[PATCH 06/10] ARM: zx: add cpu hotplug support

Jun Nie
2015-03-14T11:49:41Z

It's a clone of vexpress cpu hotplug implementation.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Jun Nie <jun.nie@linaro.org>
---
arch/arm/mach-zx/Makefile | 1 +
arch/arm/mach-zx/core.h | 1 +
arch/arm/mach-zx/hotplug.c | 108 +++++++++++++++++++++++++++++++++++++++++++++
arch/arm/mach-zx/platsmp.c | 3 ++
4 files changed, 113 insertions(+)
create mode 100644 arch/arm/mach-zx/hotplug.c

diff --git a/arch/arm/mach-zx/Makefile b/arch/arm/mach-zx/Makefile
index 7c2edf6..a3b386e7 100644
--- a/arch/arm/mach-zx/Makefile
+++ b/arch/arm/mach-zx/Makefile
@@ -1,2 +1,3 @@
obj-$(CONFIG_SOC_ZX296702) += zx296702.o
obj-$(CONFIG_SMP) += headsmp.o platsmp.o
+obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
diff --git a/arch/arm/mach-zx/core.h b/arch/arm/mach-zx/core.h
index 400c7b4..9f6b719 100644
--- a/arch/arm/mach-zx/core.h
+++ b/arch/arm/mach-zx/core.h
@@ -13,5 +13,6 @@
extern struct smp_operations zx_smp_ops;

void zx_secondary_startup(void);
+void zx_cpu_die(unsigned int cpu);

#endif /* __MACH_ZX_CORE_H */
diff --git a/arch/arm/mach-zx/hotplug.c b/arch/arm/mach-zx/hotplug.c
new file mode 100644
index 0000000..1b660e1
--- /dev/null
+++ b/arch/arm/mach-zx/hotplug.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright 2014 Linaro Ltd.
+ * Copyright (C) 2014 ZTE Corporation.
+ *
+ * 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/kernel.h>
+#include <linux/errno.h>
+#include <linux/smp.h>
+
+#include <asm/smp_plat.h>
+#include <asm/cp15.h>
+
+static inline void cpu_enter_lowpower(void)
+{
+ unsigned int v;
+
+ asm volatile(
+ "mcr p15, 0, %1, c7, c5, 0\n"
+ " mcr p15, 0, %1, c7, c10, 4\n"
+ /*
+ * Turn off coherency
+ */
+ " mrc p15, 0, %0, c1, c0, 1\n"
+ " bic %0, %0, %3\n"
+ " mcr p15, 0, %0, c1, c0, 1\n"
+ " mrc p15, 0, %0, c1, c0, 0\n"
+ " bic %0, %0, %2\n"
+ " mcr p15, 0, %0, c1, c0, 0\n"
+ : "=&r" (v)
+ : "r" (0), "Ir" (CR_C), "Ir" (0x40)
+ : "cc");
+}
+
+static inline void cpu_leave_lowpower(void)
+{
+ unsigned int v;
+
+ asm volatile(
+ "mrc p15, 0, %0, c1, c0, 0\n"
+ " orr %0, %0, %1\n"
+ " mcr p15, 0, %0, c1, c0, 0\n"
+ " mrc p15, 0, %0, c1, c0, 1\n"
+ " orr %0, %0, %2\n"
+ " mcr p15, 0, %0, c1, c0, 1\n"
+ : "=&r" (v)
+ : "Ir" (CR_C), "Ir" (0x40)
+ : "cc");
+}
+
+static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
+{
+ /*
+ * there is no power-control hardware on this platform, so all
+ * we can do is put the core into WFI; this is safe as the calling
+ * code will have already disabled interrupts
+ */
+ for (;;) {
+ wfi();
+
+ if (pen_release == cpu_logical_map(cpu)) {
+ /*
+ * OK, proper wakeup, we're done
+ */
+ break;
+ }
+
+ /*
+ * Getting here, means that we have come out of WFI without
+ * having been woken up - this shouldn't happen
+ *
+ * Just note it happening - when we're woken, we can report
+ * its occurrence.
+ */
+ (*spurious)++;
+ }
+}
+
+/*
+ * platform-specific code to shutdown a CPU
+ *
+ * Called with IRQs disabled
+ */
+void __ref zx_cpu_die(unsigned int cpu)
+{
+ int spurious = 0;
+
+ /*
+ * we're ready for shutdown now, so do it
+ */
+ cpu_enter_lowpower();
+ platform_do_lowpower(cpu, &spurious);
+
+ /*
+ * bring this CPU back into the world of cache
+ * coherency, and then restore interrupts
+ */
+ cpu_leave_lowpower();
+
+ if (spurious)
+ pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
+}
diff --git a/arch/arm/mach-zx/platsmp.c b/arch/arm/mach-zx/platsmp.c
index e508a9c..ca157c3 100644
--- a/arch/arm/mach-zx/platsmp.c
+++ b/arch/arm/mach-zx/platsmp.c
@@ -144,4 +144,7 @@ struct smp_operations zx_smp_ops __initdata = {
.smp_prepare_cpus = zx_smp_prepare_cpus,
.smp_secondary_init = zx_secondary_init,
.smp_boot_secondary = zx_boot_secondary,
+#ifdef CONFIG_HOTPLUG_CPU
+ .cpu_die = zx_cpu_die,
+#endif
};
--
1.9.1