arch/arm/common/bL_switcher.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  * arch/arm/common/bL_switcher.c -- big.LITTLE cluster switcher core driver
  *
  * Created by:	Nicolas Pitre, March 2012
  * Copyright:	(C) 2012-2013  Linaro Limited
  *
  * 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/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/interrupt.h>
 #include <linux/cpu_pm.h>
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
 #include <linux/kthread.h>
 #include <linux/wait.h>
 #include <linux/clockchips.h>
 #include <linux/hrtimer.h>
 #include <linux/tick.h>
 #include <linux/mm.h>
 #include <linux/string.h>
 #include <linux/irqchip/arm-gic.h>

 #include <asm/smp_plat.h>
 #include <asm/suspend.h>
 #include <asm/mcpm.h>
 #include <asm/bL_switcher.h>


 /*
  * Use our own MPIDR accessors as the generic ones in asm/cputype.h have
  * __attribute_const__ and we don't want the compiler to assume any
  * constness here as the value _does_ change along some code paths.
  */

 static int read_mpidr(void)
 {
 	unsigned int id;
 	asm volatile ("mrc p15, 0, %0, c0, c0, 5" : "=r" (id));
 	return id & MPIDR_HWID_BITMASK;
 }

 /*
  * bL switcher core code.
  */

 static void bL_do_switch(void *_unused)
 {
 	unsigned mpidr, cpuid, clusterid, ob_cluster, ib_cluster;

 	pr_debug("%s\n", __func__);

 	mpidr = read_mpidr();
 	cpuid = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 	clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 	ob_cluster = clusterid;
 	ib_cluster = clusterid ^ 1;

 	/*
 	 * Our state has been saved at this point.  Let's release our
 	 * inbound CPU.
 	 */
 	mcpm_set_entry_vector(cpuid, ib_cluster, cpu_resume);
 	sev();

 	/*
 	 * From this point, we must assume that our counterpart CPU might
 	 * have taken over in its parallel world already, as if execution
 	 * just returned from cpu_suspend().  It is therefore important to
 	 * be very careful not to make any change the other guy is not
 	 * expecting.  This is why we need stack isolation.
 	 *
 	 * Fancy under cover tasks could be performed here.  For now
 	 * we have none.
 	 */

 	/* Let's put ourself down. */
 	mcpm_cpu_power_down();

 	/* should never get here */
 	BUG();
 }

 /*
  * Stack isolation.  To ensure 'current' remains valid, we just use another
  * piece of our thread's stack space which should be fairly lightly used.
  * The selected area starts just above the thread_info structure located
  * at the very bottom of the stack, aligned to a cache line, and indexed
  * with the cluster number.
  */
 #define STACK_SIZE 512
 extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
 static int bL_switchpoint(unsigned long _arg)
 {
 	unsigned int mpidr = read_mpidr();
 	unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 	void *stack = current_thread_info() + 1;
 	stack = PTR_ALIGN(stack, L1_CACHE_BYTES);
 	stack += clusterid * STACK_SIZE + STACK_SIZE;
 	call_with_stack(bL_do_switch, (void *)_arg, stack);
 	BUG();
 }

 /*
  * Generic switcher interface
  */

 /*
  * bL_switch_to - Switch to a specific cluster for the current CPU
  * @new_cluster_id: the ID of the cluster to switch to.
  *
  * This function must be called on the CPU to be switched.
  * Returns 0 on success, else a negative status code.
  */
 static int bL_switch_to(unsigned int new_cluster_id)
 {
 	unsigned int mpidr, cpuid, clusterid, ob_cluster, ib_cluster, this_cpu;
 	struct tick_device *tdev;
 	enum clock_event_mode tdev_mode;
 	int ret;

 	mpidr = read_mpidr();
 	cpuid = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 	clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 	ob_cluster = clusterid;
 	ib_cluster = clusterid ^ 1;

 	if (new_cluster_id == clusterid)
 		return 0;

 	pr_debug("before switch: CPU %d in cluster %d\n", cpuid, clusterid);

 	/* Close the gate for our entry vectors */
 	mcpm_set_entry_vector(cpuid, ob_cluster, NULL);
 	mcpm_set_entry_vector(cpuid, ib_cluster, NULL);

 	/*
 	 * Let's wake up the inbound CPU now in case it requires some delay
 	 * to come online, but leave it gated in our entry vector code.
 	 */
 	ret = mcpm_cpu_power_up(cpuid, ib_cluster);
 	if (ret) {
 		pr_err("%s: mcpm_cpu_power_up() returned %d\n", __func__, ret);
 		return ret;
 	}

 	/*
 	 * From this point we are entering the switch critical zone
 	 * and can't take any interrupts anymore.
 	 */
 	local_irq_disable();
 	local_fiq_disable();

 	this_cpu = smp_processor_id();

 	/* redirect GIC's SGIs to our counterpart */
 	gic_migrate_target(cpuid + ib_cluster*4);

 	/*
 	 * Raise a SGI on the inbound CPU to make sure it doesn't stall
 	 * in a possible WFI, such as in mcpm_power_down().
 	 */
 	arch_send_wakeup_ipi_mask(cpumask_of(this_cpu));

 	tdev = tick_get_device(this_cpu);
 	if (tdev && !cpumask_equal(tdev->evtdev->cpumask, cpumask_of(this_cpu)))
 		tdev = NULL;
 	if (tdev) {
 		tdev_mode = tdev->evtdev->mode;
 		clockevents_set_mode(tdev->evtdev, CLOCK_EVT_MODE_SHUTDOWN);
 	}

 	ret = cpu_pm_enter();

 	/* we can not tolerate errors at this point */
 	if (ret)
 		panic("%s: cpu_pm_enter() returned %d\n", __func__, ret);

 	/* Flip the cluster in the CPU logical map for this CPU. */
 	cpu_logical_map(this_cpu) ^= (1 << 8);

 	/* Let's do the actual CPU switch. */
 	ret = cpu_suspend(0, bL_switchpoint);
 	if (ret > 0)
 		panic("%s: cpu_suspend() returned %d\n", __func__, ret);

 	/* We are executing on the inbound CPU at this point */
 	mpidr = read_mpidr();
 	cpuid = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 	clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 	pr_debug("after switch: CPU %d in cluster %d\n", cpuid, clusterid);
 	BUG_ON(clusterid != ib_cluster);

 	mcpm_cpu_powered_up();

 	ret = cpu_pm_exit();

 	if (tdev) {
 		clockevents_set_mode(tdev->evtdev, tdev_mode);
 		clockevents_program_event(tdev->evtdev,
 					  tdev->evtdev->next_event, 1);
 	}

 	local_fiq_enable();
 	local_irq_enable();

 	if (ret)
 		pr_err("%s exiting with error %d\n", __func__, ret);
 	return ret;
 }

 struct bL_thread {
 	struct task_struct *task;
 	wait_queue_head_t wq;
 	int wanted_cluster;
 };

 static struct bL_thread bL_threads[NR_CPUS];

 static int bL_switcher_thread(void *arg)
 {
 	struct bL_thread *t = arg;
 	struct sched_param param = { .sched_priority = 1 };
 	int cluster;

 	sched_setscheduler_nocheck(current, SCHED_FIFO, &param);

 	do {
 		if (signal_pending(current))
 			flush_signals(current);
 		wait_event_interruptible(t->wq,
 				t->wanted_cluster != -1 ||
 				kthread_should_stop());
 		cluster = xchg(&t->wanted_cluster, -1);
 		if (cluster != -1)
 			bL_switch_to(cluster);
 	} while (!kthread_should_stop());

 	return 0;
 }

 static struct task_struct * __init bL_switcher_thread_create(int cpu, void *arg)
 {
 	struct task_struct *task;

 	task = kthread_create_on_node(bL_switcher_thread, arg,
 				      cpu_to_node(cpu), "kswitcher_%d", cpu);
 	if (!IS_ERR(task)) {
 		kthread_bind(task, cpu);
 		wake_up_process(task);
 	} else
 		pr_err("%s failed for CPU %d\n", __func__, cpu);
 	return task;
 }

 /*
  * bL_switch_request - Switch to a specific cluster for the given CPU
  *
  * @cpu: the CPU to switch
  * @new_cluster_id: the ID of the cluster to switch to.
  *
  * This function causes a cluster switch on the given CPU by waking up
  * the appropriate switcher thread.  This function may or may not return
  * before the switch has occurred.
  */
 int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id)
 {
 	struct bL_thread *t;

 	if (cpu >= ARRAY_SIZE(bL_threads)) {
 		pr_err("%s: cpu %d out of bounds\n", __func__, cpu);
 		return -EINVAL;
 	}

 	t = &bL_threads[cpu];
 	if (IS_ERR(t->task))
 		return PTR_ERR(t->task);
 	if (!t->task)
 		return -ESRCH;

 	t->wanted_cluster = new_cluster_id;
 	wake_up(&t->wq);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(bL_switch_request);

 /*
  * Activation and configuration code.
  */

 static cpumask_t bL_switcher_removed_logical_cpus;

 static void __init bL_switcher_restore_cpus(void)
 {
 	int i;

 	for_each_cpu(i, &bL_switcher_removed_logical_cpus)
 		cpu_up(i);
 }

 static int __init bL_switcher_halve_cpus(void)
 {
 	int cpu, cluster, i, ret;
 	cpumask_t cluster_mask[2], common_mask;

 	cpumask_clear(&bL_switcher_removed_logical_cpus);
 	cpumask_clear(&cluster_mask[0]);
 	cpumask_clear(&cluster_mask[1]);

 	for_each_online_cpu(i) {
 		cpu = cpu_logical_map(i) & 0xff;
 		cluster = (cpu_logical_map(i) >> 8) & 0xff;
 		if (cluster >= 2) {
 			pr_err("%s: only dual cluster systems are supported\n", __func__);
 			return -EINVAL;
 		}
 		cpumask_set_cpu(cpu, &cluster_mask[cluster]);
 	}

 	if (!cpumask_and(&common_mask, &cluster_mask[0], &cluster_mask[1])) {
 		pr_err("%s: no common set of CPUs\n", __func__);
 		return -EINVAL;
 	}

 	for_each_online_cpu(i) {
 		cpu = cpu_logical_map(i) & 0xff;
 		cluster = (cpu_logical_map(i) >> 8) & 0xff;

 		if (cpumask_test_cpu(cpu, &common_mask)) {
 			/*
 			 * We keep only those logical CPUs which number
 			 * is equal to their physical CPU number. This is
 			 * not perfect but good enough for now.
 			 */
 			if (cpu == i)
 				continue;
 		}

 		ret = cpu_down(i);
 		if (ret) {
 			bL_switcher_restore_cpus();
 			return ret;
 		}
 		cpumask_set_cpu(i, &bL_switcher_removed_logical_cpus);
 	}

 	return 0;
 }

 static int __init bL_switcher_init(void)
 {
 	int cpu, ret;

 	pr_info("big.LITTLE switcher initializing\n");

 	if (MAX_NR_CLUSTERS != 2) {
 		pr_err("%s: only dual cluster systems are supported\n", __func__);
 		return -EINVAL;
 	}

 	cpu_hotplug_driver_lock();
 	ret = bL_switcher_halve_cpus();
 	if (ret) {
 		cpu_hotplug_driver_unlock();
 		return ret;
 	}

 	for_each_online_cpu(cpu) {
 		struct bL_thread *t = &bL_threads[cpu];
 		init_waitqueue_head(&t->wq);
 		t->wanted_cluster = -1;
 		t->task = bL_switcher_thread_create(cpu, t);
 	}
 	cpu_hotplug_driver_unlock();

 	pr_info("big.LITTLE switcher initialized\n");
 	return 0;
 }

 late_initcall(bL_switcher_init);
	/*
	* arch/arm/common/bL_switcher.c -- big.LITTLE cluster switcher core driver
	*
	* Created by: Nicolas Pitre, March 2012
	* Copyright: (C) 2012-2013 Linaro Limited
	*
	* 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/init.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/sched.h>
	#include <linux/interrupt.h>
	#include <linux/cpu_pm.h>
	#include <linux/cpu.h>
	#include <linux/cpumask.h>
	#include <linux/kthread.h>
	#include <linux/wait.h>
	#include <linux/clockchips.h>
	#include <linux/hrtimer.h>
	#include <linux/tick.h>
	#include <linux/mm.h>
	#include <linux/string.h>
	#include <linux/irqchip/arm-gic.h>

	#include <asm/smp_plat.h>
	#include <asm/suspend.h>
	#include <asm/mcpm.h>
	#include <asm/bL_switcher.h>


	/*
	* Use our own MPIDR accessors as the generic ones in asm/cputype.h have
	* __attribute_const__ and we don't want the compiler to assume any
	* constness here as the value _does_ change along some code paths.
	*/

	static int read_mpidr(void)
	{
	unsigned int id;
	asm volatile ("mrc p15, 0, %0, c0, c0, 5" : "=r" (id));
	return id & MPIDR_HWID_BITMASK;
	}

	/*
	* bL switcher core code.
	*/

	static void bL_do_switch(void *_unused)
	{
	unsigned mpidr, cpuid, clusterid, ob_cluster, ib_cluster;

	pr_debug("%s\n", __func__);

	mpidr = read_mpidr();
	cpuid = MPIDR_AFFINITY_LEVEL(mpidr, 0);
	clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
	ob_cluster = clusterid;
	ib_cluster = clusterid ^ 1;

	/*
	* Our state has been saved at this point. Let's release our
	* inbound CPU.
	*/
	mcpm_set_entry_vector(cpuid, ib_cluster, cpu_resume);
	sev();

	/*
	* From this point, we must assume that our counterpart CPU might
	* have taken over in its parallel world already, as if execution
	* just returned from cpu_suspend(). It is therefore important to
	* be very careful not to make any change the other guy is not
	* expecting. This is why we need stack isolation.
	*
	* Fancy under cover tasks could be performed here. For now
	* we have none.
	*/

	/* Let's put ourself down. */
	mcpm_cpu_power_down();

	/* should never get here */
	BUG();
	}

	/*
	* Stack isolation. To ensure 'current' remains valid, we just use another
	* piece of our thread's stack space which should be fairly lightly used.
	* The selected area starts just above the thread_info structure located
	* at the very bottom of the stack, aligned to a cache line, and indexed
	* with the cluster number.
	*/
	#define STACK_SIZE 512
	extern void call_with_stack(void (fn)(void ), void arg, void sp);
	static int bL_switchpoint(unsigned long _arg)
	{
	unsigned int mpidr = read_mpidr();
	unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
	void *stack = current_thread_info() + 1;
	stack = PTR_ALIGN(stack, L1_CACHE_BYTES);
	stack += clusterid * STACK_SIZE + STACK_SIZE;
	call_with_stack(bL_do_switch, (void *)_arg, stack);
	BUG();
	}

	/*
	* Generic switcher interface
	*/

	/*
	* bL_switch_to - Switch to a specific cluster for the current CPU
	* @new_cluster_id: the ID of the cluster to switch to.
	*
	* This function must be called on the CPU to be switched.
	* Returns 0 on success, else a negative status code.
	*/
	static int bL_switch_to(unsigned int new_cluster_id)
	{
	unsigned int mpidr, cpuid, clusterid, ob_cluster, ib_cluster, this_cpu;
	struct tick_device *tdev;
	enum clock_event_mode tdev_mode;
	int ret;

	mpidr = read_mpidr();
	cpuid = MPIDR_AFFINITY_LEVEL(mpidr, 0);
	clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
	ob_cluster = clusterid;
	ib_cluster = clusterid ^ 1;

	if (new_cluster_id == clusterid)
	return 0;

	pr_debug("before switch: CPU %d in cluster %d\n", cpuid, clusterid);

	/* Close the gate for our entry vectors */
	mcpm_set_entry_vector(cpuid, ob_cluster, NULL);
	mcpm_set_entry_vector(cpuid, ib_cluster, NULL);

	/*
	* Let's wake up the inbound CPU now in case it requires some delay
	* to come online, but leave it gated in our entry vector code.
	*/
	ret = mcpm_cpu_power_up(cpuid, ib_cluster);
	if (ret) {
	pr_err("%s: mcpm_cpu_power_up() returned %d\n", __func__, ret);
	return ret;
	}

	/*
	* From this point we are entering the switch critical zone
	* and can't take any interrupts anymore.
	*/
	local_irq_disable();
	local_fiq_disable();

	this_cpu = smp_processor_id();

	/* redirect GIC's SGIs to our counterpart */
	gic_migrate_target(cpuid + ib_cluster*4);

	/*
	* Raise a SGI on the inbound CPU to make sure it doesn't stall
	* in a possible WFI, such as in mcpm_power_down().
	*/
	arch_send_wakeup_ipi_mask(cpumask_of(this_cpu));

	tdev = tick_get_device(this_cpu);
	if (tdev && !cpumask_equal(tdev->evtdev->cpumask, cpumask_of(this_cpu)))
	tdev = NULL;
	if (tdev) {
	tdev_mode = tdev->evtdev->mode;
	clockevents_set_mode(tdev->evtdev, CLOCK_EVT_MODE_SHUTDOWN);
	}

	ret = cpu_pm_enter();

	/* we can not tolerate errors at this point */
	if (ret)
	panic("%s: cpu_pm_enter() returned %d\n", __func__, ret);

	/* Flip the cluster in the CPU logical map for this CPU. */
	cpu_logical_map(this_cpu) ^= (1 << 8);

	/* Let's do the actual CPU switch. */
	ret = cpu_suspend(0, bL_switchpoint);
	if (ret > 0)
	panic("%s: cpu_suspend() returned %d\n", __func__, ret);

	/* We are executing on the inbound CPU at this point */
	mpidr = read_mpidr();
	cpuid = MPIDR_AFFINITY_LEVEL(mpidr, 0);
	clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
	pr_debug("after switch: CPU %d in cluster %d\n", cpuid, clusterid);
	BUG_ON(clusterid != ib_cluster);

	mcpm_cpu_powered_up();

	ret = cpu_pm_exit();

	if (tdev) {
	clockevents_set_mode(tdev->evtdev, tdev_mode);
	clockevents_program_event(tdev->evtdev,
	tdev->evtdev->next_event, 1);
	}

	local_fiq_enable();
	local_irq_enable();

	if (ret)
	pr_err("%s exiting with error %d\n", __func__, ret);
	return ret;
	}

	struct bL_thread {
	struct task_struct *task;
	wait_queue_head_t wq;
	int wanted_cluster;
	};

	static struct bL_thread bL_threads[NR_CPUS];

	static int bL_switcher_thread(void *arg)
	{
	struct bL_thread *t = arg;
	struct sched_param param = { .sched_priority = 1 };
	int cluster;

	sched_setscheduler_nocheck(current, SCHED_FIFO, &param);

	do {
	if (signal_pending(current))
	flush_signals(current);
	wait_event_interruptible(t->wq,
	t->wanted_cluster != -1 \|\|
	kthread_should_stop());
	cluster = xchg(&t->wanted_cluster, -1);
	if (cluster != -1)
	bL_switch_to(cluster);
	} while (!kthread_should_stop());

	return 0;
	}

	static struct task_struct * __init bL_switcher_thread_create(int cpu, void *arg)
	{
	struct task_struct *task;

	task = kthread_create_on_node(bL_switcher_thread, arg,
	cpu_to_node(cpu), "kswitcher_%d", cpu);
	if (!IS_ERR(task)) {
	kthread_bind(task, cpu);
	wake_up_process(task);
	} else
	pr_err("%s failed for CPU %d\n", __func__, cpu);
	return task;
	}

	/*
	* bL_switch_request - Switch to a specific cluster for the given CPU
	*
	* @cpu: the CPU to switch
	* @new_cluster_id: the ID of the cluster to switch to.
	*
	* This function causes a cluster switch on the given CPU by waking up
	* the appropriate switcher thread. This function may or may not return
	* before the switch has occurred.
	*/
	int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id)
	{
	struct bL_thread *t;

	if (cpu >= ARRAY_SIZE(bL_threads)) {
	pr_err("%s: cpu %d out of bounds\n", __func__, cpu);
	return -EINVAL;
	}

	t = &bL_threads[cpu];
	if (IS_ERR(t->task))
	return PTR_ERR(t->task);
	if (!t->task)
	return -ESRCH;

	t->wanted_cluster = new_cluster_id;
	wake_up(&t->wq);
	return 0;
	}
	EXPORT_SYMBOL_GPL(bL_switch_request);

	/*
	* Activation and configuration code.
	*/

	static cpumask_t bL_switcher_removed_logical_cpus;

	static void __init bL_switcher_restore_cpus(void)
	{
	int i;

	for_each_cpu(i, &bL_switcher_removed_logical_cpus)
	cpu_up(i);
	}

	static int __init bL_switcher_halve_cpus(void)
	{
	int cpu, cluster, i, ret;
	cpumask_t cluster_mask[2], common_mask;

	cpumask_clear(&bL_switcher_removed_logical_cpus);
	cpumask_clear(&cluster_mask[0]);
	cpumask_clear(&cluster_mask[1]);

	for_each_online_cpu(i) {
	cpu = cpu_logical_map(i) & 0xff;
	cluster = (cpu_logical_map(i) >> 8) & 0xff;
	if (cluster >= 2) {
	pr_err("%s: only dual cluster systems are supported\n", __func__);
	return -EINVAL;
	}
	cpumask_set_cpu(cpu, &cluster_mask[cluster]);
	}

	if (!cpumask_and(&common_mask, &cluster_mask[0], &cluster_mask[1])) {
	pr_err("%s: no common set of CPUs\n", __func__);
	return -EINVAL;
	}

	for_each_online_cpu(i) {
	cpu = cpu_logical_map(i) & 0xff;
	cluster = (cpu_logical_map(i) >> 8) & 0xff;

	if (cpumask_test_cpu(cpu, &common_mask)) {
	/*
	* We keep only those logical CPUs which number
	* is equal to their physical CPU number. This is
	* not perfect but good enough for now.
	*/
	if (cpu == i)
	continue;
	}

	ret = cpu_down(i);
	if (ret) {
	bL_switcher_restore_cpus();
	return ret;
	}
	cpumask_set_cpu(i, &bL_switcher_removed_logical_cpus);
	}

	return 0;
	}

	static int __init bL_switcher_init(void)
	{
	int cpu, ret;

	pr_info("big.LITTLE switcher initializing\n");

	if (MAX_NR_CLUSTERS != 2) {
	pr_err("%s: only dual cluster systems are supported\n", __func__);
	return -EINVAL;
	}

	cpu_hotplug_driver_lock();
	ret = bL_switcher_halve_cpus();
	if (ret) {
	cpu_hotplug_driver_unlock();
	return ret;
	}

	for_each_online_cpu(cpu) {
	struct bL_thread *t = &bL_threads[cpu];
	init_waitqueue_head(&t->wq);
	t->wanted_cluster = -1;
	t->task = bL_switcher_thread_create(cpu, t);
	}
	cpu_hotplug_driver_unlock();

	pr_info("big.LITTLE switcher initialized\n");
	return 0;
	}

	late_initcall(bL_switcher_init);