1 files changed, 517 insertions, 0 deletions
diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c
new file mode 100644
index 000000000..e37ec0548
--- /dev/null
+++ b/arch/parisc/kernel/smp.c
@@ -0,0 +1,517 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+** SMP Support
+**
+** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
+** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
+** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
+** 
+** Lots of stuff stolen from arch/alpha/kernel/smp.c
+** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
+**
+** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
+** -grant (1/12/2001)
+**
+*/
+#include <linux/types.h>
+#include <linux/spinlock.h>
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched/mm.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/smp.h>
+#include <linux/kernel_stat.h>
+#include <linux/mm.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+#include <linux/ftrace.h>
+#include <linux/cpu.h>
+#include <linux/kgdb.h>
+#include <linux/sched/hotplug.h>
+
+#include <linux/atomic.h>
+#include <asm/current.h>
+#include <asm/delay.h>
+#include <asm/tlbflush.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>		/* for CPU_IRQ_REGION and friends */
+#include <asm/mmu_context.h>
+#include <asm/page.h>
+#include <asm/processor.h>
+#include <asm/ptrace.h>
+#include <asm/unistd.h>
+#include <asm/cacheflush.h>
+
+#undef DEBUG_SMP
+#ifdef DEBUG_SMP
+static int smp_debug_lvl = 0;
+#define smp_debug(lvl, printargs...)		\
+		if (lvl >= smp_debug_lvl)	\
+			printk(printargs);
+#else
+#define smp_debug(lvl, ...)	do { } while(0)
+#endif /* DEBUG_SMP */
+
+volatile struct task_struct *smp_init_current_idle_task;
+
+/* track which CPU is booting */
+static volatile int cpu_now_booting;
+
+static DEFINE_PER_CPU(spinlock_t, ipi_lock);
+
+enum ipi_message_type {
+	IPI_NOP=0,
+	IPI_RESCHEDULE=1,
+	IPI_CALL_FUNC,
+	IPI_CPU_START,
+	IPI_CPU_STOP,
+	IPI_CPU_TEST,
+#ifdef CONFIG_KGDB
+	IPI_ENTER_KGDB,
+#endif
+};
+
+
+/********** SMP inter processor interrupt and communication routines */
+
+#undef PER_CPU_IRQ_REGION
+#ifdef PER_CPU_IRQ_REGION
+/* XXX REVISIT Ignore for now.
+**    *May* need this "hook" to register IPI handler
+**    once we have perCPU ExtIntr switch tables.
+*/
+static void
+ipi_init(int cpuid)
+{
+#error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region
+
+	if(cpu_online(cpuid) )
+	{
+		switch_to_idle_task(current);
+	}
+
+	return;
+}
+#endif
+
+
+/*
+** Yoink this CPU from the runnable list... 
+**
+*/
+static void
+halt_processor(void) 
+{
+	/* REVISIT : redirect I/O Interrupts to another CPU? */
+	/* REVISIT : does PM *know* this CPU isn't available? */
+	set_cpu_online(smp_processor_id(), false);
+	local_irq_disable();
+	__pdc_cpu_rendezvous();
+	for (;;)
+		;
+}
+
+
+irqreturn_t __irq_entry
+ipi_interrupt(int irq, void *dev_id) 
+{
+	int this_cpu = smp_processor_id();
+	struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
+	unsigned long ops;
+	unsigned long flags;
+
+	for (;;) {
+		spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
+		spin_lock_irqsave(lock, flags);
+		ops = p->pending_ipi;
+		p->pending_ipi = 0;
+		spin_unlock_irqrestore(lock, flags);
+
+		mb(); /* Order bit clearing and data access. */
+
+		if (!ops)
+		    break;
+
+		while (ops) {
+			unsigned long which = ffz(~ops);
+
+			ops &= ~(1 << which);
+
+			switch (which) {
+			case IPI_NOP:
+				smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
+				break;
+				
+			case IPI_RESCHEDULE:
+				smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
+				inc_irq_stat(irq_resched_count);
+				scheduler_ipi();
+				break;
+
+			case IPI_CALL_FUNC:
+				smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
+				inc_irq_stat(irq_call_count);
+				generic_smp_call_function_interrupt();
+				break;
+
+			case IPI_CPU_START:
+				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
+				break;
+
+			case IPI_CPU_STOP:
+				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
+				halt_processor();
+				break;
+
+			case IPI_CPU_TEST:
+				smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
+				break;
+#ifdef CONFIG_KGDB
+			case IPI_ENTER_KGDB:
+				smp_debug(100, KERN_DEBUG "CPU%d ENTER_KGDB\n", this_cpu);
+				kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
+				break;
+#endif
+			default:
+				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
+					this_cpu, which);
+				return IRQ_NONE;
+			} /* Switch */
+
+			/* before doing more, let in any pending interrupts */
+			if (ops) {
+				local_irq_enable();
+				local_irq_disable();
+			}
+		} /* while (ops) */
+	}
+	return IRQ_HANDLED;
+}
+
+
+static inline void
+ipi_send(int cpu, enum ipi_message_type op)
+{
+	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
+	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
+	unsigned long flags;
+
+	spin_lock_irqsave(lock, flags);
+	p->pending_ipi |= 1 << op;
+	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
+	spin_unlock_irqrestore(lock, flags);
+}
+
+static void
+send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
+{
+	int cpu;
+
+	for_each_cpu(cpu, mask)
+		ipi_send(cpu, op);
+}
+
+static inline void
+send_IPI_single(int dest_cpu, enum ipi_message_type op)
+{
+	BUG_ON(dest_cpu == NO_PROC_ID);
+
+	ipi_send(dest_cpu, op);
+}
+
+static inline void
+send_IPI_allbutself(enum ipi_message_type op)
+{
+	int i;
+
+	preempt_disable();
+	for_each_online_cpu(i) {
+		if (i != smp_processor_id())
+			send_IPI_single(i, op);
+	}
+	preempt_enable();
+}
+
+#ifdef CONFIG_KGDB
+void kgdb_roundup_cpus(void)
+{
+	send_IPI_allbutself(IPI_ENTER_KGDB);
+}
+#endif
+
+inline void 
+smp_send_stop(void)	{ send_IPI_allbutself(IPI_CPU_STOP); }
+
+void 
+smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
+
+void
+smp_send_all_nop(void)
+{
+	send_IPI_allbutself(IPI_NOP);
+}
+
+void arch_send_call_function_ipi_mask(const struct cpumask *mask)
+{
+	send_IPI_mask(mask, IPI_CALL_FUNC);
+}
+
+void arch_send_call_function_single_ipi(int cpu)
+{
+	send_IPI_single(cpu, IPI_CALL_FUNC);
+}
+
+/*
+ * Called by secondaries to update state and initialize CPU registers.
+ */
+static void
+smp_cpu_init(int cpunum)
+{
+	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
+	extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */
+
+	/* Set modes and Enable floating point coprocessor */
+	init_per_cpu(cpunum);
+
+	disable_sr_hashing();
+
+	mb();
+
+	/* Well, support 2.4 linux scheme as well. */
+	if (cpu_online(cpunum))	{
+		extern void machine_halt(void); /* arch/parisc.../process.c */
+
+		printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
+		machine_halt();
+	}
+
+	notify_cpu_starting(cpunum);
+
+	set_cpu_online(cpunum, true);
+
+	/* Initialise the idle task for this CPU */
+	mmgrab(&init_mm);
+	current->active_mm = &init_mm;
+	BUG_ON(current->mm);
+	enter_lazy_tlb(&init_mm, current);
+
+	init_IRQ();   /* make sure no IRQs are enabled or pending */
+	start_cpu_itimer();
+}
+
+
+/*
+ * Slaves start using C here. Indirectly called from smp_slave_stext.
+ * Do what start_kernel() and main() do for boot strap processor (aka monarch)
+ */
+void smp_callin(unsigned long pdce_proc)
+{
+	int slave_id = cpu_now_booting;
+
+#ifdef CONFIG_64BIT
+	WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
+			| PAGE0->mem_pdc) != pdce_proc);
+#endif
+
+	smp_cpu_init(slave_id);
+
+	flush_cache_all_local(); /* start with known state */
+	flush_tlb_all_local(NULL);
+
+	local_irq_enable();  /* Interrupts have been off until now */
+
+	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
+
+	/* NOTREACHED */
+	panic("smp_callin() AAAAaaaaahhhh....\n");
+}
+
+/*
+ * Bring one cpu online.
+ */
+static int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
+{
+	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
+	long timeout;
+
+#ifdef CONFIG_HOTPLUG_CPU
+	int i;
+
+	/* reset irq statistics for this CPU */
+	memset(&per_cpu(irq_stat, cpuid), 0, sizeof(irq_cpustat_t));
+	for (i = 0; i < NR_IRQS; i++) {
+		struct irq_desc *desc = irq_to_desc(i);
+
+		if (desc && desc->kstat_irqs)
+			*per_cpu_ptr(desc->kstat_irqs, cpuid) = 0;
+	}
+#endif
+
+	/* wait until last booting CPU has started. */
+	while (cpu_now_booting)
+		;
+
+	/* Let _start know what logical CPU we're booting
+	** (offset into init_tasks[],cpu_data[])
+	*/
+	cpu_now_booting = cpuid;
+
+	/* 
+	** boot strap code needs to know the task address since
+	** it also contains the process stack.
+	*/
+	smp_init_current_idle_task = idle ;
+	mb();
+
+	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
+
+	/*
+	** This gets PDC to release the CPU from a very tight loop.
+	**
+	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
+	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which 
+	** is executed after receiving the rendezvous signal (an interrupt to 
+	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the 
+	** contents of memory are valid."
+	*/
+	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
+	mb();
+
+	/* 
+	 * OK, wait a bit for that CPU to finish staggering about. 
+	 * Slave will set a bit when it reaches smp_cpu_init().
+	 * Once the "monarch CPU" sees the bit change, it can move on.
+	 */
+	for (timeout = 0; timeout < 10000; timeout++) {
+		if(cpu_online(cpuid)) {
+			/* Which implies Slave has started up */
+			cpu_now_booting = 0;
+			goto alive ;
+		}
+		udelay(100);
+		barrier();
+	}
+	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
+	return -1;
+
+alive:
+	/* Remember the Slave data */
+	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
+		cpuid, timeout * 100);
+	return 0;
+}
+
+void __init smp_prepare_boot_cpu(void)
+{
+	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
+
+	/* Setup BSP mappings */
+	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
+
+	set_cpu_online(bootstrap_processor, true);
+	set_cpu_present(bootstrap_processor, true);
+}
+
+
+
+/*
+** inventory.c:do_inventory() hasn't yet been run and thus we
+** don't 'discover' the additional CPUs until later.
+*/
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		spin_lock_init(&per_cpu(ipi_lock, cpu));
+
+	init_cpu_present(cpumask_of(0));
+}
+
+
+void __init smp_cpus_done(unsigned int cpu_max)
+{
+}
+
+
+int __cpu_up(unsigned int cpu, struct task_struct *tidle)
+{
+	if (cpu_online(cpu))
+		return 0;
+
+	if (num_online_cpus() < nr_cpu_ids &&
+		num_online_cpus() < setup_max_cpus &&
+		smp_boot_one_cpu(cpu, tidle))
+		return -EIO;
+
+	return cpu_online(cpu) ? 0 : -EIO;
+}
+
+/*
+ * __cpu_disable runs on the processor to be shutdown.
+ */
+int __cpu_disable(void)
+{
+#ifdef CONFIG_HOTPLUG_CPU
+	unsigned int cpu = smp_processor_id();
+
+	remove_cpu_topology(cpu);
+
+	/*
+	 * Take this CPU offline.  Once we clear this, we can't return,
+	 * and we must not schedule until we're ready to give up the cpu.
+	 */
+	set_cpu_online(cpu, false);
+
+	/* Find a new timesync master */
+	if (cpu == time_keeper_id) {
+		time_keeper_id = cpumask_first(cpu_online_mask);
+		pr_info("CPU %d is now promoted to time-keeper master\n", time_keeper_id);
+	}
+
+	disable_percpu_irq(IPI_IRQ);
+
+	irq_migrate_all_off_this_cpu();
+
+	flush_cache_all_local();
+	flush_tlb_all_local(NULL);
+
+	/* disable all irqs, including timer irq */
+	local_irq_disable();
+
+	/* wait for next timer irq ... */
+	mdelay(1000/HZ+100);
+
+	/* ... and then clear all pending external irqs */
+	set_eiem(0);
+	mtctl(~0UL, CR_EIRR);
+	mfctl(CR_EIRR);
+	mtctl(0, CR_EIRR);
+#endif
+	return 0;
+}
+
+/*
+ * called on the thread which is asking for a CPU to be shutdown -
+ * waits until shutdown has completed, or it is timed out.
+ */
+void __cpu_die(unsigned int cpu)
+{
+	pdc_cpu_rendezvous_lock();
+
+	if (!cpu_wait_death(cpu, 5)) {
+		pr_crit("CPU%u: cpu didn't die\n", cpu);
+		return;
+	}
+	pr_info("CPU%u: is shutting down\n", cpu);
+
+	/* set task's state to interruptible sleep */
+	set_current_state(TASK_INTERRUPTIBLE);
+	schedule_timeout((IS_ENABLED(CONFIG_64BIT) ? 8:2) * HZ);
+
+	pdc_cpu_rendezvous_unlock();
+}