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

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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@xxxxxxxx>
Cc: Tomasz Figa <tomasz.figa@xxxxxxxxx>
Reviewed-by: Hante Meuleman <meuleman@xxxxxxxxxxxx>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@xxxxxxxxxxxx>
Signed-off-by: Arend van Spriel <arend@xxxxxxxxxxxx>
---
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@01c20000 {
+	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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