Firmwares/bare-metal-bsp/include/sifive/smp.h

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#ifndef SIFIVE_SMP
#define SIFIVE_SMP
// The maximum number of HARTs this code supports
#ifndef MAX_HARTS
#define MAX_HARTS 32
#endif
#define CLINT_END_HART_IPI CLINT_CTRL_ADDR + (MAX_HARTS*4)
// The hart that non-SMP tests should run on
#ifndef NONSMP_HART
#define NONSMP_HART 0
#endif
/* If your test cannot handle multiple-threads, use this:
* smp_disable(reg1)
*/
#define smp_disable(reg1, reg2) \
csrr reg1, mhartid ;\
li reg2, NONSMP_HART ;\
beq reg1, reg2, hart0_entry ;\
42: ;\
wfi ;\
j 42b ;\
hart0_entry:
/* If your test needs to temporarily block multiple-threads, do this:
* smp_pause(reg1, reg2)
* ... single-threaded work ...
* smp_resume(reg1, reg2)
* ... multi-threaded work ...
*/
#define smp_pause(reg1, reg2) \
li reg2, 0x8 ;\
csrw mie, reg2 ;\
csrr reg2, mhartid ;\
bnez reg2, 42f
#define smp_resume(reg1, reg2) \
li reg1, CLINT_CTRL_ADDR ;\
41: ;\
li reg2, 1 ;\
sw reg2, 0(reg1) ;\
addi reg1, reg1, 4 ;\
li reg2, CLINT_END_HART_IPI ;\
blt reg1, reg2, 41b ;\
42: ;\
wfi ;\
csrr reg2, mip ;\
andi reg2, reg2, 0x8 ;\
beqz reg2, 42b ;\
li reg1, CLINT_CTRL_ADDR ;\
csrr reg2, mhartid ;\
slli reg2, reg2, 2 ;\
add reg2, reg2, reg1 ;\
sw zero, 0(reg2) ;\
41: ;\
lw reg2, 0(reg1) ;\
bnez reg2, 41b ;\
addi reg1, reg1, 4 ;\
li reg2, CLINT_END_HART_IPI ;\
blt reg1, reg2, 41b
#endif