Owners manual

System

4.14.6. Programming Guidelines

Take CPU0's synchronization with CPUS with Spinlock0 for an example, CPU0 takes the spinlock0 firstly in the instance：

CPU0

Step 1: CPU0 initializes Spinlock

writel(readl(BUS_GATING_REG1)|(1<<22) ,BUS_GATING_REG1); //open Spinlock clock gating

writel (readl(BUS_RST_REG1)|(1<<22) , BUS_RST_REG1); //software reset Spinlock

Step 2: CPU0 requests to take spinlock0

rdata=readl(SPINLOCK_STATUS_REG0); //check lock register0 status, if it is taken, check till

if(rdata != 0) rdata=readl(SPINLOCK_STATUS_REG0); // lock register0 is free

rdata=readl(SPINLOCKN_LOCK_REG0); //request to take spinlock0, if fail, retry till

if(rdata != 0) rdata=readl(SPINLOCKN_LOCK_REG0); // lock register0 is taken

---------- CPU0 critical code section ----------

Step 3: CPU0 free spinlock0

writel (0, SPINLOCKN_LOCK_REG0); //CPU0 frees spinlock0

Step 4: CPU0 waits for CPUS’ freeing spinlock0

writel (readl(SPINLOCK_STATUS_REG0) == 1); // CPU0 waits for CPUS’ freeing spinlock0

CPUS

Step 1: CPU0 has taken spinlock0, CPUS waits for CPU0’ freeing spinlock0

while(readl(SPINLOCK_STATUS_REG0) == 1); // CPUS waits for CPU0’ freeing spinlock0

Step 2: CPUS takes spinlock0 and go on

---------- CPUS critical code section ----------

Step 3: CPUS frees spinlock0

writel (0, SPINLOCKN_LOCK_REG0); //CPUS frees spinlock0

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