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Message-ID: <9C64B7751C3BCA41B64A68E23005A7BE1C6A21@039-SN1MPN1-002.039d.mgd.msft.net>
Date: Wed, 10 Aug 2011 14:36:20 +0000
From: U Bhaskar-B22300 <B22300@...escale.com>
To: Robin Holt <holt@....com>, Wolfgang Grandegger <wg@...ndegger.com>
CC: Marc Kleine-Budde <mkl@...gutronix.de>,
Wood Scott-B07421 <B07421@...escale.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Kumar Gala <galak@...nel.crashing.org>,
"socketcan-core@...ts.berlios.de" <socketcan-core@...ts.berlios.de>,
PPC list <linuxppc-dev@...ts.ozlabs.org>
Subject: RE: [PATCH v10 5/5] [powerpc] Fix up fsl-flexcan device tree
binding.
> -----Original Message-----
> From: Robin Holt [mailto:holt@....com]
> Sent: Wednesday, August 10, 2011 7:46 PM
> To: Wolfgang Grandegger
> Cc: Robin Holt; Marc Kleine-Budde; U Bhaskar-B22300; Wood Scott-B07421;
> netdev@...r.kernel.org; Kumar Gala; socketcan-core@...ts.berlios.de; PPC
> list
> Subject: Re: [PATCH v10 5/5] [powerpc] Fix up fsl-flexcan device tree
> binding.
>
> On Wed, Aug 10, 2011 at 03:47:43PM +0200, Wolfgang Grandegger wrote:
> > Hi Robin,
> >
> > On 08/10/2011 05:06 AM, Robin Holt wrote:
> > > In working with the socketcan developers, we have come to the
> > > conclusion the Documentation...fsl-flexcan.txt device tree
> > > documentation needs to be cleaned up. The driver does not depend
> > > upon any properties other
> >
> > Your first sentence could be misleading. Please just describe what the
> > patch does and why, something like:
> >
> > "This patch cleans up the documentation of the device-tree binding for
> > the Flexcan devices on Freescale's PowerPC and ARM cores. Extra
> > properties are not needed as the frequency of the source clock is
> > fixed..." and so on.
>
> I borrowed heavily from your message. ;)
>
> > > than the required properties so we are removing the file.
> > > Additionally, the p1010*dts* files are not following the standard
> > > for node naming in that they have a trailing -v1.0.
> >
> > > Signed-off-by: Robin Holt <holt@....com>
> > > To: Marc Kleine-Budde <mkl@...gutronix.de>,
> > > To: Wolfgang Grandegger <wg@...ndegger.com>,
> > > To: U Bhaskar-B22300 <B22300@...escale.com>
> > > To: Scott Wood <scottwood@...escale.com>
> > > Cc: socketcan-core@...ts.berlios.de,
> > > Cc: netdev@...r.kernel.org,
> > > Cc: PPC list <linuxppc-dev@...ts.ozlabs.org>
> > > Cc: Kumar Gala <galak@...nel.crashing.org>
> > > ---
> > > .../devicetree/bindings/net/can/fsl-flexcan.txt | 61 ----------
> ----------
> > > arch/powerpc/boot/dts/p1010rdb.dts | 8 ---
> > > arch/powerpc/boot/dts/p1010si.dtsi | 8 +-
> > > 3 files changed, 4 insertions(+), 73 deletions(-) delete mode
> > > 100644 Documentation/devicetree/bindings/net/can/fsl-flexcan.txt
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt
> > > b/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt
> > > deleted file mode 100644
> > > index 1a729f0..0000000
> > > --- a/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt
> > > +++ /dev/null
> > > @@ -1,61 +0,0 @@
> > > -CAN Device Tree Bindings
> > > -------------------------
> > > -2011 Freescale Semiconductor, Inc.
> > > -
> > > -fsl,flexcan-v1.0 nodes
> > > ------------------------
> > > -In addition to the required compatible-, reg- and
> > > interrupt-properties, you can -also specify which clock source shall
> be used for the controller.
> > > -
> > > -CPI Clock- Can Protocol Interface Clock
> > > - This CLK_SRC bit of CTRL(control register) selects the clock source
> to
> > > - the CAN Protocol Interface(CPI) to be either the peripheral clock
> > > - (driven by the PLL) or the crystal oscillator clock. The selected
> clock
> > > - is the one fed to the prescaler to generate the Serial Clock
> (Sclock).
> > > - The PRESDIV field of CTRL(control register) controls a prescaler
> that
> > > - generates the Serial Clock (Sclock), whose period defines the
> > > - time quantum used to compose the CAN waveform.
> > > -
> > > -Can Engine Clock Source
> > > - There are two sources for CAN clock
> > > - - Platform Clock It represents the bus clock
> > > - - Oscillator Clock
> > > -
> > > - Peripheral Clock (PLL)
> > > - --------------
> > > - |
> > > - --------- -------------
> > > - | |CPI Clock | Prescaler | Sclock
> > > - | |---------------->| (1.. 256) |------------>
> > > - --------- -------------
> > > - | |
> > > - -------------- ---------------------CLK_SRC
> > > - Oscillator Clock
> > > -
> > > -- fsl,flexcan-clock-source : CAN Engine Clock Source.This property
> selects
> > > - the peripheral clock. PLL clock is fed to the
> > > - prescaler to generate the Serial Clock (Sclock).
> > > - Valid values are "oscillator" and "platform"
> > > - "oscillator": CAN engine clock source is
> oscillator clock.
> > > - "platform" The CAN engine clock source is the bus
> clock
> > > - (platform clock).
> > > -
> > > -- fsl,flexcan-clock-divider : for the reference and system clock, an
> additional
> > > - clock divider can be specified.
> > > -- clock-frequency: frequency required to calculate the bitrate for
> FlexCAN.
> > > -
> > > -Note:
> > > - - v1.0 of flexcan-v1.0 represent the IP block version for P1010
> SOC.
> > > - - P1010 does not have oscillator as the Clock Source.So the default
> > > - Clock Source is platform clock.
> > > -Examples:
> > > -
> > > - can0@...00 {
> > > - compatible = "fsl,flexcan-v1.0";
> > > - reg = <0x1c000 0x1000>;
> > > - interrupts = <48 0x2>;
> > > - interrupt-parent = <&mpic>;
> > > - fsl,flexcan-clock-source = "platform";
> > > - fsl,flexcan-clock-divqider = <2>;
> > > - clock-frequency = <fixed by u-boot>;
> > > - };
> >
> > Do we really want to drop the documentation for that binding. I think
> > something like the following text would be still useful:
> >
> > ------------------------
> > Flexcan CAN contoller on Freescale's ARM and PowerPC processors
> >
> > Required properties:
> >
> > - compatible : Should be "fsl,flexcan" and optionally
> > "fsl,flexcan-<processor>"
> > - reg : Offset and length of the register set for this device
> > - interrupts : Interrupt tuple for this device
> >
> > Example:
> >
> > can@...00 {
> > compatible = "fsl,p1010-flexcan", "fsl,flexcan";
> > reg = <0x1c000 0x1000>;
> > interrupts = <48 0x2>;
> > interrupt-parent = <&mpic>;
> > };
> > -------------------------
>
> Done, except the
> > compatible = "fsl,p1010-flexcan", "fsl,flexcan";
>
> line is
> compatible = "fsl,flexcan", "fsl,flexcan-p1010";
>
> >
> > What do you think?
> >
> > > diff --git a/arch/powerpc/boot/dts/p1010rdb.dts
> > > b/arch/powerpc/boot/dts/p1010rdb.dts
> > > index 6b33b73..d6a0bb2 100644
> > > --- a/arch/powerpc/boot/dts/p1010rdb.dts
> > > +++ b/arch/powerpc/boot/dts/p1010rdb.dts
> > > @@ -169,14 +169,6 @@
> > > };
> > > };
> > >
> > > - can0@...00 {
> > > - fsl,flexcan-clock-source = "platform";
> > > - };
> > > -
> > > - can1@...00 {
> > > - fsl,flexcan-clock-source = "platform";
> > > - };
> > > -
> > > usb@...00 {
> > > phy_type = "utmi";
> > > };
> > > diff --git a/arch/powerpc/boot/dts/p1010si.dtsi
> > > b/arch/powerpc/boot/dts/p1010si.dtsi
> > > index 7f51104..20c396d 100644
> > > --- a/arch/powerpc/boot/dts/p1010si.dtsi
> > > +++ b/arch/powerpc/boot/dts/p1010si.dtsi
> > > @@ -141,19 +141,19 @@
> > > };
> > >
> > > can0@...00 {
> > > - compatible = "fsl,flexcan-v1.0";
> > > + compatible = "fsl,p1010-flexcan",
> > > + "fsl,flexcan";
> >
> > Does fit on one line.
> >
> > > reg = <0x1c000 0x1000>;
> > > interrupts = <48 0x2>;
> > > interrupt-parent = <&mpic>;
> > > - fsl,flexcan-clock-divider = <2>;
> > > };
> > >
> > > can1@...00 {
> > > - compatible = "fsl,flexcan-v1.0";
> > > + compatible = "fsl,p1010-flexcan",
> > > + "fsl,flexcan";
> >
> > Ditto
> >
> > > reg = <0x1d000 0x1000>;
> > > interrupts = <61 0x2>;
> > > interrupt-parent = <&mpic>;
> > > - fsl,flexcan-clock-divider = <2>;
> > > };
> > >
> > > L2: l2-cache-controller@...00 {
> >
> > Please also correct the node names (not using the number suffix).
>
> So the node names should be
> can@...00 {
> can@...00 {
> correct?
>
[Bhaskar] As there are two CAN controllers on P1010,So won't it be better
to distinguish it by can0 and can1 instead by simple "can" ?
> Robin
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