1 files changed, 249 insertions, 0 deletions
diff --git a/arch/hexagon/kernel/smp.c b/arch/hexagon/kernel/smp.c
new file mode 100644
index 000000000..4ba93e593
--- /dev/null
+++ b/arch/hexagon/kernel/smp.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SMP support for Hexagon
+ *
+ * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/sched/mm.h>
+#include <linux/smp.h>
+#include <linux/spinlock.h>
+#include <linux/cpu.h>
+#include <linux/mm_types.h>
+
+#include <asm/time.h>    /*  timer_interrupt  */
+#include <asm/hexagon_vm.h>
+
+#define BASE_IPI_IRQ 26
+
+/*
+ * cpu_possible_mask needs to be filled out prior to setup_per_cpu_areas
+ * (which is prior to any of our smp_prepare_cpu crap), in order to set
+ * up the...  per_cpu areas.
+ */
+
+struct ipi_data {
+	unsigned long bits;
+};
+
+static DEFINE_PER_CPU(struct ipi_data, ipi_data);
+
+static inline void __handle_ipi(unsigned long *ops, struct ipi_data *ipi,
+				int cpu)
+{
+	unsigned long msg = 0;
+	do {
+		msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
+
+		switch (msg) {
+
+		case IPI_TIMER:
+			ipi_timer();
+			break;
+
+		case IPI_CALL_FUNC:
+			generic_smp_call_function_interrupt();
+			break;
+
+		case IPI_CPU_STOP:
+			/*
+			 * call vmstop()
+			 */
+			__vmstop();
+			break;
+
+		case IPI_RESCHEDULE:
+			scheduler_ipi();
+			break;
+		}
+	} while (msg < BITS_PER_LONG);
+}
+
+/*  Used for IPI call from other CPU's to unmask int  */
+void smp_vm_unmask_irq(void *info)
+{
+	__vmintop_locen((long) info);
+}
+
+
+/*
+ * This is based on Alpha's IPI stuff.
+ * Supposed to take (int, void*) as args now.
+ * Specifically, first arg is irq, second is the irq_desc.
+ */
+
+irqreturn_t handle_ipi(int irq, void *desc)
+{
+	int cpu = smp_processor_id();
+	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
+	unsigned long ops;
+
+	while ((ops = xchg(&ipi->bits, 0)) != 0)
+		__handle_ipi(&ops, ipi, cpu);
+	return IRQ_HANDLED;
+}
+
+void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
+{
+	unsigned long flags;
+	unsigned long cpu;
+	unsigned long retval;
+
+	local_irq_save(flags);
+
+	for_each_cpu(cpu, cpumask) {
+		struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
+
+		set_bit(msg, &ipi->bits);
+		/*  Possible barrier here  */
+		retval = __vmintop_post(BASE_IPI_IRQ+cpu);
+
+		if (retval != 0) {
+			printk(KERN_ERR "interrupt %ld not configured?\n",
+				BASE_IPI_IRQ+cpu);
+		}
+	}
+
+	local_irq_restore(flags);
+}
+
+void __init smp_prepare_boot_cpu(void)
+{
+}
+
+/*
+ * interrupts should already be disabled from the VM
+ * SP should already be correct; need to set THREADINFO_REG
+ * to point to current thread info
+ */
+
+void start_secondary(void)
+{
+	unsigned long thread_ptr;
+	unsigned int cpu, irq;
+
+	/*  Calculate thread_info pointer from stack pointer  */
+	__asm__ __volatile__(
+		"%0 = SP;\n"
+		: "=r" (thread_ptr)
+	);
+
+	thread_ptr = thread_ptr & ~(THREAD_SIZE-1);
+
+	__asm__ __volatile__(
+		QUOTED_THREADINFO_REG " = %0;\n"
+		:
+		: "r" (thread_ptr)
+	);
+
+	/*  Set the memory struct  */
+	mmgrab(&init_mm);
+	current->active_mm = &init_mm;
+
+	cpu = smp_processor_id();
+
+	irq = BASE_IPI_IRQ + cpu;
+	if (request_irq(irq, handle_ipi, IRQF_TRIGGER_RISING, "ipi_handler",
+			NULL))
+		pr_err("Failed to request irq %u (ipi_handler)\n", irq);
+
+	/*  Register the clock_event dummy  */
+	setup_percpu_clockdev();
+
+	printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
+
+	notify_cpu_starting(cpu);
+
+	set_cpu_online(cpu, true);
+
+	local_irq_enable();
+
+	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
+}
+
+
+/*
+ * called once for each present cpu
+ * apparently starts up the CPU and then
+ * maintains control until "cpu_online(cpu)" is set.
+ */
+
+int __cpu_up(unsigned int cpu, struct task_struct *idle)
+{
+	struct thread_info *thread = (struct thread_info *)idle->stack;
+	void *stack_start;
+
+	thread->cpu = cpu;
+
+	/*  Boot to the head.  */
+	stack_start =  ((void *) thread) + THREAD_SIZE;
+	__vmstart(start_secondary, stack_start);
+
+	while (!cpu_online(cpu))
+		barrier();
+
+	return 0;
+}
+
+void __init smp_cpus_done(unsigned int max_cpus)
+{
+}
+
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+	int i, irq = BASE_IPI_IRQ;
+
+	/*
+	 * should eventually have some sort of machine
+	 * descriptor that has this stuff
+	 */
+
+	/*  Right now, let's just fake it. */
+	for (i = 0; i < max_cpus; i++)
+		set_cpu_present(i, true);
+
+	/*  Also need to register the interrupts for IPI  */
+	if (max_cpus > 1) {
+		if (request_irq(irq, handle_ipi, IRQF_TRIGGER_RISING,
+				"ipi_handler", NULL))
+			pr_err("Failed to request irq %d (ipi_handler)\n", irq);
+	}
+}
+
+void smp_send_reschedule(int cpu)
+{
+	send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
+}
+
+void smp_send_stop(void)
+{
+	struct cpumask targets;
+	cpumask_copy(&targets, cpu_online_mask);
+	cpumask_clear_cpu(smp_processor_id(), &targets);
+	send_ipi(&targets, IPI_CPU_STOP);
+}
+
+void arch_send_call_function_single_ipi(int cpu)
+{
+	send_ipi(cpumask_of(cpu), IPI_CALL_FUNC);
+}
+
+void arch_send_call_function_ipi_mask(const struct cpumask *mask)
+{
+	send_ipi(mask, IPI_CALL_FUNC);
+}
+
+void smp_start_cpus(void)
+{
+	int i;
+
+	for (i = 0; i < NR_CPUS; i++)
+		set_cpu_possible(i, true);
+}