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

Rafał Miłecki
2016-08-11T08:50:29Z

On 10 August 2016 at 20:21, Jon Mason <jon.mason@broadcom.com> wrote:
> On Wed, Aug 10, 2016 at 1:44 PM, Ray Jui <ray.jui@broadcom.com> wrote:
>> On 8/10/2016 10:28 AM, Rafał Miłecki wrote:
>>>
>>> On 10 August 2016 at 19:22, Jon Mason <jon.mason@broadcom.com> wrote:
>>>>
>>>> On Wed, Aug 10, 2016 at 8:05 AM, Rafał Miłecki <zajec5@gmail.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@18012000 {
>>>>> + 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.
>
> 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".

Yes, I said clearly it uses Corex-A7 in the commit message and
Documentation entry.

Florian already shared his doubts about BCM53573 belonging to the
Northstar, but I found out [1] that your (Broadcom's) SDK treats it as
Northstar device:

Asus RT-AC1200G+

# cat /proc/cpuinfo
Processor : ARMv7 Processor rev 5 (v7l)
BogoMIPS : 1795.68
Features : swp half thumb fastmult edsp
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xc07
CPU revision : 5

Hardware : Northstar Prototype
Revision : 0000
Serial : 0000000000000000

It seems Broadcom's WLAN team claims it's a Northstar and you claim
it's not. Could you discuss this internally and let us know, please?

[1] https://lkml.org/lkml/2016/7/29/345

--
Rafał