From: Rob Herring <robh@kernel.org>
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Wolfram Sang <wsa@the-dreams.de>,
linux-i2c@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
linux-doc@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Arnd Bergmann <arnd@arndb.de>,
Przemyslaw Sroka <psroka@cadence.com>,
Arkadiusz Golec <agolec@cadence.com>,
Alan Douglas <adouglas@cadence.com>,
Bartosz Folta <bfolta@cadence.com>, Damian Kos <dkos@cadence.com>,
Alicja Jurasik-Urbaniak <alicja@cadence.com>,
Jan Kotas <jank@cadence.com>,
Cyprian Wronka <cwronka@cadence.com>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
Nishanth Menon <nm@ti.com>, Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Kumar
Subject: Re: [RFC 3/5] dt-bindings: i3c: Document core bindings
Date: Wed, 9 Aug 2017 18:43:02 -0500 [thread overview]
Message-ID: <20170809234302.ffcr3gwpiy4roj7l@rob-hp-laptop> (raw)
In-Reply-To: <1501518290-5723-4-git-send-email-boris.brezillon@free-electrons.com>
On Mon, Jul 31, 2017 at 06:24:48PM +0200, Boris Brezillon wrote:
> A new I3C subsystem has been added and a generic description has been
> created to represent the I3C bus and the devices connected on it.
>
> Document this generic representation.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> ---
> Documentation/devicetree/bindings/i3c/i3c.txt | 90 +++++++++++++++++++++++++++
> 1 file changed, 90 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/i3c/i3c.txt
>
> diff --git a/Documentation/devicetree/bindings/i3c/i3c.txt b/Documentation/devicetree/bindings/i3c/i3c.txt
> new file mode 100644
> index 000000000000..49261dec7b01
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i3c/i3c.txt
> @@ -0,0 +1,90 @@
> +Generic device tree bindings for I3C busses
> +===========================================
> +
> +This document describes generic bindings that should be used to describe I3C
> +busses in a device tree.
> +
> +Required properties
> +-------------------
> +
> +- #address-cells - should be <1>. Read more about addresses below.
> +- #size-cells - should be <0>.
> +- compatible - name of I3C bus controller following generic names
> + recommended practice.
> +
> +For other required properties e.g. to describe register sets,
> +clocks, etc. check the binding documentation of the specific driver.
> +
> +Optional properties
> +-------------------
> +
> +These properties may not be supported by all I3C master drivers. Each I3C
> +master bindings should specify which of them are supported.
> +
> +- i3c-scl-frequency: frequency (in Hz) of the SCL signal used for I3C
> + transfers. When undefined the core set it to 12.5MHz.
> +
> +- i2c-scl-frequency: frequency (in Hz) of the SCL signal used for I2C
> + transfers. When undefined, the core looks at LVR values
> + of I2C devices described in the device tree to determine
> + the maximum I2C frequency.
> +
> +I2C devices
> +===========
> +
> +Each I2C device connected to the bus should be described in a subnode with
> +the following properties:
> +
> +All properties described in Documentation/devicetree/bindings/i2c/i2c.txt are
> +valid here.
> +
> +New required properties:
> +------------------------
> +- i3c-lvr: 32 bits integer property (only the lowest 8 bits are meaningful)
What does lvr mean?
> + describing device capabilities as described in the I3C
> + specification.
> +
> + bit[31:8]: unused
> + bit[7:5]: I2C device index. Possible values
index? Seems more like flags
> + * 0: I2C device has a 50 ns spike filter
> + * 1: I2C device does not have a 50 ns spike filter but supports high
> + frequency on SCL
> + * 2: I2C device does not have a 50 ns spike filter and is not
> + tolerant to high frequencies
> + * 3-7: reserved
> +
> + bit[4]: tell whether the device operates in FM or FM+ mode
> + * 0: FM+ mode
> + * 1: FM mode
> +
> + bit[3:0]: device type
> + * 0-15: reserved
That's useful...
> +
> +I3C devices
> +===========
> +
> +I3C are not described in the device tree yet. We could decide to represent them
> +at some point to assign a specific dynamic address to a device or to force an
> +I3C device to act as an I2C device if it has a static address.
I think we need to define this sooner rather than later if there's not a
standard connector. That's the only thing that would enforce any sort of
standard. Of course, that didn't help with SDIO.
> +
> +Example:
> +
> + i3c-master@0d040000 {
The node name should go into the DT spec. I tend to think "i3c" would be
sufficient and aligned with i2c.
> + compatible = "cdns,i3c-master";
> + clocks = <&coreclock>, <&i3csysclock>;
> + clock-names = "pclk", "sysclk";
> + interrupts = <3 0>;
> + reg = <0x0d040000 0x1000>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + status = "okay";
> + i2c-scl-frequency = <100000>;
> +
> + nunchuk: nunchuk@52 {
> + compatible = "nintendo,nunchuk";
> + reg = <0x52>;
> + i3c-lvr = <0x10>;
> + };
> + };
> +
> --
> 2.7.4
>
next prev parent reply other threads:[~2017-08-09 23:43 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-31 16:24 [RFC 0/5] Add I3C subsystem Boris Brezillon
2017-07-31 16:24 ` [RFC 1/5] i2c: Export of_i2c_get_board_info() Boris Brezillon
2017-07-31 16:24 ` [RFC 2/5] i3c: Add core I3C infrastructure Boris Brezillon
2017-07-31 19:17 ` Wolfram Sang
2017-07-31 20:46 ` Boris Brezillon
2017-07-31 20:16 ` Arnd Bergmann
[not found] ` <CAK8P3a06GoMdKdn=3Cq0FUwYnjGX0oG+FQLjxfiasVDpbonWRw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-07-31 21:15 ` Boris Brezillon
2017-07-31 21:32 ` Peter Rosin
2017-07-31 21:42 ` Wolfram Sang
2017-08-01 16:47 ` Andrew F. Davis
2017-08-01 17:27 ` Wolfram Sang
2017-08-01 21:47 ` Boris Brezillon
2017-08-02 10:21 ` Wolfram Sang
2017-08-01 12:00 ` Arnd Bergmann
2017-08-01 12:29 ` Boris Brezillon
2017-08-01 13:11 ` Arnd Bergmann
2017-08-01 13:34 ` Boris Brezillon
2017-08-01 13:58 ` Boris Brezillon
2017-08-01 14:22 ` Arnd Bergmann
2017-08-01 15:14 ` Boris Brezillon
2017-08-01 20:16 ` Arnd Bergmann
2017-08-01 14:12 ` Wolfram Sang
2017-08-01 14:48 ` Boris Brezillon
2017-08-01 15:01 ` Wolfram Sang
2017-08-01 15:20 ` Boris Brezillon
2017-08-03 8:03 ` Boris Brezillon
2017-08-16 21:03 ` Geert Uytterhoeven
2017-08-17 7:48 ` Boris Brezillon
2017-08-01 1:40 ` Greg Kroah-Hartman
[not found] ` <20170801014021.GA20004-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-08-01 10:48 ` Boris Brezillon
2017-08-01 17:51 ` Greg Kroah-Hartman
2017-08-01 21:30 ` Boris Brezillon
2017-08-02 0:54 ` Greg Kroah-Hartman
2017-08-02 2:13 ` Greg Kroah-Hartman
[not found] ` <20170802021327.GB23033-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-12-13 16:20 ` Boris Brezillon
2017-12-13 16:51 ` Greg Kroah-Hartman
2017-08-17 9:03 ` Linus Walleij
2017-08-17 9:28 ` Boris Brezillon
[not found] ` <1501518290-5723-1-git-send-email-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-07-31 16:24 ` [RFC 3/5] dt-bindings: i3c: Document core bindings Boris Brezillon
2017-08-09 23:43 ` Rob Herring [this message]
2017-08-10 8:49 ` Boris Brezillon
2017-07-31 16:24 ` [RFC 4/5] i3c: master: Add driver for Cadence IP Boris Brezillon
2017-07-31 16:24 ` [RFC 5/5] dt-bindings: i3c: Document Cadence I3C master bindings Boris Brezillon
2017-07-31 19:17 ` [RFC 0/5] Add I3C subsystem Wolfram Sang
2017-07-31 20:40 ` Boris Brezillon
2017-07-31 20:47 ` Wolfram Sang
2017-12-12 19:58 ` Boris Brezillon
2017-12-12 22:01 ` Wolfram Sang
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