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>

arch/arm/mach-realview/Makefile

@@ -5,4 +5,3 @@ ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/arch/arm/plat-versatile/inc
 
 obj-y					+= realview-dt.o
 obj-$(CONFIG_SMP)			+= platsmp-dt.o
-obj-$(CONFIG_HOTPLUG_CPU)		+= hotplug.o

arch/arm/mach-realview/hotplug.c

-/*
- *  linux/arch/arm/mach-realview/hotplug.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/kernel.h>
-#include <linux/errno.h>
-#include <linux/smp.h>
-
-#include <asm/cp15.h>
-#include <asm/smp_plat.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, #0x20\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)
-	  : "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, #0x20\n"
-	"	mcr	p15, 0, %0, c1, c0, 1\n"
-	  : "=&r" (v)
-	  : "Ir" (CR_C)
-	  : "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 (;;) {
-		/*
-		 * here's the WFI
-		 */
-		asm(".word	0xe320f003\n"
-		    :
-		    :
-		    : "memory", "cc");
-
-		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 realview_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);
-}

arch/arm/mach-realview/hotplug.h

-void realview_cpu_die(unsigned int cpu);

arch/arm/mach-realview/platsmp-dt.c

@@ -17,7 +17,6 @@
 #include <asm/smp_scu.h>
 
 #include <plat/platsmp.h>
-#include "hotplug.h"
 
 #define REALVIEW_SYS_FLAGSSET_OFFSET	0x30
 
@@ -79,6 +78,13 @@ static void __init realview_smp_prepare_cpus(unsigned int max_cpus)
 		     __pa_symbol(versatile_secondary_startup));
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+static void realview_cpu_die(unsigned int cpu)
+{
+	return versatile_immitation_cpu_die(cpu, 0x20);
+}
+#endif
+
 static const struct smp_operations realview_dt_smp_ops __initconst = {
 	.smp_prepare_cpus	= realview_smp_prepare_cpus,
 	.smp_secondary_init	= versatile_secondary_init,

arch/arm/mach-vexpress/Makefile

@@ -15,6 +15,5 @@ obj-$(CONFIG_ARCH_VEXPRESS_TC2_PM)	+= tc2_pm.o
 CFLAGS_tc2_pm.o				+= -march=armv7-a
 CFLAGS_REMOVE_tc2_pm.o			= -pg
 obj-$(CONFIG_SMP)			+= platsmp.o
-obj-$(CONFIG_HOTPLUG_CPU)		+= hotplug.o
 
 obj-$(CONFIG_ARCH_MPS2)			+= v2m-mps2.o

arch/arm/mach-vexpress/core.h

 bool vexpress_smp_init_ops(void);
 
 extern const struct smp_operations vexpress_smp_dt_ops;
-
-extern void vexpress_cpu_die(unsigned int cpu);

arch/arm/mach-vexpress/platsmp.c

@@ -82,6 +82,13 @@ static void __init vexpress_smp_dt_prepare_cpus(unsigned int max_cpus)
 	vexpress_flags_set(__pa_symbol(versatile_secondary_startup));
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+static void vexpress_cpu_die(unsigned int cpu)
+{
+	versatile_immitation_cpu_die(cpu, 0x40);
+}
+#endif
+
 const struct smp_operations vexpress_smp_dt_ops __initconst = {
 	.smp_prepare_cpus	= vexpress_smp_dt_prepare_cpus,
 	.smp_secondary_init	= versatile_secondary_init,

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

arch/arm/mach-vexpress/hotplug.c → arch/arm/plat-versatile/hotplug.c

 /*
- *  linux/arch/arm/mach-realview/hotplug.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.
+ *
+ * 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>
@@ -15,9 +18,7 @@
 #include <asm/smp_plat.h>
 #include <asm/cp15.h>
 
-#include "core.h"
-
-static inline void cpu_enter_lowpower(void)
+static inline void versatile_immitation_enter_lowpower(unsigned int actrl_mask)
 {
 	unsigned int v;
 
@@ -34,11 +35,11 @@ static inline void cpu_enter_lowpower(void)
 	"	bic	%0, %0, %2\n"
 	"	mcr	p15, 0, %0, c1, c0, 0\n"
 	  : "=&r" (v)
-	  : "r" (0), "Ir" (CR_C), "Ir" (0x40)
+	  : "r" (0), "Ir" (CR_C), "Ir" (actrl_mask)
 	  : "cc");
 }
 
-static inline void cpu_leave_lowpower(void)
+static inline void versatile_immitation_leave_lowpower(unsigned int actrl_mask)
 {
 	unsigned int v;
 
@@ -50,16 +51,18 @@ static inline void cpu_leave_lowpower(void)
 	"	orr	%0, %0, %2\n"
 	"	mcr	p15, 0, %0, c1, c0, 1\n"
 	  : "=&r" (v)
-	  : "Ir" (CR_C), "Ir" (0x40)
+	  : "Ir" (CR_C), "Ir" (actrl_mask)
 	  : "cc");
 }
 
-static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
+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
+	 * code will have already disabled interrupts.
+	 *
+	 * This code should not be used outside Versatile platforms.
 	 */
 	for (;;) {
 		wfi();
@@ -83,25 +86,17 @@ static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
 }
 
 /*
- * platform-specific code to shutdown a CPU
- *
- * Called with IRQs disabled
+ * 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 vexpress_cpu_die(unsigned int cpu)
+void versatile_immitation_cpu_die(unsigned int cpu, unsigned int actrl_mask)
 {
 	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();
+	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);

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);