smp.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <arch/barrier.h>
#include <arch/encoding.h>
#include <arch/smp/smp.h>
#include <arch/smp/atomic.h>
#include <console/console.h>
#include <mcall.h>
 
void smp_pause(int working_hartid)
{
#define SYNCA (OTHER_HLS(working_hartid)->entry.sync_a)
#define SYNCB (OTHER_HLS(working_hartid)->entry.sync_b)
 
        int hartid = read_csr(mhartid);
 
        if (hartid != working_hartid) {
                /* waiting for work hart */
                do {
                        barrier();
                } while (atomic_read(&SYNCA) != 0x01234567);
 
                clear_csr(mstatus, MSTATUS_MIE);
                write_csr(mie, MIP_MSIP);
 
                /* count how many cores enter the halt */
                atomic_add(&SYNCB, 1);
 
                do {
                        barrier();
                        __asm__ volatile ("wfi");
                } while ((read_csr(mip) & MIP_MSIP) == 0);
                set_msip(hartid, 0);
                HLS()->entry.fn(HLS()->entry.arg);
        } else {
                /* Initialize the counter and
                 * mark the work hart into smp_pause */
                atomic_set(&SYNCB, 0);
                atomic_set(&SYNCA, 0x01234567);
 
                /* waiting for other Hart to enter the halt */
                do {
                        barrier();
                } while (atomic_read(&SYNCB) + 1 < CONFIG_MAX_CPUS);
 
                /* initialize for the next call */
                atomic_set(&SYNCA, 0);
                atomic_set(&SYNCB, 0);
        }
#undef SYNCA
#undef SYNCB
}
 
void smp_resume(void (*fn)(void *), void *arg)
{
        int hartid = read_csr(mhartid);
 
        if (fn == NULL)
                die("must pass a non-null function pointer\n");
 
        for (int i = 0; i < CONFIG_MAX_CPUS; i++) {
                OTHER_HLS(i)->entry.fn = fn;
                OTHER_HLS(i)->entry.arg = arg;
        }
 
        for (int i = 0; i < CONFIG_MAX_CPUS; i++)
                if (i != hartid)
                        set_msip(i, 1);
 
        if (HLS()->entry.fn == NULL)
                die("entry fn not set\n");
 
        HLS()->entry.fn(HLS()->entry.arg);
}