linux-kernel - [PATCH v9 0/7] I3C mastership handover support

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Date:   Sat, 28 Nov 2020 15:44:34 +0100
From:   Parshuram Thombare <pthombar@...ence.com>
To:     <alexandre.belloni@...tlin.com>, <slongerbeam@...il.com>,
        <vitor.soares@...opsys.com>
CC:     <linux-i3c@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <mparab@...ence.com>, <praneeth@...com>,
        Parshuram Thombare <pthombar@...ence.com>
Subject: [PATCH v9 0/7] I3C mastership handover support

Main changes between v8 and v9 are:
- Fix NULL dereference issue in current_master_show when
  cat'ing sysfs key current_master for secondary master
  before primary master gets initialized.

Main changes between v7 and v8 are:
- Document format changed from table to DOT diagram
- Appropriate names for few functions
- Moved mastership request process entirely to the driver
- Reuse of i3c_master_add_i3c_dev_locked in core defslvs
  processing

Main changes between v6 and v7 are:
- Added separate functions for main and secondary
  master initialization
- Secondary master initialization don't wait for
  DEFSLSVS.
- Change to use I2C device information from DTS,
  and corresponding changes in controller driver
  and I3C core DEFSLVS processing to ignore I2C
  devices received in DEFSLVS
- Reverted bus_init split
- Fixed formatting issues in document

Main changes between v5 and v6 are:
- Moved populate_bus() hook to master subsystem code.
- For secondary master initialization i3c_master_register
  spawan separate threads, as secondary master may have to
  wait for DEFSLVS and bus mastership.
- Populate bus info is based on DEFSLVS data and take care
  of hot plugged / unplugged I3C devices.
- Split bus_init into bus_init and master_set_info callbacks
- Moved mastership aquire and handover to separate state 
  machines.
- Added DEFSLVS processing code.
- Moved back all locks in side the subsystem code.
- Secondary mastership support to Cadence I3C master
  controller driver
- Sysfs key 'i3c_acquire_bus' to acauire bus.
- NULL check for pool pointer in i3c_generic_ibi_free_pool.

Main changes between v4 and v5 are:
- Add populate_bus() hook
- Split i3c_master_register into init and register pair
- Split device information retrieval, let add partialy discovered devices
- Make i3c_master_set_info private
- Add separate function to register secondary master
- Reworked secondary master register in CDNS driver
- Export i3c_bus_set_mode

Main changes between v3 and v4 are:
- Reworked acquire bus ownership
- Refactored the code

Main changes between v2 and v3 are:
- Added DEFSLVS devices are registered from master driver
- Reworked I2C registering on secondary master side
- Reworked Mastership event is enabled/disabled globally (for all devices)

Main changes between initial version and v2 are:
- Reworked devices registration on secondary master side
- Reworked mastership event disabling/enabling
- Reworked bus locking during mastership takeover process
- Added DEFSLVS devices registration during initialization
- Fixed style issues

Parshuram Thombare (7):
  i3c: master: master initialization flow document
  i3c: master: use i3c_master_register only for main master
  i3c: master: add i3c_secondary_master_register
  i3c: master: add mastership handover support
  i3c: master: add defslvs processing
  i3c: master: sysfs key for acquire bus
  i3c: master: mastership handover, defslvs processing in cdns
    controller driver

 Documentation/driver-api/i3c/index.rst             |    1 +
 .../driver-api/i3c/master-initialization-flow.rst  |  187 ++++++++
 drivers/i3c/master.c                               |  497 ++++++++++++++++++--
 drivers/i3c/master/dw-i3c-master.c                 |    4 +-
 drivers/i3c/master/i3c-master-cdns.c               |  329 ++++++++++++-
 include/linux/i3c/master.h                         |   23 +-
 6 files changed, 968 insertions(+), 73 deletions(-)
 create mode 100644 Documentation/driver-api/i3c/master-initialization-flow.rst