[PATCH 1/8] ARM: SCU: Add common routines for secondary CPU bootup

Anton Vorontsov
2010-11-30T17:16:58Z

For CNS3xxx we want to reuse the original ARM approach of booting
secondary CPUs. This patch factors out VExpress' code into a common
file, so that now platform code can call these routines.

Note that this patch doesn't convert VExpress platform to the
generic routines. Plus, there are also a lot of other platforms
that might benefit from this change, but we'll convert them via
separate patches.

Signed-off-by: Anton Vorontsov <avorontsov@mvista.com>
---
arch/arm/include/asm/smp_scu.h | 9 +++
arch/arm/kernel/Makefile | 2 +-
arch/arm/kernel/smp_scu_boot.c | 149 ++++++++++++++++++++++++++++++++++++++++
arch/arm/kernel/smp_scu_head.S | 40 +++++++++++
4 files changed, 199 insertions(+), 1 deletions(-)
create mode 100644 arch/arm/kernel/smp_scu_boot.c
create mode 100644 arch/arm/kernel/smp_scu_head.S

diff --git a/arch/arm/include/asm/smp_scu.h b/arch/arm/include/asm/smp_scu.h
index 2376835..271b252 100644
--- a/arch/arm/include/asm/smp_scu.h
+++ b/arch/arm/include/asm/smp_scu.h
@@ -1,7 +1,16 @@
#ifndef __ASMARM_ARCH_SCU_H
#define __ASMARM_ARCH_SCU_H

+#include <linux/init.h>
+
unsigned int scu_get_core_count(void __iomem *);
void scu_enable(void __iomem *);

+extern volatile int __cpuinitdata scu_pen_release;
+void scu_secondary_startup(void);
+void __cpuinit scu_secondary_init(unsigned int cpu);
+int __cpuinit scu_boot_secondary(unsigned int cpu, struct task_struct *idle);
+void __init scu_init_cpus(void __iomem *scu_base);
+void __init scu_prepare_cpus(void __iomem *scu_base, unsigned int max_cpus);
+
#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 806d5e1..11d946a 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -30,7 +30,7 @@ obj-$(CONFIG_ARTHUR) += arthur.o
obj-$(CONFIG_ISA_DMA) += dma-isa.o
obj-$(CONFIG_PCI) += bios32.o isa.o
obj-$(CONFIG_SMP) += smp.o
-obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o
+obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o smp_scu_head.o smp_scu_boot.o
obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
diff --git a/arch/arm/kernel/smp_scu_boot.c b/arch/arm/kernel/smp_scu_boot.c
new file mode 100644
index 0000000..32a1658
--- /dev/null
+++ b/arch/arm/kernel/smp_scu_boot.c
@@ -0,0 +1,149 @@
+/*
+ * 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/compiler.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+
+#include <asm/smp_scu.h>
+#include <asm/localtimer.h>
+#include <asm/cacheflush.h>
+
+/*
+ * control for which core is the next to come out of the secondary
+ * boot "holding pen"
+ */
+volatile int __cpuinitdata scu_pen_release = -1;
+
+static DEFINE_SPINLOCK(boot_lock);
+
+void __cpuinit scu_secondary_init(unsigned int cpu)
+{
+ /*
+ * let the primary processor know we're out of the
+ * pen, then head off into the C entry point
+ */
+ scu_pen_release = -1;
+ smp_wmb();
+
+ /*
+ * Synchronise with the boot thread.
+ */
+ spin_lock(&boot_lock);
+ spin_unlock(&boot_lock);
+}
+
+int __cpuinit scu_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.
+ */
+ scu_pen_release = cpu;
+ __cpuc_flush_dcache_area((void *)&scu_pen_release,
+ sizeof(scu_pen_release));
+ outer_clean_range(__pa(&scu_pen_release), __pa(&scu_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), 1);
+
+ timeout = jiffies + (1 * HZ);
+ while (time_before(jiffies, timeout)) {
+ smp_rmb();
+ if (scu_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 scu_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 scu_init_cpus(void __iomem *scu_base)
+{
+ unsigned int ncores = scu_base ? scu_get_core_count(scu_base) : 1;
+ unsigned int i;
+
+ /* sanity check */
+ if (ncores == 0) {
+ pr_err("%s: strange CM count of 0? Default to 1\n", __func__);
+ ncores = 1;
+ }
+
+ if (ncores > NR_CPUS) {
+ pr_warn("%s: no. of cores (%d) greater than configured "
+ "maximum of %d - clipping\n", __func__, ncores, NR_CPUS);
+ ncores = NR_CPUS;
+ }
+
+ for (i = 0; i < ncores; i++)
+ set_cpu_possible(i, true);
+}
+
+void __init scu_prepare_cpus(void __iomem *scu_base, 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);
+ }
+}
diff --git a/arch/arm/kernel/smp_scu_head.S b/arch/arm/kernel/smp_scu_head.S
new file mode 100644
index 0000000..e1ceb25
--- /dev/null
+++ b/arch/arm/kernel/smp_scu_head.S
@@ -0,0 +1,40 @@
+/*
+ * 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
+
+/*
+ * SCU 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(scu_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
+#if __LINUX_ARM_ARCH__ >= 7
+ dsb
+#endif
+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 scu_pen_release
--
1.7.0.5