smp.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2001, 2002, 2003 Broadcom Corporation
 */

#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/sched/task_stack.h>

#include <asm/mmu_context.h>
#include <asm/io.h>
#include <asm/fw/cfe/cfe_api.h>
#include <asm/sibyte/sb1250.h>
#include <asm/sibyte/sb1250_regs.h>
#include <asm/sibyte/sb1250_int.h>

static void *mailbox_set_regs[] = {
	IOADDR(A_IMR_CPU0_BASE + R_IMR_MAILBOX_SET_CPU),
	IOADDR(A_IMR_CPU1_BASE + R_IMR_MAILBOX_SET_CPU)
};

static void *mailbox_clear_regs[] = {
	IOADDR(A_IMR_CPU0_BASE + R_IMR_MAILBOX_CLR_CPU),
	IOADDR(A_IMR_CPU1_BASE + R_IMR_MAILBOX_CLR_CPU)
};

static void *mailbox_regs[] = {
	IOADDR(A_IMR_CPU0_BASE + R_IMR_MAILBOX_CPU),
	IOADDR(A_IMR_CPU1_BASE + R_IMR_MAILBOX_CPU)
};

/*
 * SMP init and finish on secondary CPUs
 */
void sb1250_smp_init(void)
{
	unsigned int imask = STATUSF_IP4 | STATUSF_IP3 | STATUSF_IP2 |
		STATUSF_IP1 | STATUSF_IP0;

	/* Set interrupt mask, but don't enable */
	change_c0_status(ST0_IM, imask);
}

/*
 * These are routines for dealing with the sb1250 smp capabilities
 * independent of board/firmware
 */

/*
 * Simple enough; everything is set up, so just poke the appropriate mailbox
 * register, and we should be set
 */
static void sb1250_send_ipi_single(int cpu, unsigned int action)
{
	__raw_writeq((((u64)action) << 48), mailbox_set_regs[cpu]);
}

static inline void sb1250_send_ipi_mask(const struct cpumask *mask,
					unsigned int action)
{
	unsigned int i;

	for_each_cpu(i, mask)
		sb1250_send_ipi_single(i, action);
}

/*
 * Code to run on secondary just after probing the CPU
 */
static void sb1250_init_secondary(void)
{
	extern void sb1250_smp_init(void);

	sb1250_smp_init();
}

/*
 * Do any tidying up before marking online and running the idle
 * loop
 */
static void sb1250_smp_finish(void)
{
	extern void sb1250_clockevent_init(void);

	sb1250_clockevent_init();
	local_irq_enable();
}

/*
 * Setup the PC, SP, and GP of a secondary processor and start it
 * running!
 */
static int sb1250_boot_secondary(int cpu, struct task_struct *idle)
{
	int retval;

	retval = cfe_cpu_start(cpu_logical_map(cpu), &smp_bootstrap,
			       __KSTK_TOS(idle),
			       (unsigned long)task_thread_info(idle), 0);
	if (retval != 0)
		printk("cfe_start_cpu(%i) returned %i\n" , cpu, retval);
	return retval;
}

/*
 * Use CFE to find out how many CPUs are available, setting up
 * cpu_possible_mask and the logical/physical mappings.
 * XXXKW will the boot CPU ever not be physical 0?
 *
 * Common setup before any secondaries are started
 */
static void __init sb1250_smp_setup(void)
{
	int i, num;

	init_cpu_possible(cpumask_of(0));
	__cpu_number_map[0] = 0;
	__cpu_logical_map[0] = 0;

	for (i = 1, num = 0; i < NR_CPUS; i++) {
		if (cfe_cpu_stop(i) == 0) {
			set_cpu_possible(i, true);
			__cpu_number_map[i] = ++num;
			__cpu_logical_map[num] = i;
		}
	}
	printk(KERN_INFO "Detected %i available secondary CPU(s)\n", num);
}

static void __init sb1250_prepare_cpus(unsigned int max_cpus)
{
}

const struct plat_smp_ops sb_smp_ops = {
	.send_ipi_single	= sb1250_send_ipi_single,
	.send_ipi_mask		= sb1250_send_ipi_mask,
	.init_secondary		= sb1250_init_secondary,
	.smp_finish		= sb1250_smp_finish,
	.boot_secondary		= sb1250_boot_secondary,
	.smp_setup		= sb1250_smp_setup,
	.prepare_cpus		= sb1250_prepare_cpus,
};

void sb1250_mailbox_interrupt(void)
{
	int cpu = smp_processor_id();
	int irq = K_INT_MBOX_0;
	unsigned int action;

	kstat_incr_irq_this_cpu(irq);
	/* Load the mailbox register to figure out what we're supposed to do */
	action = (____raw_readq(mailbox_regs[cpu]) >> 48) & 0xffff;

	/* Clear the mailbox to clear the interrupt */
	____raw_writeq(((u64)action) << 48, mailbox_clear_regs[cpu]);

	if (action & SMP_RESCHEDULE_YOURSELF)
		scheduler_ipi();

	if (action & SMP_CALL_FUNCTION) {
		irq_enter();
		generic_smp_call_function_interrupt();
		irq_exit();
	}
}