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Re: [RFC PATCH 0/3] UART slave device bus

From One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Newsgroups linux.kernel
Subject Re: [RFC PATCH 0/3] UART slave device bus
Date 2016-08-22 19:20 +0200
Message-ID <s913b-JI-3@gated-at.bofh.it> (permalink)
References <s7k9X-TX-3@gated-at.bofh.it> <s8WGd-6h8-15@gated-at.bofh.it> <s8XLY-6Xy-19@gated-at.bofh.it> <s8ZkJ-81a-13@gated-at.bofh.it>
Organization Intel Corporation

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> Would it make sense then to define a DT binding that can cover these
> four cases independent of the Linux usage:
> 
> a) an existing tty line discipline matched to a tty port
> b) a serio device using the N_MOUSE line discipline (which
>    happens to cover non-mouse devices these days)

These two are the same basic thing

	port x expects ldisc y {with properties ...}

> c) a uart_port slave attached directly to the uart (like in your
>    current code)

c) needs to be a tty_port slave attached directly to a tty_port.
Important detail, but as uart_port is just a subset of tty_port it's a
trivial detail to the DT.

> d) the same slave drivers using a new tty line discipline

and this is also just a/b again.


What use cases and connectivity do you need to describe. Looking at the
ACPI platforms we have

- the expected serial port configuration
- the properties of the port (FIFO etc)
- the power management for the port

- the children of the port
- the power management of the children (at a very simplistic abstracted
  level)

So we want to be able to describe something like

  ttyS0 {
	baud: 1152008N1
	protocol: bluetooth hci
	fixed: yes
	powermanagement: { ... }
  }

and if I look at the usermode crapfest on a lot of Android systems it
looks similar but with the notion of things like being able to describe

-	Use GPIO mode sleeping and assume first char is X to save power

-	Power up, wait n ms, write, read, wait n ms, power down (which
	has to be driven at the ldisc/user level as only the ldisc
	understands transactions, or via ioctls (right now Android user
	space tends to do hardcoded writes to /sys.. gpio to drive power

-	And a few variants thereof (power up on write, off on a timer
  	etc)

So I can imagine wanting to describe something like

-	The bluetooth HCI hardware is managed by gpio 11 (or UART DTR,
	or PMIC n etc)
	The uart can switch into GPIO mode and is gpio 15

or

-	Raise gpio 4 when writing, drop it after 50mS with no read/write

Then the ldisc needs to make port->ops. calls for enabling/disabling low
power mode and expected char, and the uarts that can do it need to
implement the gpio/uart switching and any timers.

Alan

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Thread

[RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-18 03:20 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 12:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 12:40 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 13:00 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-18 16:00 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-18 15:20 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-19 03:50 +0200
        Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-19 13:10 +0200
  Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 12:40 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 12:50 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 13:00 +0200
        Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:20 +0200
        Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-18 16:50 +0200
      Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:00 +0200
      Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 13:00 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:10 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 13:30 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 13:50 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 14:00 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 13:20 +0200
        Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:20 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:50 +0200
            Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 14:20 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:50 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 15:10 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:00 +0200
      Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:10 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:50 +0200
          Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 14:10 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 13:10 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Linus Walleij <linus.walleij@linaro.org> - 2016-08-18 15:20 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-19 03:50 +0200
  Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-18 16:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 03:10 +0200
    Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 03:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-19 04:50 +0200
      Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-19 13:40 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-19 17:40 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-19 03:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-19 03:40 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-19 07:30 +0200
        Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 09:40 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Oleksij Rempel <linux@rempel-privat.de> - 2016-08-19 10:00 +0200
            Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 20:00 +0200
              Re: [RFC PATCH 0/3] UART slave device bus Oleksij Rempel <linux@rempel-privat.de> - 2016-08-19 22:30 +0200
              Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-20 15:40 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-21 10:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-22 22:50 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-22 23:30 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Arnd Bergmann <arnd@arndb.de> - 2016-08-22 23:50 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 00:50 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 01:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 01:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-23 09:30 +0200
          Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-19 13:10 +0200
            Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 19:50 +0200
              Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-20 15:30 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-21 10:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-21 19:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-21 20:30 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 11:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-22 11:40 +0200
        Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-19 13:10 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-19 16:50 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Arnd Bergmann <arnd@arndb.de> - 2016-08-22 14:40 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-22 15:50 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Arnd Bergmann <arnd@arndb.de> - 2016-08-22 17:30 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-22 17:30 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Arnd Bergmann <arnd@arndb.de> - 2016-08-22 18:00 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-22 18:50 +0200
          Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 19:10 +0200
            Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 19:40 +0200
              Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-22 23:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 23:40 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-23 00:10 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 01:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 02:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 02:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 03:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-24 16:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-24 16:40 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-23 13:50 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 01:10 +0200
            Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-22 19:40 +0200
              Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-22 22:10 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-23 00:10 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 00:20 +0200
        Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 19:20 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-22 23:10 +0200
            Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 00:10 +0200
              Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 01:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 01:50 +0200
            Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 00:20 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Linus Walleij <linus.walleij@linaro.org> - 2016-08-24 14:30 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-23 23:20 +0200

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