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authorRussell King <rmk+kernel@armlinux.org.uk>2018-12-13 12:54:26 +0000
committerRussell King <rmk+kernel@armlinux.org.uk>2018-12-14 14:44:59 +0000
commit4fb68e12f2cf93176f1b7542c754a4d0413eb290 (patch)
treebd7fb50a09268f2012b1a6be1864641eaf10cc47 /arch/arm/plat-versatile
parent651022382c7f8da46cb4872a545ee1da6d097d2a (diff)
downloadlinux-4fb68e12f2cf93176f1b7542c754a4d0413eb290.tar.bz2
ARM: vexpress/realview: consolidate immitation CPU hotplug
The only difference between the hotplug implementation for Realview and Versatile Express are the bit in the auxiliary control register to disable coherency. Combine the two implentations accounting for that difference. Rename the functions to try to discourage cargo-cult copying of this code. Tested-by: Sudeep Holla <sudeep.holla@arm.com> Acked-by: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/plat-versatile')
-rw-r--r--arch/arm/plat-versatile/Makefile1
-rw-r--r--arch/arm/plat-versatile/hotplug.c103
-rw-r--r--arch/arm/plat-versatile/include/plat/platsmp.h1
3 files changed, 105 insertions, 0 deletions
diff --git a/arch/arm/plat-versatile/Makefile b/arch/arm/plat-versatile/Makefile
index bff3ba889882..b2f0ddfdc4cc 100644
--- a/arch/arm/plat-versatile/Makefile
+++ b/arch/arm/plat-versatile/Makefile
@@ -2,3 +2,4 @@ ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include
obj-$(CONFIG_PLAT_VERSATILE_SCHED_CLOCK) += sched-clock.o
obj-$(CONFIG_SMP) += headsmp.o platsmp.o
+obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
diff --git a/arch/arm/plat-versatile/hotplug.c b/arch/arm/plat-versatile/hotplug.c
new file mode 100644
index 000000000000..e2d3e9035d0f
--- /dev/null
+++ b/arch/arm/plat-versatile/hotplug.c
@@ -0,0 +1,103 @@
+/*
+ * 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.
+ *
+ * This hotplug implementation is _specific_ to the situation found on
+ * ARM development platforms where there is _no_ possibility of actually
+ * taking a CPU offline, resetting it, or otherwise. Real platforms must
+ * NOT copy this code.
+ */
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/smp.h>
+
+#include <asm/smp_plat.h>
+#include <asm/cp15.h>
+
+static inline void versatile_immitation_enter_lowpower(unsigned int actrl_mask)
+{
+ 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" (actrl_mask)
+ : "cc");
+}
+
+static inline void versatile_immitation_leave_lowpower(unsigned int actrl_mask)
+{
+ 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" (actrl_mask)
+ : "cc");
+}
+
+static inline void versatile_immitation_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.
+ *
+ * This code should not be used outside Versatile platforms.
+ */
+ 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.
+ * This code supports immitation-style CPU hotplug for Versatile/Realview/
+ * Versatile Express platforms that are unable to do real CPU hotplug.
+ */
+void versatile_immitation_cpu_die(unsigned int cpu, unsigned int actrl_mask)
+{
+ int spurious = 0;
+
+ versatile_immitation_enter_lowpower(actrl_mask);
+ versatile_immitation_do_lowpower(cpu, &spurious);
+ versatile_immitation_leave_lowpower(actrl_mask);
+
+ if (spurious)
+ pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
+}
diff --git a/arch/arm/plat-versatile/include/plat/platsmp.h b/arch/arm/plat-versatile/include/plat/platsmp.h
index 50fb830192e0..9fff1f241c9e 100644
--- a/arch/arm/plat-versatile/include/plat/platsmp.h
+++ b/arch/arm/plat-versatile/include/plat/platsmp.h
@@ -12,3 +12,4 @@
extern void versatile_secondary_startup(void);
extern void versatile_secondary_init(unsigned int cpu);
extern int versatile_boot_secondary(unsigned int cpu, struct task_struct *idle);
+void versatile_immitation_cpu_die(unsigned int cpu, unsigned int actrl_mask);