Re: [PATCH 0/2] Resolve MPM register space situation

Konrad Dybcio
2023-03-29T11:18:45Z

On 29.03.2023 05:58, Shawn Guo wrote:
> On Tue, Mar 28, 2023 at 12:02:51PM +0200, Konrad Dybcio wrote:
>> The MPM (and some other things, irrelevant to this patchset) resides
>> (as far as the ARM cores are concerned, anyway) in a MMIO-mapped region
>> that's a portion of the RPM (low-power management core)'s RAM, known
>> as the RPM Message RAM. Representing this relation in the Device Tree
>> creates some challenges, as one would either have to treat a memory
>> region as a bus, map nodes in a way such that their reg-s would be
>> overlapping, or supply the nodes with a slice of that region.
>>
>> This series implements the third option, by adding a qcom,rpm-msg-ram
>> property, which has been used for some drivers poking into this region
>> before. Bindings ABI compatibility is preserved through keeping the
>> "normal" (a.k.a read the reg property and map that region) way of
>> passing the register space.
>>
>> Example representation with this patchset:
>>
>> / {
>> [...]
>>
>> mpm: interrupt-controller {
>> compatible = "qcom,mpm";
>> qcom,rpm-msg-ram = <&apss_mpm>;
>> [...]
>> };
>>
>> [...]
>>
>> soc: soc@0 {
>> [...]
>>
>> rpm_msg_ram: sram@45f0000 {
>> compatible = "qcom,rpm-msg-ram", "mmio-sram";
>> reg = <0 0x045f0000 0 0x7000>;
>> #address-cells = <1>;
>> #size-cells = <1>;
>> ranges = <0 0x0 0x045f0000 0x7000>;
>>
>> apss_mpm: sram@1b8 {
>> reg = <0x1b8 0x48>;
>
> Per "vMPM register map" in the driver, the slice size should be 0x44
> instead of 0x48. Is there one register missing from the driver
> comment?
Yeah we should be using 0x44..

>
> PS. It seems the "n" formula in the driver comment should be corrected
> as below.
>
> n = DIV_ROUND_UP(pin_cnt, 32) - 1
Or since we're counting from zero, the ENABLEn should become
ENABLE(n-1) etc.

Konrad

>
> Shawn
>
>> };
>> };
>> };
>> };