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Commit 12927835 authored by Bryan O'Donoghue's avatar Bryan O'Donoghue Committed by Greg Kroah-Hartman
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greybus: loopback: Add asynchronous bi-directional support 



A particular ask from the firmware people for some time now has been the
ability to drive multiple outstanding bi-directional operations from
loopback to loopback Interfaces. This patch implments that change.

The approach taken is to make a call to gb_operation_send() and have
loopback capture the completion callback itself, with a parallel timer to
timeout completion callbacks that take too long. The calling thread will
issue each gb_operation_send() as fast as it can within the constraints of
thread-safety.

In order to support this addition the following new sysfs entries are
created on a per-connection basis.

- async
  Zero indicates loopback should use the traditional synchronous model
  i.e. gb_operation_request_send_sync().

  Non-zero indicates loopback should use the new asynchronous model i.e.
  gb_operation_send()

- requests_completed
  This value indicates the number of requests successfully completed.

- requests_timedout
  This value indicates the number of requests which timed out.

- timeout
  The number of microseconds to give an individual asynchronous request
  before timing that request out.

- timeout_min
  Read-only attribute informs user-space of the minimum allowed timeout.

- timeout_max
  Read-only attribute informs user-space of the maximum allowed timeout.

Note requests_completed + requests_timedout should always equal
iteration_max, once iteration_count == iteration_max. Also, at this time we
support either synchronous or asynchronous operations in one set of
transactions.

Signed-off-by: default avatarBryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 2e238d71

drivers/staging/greybus/loopback.c

+369 −19
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/debugfs.h>

#include <linux/list_sort.h>

#include <linux/spinlock.h>

#include <linux/workqueue.h>



#include <asm/div64.h>
@@ -43,10 +44,24 @@ struct gb_loopback_device { 
	/* We need to take a lock in atomic context */

	spinlock_t lock;

	struct list_head list;

	struct list_head list_op_async;

	wait_queue_head_t wq;

};



static struct gb_loopback_device gb_dev;



struct gb_loopback_async_operation {

	struct gb_loopback *gb;

	struct gb_operation *operation;

	struct timeval ts;

	struct timer_list timer;

	struct list_head entry;

	struct work_struct work;

	struct kref kref;

	bool pending;

	int (*completion)(struct gb_loopback_async_operation *op_async);

};



struct gb_loopback {

	struct gb_connection *connection;
@@ -66,18 +81,29 @@ struct gb_loopback { 
	struct gb_loopback_stats gpbridge_firmware_latency;



	int type;

	int async;

	u32 mask;

	u32 size;

	u32 iteration_max;

	u32 iteration_count;

	int ms_wait;

	u32 error;

	u32 requests_completed;

	u32 requests_timedout;

	u32 timeout;

	u32 jiffy_timeout;

	u32 timeout_min;

	u32 timeout_max;

	u32 lbid;

	u64 elapsed_nsecs;

	u32 apbridge_latency_ts;

	u32 gpbridge_latency_ts;

};



/* Min/max values in jiffies */

#define GB_LOOPBACK_TIMEOUT_MIN				1

#define GB_LOOPBACK_TIMEOUT_MAX				10000



#define GB_LOOPBACK_FIFO_DEFAULT			8192



static unsigned kfifo_depth = GB_LOOPBACK_FIFO_DEFAULT;
@@ -215,6 +241,8 @@ static void gb_loopback_check_attr(struct gb_loopback *gb, 
		gb->ms_wait = GB_LOOPBACK_MS_WAIT_MAX;

	if (gb->size > gb_dev.size_max)

		gb->size = gb_dev.size_max;

	gb->requests_timedout = 0;

	gb->requests_completed = 0;

	gb->iteration_count = 0;

	gb->error = 0;
@@ -230,6 +258,11 @@ static void gb_loopback_check_attr(struct gb_loopback *gb, 
	case GB_LOOPBACK_TYPE_PING:

	case GB_LOOPBACK_TYPE_TRANSFER:

	case GB_LOOPBACK_TYPE_SINK:

		gb->jiffy_timeout = usecs_to_jiffies(gb->timeout);

		if (!gb->jiffy_timeout)

			gb->jiffy_timeout = GB_LOOPBACK_TIMEOUT_MIN;

		else if (gb->jiffy_timeout > GB_LOOPBACK_TIMEOUT_MAX)

			gb->jiffy_timeout = GB_LOOPBACK_TIMEOUT_MAX;

		gb_loopback_reset_stats(gb);

		wake_up(&gb->wq);

		break;
@@ -252,6 +285,14 @@ gb_loopback_stats_attrs(gpbridge_firmware_latency); 


/* Number of errors encountered during loop */

gb_loopback_ro_attr(error);

/* Number of requests successfully completed async */

gb_loopback_ro_attr(requests_completed);

/* Number of requests timed out async */

gb_loopback_ro_attr(requests_timedout);

/* Timeout minimum in useconds */

gb_loopback_ro_attr(timeout_min);

/* Timeout minimum in useconds */

gb_loopback_ro_attr(timeout_max);



/*

 * Type of loopback message to send based on protocol type definitions
@@ -270,8 +311,12 @@ gb_dev_loopback_rw_attr(ms_wait, d); 
gb_dev_loopback_rw_attr(iteration_max, u);

/* The current index of the for (i = 0; i < iteration_max; i++) loop */

gb_dev_loopback_ro_attr(iteration_count, false);

/* A bit-mask of destination connecitons to include in the test run */

/* A bit-mask of destination connections to include in the test run */

gb_dev_loopback_rw_attr(mask, u);

/* A flag to indicate synchronous or asynchronous operations */

gb_dev_loopback_rw_attr(async, u);

/* Timeout of an individual asynchronous request */

gb_dev_loopback_rw_attr(timeout, u);



static struct attribute *loopback_attrs[] = {

	&dev_attr_latency_min.attr,
@@ -295,11 +340,19 @@ static struct attribute *loopback_attrs[] = { 
	&dev_attr_iteration_count.attr,

	&dev_attr_iteration_max.attr,

	&dev_attr_mask.attr,

	&dev_attr_async.attr,

	&dev_attr_error.attr,

	&dev_attr_requests_completed.attr,

	&dev_attr_requests_timedout.attr,

	&dev_attr_timeout.attr,

	&dev_attr_timeout_min.attr,

	&dev_attr_timeout_max.attr,

	NULL,

};

ATTRIBUTE_GROUPS(loopback);



static void gb_loopback_calculate_stats(struct gb_loopback *gb);



static u32 gb_loopback_nsec_to_usec_latency(u64 elapsed_nsecs)

{

	u32 lat;
@@ -381,7 +434,200 @@ static int gb_loopback_operation_sync(struct gb_loopback *gb, int type, 
	return ret;

}



static int gb_loopback_sink(struct gb_loopback *gb, u32 len)

static void __gb_loopback_async_operation_destroy(struct kref *kref)

{

	struct gb_loopback_async_operation *op_async;



	op_async = container_of(kref, struct gb_loopback_async_operation, kref);



	list_del(&op_async->entry);

	if (op_async->operation)

		gb_operation_put(op_async->operation);

	kfree(op_async);

}



static void gb_loopback_async_operation_get(struct gb_loopback_async_operation

					    *op_async)

{

	kref_get(&op_async->kref);

}



static void gb_loopback_async_operation_put(struct gb_loopback_async_operation

					    *op_async)

{

	unsigned long flags;



	spin_lock_irqsave(&gb_dev.lock, flags);

	kref_put(&op_async->kref, __gb_loopback_async_operation_destroy);

	spin_unlock_irqrestore(&gb_dev.lock, flags);

}



static struct gb_loopback_async_operation *

	gb_loopback_operation_find(u16 id)

{

	struct gb_loopback_async_operation *op_async;

	bool found = false;

	unsigned long flags;



	spin_lock_irqsave(&gb_dev.lock, flags);

	list_for_each_entry(op_async, &gb_dev.list_op_async, entry) {

		if (op_async->operation->id == id) {

			gb_loopback_async_operation_get(op_async);

			found = true;

			break;

		}

	}

	spin_unlock_irqrestore(&gb_dev.lock, flags);



	return found ? op_async : NULL;

}



static void gb_loopback_async_operation_callback(struct gb_operation *operation)

{

	struct gb_loopback_async_operation *op_async;

	struct gb_loopback *gb;

	struct timeval te;

	bool err = false;



	do_gettimeofday(&te);

	op_async = gb_loopback_operation_find(operation->id);

	if (!op_async)

		return;



	gb = op_async->gb;

	mutex_lock(&gb->mutex);



	if (!op_async->pending || gb_operation_result(operation)) {

		err = true;

	} else {

		if (op_async->completion)

			if (op_async->completion(op_async))

				err = true;

	}



	if (err) {

		gb->error++;

	} else {

		gb->requests_completed++;

		gb_loopback_push_latency_ts(gb, &op_async->ts, &te);

		gb->elapsed_nsecs = gb_loopback_calc_latency(&op_async->ts,

							     &te);

		gb_loopback_calculate_stats(gb);

	}



	if (op_async->pending) {

		gb->iteration_count++;

		op_async->pending = false;

		del_timer_sync(&op_async->timer);

		gb_loopback_async_operation_put(op_async);

	}

	mutex_unlock(&gb->mutex);



	dev_dbg(&gb->connection->bundle->dev, "complete operation %d\n",

		operation->id);



	gb_loopback_async_operation_put(op_async);

}



static void gb_loopback_async_operation_work(struct work_struct *work)

{

	struct gb_loopback *gb;

	struct gb_operation *operation;

	struct gb_loopback_async_operation *op_async;



	op_async = container_of(work, struct gb_loopback_async_operation, work);

	if (!op_async)

		return;



	gb = op_async->gb;

	operation = op_async->operation;



	mutex_lock(&gb->mutex);

	if (op_async->pending) {

		gb->requests_timedout++;

		gb->error++;

		gb->iteration_count++;

		op_async->pending = false;

		gb_loopback_async_operation_put(op_async);

	}

	mutex_unlock(&gb->mutex);



	dev_dbg(&gb->connection->bundle->dev, "timeout operation %d\n",

		operation->id);



	gb_operation_cancel(operation, -ETIMEDOUT);

	gb_loopback_async_operation_put(op_async);

}



static void gb_loopback_async_operation_timeout(unsigned long data)

{

	struct gb_loopback_async_operation *op_async;

	u16 id = data;



	op_async = gb_loopback_operation_find(id);

	if (!op_async) {

		pr_err("operation %d not found - time out ?\n", id);

		return;

	}

	schedule_work(&op_async->work);

}



static int gb_loopback_async_operation(struct gb_loopback *gb, int type,

				       void *request, int request_size,

				       int response_size,

				       void *completion)

{

	struct gb_loopback_async_operation *op_async;

	struct gb_operation *operation;

	int ret;

	unsigned long flags;



	op_async = kzalloc(sizeof(*op_async), GFP_KERNEL);

	if (!op_async)

		return -ENOMEM;



	INIT_WORK(&op_async->work, gb_loopback_async_operation_work);

	init_timer(&op_async->timer);

	kref_init(&op_async->kref);



	operation = gb_operation_create(gb->connection, type, request_size,

					response_size, GFP_KERNEL);

	if (!operation) {

		ret = -ENOMEM;

		goto error;

	}



	if (request_size)

		memcpy(operation->request->payload, request, request_size);



	op_async->gb = gb;

	op_async->operation = operation;

	op_async->completion = completion;



	spin_lock_irqsave(&gb_dev.lock, flags);

	list_add_tail(&op_async->entry, &gb_dev.list_op_async);

	spin_unlock_irqrestore(&gb_dev.lock, flags);



	do_gettimeofday(&op_async->ts);

	op_async->pending = true;

	ret = gb_operation_request_send(operation,

					gb_loopback_async_operation_callback,

					GFP_KERNEL);

	if (ret)

		goto error;



	op_async->timer.function = gb_loopback_async_operation_timeout;

	op_async->timer.expires = jiffies + gb->jiffy_timeout;

	op_async->timer.data = (unsigned long)operation->id;

	add_timer(&op_async->timer);



	return ret;

error:

	gb_loopback_async_operation_put(op_async);

	return ret;

}



static int gb_loopback_sync_sink(struct gb_loopback *gb, u32 len)

{

	struct gb_loopback_transfer_request *request;

	int retval;
@@ -398,7 +644,7 @@ static int gb_loopback_sink(struct gb_loopback *gb, u32 len) 
	return retval;

}



static int gb_loopback_transfer(struct gb_loopback *gb, u32 len)

static int gb_loopback_sync_transfer(struct gb_loopback *gb, u32 len)

{

	struct gb_loopback_transfer_request *request;

	struct gb_loopback_transfer_response *response;
@@ -440,12 +686,91 @@ static int gb_loopback_transfer(struct gb_loopback *gb, u32 len) 
	return retval;

}



static int gb_loopback_ping(struct gb_loopback *gb)

static int gb_loopback_sync_ping(struct gb_loopback *gb)

{

	return gb_loopback_operation_sync(gb, GB_LOOPBACK_TYPE_PING,

					  NULL, 0, NULL, 0);

}



static int gb_loopback_async_sink(struct gb_loopback *gb, u32 len)

{

	struct gb_loopback_transfer_request *request;

	int retval;



	request = kmalloc(len + sizeof(*request), GFP_KERNEL);

	if (!request)

		return -ENOMEM;



	request->len = cpu_to_le32(len);

	retval = gb_loopback_async_operation(gb, GB_LOOPBACK_TYPE_SINK,

					     request, len + sizeof(*request),

					     0, NULL);

	kfree(request);

	return retval;

}



static int gb_loopback_async_transfer_complete(

				struct gb_loopback_async_operation *op_async)

{

	struct gb_loopback *gb;

	struct gb_operation *operation;

	struct gb_loopback_transfer_request *request;

	struct gb_loopback_transfer_response *response;

	size_t len;

	int retval = 0;



	gb = op_async->gb;

	operation = op_async->operation;

	request = operation->request->payload;

	response = operation->response->payload;

	len = le32_to_cpu(request->len);



	if (memcmp(request->data, response->data, len)) {

		dev_err(&gb->connection->bundle->dev,

			"Loopback Data doesn't match operation id %d\n",

			operation->id);

		retval = -EREMOTEIO;

	} else {

		gb->apbridge_latency_ts =

			(u32)__le32_to_cpu(response->reserved0);

		gb->gpbridge_latency_ts =

			(u32)__le32_to_cpu(response->reserved1);

	}



	return retval;

}



static int gb_loopback_async_transfer(struct gb_loopback *gb, u32 len)

{

	struct gb_loopback_transfer_request *request;

	int retval, response_len;



	request = kmalloc(len + sizeof(*request), GFP_KERNEL);

	if (!request)

		return -ENOMEM;



	memset(request->data, 0x5A, len);



	request->len = cpu_to_le32(len);

	response_len = sizeof(struct gb_loopback_transfer_response);

	retval = gb_loopback_async_operation(gb, GB_LOOPBACK_TYPE_TRANSFER,

					     request, len + sizeof(*request),

					     len + response_len,

					     gb_loopback_async_transfer_complete);

	if (retval)

		goto gb_error;



gb_error:

	kfree(request);

	return retval;

}



static int gb_loopback_async_ping(struct gb_loopback *gb)

{

	return gb_loopback_async_operation(gb, GB_LOOPBACK_TYPE_PING,

					   NULL, 0, 0, NULL);

}



static int gb_loopback_request_recv(u8 type, struct gb_operation *operation)

{

	struct gb_connection *connection = operation->connection;
@@ -512,6 +837,10 @@ static void gb_loopback_reset_stats(struct gb_loopback *gb) 
	memcpy(&gb->gpbridge_firmware_latency, &reset,

	       sizeof(struct gb_loopback_stats));



	/* Set values to report min/max timeout to user-space */

	gb->timeout_min = jiffies_to_usecs(GB_LOOPBACK_TIMEOUT_MIN);

	gb->timeout_max = jiffies_to_usecs(GB_LOOPBACK_TIMEOUT_MAX);



	/* Reset aggregate stats */

	memcpy(&gb->latency, &reset, sizeof(struct gb_loopback_stats));

	memcpy(&gb->throughput, &reset, sizeof(struct gb_loopback_stats));
@@ -599,23 +928,25 @@ static int gb_loopback_fn(void *data) 
	int ms_wait = 0;

	int type;

	u32 size;

	u32 send_count = 0;

	struct gb_loopback *gb = data;



	while (1) {

		if (!gb->type)

			wait_event_interruptible(gb->wq, gb->type ||

						 kthread_should_stop());



		if (kthread_should_stop())

			break;



		mutex_lock(&gb->mutex);



		sysfs_notify(&gb->connection->bundle->dev.kobj,

			     NULL, "iteration_count");



		/* Optionally terminate */

		if (gb->iteration_count == gb->iteration_max) {

		if (send_count == gb->iteration_max) {

			gb->type = 0;

			send_count = 0;

			mutex_unlock(&gb->mutex);

			continue;

		}
@@ -625,19 +956,33 @@ static int gb_loopback_fn(void *data) 
		mutex_unlock(&gb->mutex);



		/* Else operations to perform */

		if (gb->async) {

			if (type == GB_LOOPBACK_TYPE_PING) {

				error = gb_loopback_async_ping(gb);

				gb_loopback_calculate_stats(gb);

			} else if (type == GB_LOOPBACK_TYPE_TRANSFER) {

				error = gb_loopback_async_transfer(gb, size);

			} else if (type == GB_LOOPBACK_TYPE_SINK) {

				error = gb_loopback_async_sink(gb, size);

			}



			if (error)

				gb->error++;

		} else {

			/* We are effectively single threaded here */

			if (type == GB_LOOPBACK_TYPE_PING)

			error = gb_loopback_ping(gb);

				error = gb_loopback_sync_ping(gb);

			else if (type == GB_LOOPBACK_TYPE_TRANSFER)

			error = gb_loopback_transfer(gb, size);

				error = gb_loopback_sync_transfer(gb, size);

			else if (type == GB_LOOPBACK_TYPE_SINK)

			error = gb_loopback_sink(gb, size);

				error = gb_loopback_sync_sink(gb, size);



			if (error)

				gb->error++;



		gb_loopback_calculate_stats(gb);

			gb->iteration_count++;



			gb_loopback_calculate_stats(gb);

		}

		send_count++;

		if (ms_wait)

			msleep(ms_wait);

	}
@@ -742,6 +1087,10 @@ static int gb_loopback_connection_init(struct gb_connection *connection) 
	init_waitqueue_head(&gb->wq);

	gb_loopback_reset_stats(gb);



	/* Reported values to user-space for min/max timeouts */

	gb->timeout_min = jiffies_to_usecs(GB_LOOPBACK_TIMEOUT_MIN);

	gb->timeout_max = jiffies_to_usecs(GB_LOOPBACK_TIMEOUT_MAX);



	if (!gb_dev.count) {

		/* Calculate maximum payload */

		gb_dev.size_max = gb_operation_get_payload_size_max(connection);
@@ -847,6 +1196,7 @@ static int loopback_init(void) 
	int retval;



	INIT_LIST_HEAD(&gb_dev.list);

	INIT_LIST_HEAD(&gb_dev.list_op_async);

	spin_lock_init(&gb_dev.lock);

	gb_dev.root = debugfs_create_dir("gb_loopback", NULL);