[PATCH] ARM: Add Versatile Express SMP support
Russell King
linux at arm.linux.org.uk
Thu Mar 4 14:11:57 EST 2010
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
---
arch/arm/Kconfig | 5 +-
arch/arm/mach-vexpress/Makefile | 2 +
arch/arm/mach-vexpress/headsmp.S | 39 ++++++
arch/arm/mach-vexpress/include/mach/smp.h | 21 +++
arch/arm/mach-vexpress/localtimer.c | 26 ++++
arch/arm/mach-vexpress/platsmp.c | 190 +++++++++++++++++++++++++++++
6 files changed, 281 insertions(+), 2 deletions(-)
create mode 100644 arch/arm/mach-vexpress/headsmp.S
create mode 100644 arch/arm/mach-vexpress/include/mach/smp.h
create mode 100644 arch/arm/mach-vexpress/localtimer.c
create mode 100644 arch/arm/mach-vexpress/platsmp.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2213d61..b82eb04 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1060,10 +1060,11 @@ source "kernel/time/Kconfig"
config SMP
bool "Symmetric Multi-Processing (EXPERIMENTAL)"
depends on EXPERIMENTAL && (REALVIEW_EB_ARM11MP || REALVIEW_EB_A9MP ||\
- MACH_REALVIEW_PB11MP || MACH_REALVIEW_PBX || ARCH_OMAP4 || ARCH_U8500)
+ MACH_REALVIEW_PB11MP || MACH_REALVIEW_PBX || ARCH_OMAP4 ||\
+ ARCH_U8500 || ARCH_VEXPRESS_CA9X4)
depends on GENERIC_CLOCKEVENTS
select USE_GENERIC_SMP_HELPERS
- select HAVE_ARM_SCU if (ARCH_REALVIEW || ARCH_OMAP4 || ARCH_U8500)
+ select HAVE_ARM_SCU if (ARCH_REALVIEW || ARCH_OMAP4 || ARCH_U8500 || ARCH_VEXPRESS_CA9X4)
help
This enables support for systems with more than one CPU. If you have
a system with only one CPU, like most personal computers, say N. If
diff --git a/arch/arm/mach-vexpress/Makefile b/arch/arm/mach-vexpress/Makefile
index 3c5e160..1b71b77 100644
--- a/arch/arm/mach-vexpress/Makefile
+++ b/arch/arm/mach-vexpress/Makefile
@@ -4,3 +4,5 @@
obj-y := v2m.o
obj-$(CONFIG_ARCH_VEXPRESS_CA9X4) += ct-ca9x4.o
+obj-$(CONFIG_SMP) += platsmp.o headsmp.o
+obj-$(CONFIG_LOCAL_TIMERS) += localtimer.o
diff --git a/arch/arm/mach-vexpress/headsmp.S b/arch/arm/mach-vexpress/headsmp.S
new file mode 100644
index 0000000..de02324
--- /dev/null
+++ b/arch/arm/mach-vexpress/headsmp.S
@@ -0,0 +1,39 @@
+/*
+ * linux/arch/arm/mach-vexpress/headsmp.S
+ *
+ * Copyright (c) 2003 ARM Limited
+ * 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/linkage.h>
+#include <linux/init.h>
+
+ __INIT
+
+/*
+ * Realview specific entry point for secondary CPUs. This provides
+ * a "holding pen" into which all secondary cores are held until we're
+ * ready for them to initialise.
+ */
+ENTRY(vexpress_secondary_startup)
+ mrc p15, 0, r0, c0, c0, 5
+ and r0, r0, #15
+ adr r4, 1f
+ ldmia r4, {r5, r6}
+ sub r4, r4, r5
+ add r6, r6, r4
+pen: ldr r7, [r6]
+ cmp r7, r0
+ bne pen
+
+ /*
+ * we've been released from the holding pen: secondary_stack
+ * should now contain the SVC stack for this core
+ */
+ b secondary_startup
+
+1: .long .
+ .long pen_release
diff --git a/arch/arm/mach-vexpress/include/mach/smp.h b/arch/arm/mach-vexpress/include/mach/smp.h
new file mode 100644
index 0000000..72a9621
--- /dev/null
+++ b/arch/arm/mach-vexpress/include/mach/smp.h
@@ -0,0 +1,21 @@
+#ifndef __MACH_SMP_H
+#define __MACH_SMP_H
+
+#include <asm/hardware/gic.h>
+
+#define hard_smp_processor_id() \
+ ({ \
+ unsigned int cpunum; \
+ __asm__("mrc p15, 0, %0, c0, c0, 5" \
+ : "=r" (cpunum)); \
+ cpunum &= 0x0F; \
+ })
+
+/*
+ * We use IRQ1 as the IPI
+ */
+static inline void smp_cross_call(const struct cpumask *mask)
+{
+ gic_raise_softirq(mask, 1);
+}
+#endif
diff --git a/arch/arm/mach-vexpress/localtimer.c b/arch/arm/mach-vexpress/localtimer.c
new file mode 100644
index 0000000..c0e3a59
--- /dev/null
+++ b/arch/arm/mach-vexpress/localtimer.c
@@ -0,0 +1,26 @@
+/*
+ * linux/arch/arm/mach-vexpress/localtimer.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/smp.h>
+#include <linux/clockchips.h>
+
+#include <asm/smp_twd.h>
+#include <asm/localtimer.h>
+#include <mach/irqs.h>
+
+/*
+ * Setup the local clock events for a CPU.
+ */
+void __cpuinit local_timer_setup(struct clock_event_device *evt)
+{
+ evt->irq = IRQ_LOCALTIMER;
+ twd_timer_setup(evt);
+}
diff --git a/arch/arm/mach-vexpress/platsmp.c b/arch/arm/mach-vexpress/platsmp.c
new file mode 100644
index 0000000..6709706
--- /dev/null
+++ b/arch/arm/mach-vexpress/platsmp.c
@@ -0,0 +1,190 @@
+/*
+ * linux/arch/arm/mach-vexpress/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 <asm/localtimer.h>
+#include <asm/smp_scu.h>
+#include <asm/unified.h>
+
+#include <mach/ct-ca9x4.h>
+#include <mach/motherboard.h>
+#define V2M_PA_CS7 0x10000000
+
+#include "core.h"
+
+extern void vexpress_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 MMIO_P2V(A9_MPCORE_SCU);
+}
+
+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)
+{
+ unsigned long timeout;
+
+ /*
+ * Set synchronisation state between this boot processor
+ * and the secondary one
+ */
+ spin_lock(&boot_lock);
+
+ /*
+ * This is really belt and braces; we hold unintended secondary
+ * CPUs in the holding pen until we're ready for them. However,
+ * since we haven't sent them a soft interrupt, they shouldn't
+ * be there.
+ */
+ pen_release = cpu;
+ __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
+ outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
+
+ /*
+ * Send the secondary CPU a soft interrupt, thereby causing
+ * the boot monitor to read the system wide flags register,
+ * and branch to the address found there.
+ */
+ 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;
+}
+
+/*
+ * 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)
+{
+ void __iomem *scu_base = scu_base_addr();
+ unsigned int i, ncores;
+
+ ncores = scu_base ? scu_get_core_count(scu_base) : 1;
+
+ /* sanity check */
+ if (ncores == 0) {
+ printk(KERN_ERR
+ "vexpress: strange CM count of 0? Default to 1\n");
+
+ ncores = 1;
+ }
+
+ if (ncores > NR_CPUS) {
+ printk(KERN_WARNING
+ "vexpress: no. of cores (%d) greater than configured "
+ "maximum of %d - clipping\n",
+ ncores, NR_CPUS);
+ ncores = NR_CPUS;
+ }
+
+ for (i = 0; i < ncores; i++)
+ set_cpu_possible(i, true);
+}
+
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+ unsigned int ncores = num_possible_cpus();
+ unsigned int cpu = smp_processor_id();
+ int i;
+
+ 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.
+ */
+ 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());
+
+ /*
+ * Write the address of secondary startup into the
+ * system-wide flags register. The boot monitor waits
+ * until it receives a soft interrupt, and then the
+ * secondary CPU branches to this address.
+ */
+ writel(~0, MMIO_P2V(V2M_SYS_FLAGSCLR));
+ writel(BSYM(virt_to_phys(vexpress_secondary_startup)),
+ MMIO_P2V(V2M_SYS_FLAGSSET));
+ }
+}
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