ARM: tegra30: add CPU hotplug support

Hotplug function put CPUs in offline or online state at runtime.
When the CPU been put in the offline state, it was been clock and
power gated. Except primary CPU other CPUs can be hotplugged.

Based on the work by:
Scott Williams <scwilliams@nvidia.com>
Colin Cross <ccross@android.com>
Gary King <gking@nvidia.com>

Signed-off-by: Joseph Lo <josephl@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

1 files changed, 24 insertions, 86 deletions

diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
index d8dc9ddd6d18..be92d4c07606 100644
--- a/arch/arm/mach-tegra/hotplug.c
+++ b/arch/arm/mach-tegra/hotplug.c
@@ -1,91 +1,23 @@
 /*
- *  linux/arch/arm/mach-realview/hotplug.c
  *
  *  Copyright (C) 2002 ARM Ltd.
  *  All Rights Reserved
+ *  Copyright (c) 2010, 2012 NVIDIA Corporation. 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/cacheflush.h>
-#include <asm/cp15.h>
+#include <asm/smp_plat.h>
 
-static inline void cpu_enter_lowpower(void)
-{
-	unsigned int v;
+#include "sleep.h"
+#include "tegra_cpu_car.h"
 
-	flush_cache_all();
-	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) {*/
-			/*
-			 * 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)++;
-	}
-}
+static void (*tegra_hotplug_shutdown)(void);
 
 int platform_cpu_kill(unsigned int cpu)
 {
@@ -99,22 +31,20 @@ int platform_cpu_kill(unsigned int cpu)
  */
 void platform_cpu_die(unsigned int cpu)
 {
-	int spurious = 0;
+	cpu = cpu_logical_map(cpu);
 
-	/*
-	 * we're ready for shutdown now, so do it
-	 */
-	cpu_enter_lowpower();
-	platform_do_lowpower(cpu, &spurious);
+	/* Flush the L1 data cache. */
+	flush_cache_all();
 
-	/*
-	 * bring this CPU back into the world of cache
-	 * coherency, and then restore interrupts
-	 */
-	cpu_leave_lowpower();
+	/* Shut down the current CPU. */
+	tegra_hotplug_shutdown();
+
+	/* Clock gate the CPU */
+	tegra_wait_cpu_in_reset(cpu);
+	tegra_disable_cpu_clock(cpu);
 
-	if (spurious)
-		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
+	/* Should never return here. */
+	BUG();
 }
 
 int platform_cpu_disable(unsigned int cpu)
@@ -125,3 +55,11 @@ int platform_cpu_disable(unsigned int cpu)
 	 */
 	return cpu == 0 ? -EPERM : 0;
 }
+
+#ifdef CONFIG_ARCH_TEGRA_3x_SOC
+extern void tegra30_hotplug_shutdown(void);
+void __init tegra30_hotplug_init(void)
+{
+	tegra_hotplug_shutdown = tegra30_hotplug_shutdown;
+}
+#endif