ARM: tegra: add hotplug support

Hotplug uses the same CPU wfi code as cpuidle to put either cpu
into a slightly lower power mode (clock gated, but still powered).
If the remaining cpu enters LP2, the hotplugged cpu will be power
gated until the remaining cpu is active.

Change-Id: Ib7428709043415dc759136cf91668f6f63fe5a5c
Signed-off-by: Colin Cross <ccross@android.com>

1 files changed, 33 insertions, 89 deletions

diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
index f3294040d357..97d9746cee25 100644
--- a/arch/arm/mach-tegra/hotplug.c
+++ b/arch/arm/mach-tegra/hotplug.c
@@ -1,119 +1,63 @@
 /*
- *  linux/arch/arm/mach-realview/hotplug.c
+ *  linux/arch/arm/mach-tegra/hotplug.c
  *
- *  Copyright (C) 2002 ARM Ltd.
- *  All Rights Reserved
+ *  Copyright (C) 2010 NVIDIA Corporation
  *
  * 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/io.h>
 #include <linux/smp.h>
 
-#include <asm/cacheflush.h>
+#include <asm/cpu_pm.h>
 
-static inline void cpu_enter_lowpower(void)
-{
-	unsigned int v;
+#include <mach/iomap.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");
-}
+#include "sleep.h"
 
-static inline void cpu_leave_lowpower(void)
-{
-	unsigned int v;
+#define CLK_RST_CONTROLLER_CLK_CPU_CMPLX \
+	(IO_ADDRESS(TEGRA_CLK_RESET_BASE) + 0x4c)
+#define CLK_RST_CONTROLLER_RST_CPU_CMPLX_SET \
+	(IO_ADDRESS(TEGRA_CLK_RESET_BASE) + 0x340)
+#define CLK_RST_CONTROLLER_RST_CPU_CMPLX_CLR \
+	(IO_ADDRESS(TEGRA_CLK_RESET_BASE) + 0x344)
 
-	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)
+int platform_cpu_kill(unsigned int cpu)
 {
-	/*
-	 * 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");
+	unsigned int reg;
 
-		/*if (pen_release == cpu) {*/
-			/*
-			 * OK, proper wakeup, we're done
-			 */
-			break;
-		/*}*/
+	do {
+		reg = readl(CLK_RST_CONTROLLER_RST_CPU_CMPLX_SET);
+		cpu_relax();
+	} while (!(reg & (1<<cpu)));
 
-		/*
-		 * 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)++;
-	}
-}
+	reg = readl(CLK_RST_CONTROLLER_CLK_CPU_CMPLX);
+	writel(reg | (1<<(8+cpu)), CLK_RST_CONTROLLER_CLK_CPU_CMPLX);
 
-int platform_cpu_kill(unsigned int cpu)
-{
 	return 1;
 }
 
-/*
- * platform-specific code to shutdown a CPU
- *
- * Called with IRQs disabled
- */
 void platform_cpu_die(unsigned int cpu)
 {
-	int spurious = 0;
+#ifdef DEBUG
+	unsigned int this_cpu = hard_smp_processor_id();
 
-	/*
-	 * we're ready for shutdown now, so do it
-	 */
-	cpu_enter_lowpower();
-	platform_do_lowpower(cpu, &spurious);
+	if (cpu != this_cpu) {
+		printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n",
+			   this_cpu, cpu);
+		BUG();
+	}
+#endif
+
+	tegra_sleep_reset();
 
 	/*
-	 * bring this CPU back into the world of cache
-	 * coherency, and then restore interrupts
+	 * tegra_cpu_suspend can return through tegra_cpu_resume, but that
+	 * should never happen for a hotplugged cpu
 	 */
-	cpu_leave_lowpower();
-
-	if (spurious)
-		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
+	BUG();
 }
 
 int platform_cpu_disable(unsigned int cpu)