linux-kernel - Re: [PATCH V3] clk: bcm: Add driver for Northstar ILP clock

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Message-ID: <CAC3K-4pWS2SgdzHxJ6rcMmbYHYNwoCx9th0cp+wWeW=CQc+ySA@mail.gmail.com>
Date:	Wed, 10 Aug 2016 14:21:40 -0400
From:	Jon Mason <jon.mason@...adcom.com>
To:	Ray Jui <ray.jui@...adcom.com>
Cc:	Rafał Miłecki <zajec5@...il.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>, linux-clk@...r.kernel.org,
	BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
	Rafał Miłecki <rafal@...ecki.pl>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Eric Anholt <eric@...olt.net>,
	Florian Fainelli <f.fainelli@...il.com>,
	Jon Mason <jonmason@...adcom.com>,
	Stephen Warren <swarren@...dotorg.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3] clk: bcm: Add driver for Northstar ILP clock

On Wed, Aug 10, 2016 at 1:44 PM, Ray Jui <ray.jui@...adcom.com> wrote:
>
>
> On 8/10/2016 10:28 AM, Rafał Miłecki wrote:
>>
>> On 10 August 2016 at 19:22, Jon Mason <jon.mason@...adcom.com> wrote:
>>>
>>> On Wed, Aug 10, 2016 at 8:05 AM, Rafał Miłecki <zajec5@...il.com> wrote:
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/clock/brcm,ns-ilp.txt
>>>> b/Documentation/devicetree/bindings/clock/brcm,ns-ilp.txt
>>>> new file mode 100644
>>>> index 0000000..a18c73f
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/clock/brcm,ns-ilp.txt
>>>> @@ -0,0 +1,40 @@
>>>> +Broadcom Northstar ILP clock
>>>> +============================
>>>> +
>>>> +This binding uses the common clock binding:
>>>> +    Documentation/devicetree/bindings/clock/clock-bindings.txt
>>>> +
>>>> +This binding is used for ILP clock (sometimes referred as "slow clock")
>>>> +on Broadcom Northstar devices using Corex-A7 CPU.
>>>> +
>>>> +This clock is part of PMU (Power Management Unit), a Broadcom's device
>>>> +handing power-related aspects. Please note PMU contains more
>>>> subdevices,
>>>> +ILP is only one of them.
>>>> +
>>>> +ILP's rate has to be calculated on runtime and it depends on ALP clock
>>>> +which has to be referenced.
>>>> +
>>>> +Required properties:
>>>> +- compatible: "brcm,ns-ilp"
>>>> +- reg: iomem address range of PMU (Power Management Unit)
>>>> +- reg-names: "pmu", the only needed & supported reg right now
>>>> +- clocks: has to reference an ALP clock
>>>> +- #clock-cells: should be <0>
>>>> +
>>>> +Example:
>>>> +
>>>> +pmu@...12000 {
>>>> +       compatible = "simple-bus";
>>>> +       ranges = <0x00000000 0x18012000 0x00001000>;
>>>
>>>
>>> I don't see a corresponding DT entry in this patch, but 18012000 is
>>> the PCI block.  So, I am concerned this will collide if used there.
>>>
>>> I looked at the NS register reference guide, and I cannot find the
>>> registers you are trying to reference.  Is this supposed to be
>>> referencing the LCPLL clock registers in DMU?  If so, there is already
>>> a driver in there for this (see drivers/clk/bcm/clk-nsp.c).
>>
>>
>> This patch is for BCM53573 family, not BCM4708 family you are looking at.
>>
>> Found chip with id 53573, rev 0x02 and package 0x01
>> Core 0 found: ChipCommon (manuf 0x4BF, id 0x800, rev 0x36, class 0x0)
>> Core 1 found: IEEE 802.11 (manuf 0x4BF, id 0x812, rev 0x38, class 0x0)
>> Core 2 found: PCIe Gen 2 (manuf 0x4BF, id 0x501, rev 0x05, class 0x0)
>> Core 3 found: ARM CA7 (manuf 0x4BF, id 0x847, rev 0x00, class 0x0)
>> Core 4 found: USB 2.0 Host (manuf 0x4BF, id 0x819, rev 0x05, class 0x0)
>> Core 5 found: GBit MAC (manuf 0x4BF, id 0x82D, rev 0x08, class 0x0)
>> Core 6 found: I2S (manuf 0x4BF, id 0x834, rev 0x06, class 0x0)
>> Core 7 found: CNDS DDR2/3 memory controller (manuf 0x4BF, id 0x846,
>> rev 0x00, class 0x0)
>> Core 8 found: NAND flash controller (manuf 0x4BF, id 0x509, rev 0x01,
>> class 0x0)
>> Core 9 found: IEEE 802.11 (manuf 0x4BF, id 0x812, rev 0x38, class 0x0)
>> Core 10 found: GBit MAC (manuf 0x4BF, id 0x82D, rev 0x08, class 0x0)
>> Core 11 found: I2S (manuf 0x4BF, id 0x834, rev 0x06, class 0x0)
>> Core 12 found: GCI (manuf 0x4BF, id 0x840, rev 0x08, class 0x0)
>> Core 13 found: PMU (manuf 0x4BF, id 0x827, rev 0x1C, class 0x0)
>>
>
> Out of curiosity, I searched the datasheet and found this is a wireless
> router SoC done by the WLAN team. It happens to share some peripherals with
> other iProc based SoCs.
>
> I cannot find a code name for this SoC from our internal documents. I guess
> that name "Northstar" used here has confused both Jon and me.
>
> Thanks,
>
> Ray

Ray is right.  I just spoke to one of the people here with knowledge
of the HW, and this is not related at all to the 4708/9/5301X.  It MAY
have some of the same peripherals, but the core is different (Cortex
A7 instead of A9).

I think we are best off to change the name and turn this into a
separate device tree, driver base, etc.  I wasn't able to get a code
name, so perhaps simply call it "BCM53573".

Thanks,
Jon