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Photon
Level 1
Level 1
5 sign-ins First question asked First like given

I can read/write the core special function registers with their respective offset address of registers for a given core using the instruction mfcr/mtcr.

But how I can read/write a core special function register from other core ?

The scenario is here that a piece of code is executing in core1 and for a particular scenario this piece of code needs to read the core register values for current core and other core such as core 0 & core 2.

How I can achieve this with the instruction mfcr ?

Thanks in advance for your support.

 

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1 Solution
Prudhvi
Moderator
Moderator
Moderator
50 solutions authored 250 sign-ins 10 likes given

Hello,

You cannot not use the instructions mfcr/mtcr  to access the CSFR registers of a different core. You need to use load and store instructions to access the CSFRs of another core. For the same core, you must use mfcr/mtcr  instructions.

For ex if you want to access DATR registers of all cores from CPU-0 then you may consider implementing one of the following approaches:

           volatile uint32 g_datrRegValCore0, g_datrRegValCore1, g_datrRegValCore2;

           g_datrRegValCore0 = __mfcr(CPU_DATR);

           g_datrRegValCore1 = CPU1_DATR.U;

           g_datrRegValCore2 = CPU2_DATR.U;

         (OR)

         If your function is called by multiple cores, use GetCoreId function first and based on Core implement a                 switch case where for each core you update the above variables using mfcr/mtcr instructions.

Please see section "3.12 Accessing Core Special Function Registers (CSFRs)" in the Vol_1 and section "2.12.3 Access to the Core Special Function Registers (CSFRs)" and the usage of mfcr/mtcr in the Vol_2.

Regards,

Prudhvi.

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1 Reply
Prudhvi
Moderator
Moderator
Moderator
50 solutions authored 250 sign-ins 10 likes given

Hello,

You cannot not use the instructions mfcr/mtcr  to access the CSFR registers of a different core. You need to use load and store instructions to access the CSFRs of another core. For the same core, you must use mfcr/mtcr  instructions.

For ex if you want to access DATR registers of all cores from CPU-0 then you may consider implementing one of the following approaches:

           volatile uint32 g_datrRegValCore0, g_datrRegValCore1, g_datrRegValCore2;

           g_datrRegValCore0 = __mfcr(CPU_DATR);

           g_datrRegValCore1 = CPU1_DATR.U;

           g_datrRegValCore2 = CPU2_DATR.U;

         (OR)

         If your function is called by multiple cores, use GetCoreId function first and based on Core implement a                 switch case where for each core you update the above variables using mfcr/mtcr instructions.

Please see section "3.12 Accessing Core Special Function Registers (CSFRs)" in the Vol_1 and section "2.12.3 Access to the Core Special Function Registers (CSFRs)" and the usage of mfcr/mtcr in the Vol_2.

Regards,

Prudhvi.