Merge branch 'mailbox-devel' of git://git.linaro.org/landing-teams/working/fujitsu/integration

Pull mailbox framework updates from Jassi Brar.

* 'mailbox-devel' of git://git.linaro.org/landing-teams/working/fujitsu/integration:
  Mailbox: Add support for Platform Communication Channel
  mailbox/omap: adapt to the new mailbox framework
  mailbox: add tx_prepare client callback
  mailbox: Don't unnecessarily re-arm the polling timer

10 files changed, 701 insertions, 188 deletions

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));
+        _omap_mbox_enable_irq(mbox, irq);
+}
+EXPORT_SYMBOL(omap_mbox_enable_irq);
 
-                mbox_fifo_write(mbox, msg);
-        }
+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;
-
-        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);
+        if (!mq)
+                return -ENOMEM;
+        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;
+        }
 
-                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);
 
-                omap_mbox_enable_irq(mbox, IRQ_RX);
-        }
-        mutex_unlock(&mdev->cfg_lock);
         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;
-}
-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);
+        return chan;
 }
-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 */