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iio: Add callback to check whether a scan mask is valid 

This is useful for cases where the number of valid scan masks grows
exponentially, but it is rather easy to check whether a mask is valid or not
programmatically.

An example of such a case is a device with multiple ADCs where each ADC has a
upstream MUX, which allows to select from a number of physical channels.

  +-------+   +-------+
  |       |   |       | --- Channel 1
  | ADC 1 |---| MUX 1 | ---   ...
  |       |   |       | --- Channel M
  +-------+   +-------+

     .            .            .
     .            .            .
     .            .            .

  +-------+   +-------+
  |       |   |       | --- Channel M * N + 1
  | ADC N |---| MUX N | ---       ...
  |       |   |       | --- Channel M * N + M
  +-------+   +-------+

The number of necessary scan masks for this case is (M+1)**N - 1, on the other
hand it is easy to check whether subsets for each ADC of the scanmask have only
one bit set.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Lars-Peter Clausen 2012-07-09 10:00:00 +01:00 committed by Jonathan Cameron
parent c732a24c5a
commit 939546d1a9
2 changed files with 24 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
drivers/iio/industrialio-buffer.c
View File

@ -570,6 +570,15 @@ int iio_sw_buffer_preenable(struct iio_dev *indio_dev)
}
EXPORT_SYMBOL(iio_sw_buffer_preenable);
static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
const unsigned long *mask)
{
if (!indio_dev->setup_ops->validate_scan_mask)
return true;
return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
}
/**
* iio_scan_mask_set() - set particular bit in the scan mask
* @buffer: the buffer whose scan mask we are interested in
@ -589,27 +598,31 @@ int iio_scan_mask_set(struct iio_dev *indio_dev,
return -ENOMEM;
if (!indio_dev->masklength) {
WARN_ON("trying to set scanmask prior to registering buffer\n");
kfree(trialmask);
return -EINVAL;
goto err_invalid_mask;
}
bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
set_bit(bit, trialmask);
if (!iio_validate_scan_mask(indio_dev, trialmask))
goto err_invalid_mask;
if (indio_dev->available_scan_masks) {
mask = iio_scan_mask_match(indio_dev->available_scan_masks,
indio_dev->masklength,
trialmask);
if (!mask) {
kfree(trialmask);
return -EINVAL;
}
if (!mask)
goto err_invalid_mask;
}
bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
kfree(trialmask);
return 0;
};
err_invalid_mask:
kfree(trialmask);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(iio_scan_mask_set);
int iio_scan_mask_query(struct iio_dev *indio_dev,

4
include/linux/iio/iio.h
View File

@ -363,12 +363,16 @@ struct iio_info {
* @predisable: [DRIVER] function to run prior to marking buffer
* disabled
* @postdisable: [DRIVER] function to run after marking buffer disabled
* @validate_scan_mask: [DRIVER] function callback to check whether a given
* scan mask is valid for the device.
*/
struct iio_buffer_setup_ops {
int (*preenable)(struct iio_dev *);
int (*postenable)(struct iio_dev *);
int (*predisable)(struct iio_dev *);
int (*postdisable)(struct iio_dev *);
bool (*validate_scan_mask)(struct iio_dev *indio_dev,
const unsigned long *scan_mask);
};
/**