Subject: Re: [PATCH][upstream] powerpc: Adding bindings for flexcan controller

From: Wolfgang Grandegger <[email-masked]>
Date: Sun, 26 Jun 2011 21:10:47 +0200

On 04/19/2011 03:58 PM, Bhaskar Upadhaya wrote:
> From: Bhaskar Upadhaya <[email-masked]>
> 
> Signed-off-by: Bhaskar Upadhaya <[email-masked]>
> Acked-By: Scott Wood <[email-masked]>
> ---
> Based upon git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git (branch -> master)
> 
>  .../devicetree/bindings/net/can/fsl-flexcan.txt    |   61 ++++++++++++++++++++
>  1 files changed, 61 insertions(+), 0 deletions(-)
>  create mode 100755 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
> new file mode 100755
> index 0000000..1a729f0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt
> @@ -0,0 +1,61 @@
> +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@1c000 {
> +		compatible = "fsl,flexcan-v1.0";
> +		reg = <0x1c000 0x1000>;
> +		interrupts = <48 0x2>;
> +		interrupt-parent = <&mpic>;
> +		fsl,flexcan-clock-source = "platform";
> +		fsl,flexcan-clock-divider = <2>;
> +		clock-frequency = <fixed by u-boot>;
> +	};

I just realized that this patch has hit the mainline kernel but I do not
find the implementation for that new binding. Have I missed something?

Wolfgang.