[ARM SMP] Add Realview MPcore SMP support

Add SMP support for the MPcore tile fitted to the Realview ARM
platform.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 195 insertions, 0 deletions

diff --git a/arch/arm/mach-realview/platsmp.c b/arch/arm/mach-realview/platsmp.c
new file mode 100644
index 000000000000..9844644d0fb5
--- /dev/null
+++ b/arch/arm/mach-realview/platsmp.c
@@ -0,0 +1,195 @@
+/*
+ *  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/smp.h>
+
+#include <asm/cacheflush.h>
+#include <asm/hardware/arm_scu.h>
+#include <asm/hardware.h>
+
+#include "core.h"
+
+extern void realview_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 unsigned int __init get_core_count(void)
+{
+        unsigned int ncores;
+
+        ncores = __raw_readl(IO_ADDRESS(REALVIEW_MPCORE_SCU_BASE) + SCU_CONFIG);
+
+        return (ncores & 0x03) + 1;
+}
+
+static DEFINE_SPINLOCK(boot_lock);
+
+void __cpuinit platform_secondary_init(unsigned int cpu)
+{
+        /*
+         * the primary core may have used a "cross call" soft interrupt
+         * to get this processor out of WFI in the BootMonitor - make
+         * sure that we are no longer being sent this soft interrupt
+         */
+        smp_cross_call_done(cpumask_of_cpu(cpu));
+
+        /*
+         * 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(__io_address(REALVIEW_GIC_CPU_BASE));
+
+        /*
+         * let the primary processor know we're out of the
+         * pen, then head off into the C entry point
+         */
+        pen_release = -1;
+
+        /*
+         * Synchronise with the boot thread.
+         */
+        spin_lock(&boot_lock);
+        spin_unlock(&boot_lock);
+}
+
+int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+        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(cpu));
+
+        timeout = jiffies + (1 * HZ);
+        while (time_before(jiffies, timeout)) {
+                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)
+{
+        extern void secondary_startup(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, then clear the bottom two bits, which is what
+         * BootMonitor is waiting for
+         */
+#if 1
+#define REALVIEW_SYS_FLAGSS_OFFSET 0x30
+        __raw_writel(virt_to_phys(realview_secondary_startup),
+                     (IO_ADDRESS(REALVIEW_SYS_BASE) +
+                      REALVIEW_SYS_FLAGSS_OFFSET));
+#define REALVIEW_SYS_FLAGSC_OFFSET 0x34
+        __raw_writel(3,
+                     (IO_ADDRESS(REALVIEW_SYS_BASE) +
+                      REALVIEW_SYS_FLAGSC_OFFSET));
+#endif
+
+        mb();
+}
+
+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 "
+                       "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 possible/present maps.
+         * cpu_possible_map describes the set of CPUs which may be present
+         * cpu_present_map describes the set of CPUs populated
+         */
+        for (i = 0; i < max_cpus; i++) {
+                cpu_set(i, cpu_possible_map);
+                cpu_set(i, cpu_present_map);
+        }
+
+        /*
+         * Do we need any more CPUs? If so, then 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)
+                poke_milo();
+}