csky: SMP support

/* SPDX-License-Identifier: GPL-2.0 */

#ifndef __ASM_CSKY_SMP_H

#define __ASM_CSKY_SMP_H

#include <linux/cpumask.h>

#include <linux/irqreturn.h>

#include <linux/threads.h>

#ifdef CONFIG_SMP

void __init setup_smp(void);

void __init setup_smp_ipi(void);

void arch_send_call_function_ipi_mask(struct cpumask *mask);

void arch_send_call_function_single_ipi(int cpu);

void __init set_send_ipi(void (*func)(const struct cpumask *mask), int irq);

#define raw_smp_processor_id()	(current_thread_info()->cpu)

#endif /* CONFIG_SMP */

#endif /* __ASM_CSKY_SMP_H */

// SPDX-License-Identifier: GPL-2.0

#include <linux/module.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/mm.h>

#include <linux/sched.h>

#include <linux/kernel_stat.h>

#include <linux/notifier.h>

#include <linux/cpu.h>

#include <linux/percpu.h>

#include <linux/delay.h>

#include <linux/err.h>

#include <linux/irq.h>

#include <linux/irqdomain.h>

#include <linux/of.h>

#include <linux/sched/task_stack.h>

#include <linux/sched/mm.h>

#include <asm/irq.h>

#include <asm/traps.h>

#include <asm/sections.h>

#include <asm/mmu_context.h>

#include <asm/pgalloc.h>

struct ipi_data_struct {

	unsigned long bits ____cacheline_aligned;

};

static DEFINE_PER_CPU(struct ipi_data_struct, ipi_data);

enum ipi_message_type {

	IPI_EMPTY,

	IPI_RESCHEDULE,

	IPI_CALL_FUNC,

	IPI_MAX

};

static irqreturn_t handle_ipi(int irq, void *dev)

{

	while (true) {

		unsigned long ops;

		ops = xchg(&this_cpu_ptr(&ipi_data)->bits, 0);

		if (ops == 0)

			return IRQ_HANDLED;

		if (ops & (1 << IPI_RESCHEDULE))

			scheduler_ipi();

		if (ops & (1 << IPI_CALL_FUNC))

			generic_smp_call_function_interrupt();

		BUG_ON((ops >> IPI_MAX) != 0);

	}

	return IRQ_HANDLED;

}

static void (*send_arch_ipi)(const struct cpumask *mask);

static int ipi_irq;

void __init set_send_ipi(void (*func)(const struct cpumask *mask), int irq)

{

	if (send_arch_ipi)

		return;

	send_arch_ipi = func;

	ipi_irq = irq;

}

static void

send_ipi_message(const struct cpumask *to_whom, enum ipi_message_type operation)

{

	int i;

	for_each_cpu(i, to_whom)

		set_bit(operation, &per_cpu_ptr(&ipi_data, i)->bits);

	smp_mb();

	send_arch_ipi(to_whom);

}

void arch_send_call_function_ipi_mask(struct cpumask *mask)

{

	send_ipi_message(mask, IPI_CALL_FUNC);

}

void arch_send_call_function_single_ipi(int cpu)

{

	send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC);

}

static void ipi_stop(void *unused)

{

	while (1);

}

void smp_send_stop(void)

{

	on_each_cpu(ipi_stop, NULL, 1);

}

void smp_send_reschedule(int cpu)

{

	send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE);

}

void __init smp_prepare_boot_cpu(void)

{

}

void __init smp_prepare_cpus(unsigned int max_cpus)

{

}

static void __init enable_smp_ipi(void)

{

	enable_percpu_irq(ipi_irq, 0);

}

static int ipi_dummy_dev;

void __init setup_smp_ipi(void)

{

	int rc;

	if (ipi_irq == 0)

		panic("%s IRQ mapping failed\n", __func__);

	rc = request_percpu_irq(ipi_irq, handle_ipi, "IPI Interrupt",

				&ipi_dummy_dev);

	if (rc)

		panic("%s IRQ request failed\n", __func__);

	enable_smp_ipi();

}

void __init setup_smp(void)

{

	struct device_node *node = NULL;

	int cpu;

	while ((node = of_find_node_by_type(node, "cpu"))) {

		if (!of_device_is_available(node))

			continue;

		if (of_property_read_u32(node, "reg", &cpu))

			continue;

		if (cpu >= NR_CPUS)

			continue;

		set_cpu_possible(cpu, true);

		set_cpu_present(cpu, true);

	}

}

extern void _start_smp_secondary(void);

volatile unsigned int secondary_hint;

volatile unsigned int secondary_ccr;

volatile unsigned int secondary_stack;

int __cpu_up(unsigned int cpu, struct task_struct *tidle)

{

	unsigned int tmp;

	secondary_stack = (unsigned int)tidle->stack + THREAD_SIZE;

	secondary_hint = mfcr("cr31");

	secondary_ccr  = mfcr("cr18");

	/*

	 * Because other CPUs are in reset status, we must flush data

	 * from cache to out and secondary CPUs use them in

	 * csky_start_secondary(void)

	 */

	mtcr("cr17", 0x22);

	/* Enable cpu in SMP reset ctrl reg */

	tmp = mfcr("cr<29, 0>");

	tmp |= 1 << cpu;

	mtcr("cr<29, 0>", tmp);

	/* Wait for the cpu online */

	while (!cpu_online(cpu));

	secondary_stack = 0;

	return 0;

}

void __init smp_cpus_done(unsigned int max_cpus)

{

}

int setup_profiling_timer(unsigned int multiplier)

{

	return -EINVAL;

}

void csky_start_secondary(void)

{

	struct mm_struct *mm = &init_mm;

	unsigned int cpu = smp_processor_id();

	mtcr("cr31", secondary_hint);

	mtcr("cr18", secondary_ccr);

	mtcr("vbr", vec_base);

	flush_tlb_all();

	write_mmu_pagemask(0);

	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir);

	TLBMISS_HANDLER_SETUP_PGD_KERNEL(swapper_pg_dir);

	asid_cache(smp_processor_id()) = ASID_FIRST_VERSION;

#ifdef CONFIG_CPU_HAS_FPU

	init_fpu();

#endif

	enable_smp_ipi();

	mmget(mm);

	mmgrab(mm);

	current->active_mm = mm;

	cpumask_set_cpu(cpu, mm_cpumask(mm));

	notify_cpu_starting(cpu);

	set_cpu_online(cpu, true);

	pr_info("CPU%u Online: %s...\n", cpu, __func__);

	local_irq_enable();

	preempt_disable();

	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);

}