linux-kernel - Re: [RFC] dt: bindings: add bindings for Broadcom bcm43xx sdio devices

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Message-ID: <52FC8CB3.4090305@gmail.com>
Date:	Thu, 13 Feb 2014 10:13:23 +0100
From:	Tomasz Figa <tomasz.figa@...il.com>
To:	Arend van Spriel <arend@...adcom.com>,
	Rob Herring <robh+dt@...nel.org>
CC:	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Chen-Yu Tsai <wens@...e.org>
Subject: Re: [RFC] dt: bindings: add bindings for Broadcom bcm43xx sdio devices

Hi Arend,

On 10.02.2014 20:17, Arend van Spriel wrote:
> The Broadcom bcm43xx sdio devices are fullmac devices that may be
> integrated in ARM platforms. Currently, the brcmfmac driver for
> these devices support use of platform data. This patch specifies
> the bindings that allow this platform data to be expressed in the
> devicetree.
>
> Cc: Chen-Yu Tsai <wens@...e.org>
> Cc: Tomasz Figa <tomasz.figa@...il.com>
> Reviewed-by: Hante Meuleman <meuleman@...adcom.com>
> Reviewed-by: Pieter-Paul Giesberts <pieterpg@...adcom.com>
> Signed-off-by: Arend van Spriel <arend@...adcom.com>
> ---
> This devicetree binding proposal is intended for platforms with
> Broadcom wireless device in MMC sdio slot. These devices may
> have their own interrupt and power line. Also the SDIO drive
> strength is often hardware dependent and expressed in this
> binding.
>
> Not sure if this should go in staging or not. Feel free to
> comment on this proposal.
>
> Regards,
> Arend
> ---
>   .../staging/net/wireless/brcm,bcm43xx-fmac.txt     |   37 ++++++++++++++++++++
>   1 file changed, 37 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/staging/net/wireless/brcm,bcm43xx-fmac.txt
>
> diff --git a/Documentation/devicetree/bindings/staging/net/wireless/brcm,bcm43xx-fmac.txt b/Documentation/devicetree/bindings/staging/net/wireless/brcm,bcm43xx-fmac.txt
> new file mode 100644
> index 0000000..535f343
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/staging/net/wireless/brcm,bcm43xx-fmac.txt
> @@ -0,0 +1,37 @@
> +Broadcom BCM43xx Fullmac wireless SDIO devices
> +
> +This node provides properties for controlling the Broadcom wireless device. The
> +node is expected to be specified as a child node to the MMC controller that
> +connects the device to the system.
> +
> +Required properties:
> +
> + - compatible : Should be "brcm,bcm43xx-fmac".
> + - wlan-supply : phandle for fixed regulator used to control power for
> +	the device/module.

The BCM43xx WLAN chips I used to work always have been controlled by a 
simple power enable GPIO of the chip itself. Has this changed in newer 
chips?

If you need to simply toggle a GPIO to control the power, you don't need 
to use the regulator API at all, controlling the GPIO directly.

> +
> +Optional properties:
> + - drive-strength : drive strength used for SDIO pins on device (default = 6mA).

This should be a part of the MMC binding, I think. Probably also moved 
under MMC controller's node, since it's a board-specific property 
altering the parameters of the MMC controller, not the WLAN chip.

> + - interrupt-parent : the phandle for the interrupt controller to which the
> +	device interrupt (HOST_WAKE) is connected.
> + - interrupts : interrupt specifier encoded according the interrupt controller
> +	specified by interrupt-parent property.

I would also add a clock here, since the BCM43xx chips usually need a 
32k clock to operate (or at least the ones I used to work with did). It 
can be optional, as not all systems can control this clock.

> +
> +Example:
> +
> +mmc3: mmc@...20000 {
> +	pinctrl-0 = <&mmc3_pins>;
> +	pinctrl-1 = <&wifi_host_wake>;

WLAN_HOST_WAKE pin (aka the OOB interrupt) is specific to the WLAN chip, 
so this should be rather configured in a pinctrl state of the WLAN chip 
itself.

> +	vmmc-supply = <&mmc3_supply>;
> +	bus-width = <4>;
> +
> +	bcm4335: bcm4335@0 {

nit: Why @0, if there is no reg property under this node?

Best regards,
Tomasz

> +		compatible = "brcm,bcm43xx-fmac";
> +		wlan-supply = <&wlan-reg>;
> +		drive-strength = <4>;
> +		interrupt-parent = <&gpx2>;
> +		interrupts = <5 IRQ_TYPE_LEVEL_HIGH>;
> +		interrupt-names = "HOST_WAKE";
> +	};
> +};
> +
>
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