Russell King wrote:

On Fri, Jul 16, 2010 at 05:58:28PM +0900, Kukjin Kim wrote:

quoted

diff --git a/arch/arm/mach-s5pv310/platsmp.c b/arch/arm/mach-

s5pv310/platsmp.c

quoted

new file mode 100644
index 0000000..9325ac2

--- /dev/null
+++ b/arch/arm/mach-s5pv310/platsmp.c

@@ -0,0 +1,212 @@
+/* linux/arch/arm/mach-s5pv310/platsmp.c
+ *
+ * Copyright (c) 2010 Samsung Electronics Co., Ltd.
+ *		http://www.samsung.com/
+ *
+ * Cloned from linux/arch/arm/mach-realview/platsmp.c
+ *
+ *  Copyright (C) 2002 ARM Ltd.
+ *  All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/jiffies.h>
+#include <linux/smp.h>
+#include <linux/io.h>
+
+#include <asm/cacheflush.h>
+#include <mach/hardware.h>
+#include <asm/mach-types.h>
+#include <asm/localtimer.h>
+#include <asm/unified.h>
+
+#include <asm/smp_scu.h>
+#include <mach/regs-clock.h>
+
+extern void s5pv310_secondary_startup(void);
+
+/*
+ * control for which core is the next to come out of the secondary
+ * boot "holding pen"
+ */
+volatile int __cpuinitdata pen_release = -1;
+
+static void __iomem *scu_base_addr(void)
+{
+	return (void __iomem *)(S5P_VA_SCU);
+}
+
+static inline unsigned int get_core_count(void)
+{
+	void __iomem *scu_base = scu_base_addr();
+	if (scu_base)
+		return scu_get_core_count(scu_base);
+	return 1;
+}
+
+static DEFINE_SPINLOCK(boot_lock);
+
+void __cpuinit platform_secondary_init(unsigned int cpu)
+{
+	trace_hardirqs_off();
+
+	/*
+	 * if any interrupts are already enabled for the primary
+	 * core (e.g. timer irq), then they will not have been enabled
+	 * for us: do so
+	 */
+	gic_cpu_init(0, gic_cpu_base_addr);
+
+	/*
+	 * let the primary processor know we're out of the
+	 * pen, then head off into the C entry point
+	 */
+	pen_release = -1;
+	smp_wmb();
+
+	/*
+	 * Synchronise with the boot thread.
+	 */
+	spin_lock(&boot_lock);
+	spin_unlock(&boot_lock);
+}
+
+int __cpuinit boot_secondary(unsigned int cpu, struct task_struct

*idle)

quoted

+{
+	unsigned long timeout;
+
+	/*
+	 * set synchronisation state between this boot processor
+	 * and the secondary one
+	 */
+	spin_lock(&boot_lock);
+
+	/*
+	 * The secondary processor is waiting to be released from
+	 * the holding pen - release it, then wait for it to flag
+	 * that it has been released by resetting pen_release.
+	 *
+	 * Note that "pen_release" is the hardware CPU ID, whereas
+	 * "cpu" is Linux's internal ID.
+	 */
+	pen_release = cpu;
+	flush_cache_all();
+
+	/*
+	 * XXX
+	 *
+	 * This is a later addition to the booting protocol: the
+	 * bootMonitor now puts secondary cores into WFI, so
+	 * poke_milo() no longer gets the cores moving; we need
+	 * to send a soft interrupt to wake the secondary core.
+	 * Use smp_cross_call() for this, since there's little
+	 * point duplicating the code here
+	 */
+	smp_cross_call(cpumask_of(cpu));
+
+	timeout = jiffies + (1 * HZ);
+	while (time_before(jiffies, timeout)) {
+		smp_rmb();
+		if (pen_release == -1)
+			break;
+
+		udelay(10);
+	}
+
+	/*
+	 * now the secondary core is starting up let it run its
+	 * calibrations, then wait for it to finish
+	 */
+	spin_unlock(&boot_lock);
+
+	return pen_release != -1 ? -ENOSYS : 0;
+}
+
+static void __init poke_milo(void)
+{
+	/* nobody is to be released from the pen yet */
+	pen_release = -1;
+
+	/*
+	 * Write the address of secondary startup into the system-wide flags
+	 * register. The BootMonitor waits for this register to become
+	 * non-zero.
+	 */
+	__raw_writel(BSYM(virt_to_phys(s5pv310_secondary_startup)),

S5P_INFORM0);

quoted

+
+	mb();
+}
+
+/*
+ * Initialise the CPU possible map early - this describes the CPUs
+ * which may be present or become present in the system.
+ */
+void __init smp_init_cpus(void)
+{
+	unsigned int i, ncores = get_core_count();
+
+	for (i = 0; i < ncores; i++)
+		set_cpu_possible(i, true);
+}
+
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+	unsigned int ncores = get_core_count();
+	unsigned int cpu = smp_processor_id();
+	int i;
+
+	/* sanity check */
+	if (ncores == 0) {
+		printk(KERN_ERR
+		       "Realview: strange CM count of 0? Default to 1\n");
+
+		ncores = 1;
+	}
+
+	if (ncores > NR_CPUS) {
+		printk(KERN_WARNING
+		       "Realview: no. of cores (%d) greater than configured

"

quoted

+		       "maximum of %d - clipping\n",
+		       ncores, NR_CPUS);
+		ncores = NR_CPUS;
+	}
+
+	smp_store_cpu_info(cpu);
+
+	/*
+	 * are we trying to boot more cores than exist?
+	 */
+	if (max_cpus > ncores)
+		max_cpus = ncores;
+
+	/*
+	 * Initialise the present map, which describes the set of CPUs
+	 * actually populated at the present time.
+	 */
+	for (i = 0; i < max_cpus; i++)
+		set_cpu_present(i, true);
+
+	/*
+	 * Initialise the SCU if there are more than one CPU and let
+	 * them know where to start. Note that, on modern versions of
+	 * MILO, the "poke" doesn't actually do anything until each
+	 * individual core is sent a soft interrupt to get it out of
+	 * WFI
+	 */
+	if (max_cpus > 1) {
+		/*
+		 * Enable the local timer or broadcast device for the
+		 * boot CPU, but only if we have more than one CPU.
+		 */
+		percpu_timer_setup();
+
+		scu_enable(scu_base_addr());
+		poke_milo();
+	}
+}

Please can you model this on the Versatile Express platsmp.c rather than
the Realview platsmp.c ?

Sure, will do it.

The Realview platsmp.c implementation contains a lot of left-overs from
the initial Integrator-based SMP implementation which we really shouldn't
be carrying endlessly forward.

Oh, I didn't know/check about that.
Thanks for your information and inputs.

Thanks.

Best regards,
Kgene.
--
Kukjin Kim [off-list ref], Senior Engineer,
SW Solution Development Team, Samsung Electronics Co., Ltd.