WSL2-Linux-Kernel/arch/powerpc/platforms/chrp/smp.c

/*
 * Smp support for CHRP machines.
 *
 * Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great
 * deal of code from the sparc and intel versions.
 *
 * Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
 *
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>

#include <asm/ptrace.h>
#include <asm/atomic.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/sections.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/residual.h>
#include <asm/time.h>
#include <asm/open_pic.h>
#include <asm/machdep.h>
#include <asm/smp.h>
#include <asm/mpic.h>

extern unsigned long smp_chrp_cpu_nr;

static int __init smp_chrp_probe(void)
{
	struct device_node *cpus = NULL;
	unsigned int *reg;
	int reglen;
	int ncpus = 0;
	int cpuid;
	unsigned int phys;

	/* Count CPUs in the device-tree */
	cpuid = 1;	/* the boot cpu is logical cpu 0 */
	while ((cpus = of_find_node_by_type(cpus, "cpu")) != NULL) {
		phys = ncpus;
		reg = (unsigned int *) get_property(cpus, "reg", &reglen);
		if (reg && reglen >= sizeof(unsigned int))
			/* hmmm, not having a reg property would be bad */
			phys = *reg;
		if (phys != boot_cpuid_phys) {
			set_hard_smp_processor_id(cpuid, phys);
			++cpuid;
		}
	       	++ncpus;
	}

	printk(KERN_INFO "CHRP SMP probe found %d cpus\n", ncpus);

	/* Nothing more to do if less than 2 of them */
	if (ncpus <= 1)
		return 1;

	mpic_request_ipis();

	return ncpus;
}

static void __devinit smp_chrp_kick_cpu(int nr)
{
	*(unsigned long *)KERNELBASE = nr;
	asm volatile("dcbf 0,%0"::"r"(KERNELBASE):"memory");
}

static void __devinit smp_chrp_setup_cpu(int cpu_nr)
{
	mpic_setup_this_cpu();
}

static DEFINE_SPINLOCK(timebase_lock);
static unsigned int timebase_upper = 0, timebase_lower = 0;

void __devinit smp_chrp_give_timebase(void)
{
	spin_lock(&timebase_lock);
	rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
	timebase_upper = get_tbu();
	timebase_lower = get_tbl();
	spin_unlock(&timebase_lock);

	while (timebase_upper || timebase_lower)
		barrier();
	rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
}

void __devinit smp_chrp_take_timebase(void)
{
	while (!(timebase_upper || timebase_lower))
		barrier();
	spin_lock(&timebase_lock);
	set_tb(timebase_upper, timebase_lower);
	timebase_upper = 0;
	timebase_lower = 0;
	spin_unlock(&timebase_lock);
	printk("CPU %i taken timebase\n", smp_processor_id());
}

/* CHRP with openpic */
struct smp_ops_t chrp_smp_ops = {
	.message_pass = smp_mpic_message_pass,
	.probe = smp_chrp_probe,
	.kick_cpu = smp_chrp_kick_cpu,
	.setup_cpu = smp_chrp_setup_cpu,
	.give_timebase = smp_chrp_give_timebase,
	.take_timebase = smp_chrp_take_timebase,
};