[PATCH v2 7/7] riscv: Update SiFive device tree for new CLINT driver

[Sean Anderson]

On 9/3/20 1:01 AM, Anup Patel wrote:
> On Thu, Sep 3, 2020 at 8:19 AM Bin Meng <bmeng.cn at gmail.com> wrote:
>>
>> Hi Anup,
>>
>> On Thu, Sep 3, 2020 at 10:46 AM Anup Patel <anup at brainfault.org> wrote:
>>>
>>> On Thu, Sep 3, 2020 at 7:32 AM Bin Meng <bmeng.cn at gmail.com> wrote:
>>>>
>>>> Hi Anup,
>>>>
>>>> On Tue, Aug 18, 2020 at 6:03 PM Sean Anderson <seanga2 at gmail.com> wrote:
>>>>>
>>>>> On 8/18/20 5:22 AM, Bin Meng wrote:
>>>>>> +Anup Patel
>>>>>>
>>>>>> On Wed, Jul 29, 2020 at 5:57 PM Sean Anderson <seanga2 at gmail.com> wrote:
>>>>>>>
>>>>>>> We may need to add a clock-frequency binding like for the K210.
>>>>>>>
>>>>>>> Signed-off-by: Sean Anderson <seanga2 at gmail.com>
>>>>>>> ---
>>>>>>> This patch builds but has NOT been tested.
>>>>>>>
>>>>>>> Changes in v2:
>>>>>>> - Fix SiFive CLINT not getting tick-rate from rtcclk
>>>>>>>
>>>>>>>  arch/riscv/dts/fu540-c000-u-boot.dtsi           | 8 ++++++--
>>>>>>>  arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi | 4 ++++
>>>>>>>  2 files changed, 10 insertions(+), 2 deletions(-)
>>>>>>>
>>>>>>> diff --git a/arch/riscv/dts/fu540-c000-u-boot.dtsi b/arch/riscv/dts/fu540-c000-u-boot.dtsi
>>>>>>> index afdb4f4402..f126d3e0b3 100644
>>>>>>> --- a/arch/riscv/dts/fu540-c000-u-boot.dtsi
>>>>>>> +++ b/arch/riscv/dts/fu540-c000-u-boot.dtsi
>>>>>>> @@ -53,9 +53,13 @@
>>>>>>>                         reg = <0x0 0x10070000 0x0 0x1000>;
>>>>>>>                         fuse-count = <0x1000>;
>>>>>>>                 };
>>>>>>> -               clint at 2000000 {
>>>>>>> +               clint: clint at 2000000 {
>>>>>>>                         compatible = "riscv,clint0";
>>>>>>> -                       interrupts-extended = <&cpu0_intc 3 &cpu0_intc 7 &cpu1_intc 3 &cpu1_intc 7 &cpu2_intc 3 &cpu2_intc 7 &cpu3_intc 3 &cpu3_intc 7 &cpu4_intc 3 &cpu4_intc 7>;
>>>>>>> +                       interrupts-extended = <&cpu0_intc 3 &cpu0_intc 7
>>>>>>> +                                              &cpu1_intc 3 &cpu1_intc 7
>>>>>>> +                                              &cpu2_intc 3 &cpu2_intc 7
>>>>>>> +                                              &cpu3_intc 3 &cpu3_intc 7
>>>>>>> +                                              &cpu4_intc 3 &cpu4_intc 7>;
>>>>>>>                         reg = <0x0 0x2000000 0x0 0xc0000>;
>>>>>>>                         u-boot,dm-spl;
>>>>>>>                 };
>>>>>>> diff --git a/arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi b/arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi
>>>>>>> index e037150520..3275bb1f12 100644
>>>>>>> --- a/arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi
>>>>>>> +++ b/arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi
>>>>>>> @@ -26,6 +26,10 @@
>>>>>>>
>>>>>>>  };
>>>>>>>
>>>>>>> +&clint {
>>>>>>> +       clocks = <&rtcclk>;
>>>>>>> +};
>>>>>>
>>>>>> Can we consider making this property a standard property by the kernel
>>>>>> upstream? How does the kernel CLINT timer driver determine its running
>>>>>> frequency?
>>>>>
>>>>> Currently it gets it from /cpus/timebase-frequency.
>>>>
>>>> What's your comment on this? I think this should go upstream to the
>>>> standard bindings.
>>>
>>> My apologies for delay. Too many mailing list to track.
>>>
>>> I think "clocks" should be an optional DT property for CLINT driver (both
>>> Linux and U-Boot). If "clocks" is not available then we should fallback to
>>> "/cpus/timebase-frequency"
>>>
>>
>> Agreed. The question is whether this should be mentioned in the DT
>> bindings doc in the kernel tree?
> 
> Yes, the "clocks" DT property should be updated in kernel DT bindings doc
> and kernel CLINT driver should also prefer "clocks" DT property when available.
> 
> Regards,
> Anup

Should clock-frequency be used as well, or should that be left for timebase-frequency?

--Sean