (chan->indio_dev->info == NULL) {
> +		ret = -ENODEV;
> +		goto err_unlock;
> +	}
> +
> +	ret = chan->indio_dev->info->read_raw(chan->indio_dev,
> +					      chan->channel,
> +					      val, &val2,
> +					      IIO_CHAN_INFO_OFFSET);
> +err_unlock:
> +	mutex_unlock(&chan->indio_dev->info_exist_lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iio_read_channel_offset);
> +
>  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 e2657e6..d9d69fa 100644
> --- a/include/linux/iio/consumer.h
> +++ b/include/linux/iio/consumer.h
> @@ -93,4 +93,13 @@ int iio_get_channel_type(struct iio_channel *channel,
>  int iio_read_channel_scale(struct iio_channel *chan, int *val,
>  			   int *val2);
>  
> +/**
> + * iio_read_channel_offset() - read offset from a given channel
> + * @channel:		The channel being queried.

the parameter is 'chan', not 'channel'

> + * @val:		Offset Value read back.
> + *
> + * Note offset can be used in the consumer when calculating the result
> + * such as 'result = raw * scale + offset'.
> + */
> +int iio_read_channel_offset(struct iio_channel *chan, int *val);
>  #endif
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)

RE: [PATCH 1/3] iio: add iio_read_channel_offset() consumer api

[Kim, Milo]

> >  int iio_read_channel_scale(struct iio_channel *chan, int *val,
> >  			   int *val2);
> >
> > +/**
> > + * iio_read_channel_offset() - read offset from a given channel
> > + * @channel:		The channel being queried.
> 
> the parameter is 'chan', not 'channel'
> 

Oops, this is copy-and-paste disaster.
The description of iio_read_channel_scale() also needs correction.
Thanks for catching this !

After getting other feedbacks, separate patch will be submitted.

Best Regards,
Milo

Re: [PATCH 1/3] iio: add iio_read_channel_offset() consumer api

[Jonathan Cameron]

On 08/16/2012 08:49 AM, Kim, Milo wrote:
>>>  int iio_read_channel_scale(struct iio_channel *chan, int *val,
>>>  			   int *val2);
>>>
>>> +/**
>>> + * iio_read_channel_offset() - read offset from a given channel
>>> + * @channel:		The channel being queried.
>>
>> the parameter is 'chan', not 'channel'
>>
> 
> Oops, this is copy-and-paste disaster.
> The description of iio_read_channel_scale() also needs correction.
> Thanks for catching this !
good point.  Feel free to send a separate patch fixing that ;)
> 
> After getting other feedbacks, separate patch will be submitted.
> 
> Best Regards,
> Milo
> 

Re: [PATCH 1/3] iio: add iio_read_channel_offset() consumer api

[Lars-Peter Clausen]

On 08/16/2012 09:39 AM, Kim, Milo wrote:
> This allows the iio consumer to get the offset of the channel.
> The value of offset can be used when calculating the result such
> as 'result = raw * scale + offset'.

result = (raw + offset) * scale

Otherwise it looks good, except for:

> +/**
> + * iio_read_channel_offset() - read offset from a given channel
> + * @channel:		The channel being queried.
> + * @val:		Offset Value read back.
> + *
> + * Note offset can be used in the consumer when calculating the result
> + * such as 'result = raw * scale + offset'.
> + */

The documentation should go in the c file.

> +int iio_read_channel_offset(struct iio_channel *chan, int *val);
>  #endif

Re: [PATCH 1/3] iio: add iio_read_channel_offset() consumer api

[Lars-Peter Clausen]

On 08/16/2012 10:19 AM, Lars-Peter Clausen wrote:
> On 08/16/2012 09:39 AM, Kim, Milo wrote:
>> This allows the iio consumer to get the offset of the channel.
>> The value of offset can be used when calculating the result such
>> as 'result = raw * scale + offset'.
> 
> result = (raw + offset) * scale
> 
> Otherwise it looks good, except for:
> 
>> +/**
>> + * iio_read_channel_offset() - read offset from a given channel
>> + * @channel:		The channel being queried.
>> + * @val:		Offset Value read back.
>> + *
>> + * Note offset can be used in the consumer when calculating the result
>> + * such as 'result = raw * scale + offset'.
>> + */
> 
> The documentation should go in the c file.

Just saw that for the other functions in consumer.h it is in the header as
well, so ignore that comment above.

> 
>> +int iio_read_channel_offset(struct iio_channel *chan, int *val);
>>  #endif
> 
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Re: [PATCH 1/3] iio: add iio_read_channel_offset() consumer api

[Jonathan Cameron]

On 16/08/12 09:19, Lars-Peter Clausen wrote:
> On 08/16/2012 09:39 AM, Kim, Milo wrote:
>> This allows the iio consumer to get the offset of the channel.
>> The value of offset can be used when calculating the result such
>> as 'result = raw * scale + offset'.
> result = (raw + offset) * scale
>
> Otherwise it looks good, except for:
>
>> +/**
>> + * iio_read_channel_offset() - read offset from a given channel
>> + * @channel:		The channel being queried.
>> + * @val:		Offset Value read back.
>> + *
>> + * Note offset can be used in the consumer when calculating the result
>> + * such as 'result = raw * scale + offset'.
>> + */
> The documentation should go in the c file.
I've often wondered about this myself.  Looking quickly about it does
appear that it is more popular to do it in c file...  Guess I've been wrong
for quite some time.  For now it's probably better to keep this docs
in the header and do the move all in one go given all the other docs
are here in this header.

I can see the arguments either way, but have not as yet seen anyone
stamp their foot on what is the 'one true way'.

>
>> +int iio_read_channel_offset(struct iio_channel *chan, int *val);
>>   #endif