[PATCH v2 0/3] Enhance RPMsg buffer management

[Tanmay Shah <tanmay.shah@amd.com>]

Take rx and tx buffer size from the virtio device config space in the
resource table. This allows each firmware to configure RPMsg buffer size
as needed in each direction.

Test performed:
  - Test [1/2] patch with existing firmware as it is, rpmsg working.
  - Verify [2/2] patch works with the existing firmware
  - Verify [2/2] patch works with the firmware that configures
    different tx & rx buf size via vdev config space.

Corresponding OpenAMP project PR:
  - open-amp library: https://github.com/OpenAMP/open-amp/pull/684
  - openamp-system-reference demo: 
    https://github.com/OpenAMP/openamp-system-reference/pull/106

Changes in v2:
  - Change author
  - fix commit message with better explanation
  - %s/sbuf/tx_buf
  - %s/rbuf/rx_buf
  - %s/num_rbuf/num_rx_buf/
  - %s/num_sbuf/num_tx_buf/
  - %s/sbuf_size/tx_buf_size/
  - %s/rbuf_size/rx_buf_size/
  - fix typo
  - do not use ALIGN on buf size, rely on allocator
  - make err msg more explicit, %s/vdev config:/bad vdev config/
  - fix license and add AMD copyrights in the header virtio_rpmsg.h
  - Assign bit 1 to VIRTIO_RPMSG_F_BUFSZ feature
  - use __virtio32 over __u32
  - add version field to virtio rpmsg config structure
  - Introduce new patch to print rpmsg mtu size in the sample rpmsg driver
  - move linux/virtio_rpmsg.h to linux/rpmsg/virtio_rpmsg.h

Original seris:
https://lore.kernel.org/all/1548949280-31794-1-git-send-email-xiaoxiang@xiaomi.com/

Following modificaitons are done to the original series in v1:
  - Separate dma allocation is not done for tx and rx buffers. Instead
    allocated chunk of memory is split between tx and rx buffers.
  - If vdev doesn't support VIRTIO_RPMSG_F_BUFSZ feature then use the 
    default size of 512 bytes for buffers
  - Change MAX_RPMSG_BUF_SIZE to DEFAULT_RPMSG_BUF_SIZE
  - move virtio_rpmsg.h from uapi to linux dir
  - RPMsg buffer size must be set to hold rpmsg header at minimum in the
    vdev config space of the firmware.
  - align total buf size to page size when allocating and deallocating
    memory

Tanmay Shah (3):
  rpmsg: virtio_rpmsg_bus: allow different size of tx and rx bufs
  rpmsg: virtio_rpmsg_bus: get buffer size from config space
  samples: rpmsg: add mtu size info

 drivers/rpmsg/virtio_rpmsg_bus.c    | 124 ++++++++++++++++++----------
 include/linux/rpmsg/virtio_rpmsg.h  |  27 ++++++
 samples/rpmsg/rpmsg_client_sample.c |   3 +
 3 files changed, 109 insertions(+), 45 deletions(-)
 create mode 100644 include/linux/rpmsg/virtio_rpmsg.h


base-commit: fcdf2df56d34a3f04cab0725c5bc3abdaa73c2be
-- 
2.34.1