arch/arm/mach-ux500/mbox-db5500.c - kernel/msm-5.4 - Gitiles

 /*
  * Copyright (C) ST-Ericsson SA 2010
  * Author: Stefan Nilsson <stefan.xk.nilsson@stericsson.com> for ST-Ericsson.
  * Author: Martin Persson <martin.persson@stericsson.com> for ST-Ericsson.
  * License terms: GNU General Public License (GPL), version 2.
  */

 /*
  * Mailbox nomenclature:
  *
  *       APE           MODEM
  *           mbox pairX
  *   ..........................
  *   .                       .
  *   .           peer        .
  *   .     send  ----        .
  *   .      -->  |  |        .
  *   .           |  |        .
  *   .           ----        .
  *   .                       .
  *   .           local       .
  *   .     rec   ----        .
  *   .           |  | <--    .
  *   .           |  |        .
  *   .           ----        .
  *   .........................
  */

 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
 #include <linux/errno.h>
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <linux/platform_device.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
 #include <linux/completion.h>
 #include <mach/mbox-db5500.h>

 #define MBOX_NAME "mbox"

 #define MBOX_FIFO_DATA        0x000
 #define MBOX_FIFO_ADD         0x004
 #define MBOX_FIFO_REMOVE      0x008
 #define MBOX_FIFO_THRES_FREE  0x00C
 #define MBOX_FIFO_THRES_OCCUP 0x010
 #define MBOX_FIFO_STATUS      0x014

 #define MBOX_DISABLE_IRQ 0x4
 #define MBOX_ENABLE_IRQ  0x0
 #define MBOX_LATCH 1

 /* Global list of all mailboxes */
 static struct list_head mboxs = LIST_HEAD_INIT(mboxs);

 static struct mbox *get_mbox_with_id(u8 id)
 {
 	u8 i;
 	struct list_head *pos = &mboxs;
 	for (i = 0; i <= id; i++)
 		pos = pos->next;

 	return (struct mbox *) list_entry(pos, struct mbox, list);
 }

 int mbox_send(struct mbox *mbox, u32 mbox_msg, bool block)
 {
 	int res = 0;

 	spin_lock(&mbox->lock);

 	dev_dbg(&(mbox->pdev->dev),
 		"About to buffer 0x%X to mailbox 0x%X."
 		" ri = %d, wi = %d\n",
 		mbox_msg, (u32)mbox, mbox->read_index,
 		mbox->write_index);

 	/* Check if write buffer is full */
 	while (((mbox->write_index + 1) % MBOX_BUF_SIZE) == mbox->read_index) {
 		if (!block) {
 			dev_dbg(&(mbox->pdev->dev),
 			"Buffer full in non-blocking call! "
 			"Returning -ENOMEM!\n");
 			res = -ENOMEM;
 			goto exit;
 		}
 		spin_unlock(&mbox->lock);
 		dev_dbg(&(mbox->pdev->dev),
 			"Buffer full in blocking call! Sleeping...\n");
 		mbox->client_blocked = 1;
 		wait_for_completion(&mbox->buffer_available);
 		dev_dbg(&(mbox->pdev->dev),
 			"Blocking send was woken up! Trying again...\n");
 		spin_lock(&mbox->lock);
 	}

 	mbox->buffer[mbox->write_index] = mbox_msg;
 	mbox->write_index = (mbox->write_index + 1) % MBOX_BUF_SIZE;

 	/*
 	 * Indicate that we want an IRQ as soon as there is a slot
 	 * in the FIFO
 	 */
 	writel(MBOX_ENABLE_IRQ, mbox->virtbase_peer + MBOX_FIFO_THRES_FREE);

 exit:
 	spin_unlock(&mbox->lock);
 	return res;
 }
 EXPORT_SYMBOL(mbox_send);

 #if defined(CONFIG_DEBUG_FS)
 /*
  * Expected input: <value> <nbr sends>
  * Example: "echo 0xdeadbeef 4 > mbox-node" sends 0xdeadbeef 4 times
  */
 static ssize_t mbox_write_fifo(struct device *dev,
 			       struct device_attribute *attr,
 			       const char *buf,
 			       size_t count)
 {
 	unsigned long mbox_mess;
 	unsigned long nbr_sends;
 	unsigned long i;
 	char int_buf[16];
 	char *token;
 	char *val;

 	struct mbox *mbox = (struct mbox *) dev->platform_data;

 	strncpy((char *) &int_buf, buf, sizeof(int_buf));
 	token = (char *) &int_buf;

 	/* Parse message */
 	val = strsep(&token, " ");
 	if ((val == NULL) || (strict_strtoul(val, 16, &mbox_mess) != 0))
 		mbox_mess = 0xDEADBEEF;

 	val = strsep(&token, " ");
 	if ((val == NULL) || (strict_strtoul(val, 10, &nbr_sends) != 0))
 		nbr_sends = 1;

 	dev_dbg(dev, "Will write 0x%lX %ld times using data struct at 0x%X\n",
 		mbox_mess, nbr_sends, (u32) mbox);

 	for (i = 0; i < nbr_sends; i++)
 		mbox_send(mbox, mbox_mess, true);

 	return count;
 }

 static ssize_t mbox_read_fifo(struct device *dev,
 			      struct device_attribute *attr,
 			      char *buf)
 {
 	int mbox_value;
 	struct mbox *mbox = (struct mbox *) dev->platform_data;

 	if ((readl(mbox->virtbase_local + MBOX_FIFO_STATUS) & 0x7) <= 0)
 		return sprintf(buf, "Mailbox is empty\n");

 	mbox_value = readl(mbox->virtbase_local + MBOX_FIFO_DATA);
 	writel(MBOX_LATCH, (mbox->virtbase_local + MBOX_FIFO_REMOVE));

 	return sprintf(buf, "0x%X\n", mbox_value);
 }

 static DEVICE_ATTR(fifo, S_IWUGO | S_IRUGO, mbox_read_fifo, mbox_write_fifo);

 static int mbox_show(struct seq_file *s, void *data)
 {
 	struct list_head *pos;
 	u8 mbox_index = 0;

 	list_for_each(pos, &mboxs) {
 		struct mbox *m =
 			(struct mbox *) list_entry(pos, struct mbox, list);
 		if (m == NULL) {
 			seq_printf(s,
 				   "Unable to retrieve mailbox %d\n",
 				   mbox_index);
 			continue;
 		}

 		spin_lock(&m->lock);
 		if ((m->virtbase_peer == NULL) || (m->virtbase_local == NULL)) {
 			seq_printf(s, "MAILBOX %d not setup or corrupt\n",
 				   mbox_index);
 			spin_unlock(&m->lock);
 			continue;
 		}

 		seq_printf(s,
 		"===========================\n"
 		" MAILBOX %d\n"
 		" PEER MAILBOX DUMP\n"
 		"---------------------------\n"
 		"FIFO:                 0x%X (%d)\n"
 		"Free     Threshold:   0x%.2X (%d)\n"
 		"Occupied Threshold:   0x%.2X (%d)\n"
 		"Status:               0x%.2X (%d)\n"
 		"   Free spaces  (ot):    %d (%d)\n"
 		"   Occup spaces (ot):    %d (%d)\n"
 		"===========================\n"
 		" LOCAL MAILBOX DUMP\n"
 		"---------------------------\n"
 		"FIFO:                 0x%.X (%d)\n"
 		"Free     Threshold:   0x%.2X (%d)\n"
 		"Occupied Threshold:   0x%.2X (%d)\n"
 		"Status:               0x%.2X (%d)\n"
 		"   Free spaces  (ot):    %d (%d)\n"
 		"   Occup spaces (ot):    %d (%d)\n"
 		"===========================\n"
 		"write_index: %d\n"
 		"read_index : %d\n"
 		"===========================\n"
 		"\n",
 		mbox_index,
 		readl(m->virtbase_peer + MBOX_FIFO_DATA),
 		readl(m->virtbase_peer + MBOX_FIFO_DATA),
 		readl(m->virtbase_peer + MBOX_FIFO_THRES_FREE),
 		readl(m->virtbase_peer + MBOX_FIFO_THRES_FREE),
 		readl(m->virtbase_peer + MBOX_FIFO_THRES_OCCUP),
 		readl(m->virtbase_peer + MBOX_FIFO_THRES_OCCUP),
 		readl(m->virtbase_peer + MBOX_FIFO_STATUS),
 		readl(m->virtbase_peer + MBOX_FIFO_STATUS),
 		(readl(m->virtbase_peer + MBOX_FIFO_STATUS) >> 4) & 0x7,
 		(readl(m->virtbase_peer + MBOX_FIFO_STATUS) >> 7) & 0x1,
 		(readl(m->virtbase_peer + MBOX_FIFO_STATUS) >> 0) & 0x7,
 		(readl(m->virtbase_peer + MBOX_FIFO_STATUS) >> 3) & 0x1,
 		readl(m->virtbase_local + MBOX_FIFO_DATA),
 		readl(m->virtbase_local + MBOX_FIFO_DATA),
 		readl(m->virtbase_local + MBOX_FIFO_THRES_FREE),
 		readl(m->virtbase_local + MBOX_FIFO_THRES_FREE),
 		readl(m->virtbase_local + MBOX_FIFO_THRES_OCCUP),
 		readl(m->virtbase_local + MBOX_FIFO_THRES_OCCUP),
 		readl(m->virtbase_local + MBOX_FIFO_STATUS),
 		readl(m->virtbase_local + MBOX_FIFO_STATUS),
 		(readl(m->virtbase_local + MBOX_FIFO_STATUS) >> 4) & 0x7,
 		(readl(m->virtbase_local + MBOX_FIFO_STATUS) >> 7) & 0x1,
 		(readl(m->virtbase_local + MBOX_FIFO_STATUS) >> 0) & 0x7,
 		(readl(m->virtbase_local + MBOX_FIFO_STATUS) >> 3) & 0x1,
 		m->write_index, m->read_index);
 		mbox_index++;
 		spin_unlock(&m->lock);
 	}

 	return 0;
 }

 static int mbox_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, mbox_show, NULL);
 }

 static const struct file_operations mbox_operations = {
 	.owner = THIS_MODULE,
 	.open = mbox_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
 	.release = single_release,
 };
 #endif

 static irqreturn_t mbox_irq(int irq, void *arg)
 {
 	u32 mbox_value;
 	int nbr_occup;
 	int nbr_free;
 	struct mbox *mbox = (struct mbox *) arg;

 	spin_lock(&mbox->lock);

 	dev_dbg(&(mbox->pdev->dev),
 		"mbox IRQ [%d] received. ri = %d, wi = %d\n",
 		irq, mbox->read_index, mbox->write_index);

 	/*
 	 * Check if we have any outgoing messages, and if there is space for
 	 * them in the FIFO.
 	 */
 	if (mbox->read_index != mbox->write_index) {
 		/*
 		 * Check by reading FREE for LOCAL since that indicates
 		 * OCCUP for PEER
 		 */
 		nbr_free = (readl(mbox->virtbase_local + MBOX_FIFO_STATUS)
 			    >> 4) & 0x7;
 		dev_dbg(&(mbox->pdev->dev),
 			"Status indicates %d empty spaces in the FIFO!\n",
 			nbr_free);

 		while ((nbr_free > 0) &&
 		       (mbox->read_index != mbox->write_index)) {
 			/* Write the message and latch it into the FIFO */
 			writel(mbox->buffer[mbox->read_index],
 			       (mbox->virtbase_peer + MBOX_FIFO_DATA));
 			writel(MBOX_LATCH,
 			       (mbox->virtbase_peer + MBOX_FIFO_ADD));
 			dev_dbg(&(mbox->pdev->dev),
 				"Wrote message 0x%X to addr 0x%X\n",
 				mbox->buffer[mbox->read_index],
 				(u32) (mbox->virtbase_peer + MBOX_FIFO_DATA));

 			nbr_free--;
 			mbox->read_index =
 				(mbox->read_index + 1) % MBOX_BUF_SIZE;
 		}

 		/*
 		 * Check if we still want IRQ:s when there is free
 		 * space to send
 		 */
 		if (mbox->read_index != mbox->write_index) {
 			dev_dbg(&(mbox->pdev->dev),
 				"Still have messages to send, but FIFO full. "
 				"Request IRQ again!\n");
 			writel(MBOX_ENABLE_IRQ,
 			       mbox->virtbase_peer + MBOX_FIFO_THRES_FREE);
 		} else {
 			dev_dbg(&(mbox->pdev->dev),
 				"No more messages to send. "
 				"Do not request IRQ again!\n");
 			writel(MBOX_DISABLE_IRQ,
 			       mbox->virtbase_peer + MBOX_FIFO_THRES_FREE);
 		}

 		/*
 		 * Check if we can signal any blocked clients that it is OK to
 		 * start buffering again
 		 */
 		if (mbox->client_blocked &&
 		    (((mbox->write_index + 1) % MBOX_BUF_SIZE)
 		     != mbox->read_index)) {
 			dev_dbg(&(mbox->pdev->dev),
 				"Waking up blocked client\n");
 			complete(&mbox->buffer_available);
 			mbox->client_blocked = 0;
 		}
 	}

 	/* Check if we have any incoming messages */
 	nbr_occup = readl(mbox->virtbase_local + MBOX_FIFO_STATUS) & 0x7;
 	if (nbr_occup == 0)
 		goto exit;

 	if (mbox->cb == NULL) {
 		dev_dbg(&(mbox->pdev->dev), "No receive callback registered, "
 			"leaving %d incoming messages in fifo!\n", nbr_occup);
 		goto exit;
 	}

 	/* Read and acknowledge the message */
 	mbox_value = readl(mbox->virtbase_local + MBOX_FIFO_DATA);
 	writel(MBOX_LATCH, (mbox->virtbase_local + MBOX_FIFO_REMOVE));

 	/* Notify consumer of new mailbox message */
 	dev_dbg(&(mbox->pdev->dev), "Calling callback for message 0x%X!\n",
 		mbox_value);
 	mbox->cb(mbox_value, mbox->client_data);

 exit:
 	dev_dbg(&(mbox->pdev->dev), "Exit mbox IRQ. ri = %d, wi = %d\n",
 		mbox->read_index, mbox->write_index);
 	spin_unlock(&mbox->lock);

 	return IRQ_HANDLED;
 }

 /* Setup is executed once for each mbox pair */
 struct mbox *mbox_setup(u8 mbox_id, mbox_recv_cb_t *mbox_cb, void *priv)
 {
 	struct resource *resource;
 	int irq;
 	int res;
 	struct mbox *mbox;

 	mbox = get_mbox_with_id(mbox_id);
 	if (mbox == NULL) {
 		dev_err(&(mbox->pdev->dev), "Incorrect mailbox id: %d!\n",
 			mbox_id);
 		goto exit;
 	}

 	/*
 	 * Check if mailbox has been allocated to someone else,
 	 * otherwise allocate it
 	 */
 	if (mbox->allocated) {
 		dev_err(&(mbox->pdev->dev), "Mailbox number %d is busy!\n",
 			mbox_id);
 		mbox = NULL;
 		goto exit;
 	}
 	mbox->allocated = true;

 	dev_dbg(&(mbox->pdev->dev), "Initiating mailbox number %d: 0x%X...\n",
 		mbox_id, (u32)mbox);

 	mbox->client_data = priv;
 	mbox->cb = mbox_cb;

 	/* Get addr for peer mailbox and ioremap it */
 	resource = platform_get_resource_byname(mbox->pdev,
 						IORESOURCE_MEM,
 						"mbox_peer");
 	if (resource == NULL) {
 		dev_err(&(mbox->pdev->dev),
 			"Unable to retrieve mbox peer resource\n");
 		mbox = NULL;
 		goto exit;
 	}
 	dev_dbg(&(mbox->pdev->dev),
 		"Resource name: %s start: 0x%X, end: 0x%X\n",
 		resource->name, resource->start, resource->end);
 	mbox->virtbase_peer =
 		ioremap(resource->start, resource->end - resource->start);
 	if (!mbox->virtbase_peer) {
 		dev_err(&(mbox->pdev->dev), "Unable to ioremap peer mbox\n");
 		mbox = NULL;
 		goto exit;
 	}
 	dev_dbg(&(mbox->pdev->dev),
 		"ioremapped peer physical: (0x%X-0x%X) to virtual: 0x%X\n",
 		resource->start, resource->end, (u32) mbox->virtbase_peer);

 	/* Get addr for local mailbox and ioremap it */
 	resource = platform_get_resource_byname(mbox->pdev,
 						IORESOURCE_MEM,
 						"mbox_local");
 	if (resource == NULL) {
 		dev_err(&(mbox->pdev->dev),
 			"Unable to retrieve mbox local resource\n");
 		mbox = NULL;
 		goto exit;
 	}
 	dev_dbg(&(mbox->pdev->dev),
 		"Resource name: %s start: 0x%X, end: 0x%X\n",
 		resource->name, resource->start, resource->end);
 	mbox->virtbase_local =
 		ioremap(resource->start, resource->end - resource->start);
 	if (!mbox->virtbase_local) {
 		dev_err(&(mbox->pdev->dev), "Unable to ioremap local mbox\n");
 		mbox = NULL;
 		goto exit;
 	}
 	dev_dbg(&(mbox->pdev->dev),
 		"ioremapped local physical: (0x%X-0x%X) to virtual: 0x%X\n",
 		resource->start, resource->end, (u32) mbox->virtbase_peer);

 	init_completion(&mbox->buffer_available);
 	mbox->client_blocked = 0;

 	/* Get IRQ for mailbox and allocate it */
 	irq = platform_get_irq_byname(mbox->pdev, "mbox_irq");
 	if (irq < 0) {
 		dev_err(&(mbox->pdev->dev),
 			"Unable to retrieve mbox irq resource\n");
 		mbox = NULL;
 		goto exit;
 	}

 	dev_dbg(&(mbox->pdev->dev), "Allocating irq %d...\n", irq);
 	res = request_irq(irq, mbox_irq, 0, mbox->name, (void *) mbox);
 	if (res < 0) {
 		dev_err(&(mbox->pdev->dev),
 			"Unable to allocate mbox irq %d\n", irq);
 		mbox = NULL;
 		goto exit;
 	}

 	/* Set up mailbox to not launch IRQ on free space in mailbox */
 	writel(MBOX_DISABLE_IRQ, mbox->virtbase_peer + MBOX_FIFO_THRES_FREE);

 	/*
 	 * Set up mailbox to launch IRQ on new message if we have
 	 * a callback set. If not, do not raise IRQ, but keep message
 	 * in FIFO for manual retrieval
 	 */
 	if (mbox_cb != NULL)
 		writel(MBOX_ENABLE_IRQ,
 		       mbox->virtbase_local + MBOX_FIFO_THRES_OCCUP);
 	else
 		writel(MBOX_DISABLE_IRQ,
 		       mbox->virtbase_local + MBOX_FIFO_THRES_OCCUP);

 #if defined(CONFIG_DEBUG_FS)
 	res = device_create_file(&(mbox->pdev->dev), &dev_attr_fifo);
 	if (res != 0)
 		dev_warn(&(mbox->pdev->dev),
 			 "Unable to create mbox sysfs entry");

 	(void) debugfs_create_file("mbox", S_IFREG | S_IRUGO, NULL,
 				   NULL, &mbox_operations);
 #endif

 	dev_info(&(mbox->pdev->dev),
 		 "Mailbox driver with index %d initated!\n", mbox_id);

 exit:
 	return mbox;
 }
 EXPORT_SYMBOL(mbox_setup);


 int __init mbox_probe(struct platform_device *pdev)
 {
 	struct mbox local_mbox;
 	struct mbox *mbox;
 	int res = 0;
 	dev_dbg(&(pdev->dev), "Probing mailbox (pdev = 0x%X)...\n", (u32) pdev);

 	memset(&local_mbox, 0x0, sizeof(struct mbox));

 	/* Associate our mbox data with the platform device */
 	res = platform_device_add_data(pdev,
 				       (void *) &local_mbox,
 				       sizeof(struct mbox));
 	if (res != 0) {
 		dev_err(&(pdev->dev),
 			"Unable to allocate driver platform data!\n");
 		goto exit;
 	}

 	mbox = (struct mbox *) pdev->dev.platform_data;
 	mbox->pdev = pdev;
 	mbox->write_index = 0;
 	mbox->read_index = 0;

 	INIT_LIST_HEAD(&(mbox->list));
 	list_add_tail(&(mbox->list), &mboxs);

 	sprintf(mbox->name, "%s", MBOX_NAME);
 	spin_lock_init(&mbox->lock);

 	dev_info(&(pdev->dev), "Mailbox driver loaded\n");

 exit:
 	return res;
 }

 static struct platform_driver mbox_driver = {
 	.driver = {
 		.name = MBOX_NAME,
 		.owner = THIS_MODULE,
 	},
 };

 static int __init mbox_init(void)
 {
 	return platform_driver_probe(&mbox_driver, mbox_probe);
 }

 module_init(mbox_init);

 void __exit mbox_exit(void)
 {
 	platform_driver_unregister(&mbox_driver);
 }

 module_exit(mbox_exit);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("MBOX driver");
	/*
	* Copyright (C) ST-Ericsson SA 2010
	* Author: Stefan Nilsson <stefan.xk.nilsson@stericsson.com> for ST-Ericsson.
	* Author: Martin Persson <martin.persson@stericsson.com> for ST-Ericsson.
	* License terms: GNU General Public License (GPL), version 2.
	*/

	/*
	* Mailbox nomenclature:
	*
	* APE MODEM
	* mbox pairX
	* ..........................
	* . .
	* . peer .
	* . send ---- .
	* . --> \| \| .
	* . \| \| .
	* . ---- .
	* . .
	* . local .
	* . rec ---- .
	* . \| \| <-- .
	* . \| \| .
	* . ---- .
	* .........................
	*/

	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/interrupt.h>
	#include <linux/spinlock.h>
	#include <linux/errno.h>
	#include <linux/io.h>
	#include <linux/irq.h>
	#include <linux/platform_device.h>
	#include <linux/debugfs.h>
	#include <linux/seq_file.h>
	#include <linux/completion.h>
	#include <mach/mbox-db5500.h>

	#define MBOX_NAME "mbox"

	#define MBOX_FIFO_DATA 0x000
	#define MBOX_FIFO_ADD 0x004
	#define MBOX_FIFO_REMOVE 0x008
	#define MBOX_FIFO_THRES_FREE 0x00C
	#define MBOX_FIFO_THRES_OCCUP 0x010
	#define MBOX_FIFO_STATUS 0x014

	#define MBOX_DISABLE_IRQ 0x4
	#define MBOX_ENABLE_IRQ 0x0
	#define MBOX_LATCH 1

	/* Global list of all mailboxes */
	static struct list_head mboxs = LIST_HEAD_INIT(mboxs);

	static struct mbox *get_mbox_with_id(u8 id)
	{
	u8 i;
	struct list_head *pos = &mboxs;
	for (i = 0; i <= id; i++)
	pos = pos->next;

	return (struct mbox *) list_entry(pos, struct mbox, list);
	}

	int mbox_send(struct mbox *mbox, u32 mbox_msg, bool block)
	{
	int res = 0;

	spin_lock(&mbox->lock);

	dev_dbg(&(mbox->pdev->dev),
	"About to buffer 0x%X to mailbox 0x%X."
	" ri = %d, wi = %d\n",
	mbox_msg, (u32)mbox, mbox->read_index,
	mbox->write_index);

	/* Check if write buffer is full */
	while (((mbox->write_index + 1) % MBOX_BUF_SIZE) == mbox->read_index) {
	if (!block) {
	dev_dbg(&(mbox->pdev->dev),
	"Buffer full in non-blocking call! "
	"Returning -ENOMEM!\n");
	res = -ENOMEM;
	goto exit;
	}
	spin_unlock(&mbox->lock);
	dev_dbg(&(mbox->pdev->dev),
	"Buffer full in blocking call! Sleeping...\n");
	mbox->client_blocked = 1;
	wait_for_completion(&mbox->buffer_available);
	dev_dbg(&(mbox->pdev->dev),
	"Blocking send was woken up! Trying again...\n");
	spin_lock(&mbox->lock);
	}

	mbox->buffer[mbox->write_index] = mbox_msg;
	mbox->write_index = (mbox->write_index + 1) % MBOX_BUF_SIZE;

	/*
	* Indicate that we want an IRQ as soon as there is a slot
	* in the FIFO
	*/
	writel(MBOX_ENABLE_IRQ, mbox->virtbase_peer + MBOX_FIFO_THRES_FREE);

	exit:
	spin_unlock(&mbox->lock);
	return res;
	}
	EXPORT_SYMBOL(mbox_send);

	#if defined(CONFIG_DEBUG_FS)
	/*
	* Expected input: <value> <nbr sends>
	* Example: "echo 0xdeadbeef 4 > mbox-node" sends 0xdeadbeef 4 times
	*/
	static ssize_t mbox_write_fifo(struct device *dev,
	struct device_attribute *attr,
	const char *buf,
	size_t count)
	{
	unsigned long mbox_mess;
	unsigned long nbr_sends;
	unsigned long i;
	char int_buf[16];
	char *token;
	char *val;

	struct mbox mbox = (struct mbox ) dev->platform_data;

	strncpy((char *) &int_buf, buf, sizeof(int_buf));
	token = (char *) &int_buf;

	/* Parse message */
	val = strsep(&token, " ");
	if ((val == NULL) \|\| (strict_strtoul(val, 16, &mbox_mess) != 0))
	mbox_mess = 0xDEADBEEF;

	val = strsep(&token, " ");
	if ((val == NULL) \|\| (strict_strtoul(val, 10, &nbr_sends) != 0))
	nbr_sends = 1;

	dev_dbg(dev, "Will write 0x%lX %ld times using data struct at 0x%X\n",
	mbox_mess, nbr_sends, (u32) mbox);

	for (i = 0; i < nbr_sends; i++)
	mbox_send(mbox, mbox_mess, true);

	return count;
	}

	static ssize_t mbox_read_fifo(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	int mbox_value;
	struct mbox mbox = (struct mbox ) dev->platform_data;

	if ((readl(mbox->virtbase_local + MBOX_FIFO_STATUS) & 0x7) <= 0)
	return sprintf(buf, "Mailbox is empty\n");

	mbox_value = readl(mbox->virtbase_local + MBOX_FIFO_DATA);
	writel(MBOX_LATCH, (mbox->virtbase_local + MBOX_FIFO_REMOVE));

	return sprintf(buf, "0x%X\n", mbox_value);
	}

	static DEVICE_ATTR(fifo, S_IWUGO \| S_IRUGO, mbox_read_fifo, mbox_write_fifo);

	static int mbox_show(struct seq_file s, void data)
	{
	struct list_head *pos;
	u8 mbox_index = 0;

	list_for_each(pos, &mboxs) {
	struct mbox *m =
	(struct mbox *) list_entry(pos, struct mbox, list);
	if (m == NULL) {
	seq_printf(s,
	"Unable to retrieve mailbox %d\n",
	mbox_index);
	continue;
	}

	spin_lock(&m->lock);
	if ((m->virtbase_peer == NULL) \|\| (m->virtbase_local == NULL)) {
	seq_printf(s, "MAILBOX %d not setup or corrupt\n",
	mbox_index);
	spin_unlock(&m->lock);
	continue;
	}

	seq_printf(s,
	"===========================\n"
	" MAILBOX %d\n"
	" PEER MAILBOX DUMP\n"
	"---------------------------\n"
	"FIFO: 0x%X (%d)\n"
	"Free Threshold: 0x%.2X (%d)\n"
	"Occupied Threshold: 0x%.2X (%d)\n"
	"Status: 0x%.2X (%d)\n"
	" Free spaces (ot): %d (%d)\n"
	" Occup spaces (ot): %d (%d)\n"
	"===========================\n"
	" LOCAL MAILBOX DUMP\n"
	"---------------------------\n"
	"FIFO: 0x%.X (%d)\n"
	"Free Threshold: 0x%.2X (%d)\n"
	"Occupied Threshold: 0x%.2X (%d)\n"
	"Status: 0x%.2X (%d)\n"
	" Free spaces (ot): %d (%d)\n"
	" Occup spaces (ot): %d (%d)\n"
	"===========================\n"
	"write_index: %d\n"
	"read_index : %d\n"
	"===========================\n"
	"\n",
	mbox_index,
	readl(m->virtbase_peer + MBOX_FIFO_DATA),
	readl(m->virtbase_peer + MBOX_FIFO_DATA),
	readl(m->virtbase_peer + MBOX_FIFO_THRES_FREE),
	readl(m->virtbase_peer + MBOX_FIFO_THRES_FREE),
	readl(m->virtbase_peer + MBOX_FIFO_THRES_OCCUP),
	readl(m->virtbase_peer + MBOX_FIFO_THRES_OCCUP),
	readl(m->virtbase_peer + MBOX_FIFO_STATUS),
	readl(m->virtbase_peer + MBOX_FIFO_STATUS),
	(readl(m->virtbase_peer + MBOX_FIFO_STATUS) >> 4) & 0x7,
	(readl(m->virtbase_peer + MBOX_FIFO_STATUS) >> 7) & 0x1,
	(readl(m->virtbase_peer + MBOX_FIFO_STATUS) >> 0) & 0x7,
	(readl(m->virtbase_peer + MBOX_FIFO_STATUS) >> 3) & 0x1,
	readl(m->virtbase_local + MBOX_FIFO_DATA),
	readl(m->virtbase_local + MBOX_FIFO_DATA),
	readl(m->virtbase_local + MBOX_FIFO_THRES_FREE),
	readl(m->virtbase_local + MBOX_FIFO_THRES_FREE),
	readl(m->virtbase_local + MBOX_FIFO_THRES_OCCUP),
	readl(m->virtbase_local + MBOX_FIFO_THRES_OCCUP),
	readl(m->virtbase_local + MBOX_FIFO_STATUS),
	readl(m->virtbase_local + MBOX_FIFO_STATUS),
	(readl(m->virtbase_local + MBOX_FIFO_STATUS) >> 4) & 0x7,
	(readl(m->virtbase_local + MBOX_FIFO_STATUS) >> 7) & 0x1,
	(readl(m->virtbase_local + MBOX_FIFO_STATUS) >> 0) & 0x7,
	(readl(m->virtbase_local + MBOX_FIFO_STATUS) >> 3) & 0x1,
	m->write_index, m->read_index);
	mbox_index++;
	spin_unlock(&m->lock);
	}

	return 0;
	}

	static int mbox_open(struct inode inode, struct file file)
	{
	return single_open(file, mbox_show, NULL);
	}

	static const struct file_operations mbox_operations = {
	.owner = THIS_MODULE,
	.open = mbox_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release,
	};
	#endif

	static irqreturn_t mbox_irq(int irq, void *arg)
	{
	u32 mbox_value;
	int nbr_occup;
	int nbr_free;
	struct mbox mbox = (struct mbox ) arg;

	spin_lock(&mbox->lock);

	dev_dbg(&(mbox->pdev->dev),
	"mbox IRQ [%d] received. ri = %d, wi = %d\n",
	irq, mbox->read_index, mbox->write_index);

	/*
	* Check if we have any outgoing messages, and if there is space for
	* them in the FIFO.
	*/
	if (mbox->read_index != mbox->write_index) {
	/*
	* Check by reading FREE for LOCAL since that indicates
	* OCCUP for PEER
	*/
	nbr_free = (readl(mbox->virtbase_local + MBOX_FIFO_STATUS)
	>> 4) & 0x7;
	dev_dbg(&(mbox->pdev->dev),
	"Status indicates %d empty spaces in the FIFO!\n",
	nbr_free);

	while ((nbr_free > 0) &&
	(mbox->read_index != mbox->write_index)) {
	/* Write the message and latch it into the FIFO */
	writel(mbox->buffer[mbox->read_index],
	(mbox->virtbase_peer + MBOX_FIFO_DATA));
	writel(MBOX_LATCH,
	(mbox->virtbase_peer + MBOX_FIFO_ADD));
	dev_dbg(&(mbox->pdev->dev),
	"Wrote message 0x%X to addr 0x%X\n",
	mbox->buffer[mbox->read_index],
	(u32) (mbox->virtbase_peer + MBOX_FIFO_DATA));

	nbr_free--;
	mbox->read_index =
	(mbox->read_index + 1) % MBOX_BUF_SIZE;
	}

	/*
	* Check if we still want IRQ:s when there is free
	* space to send
	*/
	if (mbox->read_index != mbox->write_index) {
	dev_dbg(&(mbox->pdev->dev),
	"Still have messages to send, but FIFO full. "
	"Request IRQ again!\n");
	writel(MBOX_ENABLE_IRQ,
	mbox->virtbase_peer + MBOX_FIFO_THRES_FREE);
	} else {
	dev_dbg(&(mbox->pdev->dev),
	"No more messages to send. "
	"Do not request IRQ again!\n");
	writel(MBOX_DISABLE_IRQ,
	mbox->virtbase_peer + MBOX_FIFO_THRES_FREE);
	}

	/*
	* Check if we can signal any blocked clients that it is OK to
	* start buffering again
	*/
	if (mbox->client_blocked &&
	(((mbox->write_index + 1) % MBOX_BUF_SIZE)
	!= mbox->read_index)) {
	dev_dbg(&(mbox->pdev->dev),
	"Waking up blocked client\n");
	complete(&mbox->buffer_available);
	mbox->client_blocked = 0;
	}
	}

	/* Check if we have any incoming messages */
	nbr_occup = readl(mbox->virtbase_local + MBOX_FIFO_STATUS) & 0x7;
	if (nbr_occup == 0)
	goto exit;

	if (mbox->cb == NULL) {
	dev_dbg(&(mbox->pdev->dev), "No receive callback registered, "
	"leaving %d incoming messages in fifo!\n", nbr_occup);
	goto exit;
	}

	/* Read and acknowledge the message */
	mbox_value = readl(mbox->virtbase_local + MBOX_FIFO_DATA);
	writel(MBOX_LATCH, (mbox->virtbase_local + MBOX_FIFO_REMOVE));

	/* Notify consumer of new mailbox message */
	dev_dbg(&(mbox->pdev->dev), "Calling callback for message 0x%X!\n",
	mbox_value);
	mbox->cb(mbox_value, mbox->client_data);

	exit:
	dev_dbg(&(mbox->pdev->dev), "Exit mbox IRQ. ri = %d, wi = %d\n",
	mbox->read_index, mbox->write_index);
	spin_unlock(&mbox->lock);

	return IRQ_HANDLED;
	}

	/* Setup is executed once for each mbox pair */
	struct mbox mbox_setup(u8 mbox_id, mbox_recv_cb_t mbox_cb, void *priv)
	{
	struct resource *resource;
	int irq;
	int res;
	struct mbox *mbox;

	mbox = get_mbox_with_id(mbox_id);
	if (mbox == NULL) {
	dev_err(&(mbox->pdev->dev), "Incorrect mailbox id: %d!\n",
	mbox_id);
	goto exit;
	}

	/*
	* Check if mailbox has been allocated to someone else,
	* otherwise allocate it
	*/
	if (mbox->allocated) {
	dev_err(&(mbox->pdev->dev), "Mailbox number %d is busy!\n",
	mbox_id);
	mbox = NULL;
	goto exit;
	}
	mbox->allocated = true;

	dev_dbg(&(mbox->pdev->dev), "Initiating mailbox number %d: 0x%X...\n",
	mbox_id, (u32)mbox);

	mbox->client_data = priv;
	mbox->cb = mbox_cb;

	/* Get addr for peer mailbox and ioremap it */
	resource = platform_get_resource_byname(mbox->pdev,
	IORESOURCE_MEM,
	"mbox_peer");
	if (resource == NULL) {
	dev_err(&(mbox->pdev->dev),
	"Unable to retrieve mbox peer resource\n");
	mbox = NULL;
	goto exit;
	}
	dev_dbg(&(mbox->pdev->dev),
	"Resource name: %s start: 0x%X, end: 0x%X\n",
	resource->name, resource->start, resource->end);
	mbox->virtbase_peer =
	ioremap(resource->start, resource->end - resource->start);
	if (!mbox->virtbase_peer) {
	dev_err(&(mbox->pdev->dev), "Unable to ioremap peer mbox\n");
	mbox = NULL;
	goto exit;
	}
	dev_dbg(&(mbox->pdev->dev),
	"ioremapped peer physical: (0x%X-0x%X) to virtual: 0x%X\n",
	resource->start, resource->end, (u32) mbox->virtbase_peer);

	/* Get addr for local mailbox and ioremap it */
	resource = platform_get_resource_byname(mbox->pdev,
	IORESOURCE_MEM,
	"mbox_local");
	if (resource == NULL) {
	dev_err(&(mbox->pdev->dev),
	"Unable to retrieve mbox local resource\n");
	mbox = NULL;
	goto exit;
	}
	dev_dbg(&(mbox->pdev->dev),
	"Resource name: %s start: 0x%X, end: 0x%X\n",
	resource->name, resource->start, resource->end);
	mbox->virtbase_local =
	ioremap(resource->start, resource->end - resource->start);
	if (!mbox->virtbase_local) {
	dev_err(&(mbox->pdev->dev), "Unable to ioremap local mbox\n");
	mbox = NULL;
	goto exit;
	}
	dev_dbg(&(mbox->pdev->dev),
	"ioremapped local physical: (0x%X-0x%X) to virtual: 0x%X\n",
	resource->start, resource->end, (u32) mbox->virtbase_peer);

	init_completion(&mbox->buffer_available);
	mbox->client_blocked = 0;

	/* Get IRQ for mailbox and allocate it */
	irq = platform_get_irq_byname(mbox->pdev, "mbox_irq");
	if (irq < 0) {
	dev_err(&(mbox->pdev->dev),
	"Unable to retrieve mbox irq resource\n");
	mbox = NULL;
	goto exit;
	}

	dev_dbg(&(mbox->pdev->dev), "Allocating irq %d...\n", irq);
	res = request_irq(irq, mbox_irq, 0, mbox->name, (void *) mbox);
	if (res < 0) {
	dev_err(&(mbox->pdev->dev),
	"Unable to allocate mbox irq %d\n", irq);
	mbox = NULL;
	goto exit;
	}

	/* Set up mailbox to not launch IRQ on free space in mailbox */
	writel(MBOX_DISABLE_IRQ, mbox->virtbase_peer + MBOX_FIFO_THRES_FREE);

	/*
	* Set up mailbox to launch IRQ on new message if we have
	* a callback set. If not, do not raise IRQ, but keep message
	* in FIFO for manual retrieval
	*/
	if (mbox_cb != NULL)
	writel(MBOX_ENABLE_IRQ,
	mbox->virtbase_local + MBOX_FIFO_THRES_OCCUP);
	else
	writel(MBOX_DISABLE_IRQ,
	mbox->virtbase_local + MBOX_FIFO_THRES_OCCUP);

	#if defined(CONFIG_DEBUG_FS)
	res = device_create_file(&(mbox->pdev->dev), &dev_attr_fifo);
	if (res != 0)
	dev_warn(&(mbox->pdev->dev),
	"Unable to create mbox sysfs entry");

	(void) debugfs_create_file("mbox", S_IFREG \| S_IRUGO, NULL,
	NULL, &mbox_operations);
	#endif

	dev_info(&(mbox->pdev->dev),
	"Mailbox driver with index %d initated!\n", mbox_id);

	exit:
	return mbox;
	}
	EXPORT_SYMBOL(mbox_setup);


	int __init mbox_probe(struct platform_device *pdev)
	{
	struct mbox local_mbox;
	struct mbox *mbox;
	int res = 0;
	dev_dbg(&(pdev->dev), "Probing mailbox (pdev = 0x%X)...\n", (u32) pdev);

	memset(&local_mbox, 0x0, sizeof(struct mbox));

	/* Associate our mbox data with the platform device */
	res = platform_device_add_data(pdev,
	(void *) &local_mbox,
	sizeof(struct mbox));
	if (res != 0) {
	dev_err(&(pdev->dev),
	"Unable to allocate driver platform data!\n");
	goto exit;
	}

	mbox = (struct mbox *) pdev->dev.platform_data;
	mbox->pdev = pdev;
	mbox->write_index = 0;
	mbox->read_index = 0;

	INIT_LIST_HEAD(&(mbox->list));
	list_add_tail(&(mbox->list), &mboxs);

	sprintf(mbox->name, "%s", MBOX_NAME);
	spin_lock_init(&mbox->lock);

	dev_info(&(pdev->dev), "Mailbox driver loaded\n");

	exit:
	return res;
	}

	static struct platform_driver mbox_driver = {
	.driver = {
	.name = MBOX_NAME,
	.owner = THIS_MODULE,
	},
	};

	static int __init mbox_init(void)
	{
	return platform_driver_probe(&mbox_driver, mbox_probe);
	}

	module_init(mbox_init);

	void __exit mbox_exit(void)
	{
	platform_driver_unregister(&mbox_driver);
	}

	module_exit(mbox_exit);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("MBOX driver");