| Message ID | 1403072180-4944-2-git-send-email-abrestic@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/18/2014 12:16 AM, Andrew Bresticker wrote: > Add device-tree bindings for the Tegra XUSB mailbox which will be used > for communication between the Tegra XHCI controller and the host. Sorry for the slow review. > diff --git a/Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt b/Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt > +NVIDIA Tegra XUSB mailbox > +========================= > + > +The Tegra XUSB mailbox is used by the Tegra XHCI controller's firmware to > +communicate with the host. Isn't the mailbox an internal implementation detail of the XUSB controller. In other words, I'd naively think that there isn't a standalone generic mailbox that can be used by anything, but we just happen to want to use for XUSB. Rather, there's an XUSB controller, and part of the interface to that controller is a mailbox. As such, I don't think we want a standalone mailbox node in DT. Rather, we should add the required reg and interrupt values into the XUSB DT node. The driver for that XUSB HW module can either: a) Register as both a mailbox driver and an EHCI driver. b) Spawn a child device to instantiate the mailbox driver. Perhaps (b) could be assisted by using the MFD framework?
On Wed, Jun 25, 2014 at 2:42 PM, Stephen Warren <swarren@wwwdotorg.org> wrote: > On 06/18/2014 12:16 AM, Andrew Bresticker wrote: >> Add device-tree bindings for the Tegra XUSB mailbox which will be used >> for communication between the Tegra XHCI controller and the host. > > Sorry for the slow review. > >> diff --git a/Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt b/Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt > >> +NVIDIA Tegra XUSB mailbox >> +========================= >> + >> +The Tegra XUSB mailbox is used by the Tegra XHCI controller's firmware to >> +communicate with the host. > > Isn't the mailbox an internal implementation detail of the XUSB controller. > > In other words, I'd naively think that there isn't a standalone generic > mailbox that can be used by anything, but we just happen to want to use > for XUSB. Rather, there's an XUSB controller, and part of the interface > to that controller is a mailbox. Yes, the mailbox isn't an actual piece of hardware but rather the interface through which the XUSB host and AP communicate. > As such, I don't think we want a standalone mailbox node in DT. Rather, > we should add the required reg and interrupt values into the XUSB DT node. > > The driver for that XUSB HW module can either: > > a) Register as both a mailbox driver and an EHCI driver. > > b) Spawn a child device to instantiate the mailbox driver. > > Perhaps (b) could be assisted by using the MFD framework? So in the RFC series I did something like (a) where the XUSB host handled the mailbox interrupt with both the PHY and host could registering notifiers to handle the messages. It was suggested by Arnd though that I make a separate mailbox driver. Instead of having a both a host and mailbox node, I could have a single XUSB host node and have the mailbox driver bind to that - thoughts?
On 06/25/2014 04:37 PM, Andrew Bresticker wrote: > On Wed, Jun 25, 2014 at 2:42 PM, Stephen Warren <swarren@wwwdotorg.org> wrote: >> On 06/18/2014 12:16 AM, Andrew Bresticker wrote: >>> Add device-tree bindings for the Tegra XUSB mailbox which will be used >>> for communication between the Tegra XHCI controller and the host. >> >> Sorry for the slow review. >> >>> diff --git a/Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt b/Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt >> >>> +NVIDIA Tegra XUSB mailbox >>> +========================= >>> + >>> +The Tegra XUSB mailbox is used by the Tegra XHCI controller's firmware to >>> +communicate with the host. >> >> Isn't the mailbox an internal implementation detail of the XUSB controller. >> >> In other words, I'd naively think that there isn't a standalone generic >> mailbox that can be used by anything, but we just happen to want to use >> for XUSB. Rather, there's an XUSB controller, and part of the interface >> to that controller is a mailbox. > > Yes, the mailbox isn't an actual piece of hardware but rather the > interface through which the XUSB host and AP communicate. > >> As such, I don't think we want a standalone mailbox node in DT. Rather, >> we should add the required reg and interrupt values into the XUSB DT node. >> >> The driver for that XUSB HW module can either: >> >> a) Register as both a mailbox driver and an EHCI driver. >> >> b) Spawn a child device to instantiate the mailbox driver. >> >> Perhaps (b) could be assisted by using the MFD framework? > > So in the RFC series I did something like (a) where the XUSB host > handled the mailbox interrupt with both the PHY and host could > registering notifiers to handle the messages. It was suggested by > Arnd though that I make a separate mailbox driver. Instead of having > a both a host and mailbox node, I could have a single XUSB host node > and have the mailbox driver bind to that - thoughts? Yes, that sounds like what I meant by (b) above. I don't think you can actually have 2 drivers bind to the same DT node though, so it'd have to work something like: * XUSB host node causes a platform device to be instantiated * XUSB host driver probe()s against that * XUSB host driver's probe() creates a platform device for the mailbox * XUSB mailbox driver probe()s against that. Or, perhaps go completely MFD, and have 2 child devices (XUSB host and XUSB mailbox) instantiated by the MFD parent, which is what is in the DT.
diff --git a/Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt b/Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt new file mode 100644 index 0000000..c1833e5 --- /dev/null +++ b/Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt @@ -0,0 +1,25 @@ +NVIDIA Tegra XUSB mailbox +========================= + +The Tegra XUSB mailbox is used by the Tegra XHCI controller's firmware to +communicate with the host. + +Required properties: +-------------------- + - compatible: Should be "nvidia,tegra124-xusb-mbox". + - reg: Address and length of the XUSB FPCI registers. + - interrupts: XUSB mailbox interrupt. + +Example: +-------- + mbox: mailbox@0,70098000 { + compatible = "nvidia,tegra124-xusb-mbox"; + reg = <0x0 0x70098000 0x0 0x1000>; + interrupts = <GIC_SPI 40 IRQ_TYPE_LEVEL_HIGH>; + }; + + usb@0,70090000 { + ... + nvidia,xusb-mbox = <&mbox>; + ... + };
Add device-tree bindings for the Tegra XUSB mailbox which will be used for communication between the Tegra XHCI controller and the host. Signed-off-by: Andrew Bresticker <abrestic@chromium.org> --- .../bindings/mailbox/nvidia,tegra124-xusb-mbox.txt | 25 ++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 Documentation/devicetree/bindings/mailbox/nvidia,tegra124-xusb-mbox.txt