[RFC PATCH 0/3] Introduce IIO interface for fingerprint sensors

[Teodora Baluta <teodora.baluta@intel.com>]

This patchset adds support for fingerprint sensors through the IIO interface.
This way userspace applications collect information in a uniform way. All
processing would be done in the upper layers as suggested in [0].

In order to test out this proposal, a minimal implementation for UPEK's
TouchChip Fingerprint Sensor via USB is also available. Although there is an
existing implementation in userspace for USB fingerprint devices, including this
particular device, the driver represents a proof of concept of how fingerprint
sensors could be integrated in the IIO framework regardless of the used bus. For
lower power requirements, the SPI bus is preferred and a kernel driver
implementation makes more sense.

A sysfs trigger is enabled and the device starts scanning. As soon as an image
is available it is written in the character device /dev/iio:deviceX.

Userspace applications will be able to calculate the expected image size using
the fingerprint attributes height, width and bit depth. Other attributes
introduced for the fingerprint channel in IIO represent information that aids in
the fingerprint image processing. Besides these, the proposed interface offers
userspace a way to read a feedback after a scan (like the swipe was too slow or
too fast) through a modified fingerprint_status channel.

[0] http://www.spinics.net/lists/linux-iio/msg11463.html

Teodora Baluta (3):
  iio: core: add support for fingerprint devices
  iio: core: change channel's storagebits/realbits to u32
  iio: fingerprint: add fingerprint sensor via USB

 Documentation/ABI/testing/sysfs-bus-iio |  51 +++
 drivers/iio/Kconfig                     |   1 +
 drivers/iio/Makefile                    |   1 +
 drivers/iio/fingerprint/Kconfig         |  15 +
 drivers/iio/fingerprint/Makefile        |   5 +
 drivers/iio/fingerprint/fp_tc.c         | 162 +++++++++
 drivers/iio/fingerprint/fp_tc.h         |  22 ++
 drivers/iio/fingerprint/fp_tc_usb.c     | 618 ++++++++++++++++++++++++++++++++
 drivers/iio/fingerprint/fp_tc_usb.h     | 144 ++++++++
 drivers/iio/industrialio-core.c         |   9 +
 include/linux/iio/iio.h                 |  11 +-
 include/linux/iio/types.h               |  10 +
 12 files changed, 1047 insertions(+), 2 deletions(-)
 create mode 100644 drivers/iio/fingerprint/Kconfig
 create mode 100644 drivers/iio/fingerprint/Makefile
 create mode 100644 drivers/iio/fingerprint/fp_tc.c
 create mode 100644 drivers/iio/fingerprint/fp_tc.h
 create mode 100644 drivers/iio/fingerprint/fp_tc_usb.c
 create mode 100644 drivers/iio/fingerprint/fp_tc_usb.h

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1.9.1