Merge branch 'iks_for_rmk' of git://git.linaro.org/people/nico/linux into devel-stable

	  for (multi-)cluster based systems, such as big.LITTLE based

	  systems.

config BIG_LITTLE

	bool "big.LITTLE support (Experimental)"

	depends on CPU_V7 && SMP

	select MCPM

	help

	  This option enables support selections for the big.LITTLE

	  system architecture.

config BL_SWITCHER

	bool "big.LITTLE switcher support"

	depends on BIG_LITTLE && MCPM && HOTPLUG_CPU

	select CPU_PM

	select ARM_CPU_SUSPEND

	help

	  The big.LITTLE "switcher" provides the core functionality to

	  transparently handle transition between a cluster of A15's

	  and a cluster of A7's in a big.LITTLE system.

config BL_SWITCHER_DUMMY_IF

	tristate "Simple big.LITTLE switcher user interface"

	depends on BL_SWITCHER && DEBUG_KERNEL

	help

	  This is a simple and dummy char dev interface to control

	  the big.LITTLE switcher core code.  It is meant for

	  debugging purposes only.

choice

	prompt "Memory split"

	default VMSPLIT_3G

AFLAGS_mcpm_head.o		:= -march=armv7-a

AFLAGS_vlock.o			:= -march=armv7-a

obj-$(CONFIG_TI_PRIV_EDMA)	+= edma.o

obj-$(CONFIG_BL_SWITCHER)	+= bL_switcher.o

obj-$(CONFIG_BL_SWITCHER_DUMMY_IF) += bL_switcher_dummy_if.o

/*

 * 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/sysfs.h>

#include <linux/irqchip/arm-gic.h>

#include <linux/moduleparam.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 ib_mpidr, ib_cpu, ib_cluster;

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

	ib_mpidr = cpu_logical_map(smp_processor_id());

	ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0);

	ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1);

	/*

	 * Our state has been saved at this point.  Let's release our

	 * inbound CPU.

	 */

	mcpm_set_entry_vector(ib_cpu, 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

 */

static unsigned int bL_gic_id[MAX_CPUS_PER_CLUSTER][MAX_NR_CLUSTERS];

static int bL_switcher_cpu_pairing[NR_CPUS];

/*

 * 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, this_cpu, that_cpu;

	unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster;

	struct tick_device *tdev;

	enum clock_event_mode tdev_mode;

	int ret;

	this_cpu = smp_processor_id();

	ob_mpidr = read_mpidr();

	ob_cpu = MPIDR_AFFINITY_LEVEL(ob_mpidr, 0);

	ob_cluster = MPIDR_AFFINITY_LEVEL(ob_mpidr, 1);

	BUG_ON(cpu_logical_map(this_cpu) != ob_mpidr);

	if (new_cluster_id == ob_cluster)

		return 0;

	that_cpu = bL_switcher_cpu_pairing[this_cpu];

	ib_mpidr = cpu_logical_map(that_cpu);

	ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0);

	ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1);

	pr_debug("before switch: CPU %d MPIDR %#x -> %#x\n",

		 this_cpu, ob_mpidr, ib_mpidr);

	/* Close the gate for our entry vectors */

	mcpm_set_entry_vector(ob_cpu, ob_cluster, NULL);

	mcpm_set_entry_vector(ib_cpu, 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(ib_cpu, 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();

	/* redirect GIC's SGIs to our counterpart */

	gic_migrate_target(bL_gic_id[ib_cpu][ib_cluster]);

	/*

	 * 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);

	/* Swap the physical CPUs in the logical map for this logical CPU. */

	cpu_logical_map(this_cpu) = ib_mpidr;

	cpu_logical_map(that_cpu) = ob_mpidr;

	/* 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();

	pr_debug("after switch: CPU %d MPIDR %#x\n", this_cpu, mpidr);

	BUG_ON(mpidr != ib_mpidr);

	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;

	struct completion started;

};

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);

	complete(&t->started);

	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 *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 unsigned int bL_switcher_active;

static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS];

static cpumask_t bL_switcher_removed_logical_cpus;

static void bL_switcher_restore_cpus(void)

{

	int i;

	for_each_cpu(i, &bL_switcher_removed_logical_cpus)

		cpu_up(i);

}

static int bL_switcher_halve_cpus(void)

{

	int i, j, cluster_0, gic_id, ret;

	unsigned int cpu, cluster, mask;

	cpumask_t available_cpus;

	/* First pass to validate what we have */

	mask = 0;

	for_each_online_cpu(i) {

		cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0);

		cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1);

		if (cluster >= 2) {

			pr_err("%s: only dual cluster systems are supported\n", __func__);

			return -EINVAL;

		}

		if (WARN_ON(cpu >= MAX_CPUS_PER_CLUSTER))

			return -EINVAL;

		mask |= (1 << cluster);

	}

	if (mask != 3) {

		pr_err("%s: no CPU pairing possible\n", __func__);

		return -EINVAL;

	}

	/*

	 * Now let's do the pairing.  We match each CPU with another CPU

	 * from a different cluster.  To get a uniform scheduling behavior

	 * without fiddling with CPU topology and compute capacity data,

	 * we'll use logical CPUs initially belonging to the same cluster.

	 */

	memset(bL_switcher_cpu_pairing, -1, sizeof(bL_switcher_cpu_pairing));

	cpumask_copy(&available_cpus, cpu_online_mask);

	cluster_0 = -1;

	for_each_cpu(i, &available_cpus) {

		int match = -1;

		cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1);

		if (cluster_0 == -1)

			cluster_0 = cluster;

		if (cluster != cluster_0)

			continue;

		cpumask_clear_cpu(i, &available_cpus);

		for_each_cpu(j, &available_cpus) {

			cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(j), 1);

			/*

			 * Let's remember the last match to create "odd"

			 * pairings on purpose in order for other code not

			 * to assume any relation between physical and

			 * logical CPU numbers.

			 */

			if (cluster != cluster_0)

				match = j;

		}

		if (match != -1) {

			bL_switcher_cpu_pairing[i] = match;

			cpumask_clear_cpu(match, &available_cpus);

			pr_info("CPU%d paired with CPU%d\n", i, match);

		}

	}

	/*

	 * Now we disable the unwanted CPUs i.e. everything that has no

	 * pairing information (that includes the pairing counterparts).

	 */

	cpumask_clear(&bL_switcher_removed_logical_cpus);

	for_each_online_cpu(i) {

		cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0);

		cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1);

		/* Let's take note of the GIC ID for this CPU */

		gic_id = gic_get_cpu_id(i);

		if (gic_id < 0) {

			pr_err("%s: bad GIC ID for CPU %d\n", __func__, i);

			bL_switcher_restore_cpus();

			return -EINVAL;

		}

		bL_gic_id[cpu][cluster] = gic_id;

		pr_info("GIC ID for CPU %u cluster %u is %u\n",

			cpu, cluster, gic_id);

		if (bL_switcher_cpu_pairing[i] != -1) {

			bL_switcher_cpu_original_cluster[i] = cluster;

			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 bL_switcher_enable(void)

{

	int cpu, ret;

	cpu_hotplug_driver_lock();

	if (bL_switcher_active) {

		cpu_hotplug_driver_unlock();

		return 0;

	}

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

	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);

		init_completion(&t->started);

		t->wanted_cluster = -1;

		t->task = bL_switcher_thread_create(cpu, t);

	}

	bL_switcher_active = 1;

	cpu_hotplug_driver_unlock();

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

	return 0;

}

#ifdef CONFIG_SYSFS

static void bL_switcher_disable(void)

{

	unsigned int cpu, cluster;

	struct bL_thread *t;

	struct task_struct *task;

	cpu_hotplug_driver_lock();

	if (!bL_switcher_active) {

		cpu_hotplug_driver_unlock();

		return;

	}

	bL_switcher_active = 0;

	/*

	 * To deactivate the switcher, we must shut down the switcher

	 * threads to prevent any other requests from being accepted.

	 * Then, if the final cluster for given logical CPU is not the

	 * same as the original one, we'll recreate a switcher thread

	 * just for the purpose of switching the CPU back without any

	 * possibility for interference from external requests.

	 */

	for_each_online_cpu(cpu) {

		t = &bL_threads[cpu];

		task = t->task;

		t->task = NULL;

		if (!task || IS_ERR(task))

			continue;

		kthread_stop(task);

		/* no more switch may happen on this CPU at this point */

		cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);

		if (cluster == bL_switcher_cpu_original_cluster[cpu])

			continue;

		init_completion(&t->started);

		t->wanted_cluster = bL_switcher_cpu_original_cluster[cpu];

		task = bL_switcher_thread_create(cpu, t);

		if (!IS_ERR(task)) {

			wait_for_completion(&t->started);

			kthread_stop(task);

			cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);

			if (cluster == bL_switcher_cpu_original_cluster[cpu])

				continue;

		}

		/* If execution gets here, we're in trouble. */

		pr_crit("%s: unable to restore original cluster for CPU %d\n",

			__func__, cpu);

		pr_crit("%s: CPU %d can't be restored\n",

			__func__, bL_switcher_cpu_pairing[cpu]);

		cpumask_clear_cpu(bL_switcher_cpu_pairing[cpu],

				  &bL_switcher_removed_logical_cpus);

	}

	bL_switcher_restore_cpus();

	cpu_hotplug_driver_unlock();

}

static ssize_t bL_switcher_active_show(struct kobject *kobj,

		struct kobj_attribute *attr, char *buf)

{

	return sprintf(buf, "%u\n", bL_switcher_active);

}

static ssize_t bL_switcher_active_store(struct kobject *kobj,

		struct kobj_attribute *attr, const char *buf, size_t count)

{

	int ret;

	switch (buf[0]) {

	case '0':

		bL_switcher_disable();

		ret = 0;

		break;

	case '1':

		ret = bL_switcher_enable();

		break;

	default:

		ret = -EINVAL;

	}

	return (ret >= 0) ? count : ret;

}

static struct kobj_attribute bL_switcher_active_attr =

	__ATTR(active, 0644, bL_switcher_active_show, bL_switcher_active_store);

static struct attribute *bL_switcher_attrs[] = {

	&bL_switcher_active_attr.attr,

	NULL,

};

static struct attribute_group bL_switcher_attr_group = {

	.attrs = bL_switcher_attrs,

};

static struct kobject *bL_switcher_kobj;

static int __init bL_switcher_sysfs_init(void)

{

	int ret;

	bL_switcher_kobj = kobject_create_and_add("bL_switcher", kernel_kobj);

	if (!bL_switcher_kobj)

		return -ENOMEM;

	ret = sysfs_create_group(bL_switcher_kobj, &bL_switcher_attr_group);

	if (ret)

		kobject_put(bL_switcher_kobj);

	return ret;

}

#endif  /* CONFIG_SYSFS */

/*

 * Veto any CPU hotplug operation on those CPUs we've removed

 * while the switcher is active.

 * We're just not ready to deal with that given the trickery involved.

 */

static int bL_switcher_hotplug_callback(struct notifier_block *nfb,

					unsigned long action, void *hcpu)

{

	if (bL_switcher_active) {

		int pairing = bL_switcher_cpu_pairing[(unsigned long)hcpu];

		switch (action & 0xf) {

		case CPU_UP_PREPARE:

		case CPU_DOWN_PREPARE:

			if (pairing == -1)

				return NOTIFY_BAD;

		}

	}

	return NOTIFY_DONE;

}

static bool no_bL_switcher;

core_param(no_bL_switcher, no_bL_switcher, bool, 0644);

static int __init bL_switcher_init(void)

{

	int ret;

	if (MAX_NR_CLUSTERS != 2) {

		pr_err("%s: only dual cluster systems are supported\n", __func__);

		return -EINVAL;

	}

	cpu_notifier(bL_switcher_hotplug_callback, 0);

	if (!no_bL_switcher) {

		ret = bL_switcher_enable();

		if (ret)

			return ret;

	}

#ifdef CONFIG_SYSFS

	ret = bL_switcher_sysfs_init();

	if (ret)

		pr_err("%s: unable to create sysfs entry\n", __func__);

#endif

	return 0;

}

late_initcall(bL_switcher_init);

/*

 * arch/arm/common/bL_switcher_dummy_if.c -- b.L switcher dummy interface

 *

 * Created by:	Nicolas Pitre, November 2012

 * Copyright:	(C) 2012-2013  Linaro Limited

 *

 * Dummy interface to user space for debugging purpose only.

 *

 * 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/module.h>

#include <linux/fs.h>

#include <linux/miscdevice.h>

#include <asm/uaccess.h>

#include <asm/bL_switcher.h>

static ssize_t bL_switcher_write(struct file *file, const char __user *buf,

			size_t len, loff_t *pos)

{

	unsigned char val[3];

	unsigned int cpu, cluster;

	int ret;

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

	if (len < 3)

		return -EINVAL;

	if (copy_from_user(val, buf, 3))

		return -EFAULT;

	/* format: <cpu#>,<cluster#> */

	if (val[0] < '0' || val[0] > '9' ||

	    val[1] != ',' ||

	    val[2] < '0' || val[2] > '1')

		return -EINVAL;

	cpu = val[0] - '0';

	cluster = val[2] - '0';

	ret = bL_switch_request(cpu, cluster);

	return ret ? : len;

}

static const struct file_operations bL_switcher_fops = {

	.write		= bL_switcher_write,

	.owner	= THIS_MODULE,

};

static struct miscdevice bL_switcher_device = {

	MISC_DYNAMIC_MINOR,

	"b.L_switcher",

	&bL_switcher_fops

};

static int __init bL_switcher_dummy_if_init(void)

{

	return misc_register(&bL_switcher_device);

}

static void __exit bL_switcher_dummy_if_exit(void)

{

	misc_deregister(&bL_switcher_device);

}

module_init(bL_switcher_dummy_if_init);

module_exit(bL_switcher_dummy_if_exit);

/*

 * arch/arm/include/asm/bL_switcher.h

 *

 * Created by:  Nicolas Pitre, April 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.

 */

#ifndef ASM_BL_SWITCHER_H

#define ASM_BL_SWITCHER_H

int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id);

#endif