Re: [PATCH 1/2] arm64: dts: exynos850: Add ACPM firmware node

[Alexey Klimov]

Hi Tudor,

On Tue Sep 29, 2026 at 10:02 AM BST, Tudor Ambarus wrote:
> Hi, Alexey,
> On 9/29/26 6:10 AM, Alexey Klimov wrote:
>> Add the ACPM firmware node with cpucl0 and cpucl1 clocks. ACPM firmware
>> protocol provides interface for all client drivers to actually use
>> features exposed by the APM co-processor.
>> 
>> Signed-off-by: Alexey Klimov <alexey.klimov@xxxxxxxxxx>
>> ---
>>  arch/arm64/boot/dts/exynos/exynos850.dtsi | 13 +++++++++++++
>>  1 file changed, 13 insertions(+)
>> 
>> diff --git a/arch/arm64/boot/dts/exynos/exynos850.dtsi b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>> index 8a4771899a8e..91c6cee8f483 100644
>> --- a/arch/arm64/boot/dts/exynos/exynos850.dtsi
>> +++ b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>> @@ -11,6 +11,7 @@
>>   */
>>  
>>  #include <dt-bindings/clock/exynos850.h>
>> +#include <dt-bindings/clock/samsung,exynos850-acpm.h>
>>  #include <dt-bindings/interrupt-controller/arm-gic.h>
>>  #include <dt-bindings/soc/samsung,exynos-usi.h>
>>  
>> @@ -170,6 +171,18 @@ timer: timer {
>>  		     <GIC_PPI 10 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_LOW)>;
>>  	};
>>  
>> +	firmware {
>> +		acpm_ipc: power-management {
>> +			compatible = "samsung,exynos850-acpm-ipc";
>> +			mboxes = <&ap2apm_mailbox>;
>> +			shmem = <&apm_sram>;
>> +			clocks = <&cmu_cpucl0 CLK_FOUT_CPUCL0_PLL>,
>> +				 <&cmu_cpucl1 CLK_FOUT_CPUCL1_PLL>;
>
> Why do you describe these clocks?

>> +			clock-names = "cpucl0", "cpucl1";

To link these clocks with ACPM clocks from this list:
(file drivers/clk/samsung/clk-acpm.c)

static const struct acpm_clk_variant exynos850_acpm_clks[] = {
	ACPM_CLK("mif"),
	ACPM_CLK("int"),
	ACPM_CLK("cpucl0"),
	ACPM_CLK("cpucl1"),
	ACPM_CLK("g3d"),
	ACPM_CLK("aud"),
	ACPM_CLK("cam"),
	ACPM_CLK("disp"),
	ACPM_CLK("cp"),
};

Eventually to have some sensible/working ->recalc_rate() for ACPM
cpucl{0,1} clocks.

Which is needed, for instance, for cpufreq_dt because it registers with:

static struct cpufreq_driver dt_cpufreq_driver = {
        .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK |
                 CPUFREQ_IS_COOLING_DEV,

Don't know if it answers the question (if I understood it correctly)?

Best regards,
Alexey