arch/arm/mach-msm/hotplug.c

/*
 *  Copyright (C) 2002 ARM Ltd.
 *  All Rights Reserved
 *  Copyright (c) 2011-2013, The Linux Foundation. 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 <linux/cpu.h>

#include <asm/cacheflush.h>
#include <asm/smp_plat.h>
#include <asm/vfp.h>

#include <mach/jtag.h>
#include <mach/msm_rtb.h>

#include "pm.h"
#include "spm.h"

extern volatile int pen_release;

struct msm_hotplug_device {
	struct completion cpu_killed;
	unsigned int warm_boot;
};


static cpumask_t cpu_dying_mask;

static DEFINE_PER_CPU_SHARED_ALIGNED(struct msm_hotplug_device,
			msm_hotplug_devices);

static inline void cpu_enter_lowpower(void)
{
	/* Just flush the cache. Changing the coherency is not yet
	 * available on msm. */
	flush_cache_all();
}

static inline void cpu_leave_lowpower(void)
{
}

static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
{
	/* Just enter wfi for now. TODO: Properly shut off the cpu. */
	for (;;) {

		msm_pm_cpu_enter_lowpower(cpu);
		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
		 *
		 * The trouble is, letting people know about this is not really
		 * possible, since we are currently running incoherently, and
		 * therefore cannot safely call printk() or anything else
		 */
		(*spurious)++;
	}
}

int platform_cpu_kill(unsigned int cpu)
{
	int ret = 0;

	if (cpumask_test_and_clear_cpu(cpu, &cpu_dying_mask))
		ret = msm_pm_wait_cpu_shutdown(cpu);

	return ret ? 0 : 1;
}

/*
 * platform-specific code to shutdown a CPU
 *
 * Called with IRQs disabled
 */
void platform_cpu_die(unsigned int cpu)
{
	int spurious = 0;

	if (unlikely(cpu != smp_processor_id())) {
		pr_crit("%s: running on %u, should be %u\n",
			__func__, smp_processor_id(), cpu);
		BUG();
	}
	complete(&__get_cpu_var(msm_hotplug_devices).cpu_killed);
	/*
	 * we're ready for shutdown now, so do it
	 */
	cpu_enter_lowpower();
	platform_do_lowpower(cpu, &spurious);

	pr_debug("CPU%u: %s: normal wakeup\n", cpu, __func__);
	cpu_leave_lowpower();

	if (spurious)
		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
}

int platform_cpu_disable(unsigned int cpu)
{
	/*
	 * we don't allow CPU 0 to be shutdown (it is still too special
	 * e.g. clock tick interrupts)
	 */
	return cpu == 0 ? -EPERM : 0;
}

#define CPU_SHIFT	0
#define CPU_MASK	0xF
#define CPU_OF(n)	(((n) & CPU_MASK) << CPU_SHIFT)
#define CPUSET_SHIFT	4
#define CPUSET_MASK	0xFFFF
#define CPUSET_OF(n)	(((n) & CPUSET_MASK) << CPUSET_SHIFT)

static int hotplug_rtb_callback(struct notifier_block *nfb,
				unsigned long action, void *hcpu)
{
	/*
	 * Bits [19:4] of the data are the online mask, lower 4 bits are the
	 * cpu number that is being changed. Additionally, changes to the
	 * online_mask that will be done by the current hotplug will be made
	 * even though they aren't necessarily in the online mask yet.
	 *
	 * XXX: This design is limited to supporting at most 16 cpus
	 */
	int this_cpumask = CPUSET_OF(1 << (int)hcpu);
	int cpumask = CPUSET_OF(cpumask_bits(cpu_online_mask)[0]);
	int cpudata = CPU_OF((int)hcpu) | cpumask;

	switch (action & (~CPU_TASKS_FROZEN)) {
	case CPU_STARTING:
		uncached_logk(LOGK_HOTPLUG, (void *)(cpudata | this_cpumask));
		break;
	case CPU_DYING:
		cpumask_set_cpu((unsigned long)hcpu, &cpu_dying_mask);
		uncached_logk(LOGK_HOTPLUG, (void *)(cpudata & ~this_cpumask));
		break;
	default:
		break;
	}

	return NOTIFY_OK;
}
static struct notifier_block hotplug_rtb_notifier = {
	.notifier_call = hotplug_rtb_callback,
};

int msm_platform_secondary_init(unsigned int cpu)
{
	int ret;
	struct msm_hotplug_device *dev = &__get_cpu_var(msm_hotplug_devices);

	if (!dev->warm_boot) {
		dev->warm_boot = 1;
		init_completion(&dev->cpu_killed);
		return 0;
	}
	msm_jtag_restore_state();
#if defined(CONFIG_VFP) && defined (CONFIG_CPU_PM)
	vfp_pm_resume();
#endif
	ret = msm_spm_set_low_power_mode(MSM_SPM_MODE_CLOCK_GATING, false);

	return ret;
}

static int __init init_hotplug(void)
{

	struct msm_hotplug_device *dev = &__get_cpu_var(msm_hotplug_devices);
	init_completion(&dev->cpu_killed);
	return register_hotcpu_notifier(&hotplug_rtb_notifier);
}
early_initcall(init_hotplug);