drivers/misc/tzdev/tz_hotplug.c

/*
 * Copyright (C) 2015 Samsung Electronics, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/completion.h>
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/kthread.h>
#include <linux/seqlock.h>

#include "sysdep.h"
#include "tz_hotplug.h"
#include "tzdev.h"

static DECLARE_COMPLETION(tzdev_hotplug_comp);

static cpumask_t nwd_cpu_mask;
static unsigned int tzdev_hotplug_run;
static DEFINE_SEQLOCK(tzdev_hotplug_lock);

static int tzdev_hotplug_callback(struct notifier_block *nfb,
			unsigned long action, void *hcpu);

static struct notifier_block tzdev_hotplug_notifier = {
	.notifier_call = tzdev_hotplug_callback,
};

void tzdev_notify_swd_cpu_mask_update(void)
{
	cpumask_t new_cpus_mask;
	unsigned long sk_cpu_mask;

	/* Check cores activation */
	sk_cpu_mask = tzdev_get_swd_cpu_mask();
	cpumask_andnot(&new_cpus_mask, to_cpumask(&sk_cpu_mask), cpu_online_mask);

	if (!cpumask_empty(&new_cpus_mask))
		complete(&tzdev_hotplug_comp);
}

static void tzdev_cpus_up(cpumask_t mask)
{
	int cpu;

	for_each_cpu_mask(cpu, mask)
		if (!cpu_online(cpu)) {
			tzdev_print(0, "tzdev: enable cpu%d\n", cpu);
			cpu_up(cpu);
		}
}

void tzdev_update_nwd_cpu_mask(unsigned long new_mask)
{
	cpumask_t new_cpus_mask;
	unsigned long new_mask_tmp = new_mask;

	write_seqlock(&tzdev_hotplug_lock);

	cpumask_copy(&nwd_cpu_mask, to_cpumask(&new_mask_tmp));

	write_sequnlock(&tzdev_hotplug_lock);

	cpumask_andnot(&new_cpus_mask, to_cpumask(&new_mask_tmp), cpu_online_mask);

	tzdev_cpus_up(new_cpus_mask);
}

static int tzdev_cpu_hotplug(void *data)
{
	int ret, seq;
	cpumask_t new_cpu_mask;
	cpumask_t nwd_cpu_mask_local;
	unsigned long sk_cpu_mask;

	while (tzdev_hotplug_run) {
		ret = wait_for_completion_interruptible(&tzdev_hotplug_comp);

		do {
			seq = read_seqbegin(&tzdev_hotplug_lock);
			cpumask_copy(&nwd_cpu_mask_local, &nwd_cpu_mask);
		} while (read_seqretry(&tzdev_hotplug_lock, seq));

		sk_cpu_mask = tzdev_get_swd_cpu_mask();
		cpumask_or(&new_cpu_mask, to_cpumask(&sk_cpu_mask), &nwd_cpu_mask_local);

		tzdev_cpus_up(new_cpu_mask);
	}

	return 0;
}

static int tzdev_hotplug_callback(struct notifier_block *nfb,
			unsigned long action, void *hcpu)
{
	int seq, set;
	unsigned long sk_cpu_mask;
	cpumask_t swd_cpu_mask;

	if (action == CPU_DOWN_PREPARE) {
		do {
			sk_cpu_mask = tzdev_get_swd_cpu_mask();
			cpumask_copy(&swd_cpu_mask, to_cpumask(&sk_cpu_mask));
			seq = read_seqbegin(&tzdev_hotplug_lock);
			set = cpu_isset((unsigned long)hcpu, swd_cpu_mask);
			set |= cpu_isset((unsigned long)hcpu, nwd_cpu_mask);
		} while (read_seqretry(&tzdev_hotplug_lock, seq));

		if (set) {
			tzdev_print(0, "deny cpu%ld shutdown\n", (unsigned long) hcpu);
			return NOTIFY_BAD;
		}
	}

	return NOTIFY_OK;
}

int tzdev_init_hotplug(void)
{
	void *th;

	/* Register PM notifier */
	register_cpu_notifier(&tzdev_hotplug_notifier);

	tzdev_hotplug_run = 1;
	th = kthread_run(tzdev_cpu_hotplug, NULL, "tzdev_hotplug");
	if (IS_ERR(th)) {
		printk("Can't start tzdev_cpu_hotplug thread\n");
		return PTR_ERR(th);
	}
	return 0;
}

void tzdev_exit_hotplug(void)
{
	tzdev_hotplug_run = 0;
	complete(&tzdev_hotplug_comp);

	unregister_cpu_notifier(&tzdev_hotplug_notifier);
}