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From: Vitor Soares <Vitor.Soares@synopsys.com>
To: linux-kernel@vger.kernel.org, linux-i3c@lists.infradead.org
Cc: Joao.Pinto@synopsys.com, arnd@arndb.de, wsa@the-dreams.de,
	gregkh@linuxfoundation.org, bbrezillon@kernel.org,
	Vitor Soares <Vitor.Soares@synopsys.com>,
	broonie@kernel.org
Subject: [RFC 0/5] Introduce i3c device userspace interface
Date: Tue, 10 Dec 2019 16:37:28 +0100
Message-ID: <cover.1575977795.git.vitor.soares@synopsys.com> (raw)

For today there is no way to use i3c devices from user space and
the introduction of such API will help developers during the i3c device
or i3c host controllers development.

The i3cdev module is highly based on i2c-dev and yet I tried to address
the concerns raised in [1].

NOTES:
- The i3cdev dynamically request an unused major number.

- The i3c devices are dynamically exposed/removed from dev/ folder based
  on if they have a device driver bound to it.

- For now, the module exposes i3c devices without device driver on
  dev/i3c-<bus>-<pid>, but we can change the path to
  dev/bus/i3c/<bus>-<pid> or dev/i3c/<bus>-<pid>.

- As in the i2c subsystem, here it is exposed the i3c_priv_xfer to
  userspace. I tried to use a dedicated structure as in spidev but I don't
  see any obvious advantage.

- Since the i3c API only exposes i3c_priv_xfer to devices, for now, the
  module just makes use of one ioctl(). This can change in the future with
  the introduction hdr commands or by the need of exposing some CCC
  commands to the device API (private contract between master-slave).
  Regarding the i3c device info, some information is already available
  through sysfs. We can add more device attributes to expose more
  information or add a dedicated ioctl() request for that purpose or both.

- Similar to i2c, I have also created a tool that you can find in [2]
  for testing purposes. If you have some time available I would appreciate
  your feedback about it as well.

[1] https://lkml.org/lkml/2018/11/15/853
[2] https://github.com/vitor-soares-snps/i3c-tools.git

Vitor Soares (5):
  i3c: master: export i3c_masterdev_type
  i3c: master: export i3c_bus_type symbol
  i3c: device: expose transfer strutures to uapi
  i3c: master: add i3c_for_each_dev helper
  i3c: add i3cdev module to expose i3c dev in /dev

 drivers/i3c/Kconfig             |  15 ++
 drivers/i3c/Makefile            |   1 +
 drivers/i3c/i3cdev.c            | 438 ++++++++++++++++++++++++++++++++++++++++
 drivers/i3c/internals.h         |   2 +
 drivers/i3c/master.c            |  16 +-
 include/linux/i3c/device.h      |  54 +----
 include/uapi/linux/i3c/device.h |  66 ++++++
 include/uapi/linux/i3c/i3cdev.h |  27 +++
 8 files changed, 565 insertions(+), 54 deletions(-)
 create mode 100644 drivers/i3c/i3cdev.c
 create mode 100644 include/uapi/linux/i3c/device.h
 create mode 100644 include/uapi/linux/i3c/i3cdev.h

-- 
2.7.4


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Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-10 15:37 Vitor Soares [this message]
2019-12-10 15:37 ` [RFC 1/5] i3c: master: export i3c_masterdev_type Vitor Soares
2019-12-10 15:37 ` [RFC 2/5] i3c: master: export i3c_bus_type symbol Vitor Soares
2019-12-10 15:37 ` [RFC 3/5] i3c: device: expose transfer strutures to uapi Vitor Soares
2019-12-12 14:42   ` Greg KH
2019-12-12 14:48     ` Vitor Soares
2019-12-10 15:37 ` [RFC 4/5] i3c: master: add i3c_for_each_dev helper Vitor Soares
2019-12-10 15:37 ` [RFC 5/5] i3c: add i3cdev module to expose i3c dev in /dev Vitor Soares
2019-12-10 17:51   ` Arnd Bergmann
2019-12-10 19:15     ` Vitor Soares
2019-12-10 19:37       ` Arnd Bergmann
2019-12-11 15:07         ` Vitor Soares
2019-12-11 15:33           ` Arnd Bergmann
2019-12-20 12:39     ` Vitor Soares
2019-12-12 14:44   ` Greg KH
2019-12-12 14:56     ` Vitor Soares
2019-12-12 16:00       ` Greg KH
2019-12-12 17:25         ` Vitor Soares
2019-12-12 17:32           ` Greg KH
2019-12-12 14:46   ` Greg KH

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