diff --git a/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt b/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt
index 48edc4b92afb..d1a043339c11 100644
--- a/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt
+++ b/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt
@@ -43,6 +43,9 @@ Required properties:
 			device. The format is dependent on which interrupt
 			controller the OMAP device uses
 - ti,hwmods:		Name of the hwmod associated with the mailbox
+- #mbox-cells:		Common mailbox binding property to identify the number
+			of cells required for the mailbox specifier. Should be
+			1
 - ti,mbox-num-users:	Number of targets (processor devices) that the mailbox
 			device can interrupt
 - ti,mbox-num-fifos:	Number of h/w fifo queues within the mailbox IP block
@@ -72,6 +75,18 @@ data that represent the following:
     Cell #3 (usr_id)  - mailbox user id for identifying the interrupt line
                         associated with generating a tx/rx fifo interrupt.
 
+Mailbox Users:
+==============
+A device needing to communicate with a target processor device should specify
+them using the common mailbox binding properties, "mboxes" and the optional
+"mbox-names" (please see Documentation/devicetree/bindings/mailbox/mailbox.txt
+for details). Each value of the mboxes property should contain a phandle to the
+mailbox controller device node and an args specifier that will be the phandle to
+the intended sub-mailbox child node to be used for communication. The equivalent
+"mbox-names" property value can be used to give a name to the communication channel
+to be used by the client user.
+
+
 Example:
 --------
 
@@ -81,6 +96,7 @@ mailbox: mailbox@4a0f4000 {
 	reg = <0x4a0f4000 0x200>;
 	interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
 	ti,hwmods = "mailbox";
+	#mbox-cells = <1>;
 	ti,mbox-num-users = <3>;
 	ti,mbox-num-fifos = <8>;
 	mbox_ipu: mbox_ipu {
@@ -93,12 +109,19 @@ mailbox: mailbox@4a0f4000 {
 	};
 };
 
+dsp {
+	...
+	mboxes = <&mailbox &mbox_dsp>;
+	...
+};
+
 /* AM33xx */
 mailbox: mailbox@480C8000 {
 	compatible = "ti,omap4-mailbox";
 	reg = <0x480C8000 0x200>;
 	interrupts = <77>;
 	ti,hwmods = "mailbox";
+	#mbox-cells = <1>;
 	ti,mbox-num-users = <4>;
 	ti,mbox-num-fifos = <8>;
 	mbox_wkupm3: wkup_m3 {
diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 9fd9c6717e0c..c04fed9eb15d 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -33,4 +33,16 @@ config OMAP_MBOX_KFIFO_SIZE
 	  Specify the default size of mailbox's kfifo buffers (bytes).
 	  This can also be changed at runtime (via the mbox_kfifo_size
 	  module parameter).
+
+config PCC
+	bool "Platform Communication Channel Driver"
+	depends on ACPI
+	help
+	  ACPI 5.0+ spec defines a generic mode of communication
+	  between the OS and a platform such as the BMC. This medium
+	  (PCC) is typically used by CPPC (ACPI CPU Performance management),
+	  RAS (ACPI reliability protocol) and MPST (ACPI Memory power
+	  states). Select this driver if your platform implements the
+	  PCC clients mentioned above.
+
 endif
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 94ed7cefb14d..dd412c22208b 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -5,3 +5,5 @@ obj-$(CONFIG_MAILBOX)		+= mailbox.o
 obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
 
 obj-$(CONFIG_OMAP2PLUS_MBOX)	+= omap-mailbox.o
+
+obj-$(CONFIG_PCC)		+= pcc.o
diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index afcb430508ec..59aad4d5da53 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -21,13 +21,13 @@
 #include <linux/mailbox_client.h>
 #include <linux/mailbox_controller.h>
 
-#define TXDONE_BY_IRQ	BIT(0) /* controller has remote RTR irq */
-#define TXDONE_BY_POLL	BIT(1) /* controller can read status of last TX */
-#define TXDONE_BY_ACK	BIT(2) /* S/W ACK recevied by Client ticks the TX */
+#include "mailbox.h"
 
 static LIST_HEAD(mbox_cons);
 static DEFINE_MUTEX(con_mutex);
 
+static void poll_txdone(unsigned long data);
+
 static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
 {
 	int idx;
@@ -60,7 +60,7 @@ static void msg_submit(struct mbox_chan *chan)
 	unsigned count, idx;
 	unsigned long flags;
 	void *data;
-	int err;
+	int err = -EBUSY;
 
 	spin_lock_irqsave(&chan->lock, flags);
 
@@ -76,6 +76,8 @@ static void msg_submit(struct mbox_chan *chan)
 
 	data = chan->msg_data[idx];
 
+	if (chan->cl->tx_prepare)
+		chan->cl->tx_prepare(chan->cl, data);
 	/* Try to submit a message to the MBOX controller */
 	err = chan->mbox->ops->send_data(chan, data);
 	if (!err) {
@@ -84,6 +86,9 @@ static void msg_submit(struct mbox_chan *chan)
 	}
 exit:
 	spin_unlock_irqrestore(&chan->lock, flags);
+
+	if (!err && chan->txdone_method == TXDONE_BY_POLL)
+		poll_txdone((unsigned long)chan->mbox);
 }
 
 static void tx_tick(struct mbox_chan *chan, int r)
@@ -117,10 +122,11 @@ static void poll_txdone(unsigned long data)
 		struct mbox_chan *chan = &mbox->chans[i];
 
 		if (chan->active_req && chan->cl) {
-			resched = true;
 			txdone = chan->mbox->ops->last_tx_done(chan);
 			if (txdone)
 				tx_tick(chan, 0);
+			else
+				resched = true;
 		}
 	}
 
@@ -252,9 +258,6 @@ int mbox_send_message(struct mbox_chan *chan, void *mssg)
 
 	msg_submit(chan);
 
-	if (chan->txdone_method	== TXDONE_BY_POLL)
-		poll_txdone((unsigned long)chan->mbox);
-
 	if (chan->cl->tx_block && chan->active_req) {
 		unsigned long wait;
 		int ret;
diff --git a/drivers/mailbox/mailbox.h b/drivers/mailbox/mailbox.h
new file mode 100644
index 000000000000..456ba68513bb
--- /dev/null
+++ b/drivers/mailbox/mailbox.h
@@ -0,0 +1,14 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __MAILBOX_H
+#define __MAILBOX_H
+
+#define TXDONE_BY_IRQ	BIT(0) /* controller has remote RTR irq */
+#define TXDONE_BY_POLL	BIT(1) /* controller can read status of last TX */
+#define TXDONE_BY_ACK	BIT(2) /* S/W ACK recevied by Client ticks the TX */
+
+#endif /* __MAILBOX_H */
diff --git a/drivers/mailbox/omap-mailbox.c b/drivers/mailbox/omap-mailbox.c
index bcc7ee129276..66b83ca94dcf 100644
--- a/drivers/mailbox/omap-mailbox.c
+++ b/drivers/mailbox/omap-mailbox.c
@@ -29,13 +29,14 @@
 #include <linux/slab.h>
 #include <linux/kfifo.h>
 #include <linux/err.h>
-#include <linux/notifier.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_data/mailbox-omap.h>
 #include <linux/omap-mailbox.h>
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
 
 #define MAILBOX_REVISION		0x000
 #define MAILBOX_MESSAGE(m)		(0x040 + 4 * (m))
@@ -80,7 +81,6 @@ struct omap_mbox_queue {
 	spinlock_t		lock;
 	struct kfifo		fifo;
 	struct work_struct	work;
-	struct tasklet_struct	tasklet;
 	struct omap_mbox	*mbox;
 	bool full;
 };
@@ -92,6 +92,7 @@ struct omap_mbox_device {
 	u32 num_users;
 	u32 num_fifos;
 	struct omap_mbox **mboxes;
+	struct mbox_controller controller;
 	struct list_head elem;
 };
 
@@ -110,15 +111,14 @@ struct omap_mbox_fifo_info {
 struct omap_mbox {
 	const char		*name;
 	int			irq;
-	struct omap_mbox_queue	*txq, *rxq;
+	struct omap_mbox_queue	*rxq;
 	struct device		*dev;
 	struct omap_mbox_device *parent;
 	struct omap_mbox_fifo	tx_fifo;
 	struct omap_mbox_fifo	rx_fifo;
 	u32			ctx[OMAP4_MBOX_NR_REGS];
 	u32			intr_type;
-	int			use_count;
-	struct blocking_notifier_head	notifier;
+	struct mbox_chan	*chan;
 };
 
 /* global variables for the mailbox devices */
@@ -129,6 +129,14 @@ static unsigned int mbox_kfifo_size = CONFIG_OMAP_MBOX_KFIFO_SIZE;
 module_param(mbox_kfifo_size, uint, S_IRUGO);
 MODULE_PARM_DESC(mbox_kfifo_size, "Size of omap's mailbox kfifo (bytes)");
 
+static struct omap_mbox *mbox_chan_to_omap_mbox(struct mbox_chan *chan)
+{
+	if (!chan || !chan->con_priv)
+		return NULL;
+
+	return (struct omap_mbox *)chan->con_priv;
+}
+
 static inline
 unsigned int mbox_read_reg(struct omap_mbox_device *mdev, size_t ofs)
 {
@@ -194,41 +202,14 @@ static int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
 	return (int)(enable & status & bit);
 }
 
-/*
- * message sender
- */
-int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
-{
-	struct omap_mbox_queue *mq = mbox->txq;
-	int ret = 0, len;
-
-	spin_lock_bh(&mq->lock);
-
-	if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	if (kfifo_is_empty(&mq->fifo) && !mbox_fifo_full(mbox)) {
-		mbox_fifo_write(mbox, msg);
-		goto out;
-	}
-
-	len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
-	WARN_ON(len != sizeof(msg));
-
-	tasklet_schedule(&mbox->txq->tasklet);
-
-out:
-	spin_unlock_bh(&mq->lock);
-	return ret;
-}
-EXPORT_SYMBOL(omap_mbox_msg_send);
-
-void omap_mbox_save_ctx(struct omap_mbox *mbox)
+void omap_mbox_save_ctx(struct mbox_chan *chan)
 {
 	int i;
 	int nr_regs;
+	struct omap_mbox *mbox = mbox_chan_to_omap_mbox(chan);
+
+	if (WARN_ON(!mbox))
+		return;
 
 	if (mbox->intr_type)
 		nr_regs = OMAP4_MBOX_NR_REGS;
@@ -243,10 +224,14 @@ void omap_mbox_save_ctx(struct omap_mbox *mbox)
 }
 EXPORT_SYMBOL(omap_mbox_save_ctx);
 
-void omap_mbox_restore_ctx(struct omap_mbox *mbox)
+void omap_mbox_restore_ctx(struct mbox_chan *chan)
 {
 	int i;
 	int nr_regs;
+	struct omap_mbox *mbox = mbox_chan_to_omap_mbox(chan);
+
+	if (WARN_ON(!mbox))
+		return;
 
 	if (mbox->intr_type)
 		nr_regs = OMAP4_MBOX_NR_REGS;
@@ -254,14 +239,13 @@ void omap_mbox_restore_ctx(struct omap_mbox *mbox)
 		nr_regs = MBOX_NR_REGS;
 	for (i = 0; i < nr_regs; i++) {
 		mbox_write_reg(mbox->parent, mbox->ctx[i], i * sizeof(u32));
-
 		dev_dbg(mbox->dev, "%s: [%02x] %08x\n", __func__,
 			i, mbox->ctx[i]);
 	}
 }
 EXPORT_SYMBOL(omap_mbox_restore_ctx);
 
-void omap_mbox_enable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
+static void _omap_mbox_enable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
 {
 	u32 l;
 	struct omap_mbox_fifo *fifo = (irq == IRQ_TX) ?
@@ -273,9 +257,8 @@ void omap_mbox_enable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
 	l |= bit;
 	mbox_write_reg(mbox->parent, l, irqenable);
 }
-EXPORT_SYMBOL(omap_mbox_enable_irq);
 
-void omap_mbox_disable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
+static void _omap_mbox_disable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
 {
 	struct omap_mbox_fifo *fifo = (irq == IRQ_TX) ?
 				&mbox->tx_fifo : &mbox->rx_fifo;
@@ -291,28 +274,28 @@ void omap_mbox_disable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
 
 	mbox_write_reg(mbox->parent, bit, irqdisable);
 }
-EXPORT_SYMBOL(omap_mbox_disable_irq);
 
-static void mbox_tx_tasklet(unsigned long tx_data)
+void omap_mbox_enable_irq(struct mbox_chan *chan, omap_mbox_irq_t irq)
 {
-	struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
-	struct omap_mbox_queue *mq = mbox->txq;
-	mbox_msg_t msg;
-	int ret;
+	struct omap_mbox *mbox = mbox_chan_to_omap_mbox(chan);
 
-	while (kfifo_len(&mq->fifo)) {
-		if (mbox_fifo_full(mbox)) {
-			omap_mbox_enable_irq(mbox, IRQ_TX);
-			break;
-		}
+	if (WARN_ON(!mbox))
+		return;
 
-		ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
-								sizeof(msg));
-		WARN_ON(ret != sizeof(msg));
-
-		mbox_fifo_write(mbox, msg);
-	}
+	_omap_mbox_enable_irq(mbox, irq);
 }
+EXPORT_SYMBOL(omap_mbox_enable_irq);
+
+void omap_mbox_disable_irq(struct mbox_chan *chan, omap_mbox_irq_t irq)
+{
+	struct omap_mbox *mbox = mbox_chan_to_omap_mbox(chan);
+
+	if (WARN_ON(!mbox))
+		return;
+
+	_omap_mbox_disable_irq(mbox, irq);
+}
+EXPORT_SYMBOL(omap_mbox_disable_irq);
 
 /*
  * Message receiver(workqueue)
@@ -328,12 +311,11 @@ static void mbox_rx_work(struct work_struct *work)
 		len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
 		WARN_ON(len != sizeof(msg));
 
-		blocking_notifier_call_chain(&mq->mbox->notifier, len,
-								(void *)msg);
+		mbox_chan_received_data(mq->mbox->chan, (void *)msg);
 		spin_lock_irq(&mq->lock);
 		if (mq->full) {
 			mq->full = false;
-			omap_mbox_enable_irq(mq->mbox, IRQ_RX);
+			_omap_mbox_enable_irq(mq->mbox, IRQ_RX);
 		}
 		spin_unlock_irq(&mq->lock);
 	}
@@ -344,9 +326,9 @@ static void mbox_rx_work(struct work_struct *work)
  */
 static void __mbox_tx_interrupt(struct omap_mbox *mbox)
 {
-	omap_mbox_disable_irq(mbox, IRQ_TX);
+	_omap_mbox_disable_irq(mbox, IRQ_TX);
 	ack_mbox_irq(mbox, IRQ_TX);
-	tasklet_schedule(&mbox->txq->tasklet);
+	mbox_chan_txdone(mbox->chan, 0);
 }
 
 static void __mbox_rx_interrupt(struct omap_mbox *mbox)
@@ -357,7 +339,7 @@ static void __mbox_rx_interrupt(struct omap_mbox *mbox)
 
 	while (!mbox_fifo_empty(mbox)) {
 		if (unlikely(kfifo_avail(&mq->fifo) < sizeof(msg))) {
-			omap_mbox_disable_irq(mbox, IRQ_RX);
+			_omap_mbox_disable_irq(mbox, IRQ_RX);
 			mq->full = true;
 			goto nomem;
 		}
@@ -388,11 +370,13 @@ static irqreturn_t mbox_interrupt(int irq, void *p)
 }
 
 static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
-					void (*work) (struct work_struct *),
-					void (*tasklet)(unsigned long))
+					void (*work)(struct work_struct *))
 {
 	struct omap_mbox_queue *mq;
 
+	if (!work)
+		return NULL;
+
 	mq = kzalloc(sizeof(struct omap_mbox_queue), GFP_KERNEL);
 	if (!mq)
 		return NULL;
@@ -402,12 +386,9 @@ static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
 	if (kfifo_alloc(&mq->fifo, mbox_kfifo_size, GFP_KERNEL))
 		goto error;
 
-	if (work)
-		INIT_WORK(&mq->work, work);
-
-	if (tasklet)
-		tasklet_init(&mq->tasklet, tasklet, (unsigned long)mbox);
+	INIT_WORK(&mq->work, work);
 	return mq;
+
 error:
 	kfree(mq);
 	return NULL;
@@ -423,71 +404,35 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
 {
 	int ret = 0;
 	struct omap_mbox_queue *mq;
-	struct omap_mbox_device *mdev = mbox->parent;
 
-	mutex_lock(&mdev->cfg_lock);
-	ret = pm_runtime_get_sync(mdev->dev);
-	if (unlikely(ret < 0))
-		goto fail_startup;
+	mq = mbox_queue_alloc(mbox, mbox_rx_work);
+	if (!mq)
+		return -ENOMEM;
+	mbox->rxq = mq;
+	mq->mbox = mbox;
 
-	if (!mbox->use_count++) {
-		mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
-		if (!mq) {
-			ret = -ENOMEM;
-			goto fail_alloc_txq;
-		}
-		mbox->txq = mq;
-
-		mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
-		if (!mq) {
-			ret = -ENOMEM;
-			goto fail_alloc_rxq;
-		}
-		mbox->rxq = mq;
-		mq->mbox = mbox;
-		ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
-							mbox->name, mbox);
-		if (unlikely(ret)) {
-			pr_err("failed to register mailbox interrupt:%d\n",
-									ret);
-			goto fail_request_irq;
-		}
-
-		omap_mbox_enable_irq(mbox, IRQ_RX);
+	ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
+			  mbox->name, mbox);
+	if (unlikely(ret)) {
+		pr_err("failed to register mailbox interrupt:%d\n", ret);
+		goto fail_request_irq;
 	}
-	mutex_unlock(&mdev->cfg_lock);
+
+	_omap_mbox_enable_irq(mbox, IRQ_RX);
+
 	return 0;
 
 fail_request_irq:
 	mbox_queue_free(mbox->rxq);
-fail_alloc_rxq:
-	mbox_queue_free(mbox->txq);
-fail_alloc_txq:
-	pm_runtime_put_sync(mdev->dev);
-	mbox->use_count--;
-fail_startup:
-	mutex_unlock(&mdev->cfg_lock);
 	return ret;
 }
 
 static void omap_mbox_fini(struct omap_mbox *mbox)
 {
-	struct omap_mbox_device *mdev = mbox->parent;
-
-	mutex_lock(&mdev->cfg_lock);
-
-	if (!--mbox->use_count) {
-		omap_mbox_disable_irq(mbox, IRQ_RX);
-		free_irq(mbox->irq, mbox);
-		tasklet_kill(&mbox->txq->tasklet);
-		flush_work(&mbox->rxq->work);
-		mbox_queue_free(mbox->txq);
-		mbox_queue_free(mbox->rxq);
-	}
-
-	pm_runtime_put_sync(mdev->dev);
-
-	mutex_unlock(&mdev->cfg_lock);
+	_omap_mbox_disable_irq(mbox, IRQ_RX);
+	free_irq(mbox->irq, mbox);
+	flush_work(&mbox->rxq->work);
+	mbox_queue_free(mbox->rxq);
 }
 
 static struct omap_mbox *omap_mbox_device_find(struct omap_mbox_device *mdev,
@@ -509,42 +454,55 @@ static struct omap_mbox *omap_mbox_device_find(struct omap_mbox_device *mdev,
 	return mbox;
 }
 
-struct omap_mbox *omap_mbox_get(const char *name, struct notifier_block *nb)
+struct mbox_chan *omap_mbox_request_channel(struct mbox_client *cl,
+					    const char *chan_name)
 {
+	struct device *dev = cl->dev;
 	struct omap_mbox *mbox = NULL;
 	struct omap_mbox_device *mdev;
+	struct mbox_chan *chan;
+	unsigned long flags;
 	int ret;
 
+	if (!dev)
+		return ERR_PTR(-ENODEV);
+
+	if (dev->of_node) {
+		pr_err("%s: please use mbox_request_channel(), this API is supported only for OMAP non-DT usage\n",
+		       __func__);
+		return ERR_PTR(-ENODEV);
+	}
+
 	mutex_lock(&omap_mbox_devices_lock);
 	list_for_each_entry(mdev, &omap_mbox_devices, elem) {
-		mbox = omap_mbox_device_find(mdev, name);
+		mbox = omap_mbox_device_find(mdev, chan_name);
 		if (mbox)
 			break;
 	}
 	mutex_unlock(&omap_mbox_devices_lock);
 
-	if (!mbox)
+	if (!mbox || !mbox->chan)
 		return ERR_PTR(-ENOENT);
 
-	if (nb)
-		blocking_notifier_chain_register(&mbox->notifier, nb);
+	chan = mbox->chan;
+	spin_lock_irqsave(&chan->lock, flags);
+	chan->msg_free = 0;
+	chan->msg_count = 0;
+	chan->active_req = NULL;
+	chan->cl = cl;
+	init_completion(&chan->tx_complete);
+	spin_unlock_irqrestore(&chan->lock, flags);
 
-	ret = omap_mbox_startup(mbox);
+	ret = chan->mbox->ops->startup(chan);
 	if (ret) {
-		blocking_notifier_chain_unregister(&mbox->notifier, nb);
-		return ERR_PTR(-ENODEV);
+		pr_err("Unable to startup the chan (%d)\n", ret);
+		mbox_free_channel(chan);
+		chan = ERR_PTR(ret);
 	}
 
-	return mbox;
+	return chan;
 }
-EXPORT_SYMBOL(omap_mbox_get);
-
-void omap_mbox_put(struct omap_mbox *mbox, struct notifier_block *nb)
-{
-	blocking_notifier_chain_unregister(&mbox->notifier, nb);
-	omap_mbox_fini(mbox);
-}
-EXPORT_SYMBOL(omap_mbox_put);
+EXPORT_SYMBOL(omap_mbox_request_channel);
 
 static struct class omap_mbox_class = { .name = "mbox", };
 
@@ -560,25 +518,25 @@ static int omap_mbox_register(struct omap_mbox_device *mdev)
 	mboxes = mdev->mboxes;
 	for (i = 0; mboxes[i]; i++) {
 		struct omap_mbox *mbox = mboxes[i];
-		mbox->dev = device_create(&omap_mbox_class,
-				mdev->dev, 0, mbox, "%s", mbox->name);
+		mbox->dev = device_create(&omap_mbox_class, mdev->dev,
+					0, mbox, "%s", mbox->name);
 		if (IS_ERR(mbox->dev)) {
 			ret = PTR_ERR(mbox->dev);
 			goto err_out;
 		}
-
-		BLOCKING_INIT_NOTIFIER_HEAD(&mbox->notifier);
 	}
 
 	mutex_lock(&omap_mbox_devices_lock);
 	list_add(&mdev->elem, &omap_mbox_devices);
 	mutex_unlock(&omap_mbox_devices_lock);
 
-	return 0;
+	ret = mbox_controller_register(&mdev->controller);
 
 err_out:
-	while (i--)
-		device_unregister(mboxes[i]->dev);
+	if (ret) {
+		while (i--)
+			device_unregister(mboxes[i]->dev);
+	}
 	return ret;
 }
 
@@ -594,12 +552,64 @@ static int omap_mbox_unregister(struct omap_mbox_device *mdev)
 	list_del(&mdev->elem);
 	mutex_unlock(&omap_mbox_devices_lock);
 
+	mbox_controller_unregister(&mdev->controller);
+
 	mboxes = mdev->mboxes;
 	for (i = 0; mboxes[i]; i++)
 		device_unregister(mboxes[i]->dev);
 	return 0;
 }
 
+static int omap_mbox_chan_startup(struct mbox_chan *chan)
+{
+	struct omap_mbox *mbox = mbox_chan_to_omap_mbox(chan);
+	struct omap_mbox_device *mdev = mbox->parent;
+	int ret = 0;
+
+	mutex_lock(&mdev->cfg_lock);
+	pm_runtime_get_sync(mdev->dev);
+	ret = omap_mbox_startup(mbox);
+	if (ret)
+		pm_runtime_put_sync(mdev->dev);
+	mutex_unlock(&mdev->cfg_lock);
+	return ret;
+}
+
+static void omap_mbox_chan_shutdown(struct mbox_chan *chan)
+{
+	struct omap_mbox *mbox = mbox_chan_to_omap_mbox(chan);
+	struct omap_mbox_device *mdev = mbox->parent;
+
+	mutex_lock(&mdev->cfg_lock);
+	omap_mbox_fini(mbox);
+	pm_runtime_put_sync(mdev->dev);
+	mutex_unlock(&mdev->cfg_lock);
+}
+
+static int omap_mbox_chan_send_data(struct mbox_chan *chan, void *data)
+{
+	struct omap_mbox *mbox = mbox_chan_to_omap_mbox(chan);
+	int ret = -EBUSY;
+
+	if (!mbox)
+		return -EINVAL;
+
+	if (!mbox_fifo_full(mbox)) {
+		mbox_fifo_write(mbox, (mbox_msg_t)data);
+		ret = 0;
+	}
+
+	/* always enable the interrupt */
+	_omap_mbox_enable_irq(mbox, IRQ_TX);
+	return ret;
+}
+
+static struct mbox_chan_ops omap_mbox_chan_ops = {
+	.startup        = omap_mbox_chan_startup,
+	.send_data      = omap_mbox_chan_send_data,
+	.shutdown       = omap_mbox_chan_shutdown,
+};
+
 static const struct of_device_id omap_mailbox_of_match[] = {
 	{
 		.compatible	= "ti,omap2-mailbox",
@@ -619,10 +629,35 @@ static const struct of_device_id omap_mailbox_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, omap_mailbox_of_match);
 
+static struct mbox_chan *omap_mbox_of_xlate(struct mbox_controller *controller,
+					    const struct of_phandle_args *sp)
+{
+	phandle phandle = sp->args[0];
+	struct device_node *node;
+	struct omap_mbox_device *mdev;
+	struct omap_mbox *mbox;
+
+	mdev = container_of(controller, struct omap_mbox_device, controller);
+	if (WARN_ON(!mdev))
+		return NULL;
+
+	node = of_find_node_by_phandle(phandle);
+	if (!node) {
+		pr_err("%s: could not find node phandle 0x%x\n",
+		       __func__, phandle);
+		return NULL;
+	}
+
+	mbox = omap_mbox_device_find(mdev, node->name);
+	of_node_put(node);
+	return mbox ? mbox->chan : NULL;
+}
+
 static int omap_mbox_probe(struct platform_device *pdev)
 {
 	struct resource *mem;
 	int ret;
+	struct mbox_chan *chnls;
 	struct omap_mbox **list, *mbox, *mboxblk;
 	struct omap_mbox_pdata *pdata = pdev->dev.platform_data;
 	struct omap_mbox_dev_info *info = NULL;
@@ -727,6 +762,11 @@ static int omap_mbox_probe(struct platform_device *pdev)
 	if (!list)
 		return -ENOMEM;
 
+	chnls = devm_kzalloc(&pdev->dev, (info_count + 1) * sizeof(*chnls),
+			     GFP_KERNEL);
+	if (!chnls)
+		return -ENOMEM;
+
 	mboxblk = devm_kzalloc(&pdev->dev, info_count * sizeof(*mbox),
 			       GFP_KERNEL);
 	if (!mboxblk)
@@ -758,6 +798,8 @@ static int omap_mbox_probe(struct platform_device *pdev)
 		mbox->irq = platform_get_irq(pdev, finfo->tx_irq);
 		if (mbox->irq < 0)
 			return mbox->irq;
+		mbox->chan = &chnls[i];
+		chnls[i].con_priv = mbox;
 		list[i] = mbox++;
 	}
 
@@ -766,6 +808,14 @@ static int omap_mbox_probe(struct platform_device *pdev)
 	mdev->num_users = num_users;
 	mdev->num_fifos = num_fifos;
 	mdev->mboxes = list;
+
+	/* OMAP does not have a Tx-Done IRQ, but rather a Tx-Ready IRQ */
+	mdev->controller.txdone_irq = true;
+	mdev->controller.dev = mdev->dev;
+	mdev->controller.ops = &omap_mbox_chan_ops;
+	mdev->controller.chans = chnls;
+	mdev->controller.num_chans = info_count;
+	mdev->controller.of_xlate = omap_mbox_of_xlate;
 	ret = omap_mbox_register(mdev);
 	if (ret)
 		return ret;
diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
new file mode 100644
index 000000000000..6dbf6fcbdfaf
--- /dev/null
+++ b/drivers/mailbox/pcc.c
@@ -0,0 +1,403 @@
+/*
+ *	Copyright (C) 2014 Linaro Ltd.
+ *	Author:	Ashwin Chaugule <ashwin.chaugule@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.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  PCC (Platform Communication Channel) is defined in the ACPI 5.0+
+ *  specification. It is a mailbox like mechanism to allow clients
+ *  such as CPPC (Collaborative Processor Performance Control), RAS
+ *  (Reliability, Availability and Serviceability) and MPST (Memory
+ *  Node Power State Table) to talk to the platform (e.g. BMC) through
+ *  shared memory regions as defined in the PCC table entries. The PCC
+ *  specification supports a Doorbell mechanism for the PCC clients
+ *  to notify the platform about new data. This Doorbell information
+ *  is also specified in each PCC table entry. See pcc_send_data()
+ *  and pcc_tx_done() for basic mode of operation.
+ *
+ *  For more details about PCC, please see the ACPI specification from
+ *  http://www.uefi.org/ACPIv5.1 Section 14.
+ *
+ *  This file implements PCC as a Mailbox controller and allows for PCC
+ *  clients to be implemented as its Mailbox Client Channels.
+ */
+
+#include <linux/acpi.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/platform_device.h>
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
+
+#include "mailbox.h"
+
+#define MAX_PCC_SUBSPACES	256
+#define PCCS_SS_SIG_MAGIC	0x50434300
+#define PCC_CMD_COMPLETE	0x1
+
+static struct mbox_chan *pcc_mbox_channels;
+
+static struct mbox_controller pcc_mbox_ctrl = {};
+/**
+ * get_pcc_channel - Given a PCC subspace idx, get
+ *	the respective mbox_channel.
+ * @id: PCC subspace index.
+ *
+ * Return: ERR_PTR(errno) if error, else pointer
+ *	to mbox channel.
+ */
+static struct mbox_chan *get_pcc_channel(int id)
+{
+	struct mbox_chan *pcc_chan;
+
+	if (id < 0 || id > pcc_mbox_ctrl.num_chans)
+		return ERR_PTR(-ENOENT);
+
+	pcc_chan = (struct mbox_chan *)
+		(unsigned long) pcc_mbox_channels +
+		(id * sizeof(*pcc_chan));
+
+	return pcc_chan;
+}
+
+/**
+ * get_subspace_id - Given a Mailbox channel, find out the
+ *		PCC subspace id.
+ * @chan: Pointer to Mailbox Channel from which we want
+ *		the index.
+ * Return: Errno if not found, else positive index number.
+ */
+static int get_subspace_id(struct mbox_chan *chan)
+{
+	unsigned int id = chan - pcc_mbox_channels;
+
+	if (id < 0 || id > pcc_mbox_ctrl.num_chans)
+		return -ENOENT;
+
+	return id;
+}
+
+/**
+ * pcc_mbox_request_channel - PCC clients call this function to
+ *		request a pointer to their PCC subspace, from which they
+ *		can get the details of communicating with the remote.
+ * @cl: Pointer to Mailbox client, so we know where to bind the
+ *		Channel.
+ * @subspace_id: The PCC Subspace index as parsed in the PCC client
+ *		ACPI package. This is used to lookup the array of PCC
+ *		subspaces as parsed by the PCC Mailbox controller.
+ *
+ * Return: Pointer to the Mailbox Channel if successful or
+ *		ERR_PTR.
+ */
+struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
+		int subspace_id)
+{
+	struct device *dev = pcc_mbox_ctrl.dev;
+	struct mbox_chan *chan;
+	unsigned long flags;
+
+	/*
+	 * Each PCC Subspace is a Mailbox Channel.
+	 * The PCC Clients get their PCC Subspace ID
+	 * from their own tables and pass it here.
+	 * This returns a pointer to the PCC subspace
+	 * for the Client to operate on.
+	 */
+	chan = get_pcc_channel(subspace_id);
+
+	if (!chan || chan->cl) {
+		dev_err(dev, "%s: PCC mailbox not free\n", __func__);
+		return ERR_PTR(-EBUSY);
+	}
+
+	spin_lock_irqsave(&chan->lock, flags);
+	chan->msg_free = 0;
+	chan->msg_count = 0;
+	chan->active_req = NULL;
+	chan->cl = cl;
+	init_completion(&chan->tx_complete);
+
+	if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
+		chan->txdone_method |= TXDONE_BY_ACK;
+
+	spin_unlock_irqrestore(&chan->lock, flags);
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
+
+/**
+ * pcc_mbox_free_channel - Clients call this to free their Channel.
+ *
+ * @chan: Pointer to the mailbox channel as returned by
+ *		pcc_mbox_request_channel()
+ */
+void pcc_mbox_free_channel(struct mbox_chan *chan)
+{
+	unsigned long flags;
+
+	if (!chan || !chan->cl)
+		return;
+
+	spin_lock_irqsave(&chan->lock, flags);
+	chan->cl = NULL;
+	chan->active_req = NULL;
+	if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
+		chan->txdone_method = TXDONE_BY_POLL;
+
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
+
+/**
+ * pcc_tx_done - Callback from Mailbox controller code to
+ *		check if PCC message transmission completed.
+ * @chan: Pointer to Mailbox channel on which previous
+ *		transmission occurred.
+ *
+ * Return: TRUE if succeeded.
+ */
+static bool pcc_tx_done(struct mbox_chan *chan)
+{
+	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
+	struct acpi_pcct_shared_memory *generic_comm_base =
+		(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
+	u16 cmd_delay = pcct_ss->latency;
+	unsigned int retries = 0;
+
+	/* Try a few times while waiting for platform to consume */
+	while (!(readw_relaxed(&generic_comm_base->status)
+		    & PCC_CMD_COMPLETE)) {
+
+		if (retries++ < 5)
+			udelay(cmd_delay);
+		else {
+			/*
+			 * If the remote is dead, this will cause the Mbox
+			 * controller to timeout after mbox client.tx_tout
+			 * msecs.
+			 */
+			pr_err("PCC platform did not respond.\n");
+			return false;
+		}
+	}
+	return true;
+}
+
+/**
+ * pcc_send_data - Called from Mailbox Controller code to finally
+ *	transmit data over channel.
+ * @chan: Pointer to Mailbox channel over which to send data.
+ * @data: Actual data to be written over channel.
+ *
+ * Return: Err if something failed else 0 for success.
+ */
+static int pcc_send_data(struct mbox_chan *chan, void *data)
+{
+	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
+	struct acpi_pcct_shared_memory *generic_comm_base =
+		(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
+	struct acpi_generic_address doorbell;
+	u64 doorbell_preserve;
+	u64 doorbell_val;
+	u64 doorbell_write;
+	u16 cmd = *(u16 *) data;
+	u16 ss_idx = -1;
+
+	ss_idx = get_subspace_id(chan);
+
+	if (ss_idx < 0) {
+		pr_err("Invalid Subspace ID from PCC client\n");
+		return -EINVAL;
+	}
+
+	doorbell = pcct_ss->doorbell_register;
+	doorbell_preserve = pcct_ss->preserve_mask;
+	doorbell_write = pcct_ss->write_mask;
+
+	/* Write to the shared comm region. */
+	writew(cmd, &generic_comm_base->command);
+
+	/* Write Subspace MAGIC value so platform can identify destination. */
+	writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
+
+	/* Flip CMD COMPLETE bit */
+	writew(0, &generic_comm_base->status);
+
+	/* Sync notification from OSPM to Platform. */
+	acpi_read(&doorbell_val, &doorbell);
+	acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
+			&doorbell);
+
+	return 0;
+}
+
+static struct mbox_chan_ops pcc_chan_ops = {
+	.send_data = pcc_send_data,
+	.last_tx_done = pcc_tx_done,
+};
+
+/**
+ * parse_pcc_subspace - Parse the PCC table and verify PCC subspace
+ *		entries. There should be one entry per PCC client.
+ * @header: Pointer to the ACPI subtable header under the PCCT.
+ * @end: End of subtable entry.
+ *
+ * Return: 0 for Success, else errno.
+ *
+ * This gets called for each entry in the PCC table.
+ */
+static int parse_pcc_subspace(struct acpi_subtable_header *header,
+		const unsigned long end)
+{
+	struct acpi_pcct_hw_reduced *pcct_ss;
+
+	if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
+		pcct_ss = (struct acpi_pcct_hw_reduced *) header;
+
+		if (pcct_ss->header.type !=
+				ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) {
+			pr_err("Incorrect PCC Subspace type detected\n");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
+ *
+ * Return: 0 for Success, else errno.
+ */
+static int __init acpi_pcc_probe(void)
+{
+	acpi_size pcct_tbl_header_size;
+	struct acpi_table_header *pcct_tbl;
+	struct acpi_subtable_header *pcct_entry;
+	int count, i;
+	acpi_status status = AE_OK;
+
+	/* Search for PCCT */
+	status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,
+			&pcct_tbl,
+			&pcct_tbl_header_size);
+
+	if (ACPI_FAILURE(status) || !pcct_tbl) {
+		pr_warn("PCCT header not found.\n");
+		return -ENODEV;
+	}
+
+	count = acpi_table_parse_entries(ACPI_SIG_PCCT,
+			sizeof(struct acpi_table_pcct),
+			ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
+			parse_pcc_subspace, MAX_PCC_SUBSPACES);
+
+	if (count <= 0) {
+		pr_err("Error parsing PCC subspaces from PCCT\n");
+		return -EINVAL;
+	}
+
+	pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
+			count, GFP_KERNEL);
+
+	if (!pcc_mbox_channels) {
+		pr_err("Could not allocate space for PCC mbox channels\n");
+		return -ENOMEM;
+	}
+
+	/* Point to the first PCC subspace entry */
+	pcct_entry = (struct acpi_subtable_header *) (
+		(unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
+
+	for (i = 0; i < count; i++) {
+		pcc_mbox_channels[i].con_priv = pcct_entry;
+		pcct_entry = (struct acpi_subtable_header *)
+			((unsigned long) pcct_entry + pcct_entry->length);
+	}
+
+	pcc_mbox_ctrl.num_chans = count;
+
+	pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
+
+	return 0;
+}
+
+/**
+ * pcc_mbox_probe - Called when we find a match for the
+ *	PCCT platform device. This is purely used to represent
+ *	the PCCT as a virtual device for registering with the
+ *	generic Mailbox framework.
+ *
+ * @pdev: Pointer to platform device returned when a match
+ *	is found.
+ *
+ *	Return: 0 for Success, else errno.
+ */
+static int pcc_mbox_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+
+	pcc_mbox_ctrl.chans = pcc_mbox_channels;
+	pcc_mbox_ctrl.ops = &pcc_chan_ops;
+	pcc_mbox_ctrl.txdone_poll = true;
+	pcc_mbox_ctrl.txpoll_period = 10;
+	pcc_mbox_ctrl.dev = &pdev->dev;
+
+	pr_info("Registering PCC driver as Mailbox controller\n");
+	ret = mbox_controller_register(&pcc_mbox_ctrl);
+
+	if (ret) {
+		pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
+		ret = -ENODEV;
+	}
+
+	return ret;
+}
+
+struct platform_driver pcc_mbox_driver = {
+	.probe = pcc_mbox_probe,
+	.driver = {
+		.name = "PCCT",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init pcc_init(void)
+{
+	int ret;
+	struct platform_device *pcc_pdev;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	/* Check if PCC support is available. */
+	ret = acpi_pcc_probe();
+
+	if (ret) {
+		pr_err("ACPI PCC probe failed.\n");
+		return -ENODEV;
+	}
+
+	pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
+			pcc_mbox_probe, NULL, 0, NULL, 0);
+
+	if (!pcc_pdev) {
+		pr_err("Err creating PCC platform bundle\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+device_initcall(pcc_init);
diff --git a/drivers/remoteproc/omap_remoteproc.c b/drivers/remoteproc/omap_remoteproc.c
index 51689721ea7a..cf92f6e7c5dc 100644
--- a/drivers/remoteproc/omap_remoteproc.c
+++ b/drivers/remoteproc/omap_remoteproc.c
@@ -27,6 +27,7 @@
 #include <linux/platform_device.h>
 #include <linux/dma-mapping.h>
 #include <linux/remoteproc.h>
+#include <linux/mailbox_client.h>
 #include <linux/omap-mailbox.h>
 
 #include <linux/platform_data/remoteproc-omap.h>
@@ -36,20 +37,19 @@
 
 /**
  * struct omap_rproc - omap remote processor state
- * @mbox: omap mailbox handle
- * @nb: notifier block that will be invoked on inbound mailbox messages
+ * @mbox: mailbox channel handle
+ * @client: mailbox client to request the mailbox channel
  * @rproc: rproc handle
  */
 struct omap_rproc {
-	struct omap_mbox *mbox;
-	struct notifier_block nb;
+	struct mbox_chan *mbox;
+	struct mbox_client client;
 	struct rproc *rproc;
 };
 
 /**
  * omap_rproc_mbox_callback() - inbound mailbox message handler
- * @this: notifier block
- * @index: unused
+ * @client: mailbox client pointer used for requesting the mailbox channel
  * @data: mailbox payload
  *
  * This handler is invoked by omap's mailbox driver whenever a mailbox
@@ -61,13 +61,13 @@ struct omap_rproc {
  * that indicates different events. Those values are deliberately very
  * big so they don't coincide with virtqueue indices.
  */
-static int omap_rproc_mbox_callback(struct notifier_block *this,
-					unsigned long index, void *data)
+static void omap_rproc_mbox_callback(struct mbox_client *client, void *data)
 {
-	mbox_msg_t msg = (mbox_msg_t) data;
-	struct omap_rproc *oproc = container_of(this, struct omap_rproc, nb);
+	struct omap_rproc *oproc = container_of(client, struct omap_rproc,
+						client);
 	struct device *dev = oproc->rproc->dev.parent;
 	const char *name = oproc->rproc->name;
+	u32 msg = (u32)data;
 
 	dev_dbg(dev, "mbox msg: 0x%x\n", msg);
 
@@ -84,8 +84,6 @@ static int omap_rproc_mbox_callback(struct notifier_block *this,
 		if (rproc_vq_interrupt(oproc->rproc, msg) == IRQ_NONE)
 			dev_dbg(dev, "no message was found in vqid %d\n", msg);
 	}
-
-	return NOTIFY_DONE;
 }
 
 /* kick a virtqueue */
@@ -96,8 +94,8 @@ static void omap_rproc_kick(struct rproc *rproc, int vqid)
 	int ret;
 
 	/* send the index of the triggered virtqueue in the mailbox payload */
-	ret = omap_mbox_msg_send(oproc->mbox, vqid);
-	if (ret)
+	ret = mbox_send_message(oproc->mbox, (void *)vqid);
+	if (ret < 0)
 		dev_err(dev, "omap_mbox_msg_send failed: %d\n", ret);
 }
 
@@ -115,17 +113,22 @@ static int omap_rproc_start(struct rproc *rproc)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct omap_rproc_pdata *pdata = pdev->dev.platform_data;
 	int ret;
+	struct mbox_client *client = &oproc->client;
 
 	if (pdata->set_bootaddr)
 		pdata->set_bootaddr(rproc->bootaddr);
 
-	oproc->nb.notifier_call = omap_rproc_mbox_callback;
+	client->dev = dev;
+	client->tx_done = NULL;
+	client->rx_callback = omap_rproc_mbox_callback;
+	client->tx_block = false;
+	client->knows_txdone = false;
 
-	/* every omap rproc is assigned a mailbox instance for messaging */
-	oproc->mbox = omap_mbox_get(pdata->mbox_name, &oproc->nb);
+	oproc->mbox = omap_mbox_request_channel(client, pdata->mbox_name);
 	if (IS_ERR(oproc->mbox)) {
-		ret = PTR_ERR(oproc->mbox);
-		dev_err(dev, "omap_mbox_get failed: %d\n", ret);
+		ret = -EBUSY;
+		dev_err(dev, "mbox_request_channel failed: %ld\n",
+			PTR_ERR(oproc->mbox));
 		return ret;
 	}
 
@@ -136,9 +139,9 @@ static int omap_rproc_start(struct rproc *rproc)
 	 * Note that the reply will _not_ arrive immediately: this message
 	 * will wait in the mailbox fifo until the remote processor is booted.
 	 */
-	ret = omap_mbox_msg_send(oproc->mbox, RP_MBOX_ECHO_REQUEST);
-	if (ret) {
-		dev_err(dev, "omap_mbox_get failed: %d\n", ret);
+	ret = mbox_send_message(oproc->mbox, (void *)RP_MBOX_ECHO_REQUEST);
+	if (ret < 0) {
+		dev_err(dev, "mbox_send_message failed: %d\n", ret);
 		goto put_mbox;
 	}
 
@@ -151,7 +154,7 @@ static int omap_rproc_start(struct rproc *rproc)
 	return 0;
 
 put_mbox:
-	omap_mbox_put(oproc->mbox, &oproc->nb);
+	mbox_free_channel(oproc->mbox);
 	return ret;
 }
 
@@ -168,7 +171,7 @@ static int omap_rproc_stop(struct rproc *rproc)
 	if (ret)
 		return ret;
 
-	omap_mbox_put(oproc->mbox, &oproc->nb);
+	mbox_free_channel(oproc->mbox);
 
 	return 0;
 }
diff --git a/include/linux/mailbox_client.h b/include/linux/mailbox_client.h
index 307d9cab2026..1726ccbd8009 100644
--- a/include/linux/mailbox_client.h
+++ b/include/linux/mailbox_client.h
@@ -25,6 +25,8 @@ struct mbox_chan;
  *			if the client receives some ACK packet for transmission.
  *			Unused if the controller already has TX_Done/RTR IRQ.
  * @rx_callback:	Atomic callback to provide client the data received
+ * @tx_prepare: 	Atomic callback to ask client to prepare the payload
+ *			before initiating the transmission if required.
  * @tx_done:		Atomic callback to tell client of data transmission
  */
 struct mbox_client {
@@ -34,6 +36,7 @@ struct mbox_client {
 	bool knows_txdone;
 
 	void (*rx_callback)(struct mbox_client *cl, void *mssg);
+	void (*tx_prepare)(struct mbox_client *cl, void *mssg);
 	void (*tx_done)(struct mbox_client *cl, void *mssg, int r);
 };
 
diff --git a/include/linux/omap-mailbox.h b/include/linux/omap-mailbox.h
index f8322d9cd235..587bbdd31f5a 100644
--- a/include/linux/omap-mailbox.h
+++ b/include/linux/omap-mailbox.h
@@ -10,20 +10,20 @@
 #define OMAP_MAILBOX_H
 
 typedef u32 mbox_msg_t;
-struct omap_mbox;
 
 typedef int __bitwise omap_mbox_irq_t;
 #define IRQ_TX ((__force omap_mbox_irq_t) 1)
 #define IRQ_RX ((__force omap_mbox_irq_t) 2)
 
-int omap_mbox_msg_send(struct omap_mbox *, mbox_msg_t msg);
+struct mbox_chan;
+struct mbox_client;
 
-struct omap_mbox *omap_mbox_get(const char *, struct notifier_block *nb);
-void omap_mbox_put(struct omap_mbox *mbox, struct notifier_block *nb);
+struct mbox_chan *omap_mbox_request_channel(struct mbox_client *cl,
+					    const char *chan_name);
 
-void omap_mbox_save_ctx(struct omap_mbox *mbox);
-void omap_mbox_restore_ctx(struct omap_mbox *mbox);
-void omap_mbox_enable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq);
-void omap_mbox_disable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq);
+void omap_mbox_save_ctx(struct mbox_chan *chan);
+void omap_mbox_restore_ctx(struct mbox_chan *chan);
+void omap_mbox_enable_irq(struct mbox_chan *chan, omap_mbox_irq_t irq);
+void omap_mbox_disable_irq(struct mbox_chan *chan, omap_mbox_irq_t irq);
 
 #endif /* OMAP_MAILBOX_H */