drivers/gpu/host1x/syncpt.c - linux/kernel/git/gregkh/char-misc - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Tegra host1x Syncpoints
  *
  * Copyright (c) 2010-2015, NVIDIA Corporation.
  */

 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/slab.h>

 #include <trace/events/host1x.h>

 #include "syncpt.h"
 #include "dev.h"
 #include "intr.h"
 #include "debug.h"

 #define SYNCPT_CHECK_PERIOD (2 * HZ)
 #define MAX_STUCK_CHECK_COUNT 15

 static struct host1x_syncpt_base *
 host1x_syncpt_base_request(struct host1x *host)
 {
 	struct host1x_syncpt_base *bases = host->bases;
 	unsigned int i;

 	for (i = 0; i < host->info->nb_bases; i++)
 		if (!bases[i].requested)
 			break;

 	if (i >= host->info->nb_bases)
 		return NULL;

 	bases[i].requested = true;
 	return &bases[i];
 }

 static void host1x_syncpt_base_free(struct host1x_syncpt_base *base)
 {
 	if (base)
 		base->requested = false;
 }

 static struct host1x_syncpt *host1x_syncpt_alloc(struct host1x *host,
 						 struct host1x_client *client,
 						 unsigned long flags)
 {
 	struct host1x_syncpt *sp = host->syncpt;
 	unsigned int i;
 	char *name;

 	mutex_lock(&host->syncpt_mutex);

 	for (i = 0; i < host->info->nb_pts && sp->name; i++, sp++)
 		;

 	if (i >= host->info->nb_pts)
 		goto unlock;

 	if (flags & HOST1X_SYNCPT_HAS_BASE) {
 		sp->base = host1x_syncpt_base_request(host);
 		if (!sp->base)
 			goto unlock;
 	}

 	name = kasprintf(GFP_KERNEL, "%02u-%s", sp->id,
 			 client ? dev_name(client->dev) : NULL);
 	if (!name)
 		goto free_base;

 	sp->client = client;
 	sp->name = name;

 	if (flags & HOST1X_SYNCPT_CLIENT_MANAGED)
 		sp->client_managed = true;
 	else
 		sp->client_managed = false;

 	mutex_unlock(&host->syncpt_mutex);
 	return sp;

 free_base:
 	host1x_syncpt_base_free(sp->base);
 	sp->base = NULL;
 unlock:
 	mutex_unlock(&host->syncpt_mutex);
 	return NULL;
 }

 /**
  * host1x_syncpt_id() - retrieve syncpoint ID
  * @sp: host1x syncpoint
  *
  * Given a pointer to a struct host1x_syncpt, retrieves its ID. This ID is
  * often used as a value to program into registers that control how hardware
  * blocks interact with syncpoints.
  */
 u32 host1x_syncpt_id(struct host1x_syncpt *sp)
 {
 	return sp->id;
 }
 EXPORT_SYMBOL(host1x_syncpt_id);

 /**
  * host1x_syncpt_incr_max() - update the value sent to hardware
  * @sp: host1x syncpoint
  * @incrs: number of increments
  */
 u32 host1x_syncpt_incr_max(struct host1x_syncpt *sp, u32 incrs)
 {
 	return (u32)atomic_add_return(incrs, &sp->max_val);
 }
 EXPORT_SYMBOL(host1x_syncpt_incr_max);

  /*
  * Write cached syncpoint and waitbase values to hardware.
  */
 void host1x_syncpt_restore(struct host1x *host)
 {
 	struct host1x_syncpt *sp_base = host->syncpt;
 	unsigned int i;

 	for (i = 0; i < host1x_syncpt_nb_pts(host); i++)
 		host1x_hw_syncpt_restore(host, sp_base + i);

 	for (i = 0; i < host1x_syncpt_nb_bases(host); i++)
 		host1x_hw_syncpt_restore_wait_base(host, sp_base + i);

 	wmb();
 }

 /*
  * Update the cached syncpoint and waitbase values by reading them
  * from the registers.
   */
 void host1x_syncpt_save(struct host1x *host)
 {
 	struct host1x_syncpt *sp_base = host->syncpt;
 	unsigned int i;

 	for (i = 0; i < host1x_syncpt_nb_pts(host); i++) {
 		if (host1x_syncpt_client_managed(sp_base + i))
 			host1x_hw_syncpt_load(host, sp_base + i);
 		else
 			WARN_ON(!host1x_syncpt_idle(sp_base + i));
 	}

 	for (i = 0; i < host1x_syncpt_nb_bases(host); i++)
 		host1x_hw_syncpt_load_wait_base(host, sp_base + i);
 }

 /*
  * Updates the cached syncpoint value by reading a new value from the hardware
  * register
  */
 u32 host1x_syncpt_load(struct host1x_syncpt *sp)
 {
 	u32 val;

 	val = host1x_hw_syncpt_load(sp->host, sp);
 	trace_host1x_syncpt_load_min(sp->id, val);

 	return val;
 }

 /*
  * Get the current syncpoint base
  */
 u32 host1x_syncpt_load_wait_base(struct host1x_syncpt *sp)
 {
 	host1x_hw_syncpt_load_wait_base(sp->host, sp);

 	return sp->base_val;
 }

 /**
  * host1x_syncpt_incr() - increment syncpoint value from CPU, updating cache
  * @sp: host1x syncpoint
  */
 int host1x_syncpt_incr(struct host1x_syncpt *sp)
 {
 	return host1x_hw_syncpt_cpu_incr(sp->host, sp);
 }
 EXPORT_SYMBOL(host1x_syncpt_incr);

 /*
  * Updated sync point form hardware, and returns true if syncpoint is expired,
  * false if we may need to wait
  */
 static bool syncpt_load_min_is_expired(struct host1x_syncpt *sp, u32 thresh)
 {
 	host1x_hw_syncpt_load(sp->host, sp);

 	return host1x_syncpt_is_expired(sp, thresh);
 }

 /**
  * host1x_syncpt_wait() - wait for a syncpoint to reach a given value
  * @sp: host1x syncpoint
  * @thresh: threshold
  * @timeout: maximum time to wait for the syncpoint to reach the given value
  * @value: return location for the syncpoint value
  */
 int host1x_syncpt_wait(struct host1x_syncpt *sp, u32 thresh, long timeout,
 		       u32 *value)
 {
 	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 	void *ref;
 	struct host1x_waitlist *waiter;
 	int err = 0, check_count = 0;
 	u32 val;

 	if (value)
 		*value = 0;

 	/* first check cache */
 	if (host1x_syncpt_is_expired(sp, thresh)) {
 		if (value)
 			*value = host1x_syncpt_load(sp);

 		return 0;
 	}

 	/* try to read from register */
 	val = host1x_hw_syncpt_load(sp->host, sp);
 	if (host1x_syncpt_is_expired(sp, thresh)) {
 		if (value)
 			*value = val;

 		goto done;
 	}

 	if (!timeout) {
 		err = -EAGAIN;
 		goto done;
 	}

 	/* allocate a waiter */
 	waiter = kzalloc(sizeof(*waiter), GFP_KERNEL);
 	if (!waiter) {
 		err = -ENOMEM;
 		goto done;
 	}

 	/* schedule a wakeup when the syncpoint value is reached */
 	err = host1x_intr_add_action(sp->host, sp, thresh,
 				     HOST1X_INTR_ACTION_WAKEUP_INTERRUPTIBLE,
 				     &wq, waiter, &ref);
 	if (err)
 		goto done;

 	err = -EAGAIN;
 	/* Caller-specified timeout may be impractically low */
 	if (timeout < 0)
 		timeout = LONG_MAX;

 	/* wait for the syncpoint, or timeout, or signal */
 	while (timeout) {
 		long check = min_t(long, SYNCPT_CHECK_PERIOD, timeout);
 		int remain;

 		remain = wait_event_interruptible_timeout(wq,
 				syncpt_load_min_is_expired(sp, thresh),
 				check);
 		if (remain > 0 || host1x_syncpt_is_expired(sp, thresh)) {
 			if (value)
 				*value = host1x_syncpt_load(sp);

 			err = 0;

 			break;
 		}

 		if (remain < 0) {
 			err = remain;
 			break;
 		}

 		timeout -= check;

 		if (timeout && check_count <= MAX_STUCK_CHECK_COUNT) {
 			dev_warn(sp->host->dev,
 				"%s: syncpoint id %u (%s) stuck waiting %d, timeout=%ld\n",
 				 current->comm, sp->id, sp->name,
 				 thresh, timeout);

 			host1x_debug_dump_syncpts(sp->host);

 			if (check_count == MAX_STUCK_CHECK_COUNT)
 				host1x_debug_dump(sp->host);

 			check_count++;
 		}
 	}

 	host1x_intr_put_ref(sp->host, sp->id, ref);

 done:
 	return err;
 }
 EXPORT_SYMBOL(host1x_syncpt_wait);

 /*
  * Returns true if syncpoint is expired, false if we may need to wait
  */
 bool host1x_syncpt_is_expired(struct host1x_syncpt *sp, u32 thresh)
 {
 	u32 current_val;
 	u32 future_val;

 	smp_rmb();

 	current_val = (u32)atomic_read(&sp->min_val);
 	future_val = (u32)atomic_read(&sp->max_val);

 	/* Note the use of unsigned arithmetic here (mod 1<<32).
 	 *
 	 * c = current_val = min_val	= the current value of the syncpoint.
 	 * t = thresh			= the value we are checking
 	 * f = future_val  = max_val	= the value c will reach when all
 	 *				  outstanding increments have completed.
 	 *
 	 * Note that c always chases f until it reaches f.
 	 *
 	 * Dtf = (f - t)
 	 * Dtc = (c - t)
 	 *
 	 *  Consider all cases:
 	 *
 	 *	A) .....c..t..f.....	Dtf < Dtc	need to wait
 	 *	B) .....c.....f..t..	Dtf > Dtc	expired
 	 *	C) ..t..c.....f.....	Dtf > Dtc	expired	   (Dct very large)
 	 *
 	 *  Any case where f==c: always expired (for any t).	Dtf == Dcf
 	 *  Any case where t==c: always expired (for any f).	Dtf >= Dtc (because Dtc==0)
 	 *  Any case where t==f!=c: always wait.		Dtf <  Dtc (because Dtf==0,
 	 *							Dtc!=0)
 	 *
 	 *  Other cases:
 	 *
 	 *	A) .....t..f..c.....	Dtf < Dtc	need to wait
 	 *	A) .....f..c..t.....	Dtf < Dtc	need to wait
 	 *	A) .....f..t..c.....	Dtf > Dtc	expired
 	 *
 	 *   So:
 	 *	   Dtf >= Dtc implies EXPIRED	(return true)
 	 *	   Dtf <  Dtc implies WAIT	(return false)
 	 *
 	 * Note: If t is expired then we *cannot* wait on it. We would wait
 	 * forever (hang the system).
 	 *
 	 * Note: do NOT get clever and remove the -thresh from both sides. It
 	 * is NOT the same.
 	 *
 	 * If future valueis zero, we have a client managed sync point. In that
 	 * case we do a direct comparison.
 	 */
 	if (!host1x_syncpt_client_managed(sp))
 		return future_val - thresh >= current_val - thresh;
 	else
 		return (s32)(current_val - thresh) >= 0;
 }

 int host1x_syncpt_init(struct host1x *host)
 {
 	struct host1x_syncpt_base *bases;
 	struct host1x_syncpt *syncpt;
 	unsigned int i;

 	syncpt = devm_kcalloc(host->dev, host->info->nb_pts, sizeof(*syncpt),
 			      GFP_KERNEL);
 	if (!syncpt)
 		return -ENOMEM;

 	bases = devm_kcalloc(host->dev, host->info->nb_bases, sizeof(*bases),
 			     GFP_KERNEL);
 	if (!bases)
 		return -ENOMEM;

 	for (i = 0; i < host->info->nb_pts; i++) {
 		syncpt[i].id = i;
 		syncpt[i].host = host;

 		/*
 		 * Unassign syncpt from channels for purposes of Tegra186
 		 * syncpoint protection. This prevents any channel from
 		 * accessing it until it is reassigned.
 		 */
 		host1x_hw_syncpt_assign_to_channel(host, &syncpt[i], NULL);
 	}

 	for (i = 0; i < host->info->nb_bases; i++)
 		bases[i].id = i;

 	mutex_init(&host->syncpt_mutex);
 	host->syncpt = syncpt;
 	host->bases = bases;

 	host1x_syncpt_restore(host);
 	host1x_hw_syncpt_enable_protection(host);

 	/* Allocate sync point to use for clearing waits for expired fences */
 	host->nop_sp = host1x_syncpt_alloc(host, NULL, 0);
 	if (!host->nop_sp)
 		return -ENOMEM;

 	return 0;
 }

 /**
  * host1x_syncpt_request() - request a syncpoint
  * @client: client requesting the syncpoint
  * @flags: flags
  *
  * host1x client drivers can use this function to allocate a syncpoint for
  * subsequent use. A syncpoint returned by this function will be reserved for
  * use by the client exclusively. When no longer using a syncpoint, a host1x
  * client driver needs to release it using host1x_syncpt_free().
  */
 struct host1x_syncpt *host1x_syncpt_request(struct host1x_client *client,
 					    unsigned long flags)
 {
 	struct host1x *host = dev_get_drvdata(client->host->parent);

 	return host1x_syncpt_alloc(host, client, flags);
 }
 EXPORT_SYMBOL(host1x_syncpt_request);

 /**
  * host1x_syncpt_free() - free a requested syncpoint
  * @sp: host1x syncpoint
  *
  * Release a syncpoint previously allocated using host1x_syncpt_request(). A
  * host1x client driver should call this when the syncpoint is no longer in
  * use. Note that client drivers must ensure that the syncpoint doesn't remain
  * under the control of hardware after calling this function, otherwise two
  * clients may end up trying to access the same syncpoint concurrently.
  */
 void host1x_syncpt_free(struct host1x_syncpt *sp)
 {
 	if (!sp)
 		return;

 	mutex_lock(&sp->host->syncpt_mutex);

 	host1x_syncpt_base_free(sp->base);
 	kfree(sp->name);
 	sp->base = NULL;
 	sp->client = NULL;
 	sp->name = NULL;
 	sp->client_managed = false;

 	mutex_unlock(&sp->host->syncpt_mutex);
 }
 EXPORT_SYMBOL(host1x_syncpt_free);

 void host1x_syncpt_deinit(struct host1x *host)
 {
 	struct host1x_syncpt *sp = host->syncpt;
 	unsigned int i;

 	for (i = 0; i < host->info->nb_pts; i++, sp++)
 		kfree(sp->name);
 }

 /**
  * host1x_syncpt_read_max() - read maximum syncpoint value
  * @sp: host1x syncpoint
  *
  * The maximum syncpoint value indicates how many operations there are in
  * queue, either in channel or in a software thread.
  */
 u32 host1x_syncpt_read_max(struct host1x_syncpt *sp)
 {
 	smp_rmb();

 	return (u32)atomic_read(&sp->max_val);
 }
 EXPORT_SYMBOL(host1x_syncpt_read_max);

 /**
  * host1x_syncpt_read_min() - read minimum syncpoint value
  * @sp: host1x syncpoint
  *
  * The minimum syncpoint value is a shadow of the current sync point value in
  * hardware.
  */
 u32 host1x_syncpt_read_min(struct host1x_syncpt *sp)
 {
 	smp_rmb();

 	return (u32)atomic_read(&sp->min_val);
 }
 EXPORT_SYMBOL(host1x_syncpt_read_min);

 /**
  * host1x_syncpt_read() - read the current syncpoint value
  * @sp: host1x syncpoint
  */
 u32 host1x_syncpt_read(struct host1x_syncpt *sp)
 {
 	return host1x_syncpt_load(sp);
 }
 EXPORT_SYMBOL(host1x_syncpt_read);

 unsigned int host1x_syncpt_nb_pts(struct host1x *host)
 {
 	return host->info->nb_pts;
 }

 unsigned int host1x_syncpt_nb_bases(struct host1x *host)
 {
 	return host->info->nb_bases;
 }

 unsigned int host1x_syncpt_nb_mlocks(struct host1x *host)
 {
 	return host->info->nb_mlocks;
 }

 /**
  * host1x_syncpt_get() - obtain a syncpoint by ID
  * @host: host1x controller
  * @id: syncpoint ID
  */
 struct host1x_syncpt *host1x_syncpt_get(struct host1x *host, unsigned int id)
 {
 	if (id >= host->info->nb_pts)
 		return NULL;

 	return host->syncpt + id;
 }
 EXPORT_SYMBOL(host1x_syncpt_get);

 /**
  * host1x_syncpt_get_base() - obtain the wait base associated with a syncpoint
  * @sp: host1x syncpoint
  */
 struct host1x_syncpt_base *host1x_syncpt_get_base(struct host1x_syncpt *sp)
 {
 	return sp ? sp->base : NULL;
 }
 EXPORT_SYMBOL(host1x_syncpt_get_base);

 /**
  * host1x_syncpt_base_id() - retrieve the ID of a syncpoint wait base
  * @base: host1x syncpoint wait base
  */
 u32 host1x_syncpt_base_id(struct host1x_syncpt_base *base)
 {
 	return base->id;
 }
 EXPORT_SYMBOL(host1x_syncpt_base_id);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Tegra host1x Syncpoints
	*
	* Copyright (c) 2010-2015, NVIDIA Corporation.
	*/

	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/slab.h>

	#include <trace/events/host1x.h>

	#include "syncpt.h"
	#include "dev.h"
	#include "intr.h"
	#include "debug.h"

	#define SYNCPT_CHECK_PERIOD (2 * HZ)
	#define MAX_STUCK_CHECK_COUNT 15

	static struct host1x_syncpt_base *
	host1x_syncpt_base_request(struct host1x *host)
	{
	struct host1x_syncpt_base *bases = host->bases;
	unsigned int i;

	for (i = 0; i < host->info->nb_bases; i++)
	if (!bases[i].requested)
	break;

	if (i >= host->info->nb_bases)
	return NULL;

	bases[i].requested = true;
	return &bases[i];
	}

	static void host1x_syncpt_base_free(struct host1x_syncpt_base *base)
	{
	if (base)
	base->requested = false;
	}

	static struct host1x_syncpt host1x_syncpt_alloc(struct host1x host,
	struct host1x_client *client,
	unsigned long flags)
	{
	struct host1x_syncpt *sp = host->syncpt;
	unsigned int i;
	char *name;

	mutex_lock(&host->syncpt_mutex);

	for (i = 0; i < host->info->nb_pts && sp->name; i++, sp++)
	;

	if (i >= host->info->nb_pts)
	goto unlock;

	if (flags & HOST1X_SYNCPT_HAS_BASE) {
	sp->base = host1x_syncpt_base_request(host);
	if (!sp->base)
	goto unlock;
	}

	name = kasprintf(GFP_KERNEL, "%02u-%s", sp->id,
	client ? dev_name(client->dev) : NULL);
	if (!name)
	goto free_base;

	sp->client = client;
	sp->name = name;

	if (flags & HOST1X_SYNCPT_CLIENT_MANAGED)
	sp->client_managed = true;
	else
	sp->client_managed = false;

	mutex_unlock(&host->syncpt_mutex);
	return sp;

	free_base:
	host1x_syncpt_base_free(sp->base);
	sp->base = NULL;
	unlock:
	mutex_unlock(&host->syncpt_mutex);
	return NULL;
	}

	/**
	* host1x_syncpt_id() - retrieve syncpoint ID
	* @sp: host1x syncpoint
	*
	* Given a pointer to a struct host1x_syncpt, retrieves its ID. This ID is
	* often used as a value to program into registers that control how hardware
	* blocks interact with syncpoints.
	*/
	u32 host1x_syncpt_id(struct host1x_syncpt *sp)
	{
	return sp->id;
	}
	EXPORT_SYMBOL(host1x_syncpt_id);

	/**
	* host1x_syncpt_incr_max() - update the value sent to hardware
	* @sp: host1x syncpoint
	* @incrs: number of increments
	*/
	u32 host1x_syncpt_incr_max(struct host1x_syncpt *sp, u32 incrs)
	{
	return (u32)atomic_add_return(incrs, &sp->max_val);
	}
	EXPORT_SYMBOL(host1x_syncpt_incr_max);

	/*
	* Write cached syncpoint and waitbase values to hardware.
	*/
	void host1x_syncpt_restore(struct host1x *host)
	{
	struct host1x_syncpt *sp_base = host->syncpt;
	unsigned int i;

	for (i = 0; i < host1x_syncpt_nb_pts(host); i++)
	host1x_hw_syncpt_restore(host, sp_base + i);

	for (i = 0; i < host1x_syncpt_nb_bases(host); i++)
	host1x_hw_syncpt_restore_wait_base(host, sp_base + i);

	wmb();
	}

	/*
	* Update the cached syncpoint and waitbase values by reading them
	* from the registers.
	*/
	void host1x_syncpt_save(struct host1x *host)
	{
	struct host1x_syncpt *sp_base = host->syncpt;
	unsigned int i;

	for (i = 0; i < host1x_syncpt_nb_pts(host); i++) {
	if (host1x_syncpt_client_managed(sp_base + i))
	host1x_hw_syncpt_load(host, sp_base + i);
	else
	WARN_ON(!host1x_syncpt_idle(sp_base + i));
	}

	for (i = 0; i < host1x_syncpt_nb_bases(host); i++)
	host1x_hw_syncpt_load_wait_base(host, sp_base + i);
	}

	/*
	* Updates the cached syncpoint value by reading a new value from the hardware
	* register
	*/
	u32 host1x_syncpt_load(struct host1x_syncpt *sp)
	{
	u32 val;

	val = host1x_hw_syncpt_load(sp->host, sp);
	trace_host1x_syncpt_load_min(sp->id, val);

	return val;
	}

	/*
	* Get the current syncpoint base
	*/
	u32 host1x_syncpt_load_wait_base(struct host1x_syncpt *sp)
	{
	host1x_hw_syncpt_load_wait_base(sp->host, sp);

	return sp->base_val;
	}

	/**
	* host1x_syncpt_incr() - increment syncpoint value from CPU, updating cache
	* @sp: host1x syncpoint
	*/
	int host1x_syncpt_incr(struct host1x_syncpt *sp)
	{
	return host1x_hw_syncpt_cpu_incr(sp->host, sp);
	}
	EXPORT_SYMBOL(host1x_syncpt_incr);

	/*
	* Updated sync point form hardware, and returns true if syncpoint is expired,
	* false if we may need to wait
	*/
	static bool syncpt_load_min_is_expired(struct host1x_syncpt *sp, u32 thresh)
	{
	host1x_hw_syncpt_load(sp->host, sp);

	return host1x_syncpt_is_expired(sp, thresh);
	}

	/**
	* host1x_syncpt_wait() - wait for a syncpoint to reach a given value
	* @sp: host1x syncpoint
	* @thresh: threshold
	* @timeout: maximum time to wait for the syncpoint to reach the given value
	* @value: return location for the syncpoint value
	*/
	int host1x_syncpt_wait(struct host1x_syncpt *sp, u32 thresh, long timeout,
	u32 *value)
	{
	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
	void *ref;
	struct host1x_waitlist *waiter;
	int err = 0, check_count = 0;
	u32 val;

	if (value)
	*value = 0;

	/* first check cache */
	if (host1x_syncpt_is_expired(sp, thresh)) {
	if (value)
	*value = host1x_syncpt_load(sp);

	return 0;
	}

	/* try to read from register */
	val = host1x_hw_syncpt_load(sp->host, sp);
	if (host1x_syncpt_is_expired(sp, thresh)) {
	if (value)
	*value = val;

	goto done;
	}

	if (!timeout) {
	err = -EAGAIN;
	goto done;
	}

	/* allocate a waiter */
	waiter = kzalloc(sizeof(*waiter), GFP_KERNEL);
	if (!waiter) {
	err = -ENOMEM;
	goto done;
	}

	/* schedule a wakeup when the syncpoint value is reached */
	err = host1x_intr_add_action(sp->host, sp, thresh,
	HOST1X_INTR_ACTION_WAKEUP_INTERRUPTIBLE,
	&wq, waiter, &ref);
	if (err)
	goto done;

	err = -EAGAIN;
	/* Caller-specified timeout may be impractically low */
	if (timeout < 0)
	timeout = LONG_MAX;

	/* wait for the syncpoint, or timeout, or signal */
	while (timeout) {
	long check = min_t(long, SYNCPT_CHECK_PERIOD, timeout);
	int remain;

	remain = wait_event_interruptible_timeout(wq,
	syncpt_load_min_is_expired(sp, thresh),
	check);
	if (remain > 0 \|\| host1x_syncpt_is_expired(sp, thresh)) {
	if (value)
	*value = host1x_syncpt_load(sp);

	err = 0;

	break;
	}

	if (remain < 0) {
	err = remain;
	break;
	}

	timeout -= check;

	if (timeout && check_count <= MAX_STUCK_CHECK_COUNT) {
	dev_warn(sp->host->dev,
	"%s: syncpoint id %u (%s) stuck waiting %d, timeout=%ld\n",
	current->comm, sp->id, sp->name,
	thresh, timeout);

	host1x_debug_dump_syncpts(sp->host);

	if (check_count == MAX_STUCK_CHECK_COUNT)
	host1x_debug_dump(sp->host);

	check_count++;
	}
	}

	host1x_intr_put_ref(sp->host, sp->id, ref);

	done:
	return err;
	}
	EXPORT_SYMBOL(host1x_syncpt_wait);

	/*
	* Returns true if syncpoint is expired, false if we may need to wait
	*/
	bool host1x_syncpt_is_expired(struct host1x_syncpt *sp, u32 thresh)
	{
	u32 current_val;
	u32 future_val;

	smp_rmb();

	current_val = (u32)atomic_read(&sp->min_val);
	future_val = (u32)atomic_read(&sp->max_val);

	/* Note the use of unsigned arithmetic here (mod 1<<32).
	*
	* c = current_val = min_val = the current value of the syncpoint.
	* t = thresh = the value we are checking
	* f = future_val = max_val = the value c will reach when all
	* outstanding increments have completed.
	*
	* Note that c always chases f until it reaches f.
	*
	* Dtf = (f - t)
	* Dtc = (c - t)
	*
	* Consider all cases:
	*
	* A) .....c..t..f..... Dtf < Dtc need to wait
	* B) .....c.....f..t.. Dtf > Dtc expired
	* C) ..t..c.....f..... Dtf > Dtc expired (Dct very large)
	*
	* Any case where f==c: always expired (for any t). Dtf == Dcf
	* Any case where t==c: always expired (for any f). Dtf >= Dtc (because Dtc==0)
	* Any case where t==f!=c: always wait. Dtf < Dtc (because Dtf==0,
	* Dtc!=0)
	*
	* Other cases:
	*
	* A) .....t..f..c..... Dtf < Dtc need to wait
	* A) .....f..c..t..... Dtf < Dtc need to wait
	* A) .....f..t..c..... Dtf > Dtc expired
	*
	* So:
	* Dtf >= Dtc implies EXPIRED (return true)
	* Dtf < Dtc implies WAIT (return false)
	*
	* Note: If t is expired then we cannot wait on it. We would wait
	* forever (hang the system).
	*
	* Note: do NOT get clever and remove the -thresh from both sides. It
	* is NOT the same.
	*
	* If future valueis zero, we have a client managed sync point. In that
	* case we do a direct comparison.
	*/
	if (!host1x_syncpt_client_managed(sp))
	return future_val - thresh >= current_val - thresh;
	else
	return (s32)(current_val - thresh) >= 0;
	}

	int host1x_syncpt_init(struct host1x *host)
	{
	struct host1x_syncpt_base *bases;
	struct host1x_syncpt *syncpt;
	unsigned int i;

	syncpt = devm_kcalloc(host->dev, host->info->nb_pts, sizeof(*syncpt),
	GFP_KERNEL);
	if (!syncpt)
	return -ENOMEM;

	bases = devm_kcalloc(host->dev, host->info->nb_bases, sizeof(*bases),
	GFP_KERNEL);
	if (!bases)
	return -ENOMEM;

	for (i = 0; i < host->info->nb_pts; i++) {
	syncpt[i].id = i;
	syncpt[i].host = host;

	/*
	* Unassign syncpt from channels for purposes of Tegra186
	* syncpoint protection. This prevents any channel from
	* accessing it until it is reassigned.
	*/
	host1x_hw_syncpt_assign_to_channel(host, &syncpt[i], NULL);
	}

	for (i = 0; i < host->info->nb_bases; i++)
	bases[i].id = i;

	mutex_init(&host->syncpt_mutex);
	host->syncpt = syncpt;
	host->bases = bases;

	host1x_syncpt_restore(host);
	host1x_hw_syncpt_enable_protection(host);

	/* Allocate sync point to use for clearing waits for expired fences */
	host->nop_sp = host1x_syncpt_alloc(host, NULL, 0);
	if (!host->nop_sp)
	return -ENOMEM;

	return 0;
	}

	/**
	* host1x_syncpt_request() - request a syncpoint
	* @client: client requesting the syncpoint
	* @flags: flags
	*
	* host1x client drivers can use this function to allocate a syncpoint for
	* subsequent use. A syncpoint returned by this function will be reserved for
	* use by the client exclusively. When no longer using a syncpoint, a host1x
	* client driver needs to release it using host1x_syncpt_free().
	*/
	struct host1x_syncpt host1x_syncpt_request(struct host1x_client client,
	unsigned long flags)
	{
	struct host1x *host = dev_get_drvdata(client->host->parent);

	return host1x_syncpt_alloc(host, client, flags);
	}
	EXPORT_SYMBOL(host1x_syncpt_request);

	/**
	* host1x_syncpt_free() - free a requested syncpoint
	* @sp: host1x syncpoint
	*
	* Release a syncpoint previously allocated using host1x_syncpt_request(). A
	* host1x client driver should call this when the syncpoint is no longer in
	* use. Note that client drivers must ensure that the syncpoint doesn't remain
	* under the control of hardware after calling this function, otherwise two
	* clients may end up trying to access the same syncpoint concurrently.
	*/
	void host1x_syncpt_free(struct host1x_syncpt *sp)
	{
	if (!sp)
	return;

	mutex_lock(&sp->host->syncpt_mutex);

	host1x_syncpt_base_free(sp->base);
	kfree(sp->name);
	sp->base = NULL;
	sp->client = NULL;
	sp->name = NULL;
	sp->client_managed = false;

	mutex_unlock(&sp->host->syncpt_mutex);
	}
	EXPORT_SYMBOL(host1x_syncpt_free);

	void host1x_syncpt_deinit(struct host1x *host)
	{
	struct host1x_syncpt *sp = host->syncpt;
	unsigned int i;

	for (i = 0; i < host->info->nb_pts; i++, sp++)
	kfree(sp->name);
	}

	/**
	* host1x_syncpt_read_max() - read maximum syncpoint value
	* @sp: host1x syncpoint
	*
	* The maximum syncpoint value indicates how many operations there are in
	* queue, either in channel or in a software thread.
	*/
	u32 host1x_syncpt_read_max(struct host1x_syncpt *sp)
	{
	smp_rmb();

	return (u32)atomic_read(&sp->max_val);
	}
	EXPORT_SYMBOL(host1x_syncpt_read_max);

	/**
	* host1x_syncpt_read_min() - read minimum syncpoint value
	* @sp: host1x syncpoint
	*
	* The minimum syncpoint value is a shadow of the current sync point value in
	* hardware.
	*/
	u32 host1x_syncpt_read_min(struct host1x_syncpt *sp)
	{
	smp_rmb();

	return (u32)atomic_read(&sp->min_val);
	}
	EXPORT_SYMBOL(host1x_syncpt_read_min);

	/**
	* host1x_syncpt_read() - read the current syncpoint value
	* @sp: host1x syncpoint
	*/
	u32 host1x_syncpt_read(struct host1x_syncpt *sp)
	{
	return host1x_syncpt_load(sp);
	}
	EXPORT_SYMBOL(host1x_syncpt_read);

	unsigned int host1x_syncpt_nb_pts(struct host1x *host)
	{
	return host->info->nb_pts;
	}

	unsigned int host1x_syncpt_nb_bases(struct host1x *host)
	{
	return host->info->nb_bases;
	}

	unsigned int host1x_syncpt_nb_mlocks(struct host1x *host)
	{
	return host->info->nb_mlocks;
	}

	/**
	* host1x_syncpt_get() - obtain a syncpoint by ID
	* @host: host1x controller
	* @id: syncpoint ID
	*/
	struct host1x_syncpt host1x_syncpt_get(struct host1x host, unsigned int id)
	{
	if (id >= host->info->nb_pts)
	return NULL;

	return host->syncpt + id;
	}
	EXPORT_SYMBOL(host1x_syncpt_get);

	/**
	* host1x_syncpt_get_base() - obtain the wait base associated with a syncpoint
	* @sp: host1x syncpoint
	*/
	struct host1x_syncpt_base host1x_syncpt_get_base(struct host1x_syncpt sp)
	{
	return sp ? sp->base : NULL;
	}
	EXPORT_SYMBOL(host1x_syncpt_get_base);

	/**
	* host1x_syncpt_base_id() - retrieve the ID of a syncpoint wait base
	* @base: host1x syncpoint wait base
	*/
	u32 host1x_syncpt_base_id(struct host1x_syncpt_base *base)
	{
	return base->id;
	}
	EXPORT_SYMBOL(host1x_syncpt_base_id);