[PATCH v5 00/17] iio: core,buffer: add support for multiple IIO buffers per IIO device

[Alexandru Ardelean]

Some tweaks in v5, and this time I merged all the changelog histories into
this final one. 

Changelog v4 -> v5:
* https://lore.kernel.org/linux-iio/20210210100823.46780-1-alexandru.ardelean@xxxxxxxxxx/T/#t
* patch 'iio: buffer: add ioctl() to support opening extra buffers for IIO device'
  don't return -EBUSY in iio_buffer_poll_wrapper(); return 0
  __poll_t is unsigned, so returning 0 is the best we can do
  Reported-by: kernel test robot <lkp@xxxxxxxxx>
* patch 'iio: buffer: dmaengine: obtain buffer object from attribute'
  removed unused 'indio_dev' variable; seems i missed this initially
* patch 'iio: buffer: add ioctl() to support opening extra buffers for IIO device'
  call 'wake_up(buffer->pollq)' in iio_buffer_chrdev_release()

Changelog v3 -> v4:
* https://lore.kernel.org/linux-iio/20210201145105.20459-1-alexandru.ardelean@xxxxxxxxxx/
* patch 'docs: ioctl-number.rst: reserve IIO subsystem ioctl() space'
   remove 'uapi/' from `uapi/linux/iio/*.h`
* patch 'iio: core: register chardev only if needed'
   add commit comment about potentially breaking userspace ABI with chardev removal
* patch 'iio: core: rework iio device group creation'
   remove NULL re-init in iio_device_unregister_sysfs() ; memory is being free'd
* patch 'iio: buffer: group attr count and attr alloc'
  extend commit comment about the 2 or 1 buffer directores
* patch 'iio: core: merge buffer/ & scan_elements/ attributes'
   fixed static checker complaints
    - removed unused global
    - initialize omitted 'ret = -ENOMEM' on error path
    - made iio_buffer_unregister_legacy_sysfs_groups() static
* patch 'iio: buffer: wrap all buffer attributes into iio_dev_attr'
   - update some omitted unwindings; seems i forgot a few originally
     this was showing up when trying to read from buffer1
* add patch 'iio: buffer: move __iio_buffer_free_sysfs_and_mask() before alloc func'
* patch 'iio: buffer: introduce support for attaching more IIO buffers'
   - removed 'iio_dev_opaque->attached_buffers = NULL' after kfree()
   - using 'iio_dev_opaque->attached_buffers_cnt' to check that we have buffers
      instead of checking 'indio_dev->buffer'
* patch 'iio: buffer: add ioctl() to support opening extra buffers for IIO device'
   - replaced -ENOENT with -ENODEV when buffer index is out of range
* add 'iio: core: rename 'dev' -> 'indio_dev' in iio_device_alloc()'
* add 'iio: buffer: dmaengine: obtain buffer object from attribute'
* add tools/iio patches for new multibuffer logic
   tools: iio: make iioutils_get_type() private in iio_utils
   tools: iio: privatize globals and functions in iio_generic_buffer.c file
   tools: iio: convert iio_generic_buffer to use new IIO buffer API 

Changelog v2 -> v3:
* https://lore.kernel.org/linux-iio/20210122155805.83012-1-alexandru.ardelean@xxxxxxxxxx/
* added commit 'docs: ioctl-number.rst: reserve IIO subsystem ioctl() space'
  reserving 'i' 0x90-0x9F ioctls for IIO
  I did not see any conflicts with others (in the doc)
  - related to this, the new IIO_BUFFER_GET_FD_IOCTL is now at 'i' 0x91
* changed approach for creating sysfs buffer directories;
  - they are now created as groups on the IIO device; that also means
    that the groups array needs to be krealloc-ed and assign later in
    the registration
  - merged bufferX/ and scan_elementsX/ directories into a single
    bufferX/ directory
  - for legacy the buffer/ & scan_elements/ directories are kept; but
    they're groups objects have been moved on the iio_dev_opaque object
  - internally, the iio_dev_attr type is being extended to hold a
    reference for an IIO buffer;
    = this is great for scan_elements attributes
    = and for the rest of the iio_buffer attributes, it means we need to
      wrap them into iio_dev_attr

Changelog v1 -> v2:
* https://lore.kernel.org/linux-iio/20201117162340.43924-1-alexandru.ardelean@xxxxxxxxxx/
* 'iio: buffer: rework buffer & scan_elements dir creation'
  add more doc-strings detailing the reasoning for this change
* 'iio: buffer: re-route scan_elements via it's kobj_type'
  move list_del() before the kfree()'s in the list destruction
* 'iio: buffer: introduce support for attaching more IIO buffers'
  - changed to 'cnt' variable vs re-using the 'i' for unwinding in
    iio_buffer_alloc_sysfs_and_mask()
  - removed kfree(old) in iio_device_attach_buffer()
  - made iio_device_attach_buffer() an int return; this means that some
    follow up patches are needed to make this return value be used;
* 'iio: buffer: add ioctl() to support opening extra buffers for IIO device'
  - tested ioctl() with a simple C program; attached to comment;
  - changed 'i' variable usage to 'sz' for alloc
  - changed logic for buffer0; returning FD 0; userspace should know
    that the IIO_BUFFER_GET_FD_IOCTL call returns 0 for buffer0;
    this is because I can't find a way to determine the FD of the
    ioctl() in the kernel; duplicating an ioctl() for buffer0 is also bad;

Alexandru Ardelean (17):
  docs: ioctl-number.rst: reserve IIO subsystem ioctl() space
  iio: core: register chardev only if needed
  iio: core-trigger: make iio_device_register_trigger_consumer() an int
    return
  iio: core: rework iio device group creation
  iio: buffer: group attr count and attr alloc
  iio: core: merge buffer/ & scan_elements/ attributes
  iio: add reference to iio buffer on iio_dev_attr
  iio: buffer: wrap all buffer attributes into iio_dev_attr
  iio: buffer: dmaengine: obtain buffer object from attribute
  iio: core: wrap iio device & buffer into struct for character devices
  iio: buffer: move __iio_buffer_free_sysfs_and_mask() before alloc
  iio: buffer: introduce support for attaching more IIO buffers
  iio: buffer: add ioctl() to support opening extra buffers for IIO
    device
  iio: core: rename 'dev' -> 'indio_dev' in iio_device_alloc()
  tools: iio: make iioutils_get_type() private in iio_utils
  tools: iio: privatize globals and functions in iio_generic_buffer.c
    file
  tools: iio: convert iio_generic_buffer to use new IIO buffer API

 .../userspace-api/ioctl/ioctl-number.rst      |   1 +
 .../buffer/industrialio-buffer-dmaengine.c    |   4 +-
 drivers/iio/iio_core.h                        |  24 +-
 drivers/iio/iio_core_trigger.h                |   4 +-
 drivers/iio/industrialio-buffer.c             | 484 ++++++++++++++----
 drivers/iio/industrialio-core.c               | 108 +++-
 drivers/iio/industrialio-event.c              |   6 +-
 drivers/iio/industrialio-trigger.c            |   6 +-
 include/linux/iio/buffer.h                    |   4 +-
 include/linux/iio/buffer_impl.h               |  21 +-
 include/linux/iio/iio-opaque.h                |  14 +
 include/linux/iio/iio.h                       |   5 -
 include/linux/iio/sysfs.h                     |   3 +
 include/uapi/linux/iio/buffer.h               |  10 +
 tools/iio/Makefile                            |   1 +
 tools/iio/iio_generic_buffer.c                | 151 ++++--
 tools/iio/iio_utils.c                         |  18 +-
 tools/iio/iio_utils.h                         |   8 +-
 18 files changed, 668 insertions(+), 204 deletions(-)
 create mode 100644 include/uapi/linux/iio/buffer.h

-- 
2.17.1