MCU-PLUS-SDK-AM243X: PRU Spinlock example needed

Hi Steve,

Steve Squires said:

I'm looking for a simple PRU Spinlock example along the lines of the ipc_spinlock_sharedmem_am243x-lp_system_freertos_nortos example. Is one available

No, there aren't any examples of the PRU using the Spinlock hardware. I checked AM64x & AM243x MCU+SDK 08_02_00_31 and the PSSP.

Using the Spinlock hardware appears simple, judging from the AM64x/AM243x TRM and the AM243x MCU+SDK driver. All that's required is to read or write the MMR for the desired lock.

The following code snippet from the MCU+SDK driver file mcu_plus_sdk_am243x_08_02_00_31\source\drivers\spinlock\v0\spinlock.c shows the lock and unlock functions:

            int32_t Spinlock_lock(uint32_t baseAddr, uint32_t lockNumber)
            {
                int32_t         lockStatus = SystemP_FAILURE;
                CSL_spinlockRegs *pSpinlockRegs = (CSL_spinlockRegs *)((uintptr_t)baseAddr);

                if(lockNumber < Spinlock_getNumLocks(baseAddr))
                {
                    lockStatus = CSL_REG32_RD(&pSpinlockRegs->LOCK_REG[lockNumber]);
                }

                return (lockStatus);
            }

            void Spinlock_unlock(uint32_t baseAddr, uint32_t lockNumber)
            {
                CSL_spinlockRegs *pSpinlockRegs = (CSL_spinlockRegs *)((uintptr_t)baseAddr);

                if(lockNumber < Spinlock_getNumLocks(baseAddr))
                {
                    CSL_REG32_WR(&pSpinlockRegs->LOCK_REG[lockNumber], CSL_SPINLOCK_LOCK_REG_TAKEN_FREE);
                }

                return;
            }

The PRU cores have access to all SOC resources, so a PRU core can to read/write the Spinlock registers in the same way.

This is not a complete example, but the following code PRU assembly snippet will read SPINLOCK_LOCK_REG_0:

            LDI32   r0, 0x2A000800
            LBBO    &r1, r0, 0, 4

Something similar should work for writing the Spinlock.

I'm looping in Nick in case he knows more about this topic.

Regards,
Frank

Thanks Nick.