drivers/mailbox/mailbox-test.c - linux-imx - Git at Google

 /*
  * Copyright (C) 2015 ST Microelectronics
  *
  * Author: Lee Jones <lee.jones@linaro.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  */

 #include <linux/debugfs.h>
 #include <linux/err.h>
 #include <linux/fs.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/mailbox_client.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/poll.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/sched/signal.h>

 #define MBOX_MAX_SIG_LEN	8
 #define MBOX_MAX_MSG_LEN	128
 #define MBOX_BYTES_PER_LINE	16
 #define MBOX_HEXDUMP_LINE_LEN	((MBOX_BYTES_PER_LINE * 4) + 2)
 #define MBOX_HEXDUMP_MAX_LEN	(MBOX_HEXDUMP_LINE_LEN *		\
 				 (MBOX_MAX_MSG_LEN / MBOX_BYTES_PER_LINE))

 static bool mbox_data_ready;
 static struct dentry *root_debugfs_dir;

 struct mbox_test_device {
 	struct device		*dev;
 	void __iomem		*tx_mmio;
 	void __iomem		*rx_mmio;
 	struct mbox_chan	*tx_channel;
 	struct mbox_chan	*rx_channel;
 	char			*rx_buffer;
 	char			*signal;
 	char			*message;
 	spinlock_t		lock;
 	wait_queue_head_t	waitq;
 	struct fasync_struct	*async_queue;
 };

 static ssize_t mbox_test_signal_write(struct file *filp,
 				       const char __user *userbuf,
 				       size_t count, loff_t *ppos)
 {
 	struct mbox_test_device *tdev = filp->private_data;

 	if (!tdev->tx_channel) {
 		dev_err(tdev->dev, "Channel cannot do Tx\n");
 		return -EINVAL;
 	}

 	if (count > MBOX_MAX_SIG_LEN) {
 		dev_err(tdev->dev,
 			"Signal length %zd greater than max allowed %d\n",
 			count, MBOX_MAX_SIG_LEN);
 		return -EINVAL;
 	}

 	/* Only allocate memory if we need to */
 	if (!tdev->signal) {
 		tdev->signal = kzalloc(MBOX_MAX_SIG_LEN, GFP_KERNEL);
 		if (!tdev->signal)
 			return -ENOMEM;
 	}

 	if (copy_from_user(tdev->signal, userbuf, count)) {
 		kfree(tdev->signal);
 		tdev->signal = NULL;
 		return -EFAULT;
 	}

 	return count;
 }

 static const struct file_operations mbox_test_signal_ops = {
 	.write	= mbox_test_signal_write,
 	.open	= simple_open,
 	.llseek	= generic_file_llseek,
 };

 static int mbox_test_message_fasync(int fd, struct file *filp, int on)
 {
 	struct mbox_test_device *tdev = filp->private_data;

 	return fasync_helper(fd, filp, on, &tdev->async_queue);
 }

 static ssize_t mbox_test_message_write(struct file *filp,
 				       const char __user *userbuf,
 				       size_t count, loff_t *ppos)
 {
 	struct mbox_test_device *tdev = filp->private_data;
 	void *data;
 	int ret;

 	if (!tdev->tx_channel) {
 		dev_err(tdev->dev, "Channel cannot do Tx\n");
 		return -EINVAL;
 	}

 	if (count > MBOX_MAX_MSG_LEN) {
 		dev_err(tdev->dev,
 			"Message length %zd greater than max allowed %d\n",
 			count, MBOX_MAX_MSG_LEN);
 		return -EINVAL;
 	}

 	tdev->message = kzalloc(MBOX_MAX_MSG_LEN, GFP_KERNEL);
 	if (!tdev->message)
 		return -ENOMEM;

 	ret = copy_from_user(tdev->message, userbuf, count);
 	if (ret) {
 		ret = -EFAULT;
 		goto out;
 	}

 	/*
 	 * A separate signal is only of use if there is
 	 * MMIO to subsequently pass the message through
 	 */
 	if (tdev->tx_mmio && tdev->signal) {
 		print_hex_dump_bytes("Client: Sending: Signal: ", DUMP_PREFIX_ADDRESS,
 				     tdev->signal, MBOX_MAX_SIG_LEN);

 		data = tdev->signal;
 	} else
 		data = tdev->message;

 	print_hex_dump_bytes("Client: Sending: Message: ", DUMP_PREFIX_ADDRESS,
 			     tdev->message, MBOX_MAX_MSG_LEN);

 	ret = mbox_send_message(tdev->tx_channel, data);
 	if (ret < 0)
 		dev_err(tdev->dev, "Failed to send message via mailbox\n");

 out:
 	kfree(tdev->signal);
 	kfree(tdev->message);
 	tdev->signal = NULL;

 	return ret < 0 ? ret : count;
 }

 static bool mbox_test_message_data_ready(struct mbox_test_device *tdev)
 {
 	bool data_ready;
 	unsigned long flags;

 	spin_lock_irqsave(&tdev->lock, flags);
 	data_ready = mbox_data_ready;
 	spin_unlock_irqrestore(&tdev->lock, flags);

 	return data_ready;
 }

 static ssize_t mbox_test_message_read(struct file *filp, char __user *userbuf,
 				      size_t count, loff_t *ppos)
 {
 	struct mbox_test_device *tdev = filp->private_data;
 	unsigned long flags;
 	char *touser, *ptr;
 	int l = 0;
 	int ret;

 	DECLARE_WAITQUEUE(wait, current);

 	touser = kzalloc(MBOX_HEXDUMP_MAX_LEN + 1, GFP_KERNEL);
 	if (!touser)
 		return -ENOMEM;

 	if (!tdev->rx_channel) {
 		ret = snprintf(touser, 20, "<NO RX CAPABILITY>\n");
 		ret = simple_read_from_buffer(userbuf, count, ppos,
 					      touser, ret);
 		goto kfree_err;
 	}

 	add_wait_queue(&tdev->waitq, &wait);

 	do {
 		__set_current_state(TASK_INTERRUPTIBLE);

 		if (mbox_test_message_data_ready(tdev))
 			break;

 		if (filp->f_flags & O_NONBLOCK) {
 			ret = -EAGAIN;
 			goto waitq_err;
 		}

 		if (signal_pending(current)) {
 			ret = -ERESTARTSYS;
 			goto waitq_err;
 		}
 		schedule();

 	} while (1);

 	spin_lock_irqsave(&tdev->lock, flags);

 	ptr = tdev->rx_buffer;
 	while (l < MBOX_HEXDUMP_MAX_LEN) {
 		hex_dump_to_buffer(ptr,
 				   MBOX_BYTES_PER_LINE,
 				   MBOX_BYTES_PER_LINE, 1, touser + l,
 				   MBOX_HEXDUMP_LINE_LEN, true);

 		ptr += MBOX_BYTES_PER_LINE;
 		l += MBOX_HEXDUMP_LINE_LEN;
 		*(touser + (l - 1)) = '\n';
 	}
 	*(touser + l) = '\0';

 	memset(tdev->rx_buffer, 0, MBOX_MAX_MSG_LEN);
 	mbox_data_ready = false;

 	spin_unlock_irqrestore(&tdev->lock, flags);

 	ret = simple_read_from_buffer(userbuf, count, ppos, touser, MBOX_HEXDUMP_MAX_LEN);
 waitq_err:
 	__set_current_state(TASK_RUNNING);
 	remove_wait_queue(&tdev->waitq, &wait);
 kfree_err:
 	kfree(touser);
 	return ret;
 }

 static unsigned int
 mbox_test_message_poll(struct file *filp, struct poll_table_struct *wait)
 {
 	struct mbox_test_device *tdev = filp->private_data;

 	poll_wait(filp, &tdev->waitq, wait);

 	if (mbox_test_message_data_ready(tdev))
 		return POLLIN | POLLRDNORM;
 	return 0;
 }

 static const struct file_operations mbox_test_message_ops = {
 	.write	= mbox_test_message_write,
 	.read	= mbox_test_message_read,
 	.fasync	= mbox_test_message_fasync,
 	.poll	= mbox_test_message_poll,
 	.open	= simple_open,
 	.llseek	= generic_file_llseek,
 };

 static int mbox_test_add_debugfs(struct platform_device *pdev,
 				 struct mbox_test_device *tdev)
 {
 	if (!debugfs_initialized())
 		return 0;

 	root_debugfs_dir = debugfs_create_dir("mailbox", NULL);
 	if (!root_debugfs_dir) {
 		dev_err(&pdev->dev, "Failed to create Mailbox debugfs\n");
 		return -EINVAL;
 	}

 	debugfs_create_file("message", 0600, root_debugfs_dir,
 			    tdev, &mbox_test_message_ops);

 	debugfs_create_file("signal", 0200, root_debugfs_dir,
 			    tdev, &mbox_test_signal_ops);

 	return 0;
 }

 static void mbox_test_receive_message(struct mbox_client *client, void *message)
 {
 	struct mbox_test_device *tdev = dev_get_drvdata(client->dev);
 	unsigned long flags;

 	spin_lock_irqsave(&tdev->lock, flags);
 	if (tdev->rx_mmio) {
 		memcpy_fromio(tdev->rx_buffer, tdev->rx_mmio, MBOX_MAX_MSG_LEN);
 		print_hex_dump_bytes("Client: Received [MMIO]: ", DUMP_PREFIX_ADDRESS,
 				     tdev->rx_buffer, MBOX_MAX_MSG_LEN);
 	} else if (message) {
 		print_hex_dump_bytes("Client: Received [API]: ", DUMP_PREFIX_ADDRESS,
 				     message, MBOX_MAX_MSG_LEN);
 		memcpy(tdev->rx_buffer, message, MBOX_MAX_MSG_LEN);
 	}
 	mbox_data_ready = true;
 	spin_unlock_irqrestore(&tdev->lock, flags);

 	wake_up_interruptible(&tdev->waitq);

 	kill_fasync(&tdev->async_queue, SIGIO, POLL_IN);
 }

 static void mbox_test_prepare_message(struct mbox_client *client, void *message)
 {
 	struct mbox_test_device *tdev = dev_get_drvdata(client->dev);

 	if (tdev->tx_mmio) {
 		if (tdev->signal)
 			memcpy_toio(tdev->tx_mmio, tdev->message, MBOX_MAX_MSG_LEN);
 		else
 			memcpy_toio(tdev->tx_mmio, message, MBOX_MAX_MSG_LEN);
 	}
 }

 static void mbox_test_message_sent(struct mbox_client *client,
 				   void *message, int r)
 {
 	if (r)
 		dev_warn(client->dev,
 			 "Client: Message could not be sent: %d\n", r);
 	else
 		dev_info(client->dev,
 			 "Client: Message sent\n");
 }

 static struct mbox_chan *
 mbox_test_request_channel(struct platform_device *pdev, const char *name)
 {
 	struct mbox_client *client;
 	struct mbox_chan *channel;

 	client = devm_kzalloc(&pdev->dev, sizeof(*client), GFP_KERNEL);
 	if (!client)
 		return ERR_PTR(-ENOMEM);

 	client->dev		= &pdev->dev;
 	client->rx_callback	= mbox_test_receive_message;
 	client->tx_prepare	= mbox_test_prepare_message;
 	client->tx_done		= mbox_test_message_sent;
 	client->tx_block	= true;
 	client->knows_txdone	= false;
 	client->tx_tout		= 500;

 	channel = mbox_request_channel_byname(client, name);
 	if (IS_ERR(channel)) {
 		dev_warn(&pdev->dev, "Failed to request %s channel\n", name);
 		return NULL;
 	}

 	return channel;
 }

 static int mbox_test_probe(struct platform_device *pdev)
 {
 	struct mbox_test_device *tdev;
 	struct resource *res;
 	resource_size_t size;
 	int ret;

 	tdev = devm_kzalloc(&pdev->dev, sizeof(*tdev), GFP_KERNEL);
 	if (!tdev)
 		return -ENOMEM;

 	/* It's okay for MMIO to be NULL */
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	size = resource_size(res);
 	tdev->tx_mmio = devm_ioremap_resource(&pdev->dev, res);
 	if (PTR_ERR(tdev->tx_mmio) == -EBUSY)
 		/* if reserved area in SRAM, try just ioremap */
 		tdev->tx_mmio = devm_ioremap(&pdev->dev, res->start, size);
 	else if (IS_ERR(tdev->tx_mmio))
 		tdev->tx_mmio = NULL;

 	/* If specified, second reg entry is Rx MMIO */
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 	size = resource_size(res);
 	tdev->rx_mmio = devm_ioremap_resource(&pdev->dev, res);
 	if (PTR_ERR(tdev->rx_mmio) == -EBUSY)
 		tdev->rx_mmio = devm_ioremap(&pdev->dev, res->start, size);
 	else if (IS_ERR(tdev->rx_mmio))
 		tdev->rx_mmio = tdev->tx_mmio;

 	tdev->tx_channel = mbox_test_request_channel(pdev, "tx");
 	tdev->rx_channel = mbox_test_request_channel(pdev, "rx");

 	if (!tdev->tx_channel && !tdev->rx_channel)
 		return -EPROBE_DEFER;

 	/* If Rx is not specified but has Rx MMIO, then Rx = Tx */
 	if (!tdev->rx_channel && (tdev->rx_mmio != tdev->tx_mmio))
 		tdev->rx_channel = tdev->tx_channel;

 	tdev->dev = &pdev->dev;
 	platform_set_drvdata(pdev, tdev);

 	spin_lock_init(&tdev->lock);

 	if (tdev->rx_channel) {
 		tdev->rx_buffer = devm_kzalloc(&pdev->dev,
 					       MBOX_MAX_MSG_LEN, GFP_KERNEL);
 		if (!tdev->rx_buffer)
 			return -ENOMEM;
 	}

 	ret = mbox_test_add_debugfs(pdev, tdev);
 	if (ret)
 		return ret;

 	init_waitqueue_head(&tdev->waitq);
 	dev_info(&pdev->dev, "Successfully registered\n");

 	return 0;
 }

 static int mbox_test_remove(struct platform_device *pdev)
 {
 	struct mbox_test_device *tdev = platform_get_drvdata(pdev);

 	debugfs_remove_recursive(root_debugfs_dir);

 	if (tdev->tx_channel)
 		mbox_free_channel(tdev->tx_channel);
 	if (tdev->rx_channel)
 		mbox_free_channel(tdev->rx_channel);

 	return 0;
 }

 static const struct of_device_id mbox_test_match[] = {
 	{ .compatible = "mailbox-test" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, mbox_test_match);

 static struct platform_driver mbox_test_driver = {
 	.driver = {
 		.name = "mailbox_test",
 		.of_match_table = mbox_test_match,
 	},
 	.probe  = mbox_test_probe,
 	.remove = mbox_test_remove,
 };
 module_platform_driver(mbox_test_driver);

 MODULE_DESCRIPTION("Generic Mailbox Testing Facility");
 MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org");
 MODULE_LICENSE("GPL v2");
	/*
	* Copyright (C) 2015 ST Microelectronics
	*
	* Author: Lee Jones <lee.jones@linaro.org>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*/

	#include <linux/debugfs.h>
	#include <linux/err.h>
	#include <linux/fs.h>
	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/mailbox_client.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/poll.h>
	#include <linux/slab.h>
	#include <linux/uaccess.h>
	#include <linux/sched/signal.h>

	#define MBOX_MAX_SIG_LEN 8
	#define MBOX_MAX_MSG_LEN 128
	#define MBOX_BYTES_PER_LINE 16
	#define MBOX_HEXDUMP_LINE_LEN ((MBOX_BYTES_PER_LINE * 4) + 2)
	#define MBOX_HEXDUMP_MAX_LEN (MBOX_HEXDUMP_LINE_LEN * \
	(MBOX_MAX_MSG_LEN / MBOX_BYTES_PER_LINE))

	static bool mbox_data_ready;
	static struct dentry *root_debugfs_dir;

	struct mbox_test_device {
	struct device *dev;
	void __iomem *tx_mmio;
	void __iomem *rx_mmio;
	struct mbox_chan *tx_channel;
	struct mbox_chan *rx_channel;
	char *rx_buffer;
	char *signal;
	char *message;
	spinlock_t lock;
	wait_queue_head_t waitq;
	struct fasync_struct *async_queue;
	};

	static ssize_t mbox_test_signal_write(struct file *filp,
	const char __user *userbuf,
	size_t count, loff_t *ppos)
	{
	struct mbox_test_device *tdev = filp->private_data;

	if (!tdev->tx_channel) {
	dev_err(tdev->dev, "Channel cannot do Tx\n");
	return -EINVAL;
	}

	if (count > MBOX_MAX_SIG_LEN) {
	dev_err(tdev->dev,
	"Signal length %zd greater than max allowed %d\n",
	count, MBOX_MAX_SIG_LEN);
	return -EINVAL;
	}

	/* Only allocate memory if we need to */
	if (!tdev->signal) {
	tdev->signal = kzalloc(MBOX_MAX_SIG_LEN, GFP_KERNEL);
	if (!tdev->signal)
	return -ENOMEM;
	}

	if (copy_from_user(tdev->signal, userbuf, count)) {
	kfree(tdev->signal);
	tdev->signal = NULL;
	return -EFAULT;
	}

	return count;
	}

	static const struct file_operations mbox_test_signal_ops = {
	.write = mbox_test_signal_write,
	.open = simple_open,
	.llseek = generic_file_llseek,
	};

	static int mbox_test_message_fasync(int fd, struct file *filp, int on)
	{
	struct mbox_test_device *tdev = filp->private_data;

	return fasync_helper(fd, filp, on, &tdev->async_queue);
	}

	static ssize_t mbox_test_message_write(struct file *filp,
	const char __user *userbuf,
	size_t count, loff_t *ppos)
	{
	struct mbox_test_device *tdev = filp->private_data;
	void *data;
	int ret;

	if (!tdev->tx_channel) {
	dev_err(tdev->dev, "Channel cannot do Tx\n");
	return -EINVAL;
	}

	if (count > MBOX_MAX_MSG_LEN) {
	dev_err(tdev->dev,
	"Message length %zd greater than max allowed %d\n",
	count, MBOX_MAX_MSG_LEN);
	return -EINVAL;
	}

	tdev->message = kzalloc(MBOX_MAX_MSG_LEN, GFP_KERNEL);
	if (!tdev->message)
	return -ENOMEM;

	ret = copy_from_user(tdev->message, userbuf, count);
	if (ret) {
	ret = -EFAULT;
	goto out;
	}

	/*
	* A separate signal is only of use if there is
	* MMIO to subsequently pass the message through
	*/
	if (tdev->tx_mmio && tdev->signal) {
	print_hex_dump_bytes("Client: Sending: Signal: ", DUMP_PREFIX_ADDRESS,
	tdev->signal, MBOX_MAX_SIG_LEN);

	data = tdev->signal;
	} else
	data = tdev->message;

	print_hex_dump_bytes("Client: Sending: Message: ", DUMP_PREFIX_ADDRESS,
	tdev->message, MBOX_MAX_MSG_LEN);

	ret = mbox_send_message(tdev->tx_channel, data);
	if (ret < 0)
	dev_err(tdev->dev, "Failed to send message via mailbox\n");

	out:
	kfree(tdev->signal);
	kfree(tdev->message);
	tdev->signal = NULL;

	return ret < 0 ? ret : count;
	}

	static bool mbox_test_message_data_ready(struct mbox_test_device *tdev)
	{
	bool data_ready;
	unsigned long flags;

	spin_lock_irqsave(&tdev->lock, flags);
	data_ready = mbox_data_ready;
	spin_unlock_irqrestore(&tdev->lock, flags);

	return data_ready;
	}

	static ssize_t mbox_test_message_read(struct file filp, char __user userbuf,
	size_t count, loff_t *ppos)
	{
	struct mbox_test_device *tdev = filp->private_data;
	unsigned long flags;
	char touser, ptr;
	int l = 0;
	int ret;

	DECLARE_WAITQUEUE(wait, current);

	touser = kzalloc(MBOX_HEXDUMP_MAX_LEN + 1, GFP_KERNEL);
	if (!touser)
	return -ENOMEM;

	if (!tdev->rx_channel) {
	ret = snprintf(touser, 20, "<NO RX CAPABILITY>\n");
	ret = simple_read_from_buffer(userbuf, count, ppos,
	touser, ret);
	goto kfree_err;
	}

	add_wait_queue(&tdev->waitq, &wait);

	do {
	__set_current_state(TASK_INTERRUPTIBLE);

	if (mbox_test_message_data_ready(tdev))
	break;

	if (filp->f_flags & O_NONBLOCK) {
	ret = -EAGAIN;
	goto waitq_err;
	}

	if (signal_pending(current)) {
	ret = -ERESTARTSYS;
	goto waitq_err;
	}
	schedule();

	} while (1);

	spin_lock_irqsave(&tdev->lock, flags);

	ptr = tdev->rx_buffer;
	while (l < MBOX_HEXDUMP_MAX_LEN) {
	hex_dump_to_buffer(ptr,
	MBOX_BYTES_PER_LINE,
	MBOX_BYTES_PER_LINE, 1, touser + l,
	MBOX_HEXDUMP_LINE_LEN, true);

	ptr += MBOX_BYTES_PER_LINE;
	l += MBOX_HEXDUMP_LINE_LEN;
	*(touser + (l - 1)) = '\n';
	}
	*(touser + l) = '\0';

	memset(tdev->rx_buffer, 0, MBOX_MAX_MSG_LEN);
	mbox_data_ready = false;

	spin_unlock_irqrestore(&tdev->lock, flags);

	ret = simple_read_from_buffer(userbuf, count, ppos, touser, MBOX_HEXDUMP_MAX_LEN);
	waitq_err:
	__set_current_state(TASK_RUNNING);
	remove_wait_queue(&tdev->waitq, &wait);
	kfree_err:
	kfree(touser);
	return ret;
	}

	static unsigned int
	mbox_test_message_poll(struct file filp, struct poll_table_struct wait)
	{
	struct mbox_test_device *tdev = filp->private_data;

	poll_wait(filp, &tdev->waitq, wait);

	if (mbox_test_message_data_ready(tdev))
	return POLLIN \| POLLRDNORM;
	return 0;
	}

	static const struct file_operations mbox_test_message_ops = {
	.write = mbox_test_message_write,
	.read = mbox_test_message_read,
	.fasync = mbox_test_message_fasync,
	.poll = mbox_test_message_poll,
	.open = simple_open,
	.llseek = generic_file_llseek,
	};

	static int mbox_test_add_debugfs(struct platform_device *pdev,
	struct mbox_test_device *tdev)
	{
	if (!debugfs_initialized())
	return 0;

	root_debugfs_dir = debugfs_create_dir("mailbox", NULL);
	if (!root_debugfs_dir) {
	dev_err(&pdev->dev, "Failed to create Mailbox debugfs\n");
	return -EINVAL;
	}

	debugfs_create_file("message", 0600, root_debugfs_dir,
	tdev, &mbox_test_message_ops);

	debugfs_create_file("signal", 0200, root_debugfs_dir,
	tdev, &mbox_test_signal_ops);

	return 0;
	}

	static void mbox_test_receive_message(struct mbox_client client, void message)
	{
	struct mbox_test_device *tdev = dev_get_drvdata(client->dev);
	unsigned long flags;

	spin_lock_irqsave(&tdev->lock, flags);
	if (tdev->rx_mmio) {
	memcpy_fromio(tdev->rx_buffer, tdev->rx_mmio, MBOX_MAX_MSG_LEN);
	print_hex_dump_bytes("Client: Received [MMIO]: ", DUMP_PREFIX_ADDRESS,
	tdev->rx_buffer, MBOX_MAX_MSG_LEN);
	} else if (message) {
	print_hex_dump_bytes("Client: Received [API]: ", DUMP_PREFIX_ADDRESS,
	message, MBOX_MAX_MSG_LEN);
	memcpy(tdev->rx_buffer, message, MBOX_MAX_MSG_LEN);
	}
	mbox_data_ready = true;
	spin_unlock_irqrestore(&tdev->lock, flags);

	wake_up_interruptible(&tdev->waitq);

	kill_fasync(&tdev->async_queue, SIGIO, POLL_IN);
	}

	static void mbox_test_prepare_message(struct mbox_client client, void message)
	{
	struct mbox_test_device *tdev = dev_get_drvdata(client->dev);

	if (tdev->tx_mmio) {
	if (tdev->signal)
	memcpy_toio(tdev->tx_mmio, tdev->message, MBOX_MAX_MSG_LEN);
	else
	memcpy_toio(tdev->tx_mmio, message, MBOX_MAX_MSG_LEN);
	}
	}

	static void mbox_test_message_sent(struct mbox_client *client,
	void *message, int r)
	{
	if (r)
	dev_warn(client->dev,
	"Client: Message could not be sent: %d\n", r);
	else
	dev_info(client->dev,
	"Client: Message sent\n");
	}

	static struct mbox_chan *
	mbox_test_request_channel(struct platform_device pdev, const char name)
	{
	struct mbox_client *client;
	struct mbox_chan *channel;

	client = devm_kzalloc(&pdev->dev, sizeof(*client), GFP_KERNEL);
	if (!client)
	return ERR_PTR(-ENOMEM);

	client->dev = &pdev->dev;
	client->rx_callback = mbox_test_receive_message;
	client->tx_prepare = mbox_test_prepare_message;
	client->tx_done = mbox_test_message_sent;
	client->tx_block = true;
	client->knows_txdone = false;
	client->tx_tout = 500;

	channel = mbox_request_channel_byname(client, name);
	if (IS_ERR(channel)) {
	dev_warn(&pdev->dev, "Failed to request %s channel\n", name);
	return NULL;
	}

	return channel;
	}

	static int mbox_test_probe(struct platform_device *pdev)
	{
	struct mbox_test_device *tdev;
	struct resource *res;
	resource_size_t size;
	int ret;

	tdev = devm_kzalloc(&pdev->dev, sizeof(*tdev), GFP_KERNEL);
	if (!tdev)
	return -ENOMEM;

	/* It's okay for MMIO to be NULL */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	size = resource_size(res);
	tdev->tx_mmio = devm_ioremap_resource(&pdev->dev, res);
	if (PTR_ERR(tdev->tx_mmio) == -EBUSY)
	/* if reserved area in SRAM, try just ioremap */
	tdev->tx_mmio = devm_ioremap(&pdev->dev, res->start, size);
	else if (IS_ERR(tdev->tx_mmio))
	tdev->tx_mmio = NULL;

	/* If specified, second reg entry is Rx MMIO */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
	size = resource_size(res);
	tdev->rx_mmio = devm_ioremap_resource(&pdev->dev, res);
	if (PTR_ERR(tdev->rx_mmio) == -EBUSY)
	tdev->rx_mmio = devm_ioremap(&pdev->dev, res->start, size);
	else if (IS_ERR(tdev->rx_mmio))
	tdev->rx_mmio = tdev->tx_mmio;

	tdev->tx_channel = mbox_test_request_channel(pdev, "tx");
	tdev->rx_channel = mbox_test_request_channel(pdev, "rx");

	if (!tdev->tx_channel && !tdev->rx_channel)
	return -EPROBE_DEFER;

	/* If Rx is not specified but has Rx MMIO, then Rx = Tx */
	if (!tdev->rx_channel && (tdev->rx_mmio != tdev->tx_mmio))
	tdev->rx_channel = tdev->tx_channel;

	tdev->dev = &pdev->dev;
	platform_set_drvdata(pdev, tdev);

	spin_lock_init(&tdev->lock);

	if (tdev->rx_channel) {
	tdev->rx_buffer = devm_kzalloc(&pdev->dev,
	MBOX_MAX_MSG_LEN, GFP_KERNEL);
	if (!tdev->rx_buffer)
	return -ENOMEM;
	}

	ret = mbox_test_add_debugfs(pdev, tdev);
	if (ret)
	return ret;

	init_waitqueue_head(&tdev->waitq);
	dev_info(&pdev->dev, "Successfully registered\n");

	return 0;
	}

	static int mbox_test_remove(struct platform_device *pdev)
	{
	struct mbox_test_device *tdev = platform_get_drvdata(pdev);

	debugfs_remove_recursive(root_debugfs_dir);

	if (tdev->tx_channel)
	mbox_free_channel(tdev->tx_channel);
	if (tdev->rx_channel)
	mbox_free_channel(tdev->rx_channel);

	return 0;
	}

	static const struct of_device_id mbox_test_match[] = {
	{ .compatible = "mailbox-test" },
	{},
	};
	MODULE_DEVICE_TABLE(of, mbox_test_match);

	static struct platform_driver mbox_test_driver = {
	.driver = {
	.name = "mailbox_test",
	.of_match_table = mbox_test_match,
	},
	.probe = mbox_test_probe,
	.remove = mbox_test_remove,
	};
	module_platform_driver(mbox_test_driver);

	MODULE_DESCRIPTION("Generic Mailbox Testing Facility");
	MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org");
	MODULE_LICENSE("GPL v2");