linux-kernel - Re: [PATCH v3 1/2] dt-bindings: hwlock: add sun8i

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Message-ID: <20201208061128.3e20f00b@monster.powergraphx.local>
Date:   Tue, 8 Dec 2020 06:11:28 +0100
From:   Wilken Gottwalt <wilken.gottwalt@...teo.net>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Maxime Ripard <maxime@...no.tech>, linux-kernel@...r.kernel.org,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Baolin Wang <baolin.wang7@...il.com>,
        Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...l.net>
Subject: Re: [PATCH v3 1/2] dt-bindings: hwlock: add sun8i_hwspinlock
 documentation

On Mon, 7 Dec 2020 21:22:23 -0600
Samuel Holland <samuel@...lland.org> wrote:

> On 12/7/20 10:12 AM, Maxime Ripard wrote:
> > Hi,
> > 
> > On Mon, Dec 07, 2020 at 05:05:03PM +0100, Wilken Gottwalt wrote:
> >> Adds documentation on how to use the sun8i_hwspinlock driver for sun8i
> >> compatible SoCs.
> >>
> >> Signed-off-by: Wilken Gottwalt <wilken.gottwalt@...teo.net>
> >> ---
> >>  .../bindings/hwlock/sun8i-hwspinlock.yaml     | 63 +++++++++++++++++++
> >>  1 file changed, 63 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/hwlock/sun8i-hwspinlock.yaml
> >>
> >> diff --git a/Documentation/devicetree/bindings/hwlock/sun8i-hwspinlock.yaml
> >> b/Documentation/devicetree/bindings/hwlock/sun8i-hwspinlock.yaml new file mode 100644
> >> index 000000000000..2954ee0b36a7
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/hwlock/sun8i-hwspinlock.yaml
> >> @@ -0,0 +1,63 @@
> >> +# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
> >> +%YAML 1.2
> >> +---
> >> +$id: http://devicetree.org/schemas/hwlock/sun8i-hwspinlock.yaml#
> >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >> +
> >> +title: SUN8I hardware spinlock driver for Allwinner sun8i compatible SoCs
> >> +
> >> +maintainers:
> >> +  - Wilken Gottwalt <wilken.gottwalt@...teo.net>
> >> +
> >> +properties:
> >> +  compatible:
> >> +    enum:
> >> +      - allwinner,sun8i-hwspinlock
> > 
> > This can be a const instead of an enum, and since it was introduced with
> > the A33 it should be sun8i-a33-hwspinlock. There's a lot of SoCs in that
> > family, some without that IP, and we could even see new SoCs in that
> > family with a different IP at some point.
> 
> I just looked at the A31 ARISC blob, and it uses the hwspinlock hardware
> as well, with the same MMIO address and gate/reset bits as A33-H3. So
> the first compatible would actually be sun6i-a31-hwspinlock.

Hmm, so it would make sense to also change the drivers symbols from sun8i to
sun6i, right? Before I do that, is there maybe a sun4i which also includes
the hwspinlock unit? Just in case :D

greetings,
Wilken

> Cheers,
> Samuel
> 
> >> +
> >> +    reg:          # 0x01C18000 (H2+, H3, H5), 0x03004000 (H6), length 0x1000
> >> +      maxItems: 1
> > 
> > There's no need for those comments
> > 
> >> +
> >> +    clocks:       # phandle to the reference clock
> > 
> > This should be the description, and it's fairly obvious so you don't
> > really need that comment.
> > 
> >> +      maxItems: 1
> >> +
> >> +    clock-names:  # name of the bus ("ahb")
> >> +      maxItems: 1
> > 
> > You don't need clock-names if there's a single clock
> > 
> >> +
> >> +    resets:       # phandle to the reset control
> >> +      maxItems: 1
> > 
> > Same thing than for the clocks
> > 
> >> +
> >> +    reset-names:  # name of the bus ("ahb")
> >> +      maxItems: 1
> >> +
> > 
> > Ditto
> > 
> >> +required:
> >> +  - compatible
> >> +  - reg
> >> +  - clocks
> >> +  - clock-names
> >> +  - resets
> >> +  - reset-names
> >> +
> >> +additionalProperties: false
> >> +
> >> +examples:
> >> +
> >> +  - |
> >> +    /* H2+ based OrangePi Zero */
> >> +    hwspinlock: hwspinlock@...8000 {
> > 
> > Unit-address's are lowercase
> > 
> >> +      compatible = "allwinner,sun8i-hwspinlock";
> >> +      reg = <0x01c18000 0x1000>;
> >> +      clocks = <&ccu CLK_BUS_SPINLOCK>;
> >> +      clock-names = "ahb";
> >> +      resets = <&ccu RST_BUS_SPINLOCK>;
> >> +      reset-names = "ahb";
> >> +    };
> >> +
> >> +    /* H6 based OrangePi 3 */
> >> +    hwspinlock: hwspinlock@...4000 {
> >> +      compatible = "allwinner,sun8i-hwspinlock";
> >> +      reg = <0x03004000 0x1000>;
> >> +      clocks = <&ccu CLK_BUS_SPINLOCK>;
> >> +      clock-names = "ahb";
> >> +      resets = <&ccu RST_BUS_SPINLOCK>;
> >> +      reset-names = "ahb";
> >> +    };
> > 
> > Different examples should be different items on that list, but both are
> > essentially the same binding so you can drop one.
> > 
> > Maxime
> > 
>