patch-2.4.6 linux/arch/mips/kernel/smp.c

• Lines: 403
• Date: Mon Jul 2 13:56:40 2001
• Orig file: v2.4.5/linux/arch/mips/kernel/smp.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.5/linux/arch/mips/kernel/smp.c linux/arch/mips/kernel/smp.c
@@ -0,0 +1,402 @@
+/*
+ *
+ *  arch/mips/kernel/smp.c
+ *
+ *  Copyright (C) 2000 Sibyte
+ * 
+ *  Written by Justin Carlson (carlson@sibyte.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ */ 
+
+
+#include <linux/config.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/threads.h>
+#include <linux/time.h>
+#include <linux/timex.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+
+#include <asm/atomic.h>
+#include <asm/processor.h>
+#include <asm/system.h>
+#include <asm/hardirq.h>
+#include <asm/softirq.h>
+#include <asm/mmu_context.h>
+#include <asm/delay.h>
+#include <asm/smp.h>
+
+/*
+ * This was written with the BRCM12500 MP SOC in mind, but tries to
+ * be generic.  It's modelled on the mips64 smp.c code, which is
+ * derived from Sparc, I'm guessing, which is derived from...
+ * 
+ * It's probably horribly designed for very large ccNUMA systems
+ * as it doesn't take any node clustering into account.  
+*/
+
+
+/* Ze Big Kernel Lock! */
+spinlock_t kernel_flag = SPIN_LOCK_UNLOCKED;
+int smp_threads_ready;  /* Not used */
+int smp_num_cpus;    
+int global_irq_holder = NO_PROC_ID;
+spinlock_t global_irq_lock = SPIN_LOCK_UNLOCKED;
+struct mips_cpuinfo cpu_data[NR_CPUS];
+
+struct smp_fn_call_struct smp_fn_call = 
+{ SPIN_LOCK_UNLOCKED, ATOMIC_INIT(0), NULL, NULL};
+
+static atomic_t cpus_booted = ATOMIC_INIT(0);
+
+
+/* These are defined by the board-specific code. */
+
+/* Cause the function described by smp_fn_call 
+   to be executed on the passed cpu.  When the function
+   has finished, increment the finished field of
+   smp_fn_call. */
+
+void core_call_function(int cpu);
+
+/*
+ * Clear all undefined state in the cpu, set up sp and gp to the passed
+ * values, and kick the cpu into smp_bootstrap(); 
+ */
+void prom_boot_secondary(int cpu, unsigned long sp, unsigned long gp);
+
+/*
+ *  After we've done initial boot, this function is called to allow the
+ *  board code to clean up state, if needed 
+ */
+
+void prom_init_secondary(void);
+
+
+void cpu_idle(void);
+
+/* Do whatever setup needs to be done for SMP at the board level.  Return
+   the number of cpus in the system, including this one */
+int prom_setup_smp(void);
+
+int start_secondary(void *unused)
+{
+	prom_init_secondary();
+	write_32bit_cp0_register(CP0_CONTEXT, smp_processor_id()<<23);
+	current_pgd[smp_processor_id()] = init_mm.pgd;
+	printk("Slave cpu booted successfully\n");
+	atomic_inc(&cpus_booted);
+	cpu_idle();
+	return 0;
+}
+
+void __init smp_boot_cpus(void)
+{
+	int i;
+
+	smp_num_cpus = prom_setup_smp();
+	init_new_context(current, &init_mm);
+	current->processor = 0;
+	atomic_set(&cpus_booted, 1);  /* Master CPU is already booted... */
+	init_idle();
+	for (i = 1; i < smp_num_cpus; i++) {
+		struct task_struct *p;
+		struct pt_regs regs;
+		printk("Starting CPU %d... ", i);
+
+		/* Spawn a new process normally.  Grab a pointer to
+		   its task struct so we can mess with it */
+		do_fork(CLONE_VM|CLONE_PID, 0, &regs, 0);
+		p = init_task.prev_task;
+
+		/* Schedule the first task manually */
+		p->processor = i;
+		p->has_cpu = 1;
+
+		/* Attach to the address space of init_task. */
+		atomic_inc(&init_mm.mm_count);
+		p->active_mm = &init_mm;
+		init_tasks[i] = p;
+
+		del_from_runqueue(p);
+		unhash_process(p);
+
+		prom_boot_secondary(i,
+				    (unsigned long)p + KERNEL_STACK_SIZE - 32,
+				    (unsigned long)p);
+
+#if 0
+
+		/* This is copied from the ip-27 code in the mips64 tree */
+
+		struct task_struct *p;
+
+		/*
+		 * The following code is purely to make sure
+		 * Linux can schedule processes on this slave.
+		 */
+		kernel_thread(0, NULL, CLONE_PID);
+		p = init_task.prev_task;
+		sprintf(p->comm, "%s%d", "Idle", i);
+		init_tasks[i] = p;
+		p->processor = i;
+		p->has_cpu = 1; /* we schedule the first task manually */
+		del_from_runqueue(p);
+		unhash_process(p);
+		/* Attach to the address space of init_task. */
+		atomic_inc(&init_mm.mm_count);
+		p->active_mm = &init_mm;
+		prom_boot_secondary(i, 
+				    (unsigned long)p + KERNEL_STACK_SIZE - 32,
+				    (unsigned long)p);
+#endif
+	}
+
+	/* Wait for everyone to come up */
+	while (atomic_read(&cpus_booted) != smp_num_cpus);
+}
+
+void __init smp_commence(void)
+{
+	/* Not sure what to do here yet */
+}
+
+static void reschedule_this_cpu(void *dummy)
+{
+	current->need_resched = 1;
+}
+
+void FASTCALL(smp_send_reschedule(int cpu))
+{
+	smp_call_function(reschedule_this_cpu, NULL, 0, 0);
+}
+
+
+/*
+ * The caller of this wants the passed function to run on every cpu.  If wait
+ * is set, wait until all cpus have finished the function before returning.
+ * The lock is here to protect the call structure.
+ */
+int smp_call_function (void (*func) (void *info), void *info, int retry, 
+								int wait)
+{
+	int cpus = smp_num_cpus - 1;
+	int i;
+
+	if (smp_num_cpus < 2) {
+		return 0;
+	}
+
+	spin_lock_bh(&smp_fn_call.lock);
+
+	atomic_set(&smp_fn_call.finished, 0);
+	smp_fn_call.fn = func;
+	smp_fn_call.data = info;
+
+	for (i = 0; i < smp_num_cpus; i++) {
+		if (i != smp_processor_id()) {
+			/* Call the board specific routine */
+			core_call_function(i);
+		}
+	}
+
+	if (wait) {
+		while(atomic_read(&smp_fn_call.finished) != cpus) {}
+	}
+
+	spin_unlock_bh(&smp_fn_call.lock);
+	return 0;
+}
+
+void synchronize_irq(void)
+{
+	panic("synchronize_irq");
+}
+
+static void stop_this_cpu(void *dummy)
+{
+	printk("Cpu stopping\n");
+	for (;;);
+}
+
+void smp_send_stop(void)
+{
+	smp_call_function(stop_this_cpu, NULL, 1, 0);
+	smp_num_cpus = 1;
+}
+
+/* Not really SMP stuff ... */
+int setup_profiling_timer(unsigned int multiplier)
+{
+	return 0;
+}
+
+
+/*
+ * Most of this code is take from the mips64 tree (ip27-irq.c).  It's virtually
+ * identical to the i386 implentation in arh/i386/irq.c, with translations for
+ * the interrupt enable bit
+ */
+
+#define MAXCOUNT 		100000000
+#define SYNC_OTHER_CORES(x)	udelay(x+1)
+
+static inline void wait_on_irq(int cpu)
+{
+	int count = MAXCOUNT;
+
+	for (;;) {
+
+		/*
+		 * Wait until all interrupts are gone. Wait
+		 * for bottom half handlers unless we're
+		 * already executing in one..
+		 */
+		if (!irqs_running())
+			if (local_bh_count(cpu) || !spin_is_locked(&global_bh_lock))
+				break;
+
+		/* Duh, we have to loop. Release the lock to avoid deadlocks */
+		spin_unlock(&global_irq_lock);
+
+		for (;;) {
+			if (!--count) {
+				printk("Count spun out.  Huh?\n");
+				count = ~0;
+			}
+			__sti();
+			SYNC_OTHER_CORES(cpu);
+			__cli();
+			if (irqs_running())
+				continue;
+			if (spin_is_locked(&global_irq_lock))
+				continue;
+			if (!local_bh_count(cpu) && spin_is_locked(&global_bh_lock))
+				continue;
+			if (spin_trylock(&global_irq_lock))
+				break;
+		}
+	}
+}
+
+
+static inline void get_irqlock(int cpu)
+{
+	if (!spin_trylock(&global_irq_lock)) {
+		/* do we already hold the lock? */
+		if ((unsigned char) cpu == global_irq_holder)
+			return;
+		/* Uhhuh.. Somebody else got it. Wait.. */
+		spin_lock(&global_irq_lock);
+	}
+	/*
+	 * We also to make sure that nobody else is running
+	 * in an interrupt context.
+	 */
+	wait_on_irq(cpu);
+
+	/*
+	 * Ok, finally..
+	 */
+	global_irq_holder = cpu;
+}
+
+
+/*
+ * A global "cli()" while in an interrupt context
+ * turns into just a local cli(). Interrupts
+ * should use spinlocks for the (very unlikely)
+ * case that they ever want to protect against
+ * each other.
+ *
+ * If we already have local interrupts disabled,
+ * this will not turn a local disable into a
+ * global one (problems with spinlocks: this makes
+ * save_flags+cli+sti usable inside a spinlock).
+ */
+void __global_cli(void)
+{
+	unsigned int flags;
+
+	__save_flags(flags);
+	if (flags & ST0_IE) {
+		int cpu = smp_processor_id();
+		__cli();
+		if (!local_irq_count(cpu))
+			get_irqlock(cpu);
+	}
+}
+
+void __global_sti(void)
+{
+	int cpu = smp_processor_id();
+
+	if (!local_irq_count(cpu))
+		release_irqlock(cpu);
+	__sti();
+}
+
+/*
+ * SMP flags value to restore to:
+ * 0 - global cli
+ * 1 - global sti
+ * 2 - local cli
+ * 3 - local sti
+ */
+unsigned long __global_save_flags(void)
+{
+	int retval;
+	int local_enabled;
+	unsigned long flags;
+	int cpu = smp_processor_id();
+
+	__save_flags(flags);
+	local_enabled = (flags & ST0_IE);
+	/* default to local */
+	retval = 2 + local_enabled;
+
+	/* check for global flags if we're not in an interrupt */
+	if (!local_irq_count(cpu)) {
+		if (local_enabled)
+			retval = 1;
+		if (global_irq_holder == cpu)
+			retval = 0;
+	}
+
+	return retval;
+}
+
+void __global_restore_flags(unsigned long flags)
+{
+	switch (flags) {
+		case 0:
+			__global_cli();
+			break;
+		case 1:
+			__global_sti();
+			break;
+		case 2:
+			__cli();
+			break;
+		case 3:
+			__sti();
+			break;
+		default:
+			printk("global_restore_flags: %08lx\n", flags);
+	}
+}