diff mbox series

[v6,09/21] mailbox: Add Gunyah message queue mailbox

Message ID 20221026185846.3983888-10-quic_eberman@quicinc.com (mailing list archive)
State New, archived
Headers show
Series Drivers for gunyah hypervisor | expand

Commit Message

Elliot Berman Oct. 26, 2022, 6:58 p.m. UTC 
Gunyah message queues are a unidirectional inter-VM pipe for messages up
to 1024 bytes. This driver supports pairing a receiver message queue and
a transmitter message queue to expose a single mailbox channel.

Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
---
 Documentation/virt/gunyah/message-queue.rst |   8 +
 MAINTAINERS                                 |   1 +
 drivers/mailbox/Kconfig                     |  10 +
 drivers/mailbox/Makefile                    |   2 +
 drivers/mailbox/gunyah-msgq.c               | 225 ++++++++++++++++++++
 include/linux/gunyah.h                      |  61 +++++-
 6 files changed, 305 insertions(+), 2 deletions(-)
 create mode 100644 drivers/mailbox/gunyah-msgq.c

Comments

Pavan Kondeti Oct. 27, 2022, 1:55 p.m. UTC | #1 
Hi Elliot,

On Wed, Oct 26, 2022 at 11:58:34AM -0700, Elliot Berman wrote:
> Gunyah message queues are a unidirectional inter-VM pipe for messages up
> to 1024 bytes. This driver supports pairing a receiver message queue and
> a transmitter message queue to expose a single mailbox channel.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>

<snip>

> +static irqreturn_t gh_msgq_tx_irq_handler(int irq, void *data)
> +{
> +	struct gh_msgq *msgq = data;
> +
> +	mbox_chan_txdone(gh_msgq_chan(msgq), 0);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void gh_msgq_txdone_tasklet(unsigned long data)
> +{
> +	struct gh_msgq *msgq = (struct gh_msgq *)data;
> +
> +	mbox_chan_txdone(gh_msgq_chan(msgq), msgq->last_status);
> +}
> +
> +static int gh_msgq_send_data(struct mbox_chan *chan, void *data)
> +{
> +	struct gh_msgq *msgq = mbox_chan_to_msgq(chan);
> +	struct gh_msgq_tx_data *msgq_data = data;
> +	u64 tx_flags = 0;
> +	unsigned long ret;
> +	bool ready;
> +
> +	if (msgq_data->push)
> +		tx_flags |= GH_HYPERCALL_MSGQ_TX_FLAGS_PUSH;
> +
> +	ret = gh_hypercall_msgq_send(msgq->tx_ghrsc->capid, msgq_data->length,
> +					(uintptr_t)msgq_data->data, tx_flags, &ready);
> +
> +	/**
> +	 * unlikely because Linux tracks state of msgq and should not try to
> +	 * send message when msgq is full.
> +	 */
> +	if (unlikely(ret == GH_ERROR_MSGQUEUE_FULL))
> +		return -EAGAIN;
> +
> +	/**
> +	 * Propagate all other errors to client. If we return error to mailbox
> +	 * framework, then no other messages can be sent and nobody will know
> +	 * to retry this message.
> +	 */
> +	msgq->last_status = gh_remap_error(ret);
> +
> +	/**
> +	 * This message was successfully sent, but message queue isn't ready to
> +	 * receive more messages because it's now full. Mailbox framework
> +	 * requires that we only report that message was transmitted only when
> +	 * we're ready to transmit another message. We'll get that in the form
> +	 * of tx IRQ once the other side starts to drain the msgq.
> +	 */
> +	if (ret == GH_ERROR_OK && !ready)
> +		return 0;
> +
> +	/**
> +	 * We can send more messages. Mailbox framework requires that tx done
> +	 * happens asynchronously to sending the message. Gunyah message queues
> +	 * tell us right away on the hypercall return whether we can send more
> +	 * messages. To work around this, defer the txdone to a tasklet.
> +	 */
> +	tasklet_schedule(&msgq->txdone_tasklet);
> +

Nice comments.

irq_work would be a better choice.

> +	return 0;
> +}
> +
> +struct mbox_chan_ops gh_msgq_ops = {
> +	.send_data = gh_msgq_send_data,
> +};
> +
> +/**
> + * gh_msgq_init() - Initialize a Gunyah message queue with an mbox_client
> + * @parent: optional, device parent used for the mailbox controller
> + * @msgq: Pointer to the gh_msgq to initialize
> + * @cl: A mailbox client to bind to the mailbox channel that the message queue creates
> + * @tx_ghrsc: optional, the transmission side of the message queue
> + * @rx_ghrsc: optional, the receiving side of the message queue
> + *
> + * At least one of tx_ghrsc and rx_ghrsc should be not NULL. Most message queue use cases come with
> + * a pair of message queues to facilitiate bidirectional communication. When tx_ghrsc is set,
> + * the client can send messages with mbox_send_message(gh_msgq_chan(msgq), msg). When rx_ghrsc
> + * is set, the mbox_client should register an .rx_callback() and the message queue driver will
> + * push all available messages upon receiving the RX ready interrupt. The messages should be
> + * consumed or copied by the client right away as the gh_msgq_rx_data will be replaced/destroyed
> + * after the callback.
> + *
> + * Returns - 0 on success, negative otherwise
> + */
> +int gh_msgq_init(struct device *parent, struct gh_msgq *msgq, struct mbox_client *cl,
> +		     struct gunyah_resource *tx_ghrsc, struct gunyah_resource *rx_ghrsc)
> +{
> +	int ret;
> +
> +	/* Must have at least a tx_ghrsc or rx_ghrsc and that they are the right device types */
> +	if ((!tx_ghrsc && !rx_ghrsc) ||
> +	    (tx_ghrsc && tx_ghrsc->type != GUNYAH_RESOURCE_TYPE_MSGQ_TX) ||
> +	    (rx_ghrsc && rx_ghrsc->type != GUNYAH_RESOURCE_TYPE_MSGQ_RX))
> +		return -EINVAL;
> +
> +	msgq->tx_ghrsc = tx_ghrsc;
> +	msgq->rx_ghrsc = rx_ghrsc;
> +
> +	msgq->mbox.dev = parent;
> +	msgq->mbox.ops = &gh_msgq_ops;
> +	msgq->mbox.chans = kcalloc(1, sizeof(*msgq->mbox.chans), GFP_KERNEL);

Error handling missing.

minor nit pick:

If you initialize num_chans to 1 before, then you can use that as the first
argument to kcalloc() which makes it more readable since you opted for kcalloc()
instead of kzalloc() there.

> +	msgq->mbox.num_chans = 1;
> +	msgq->mbox.txdone_irq = true;
> +
> +	if (gh_msgq_has_tx(msgq)) {
> +		ret = request_irq(msgq->tx_ghrsc->irq, gh_msgq_tx_irq_handler, 0, "gh_msgq_tx",
> +				msgq);
> +		if (ret)
> +			goto err_chans;
> +	}
> +
> +	if (gh_msgq_has_rx(msgq)) {
> +		ret = request_threaded_irq(msgq->rx_ghrsc->irq, NULL, gh_msgq_rx_irq_handler,
> +						IRQF_ONESHOT, "gh_msgq_rx", msgq);
> +		if (ret)
> +			goto err_tx_irq;
> +	}
> +
> +	tasklet_init(&msgq->txdone_tasklet, gh_msgq_txdone_tasklet, (unsigned long)msgq);

If you wish to use tasklets, use tasklet_setup().

> +
> +	ret = mbox_controller_register(&msgq->mbox);
> +	if (ret)
> +		goto err_rx_irq;
> +
> +	ret = mbox_bind_client(gh_msgq_chan(msgq), cl);
> +	if (ret)
> +		goto err_mbox;
> +
> +	return 0;
> +err_mbox:
> +	mbox_controller_unregister(&msgq->mbox);
> +err_rx_irq:
> +	if (gh_msgq_has_rx(msgq))
> +		free_irq(msgq->rx_ghrsc->irq, msgq);
> +err_tx_irq:
> +	if (gh_msgq_has_tx(msgq))
> +		free_irq(msgq->tx_ghrsc->irq, msgq);
> +err_chans:
> +	kfree(msgq->mbox.chans);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(gh_msgq_init);
> +
> +void gh_msgq_remove(struct gh_msgq *msgq)
> +{
> +	if (gh_msgq_has_rx(msgq))
> +		free_irq(msgq->rx_ghrsc->irq, msgq);
> +
> +	if (gh_msgq_has_tx(msgq))
> +		free_irq(msgq->tx_ghrsc->irq, msgq);
> +
> +	kfree(msgq->mbox.chans);
> +}
> +EXPORT_SYMBOL_GPL(gh_msgq_remove);
> +

Is gh_msgq_remove() supposed to undo every thing done in gh_msgq_init()?
ex: mbox controller and channel are not unregistered.

Thanks,
Pavan
Elliot Berman Nov. 1, 2022, 5:44 p.m. UTC | #2 
On 10/27/2022 6:55 AM, Pavan Kondeti wrote:
> Hi Elliot,
> 
> On Wed, Oct 26, 2022 at 11:58:34AM -0700, Elliot Berman wrote:
>> Gunyah message queues are a unidirectional inter-VM pipe for messages up
>> to 1024 bytes. This driver supports pairing a receiver message queue and
>> a transmitter message queue to expose a single mailbox channel.
>>
>> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> 
> <snip>
> 
>> +static irqreturn_t gh_msgq_tx_irq_handler(int irq, void *data)
>> +{
>> +	struct gh_msgq *msgq = data;
>> +
>> +	mbox_chan_txdone(gh_msgq_chan(msgq), 0);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static void gh_msgq_txdone_tasklet(unsigned long data)
>> +{
>> +	struct gh_msgq *msgq = (struct gh_msgq *)data;
>> +
>> +	mbox_chan_txdone(gh_msgq_chan(msgq), msgq->last_status);
>> +}
>> +
>> +static int gh_msgq_send_data(struct mbox_chan *chan, void *data)
>> +{
>> +	struct gh_msgq *msgq = mbox_chan_to_msgq(chan);
>> +	struct gh_msgq_tx_data *msgq_data = data;
>> +	u64 tx_flags = 0;
>> +	unsigned long ret;
>> +	bool ready;
>> +
>> +	if (msgq_data->push)
>> +		tx_flags |= GH_HYPERCALL_MSGQ_TX_FLAGS_PUSH;
>> +
>> +	ret = gh_hypercall_msgq_send(msgq->tx_ghrsc->capid, msgq_data->length,
>> +					(uintptr_t)msgq_data->data, tx_flags, &ready);
>> +
>> +	/**
>> +	 * unlikely because Linux tracks state of msgq and should not try to
>> +	 * send message when msgq is full.
>> +	 */
>> +	if (unlikely(ret == GH_ERROR_MSGQUEUE_FULL))
>> +		return -EAGAIN;
>> +
>> +	/**
>> +	 * Propagate all other errors to client. If we return error to mailbox
>> +	 * framework, then no other messages can be sent and nobody will know
>> +	 * to retry this message.
>> +	 */
>> +	msgq->last_status = gh_remap_error(ret);
>> +
>> +	/**
>> +	 * This message was successfully sent, but message queue isn't ready to
>> +	 * receive more messages because it's now full. Mailbox framework
>> +	 * requires that we only report that message was transmitted only when
>> +	 * we're ready to transmit another message. We'll get that in the form
>> +	 * of tx IRQ once the other side starts to drain the msgq.
>> +	 */
>> +	if (ret == GH_ERROR_OK && !ready)
>> +		return 0;
>> +
>> +	/**
>> +	 * We can send more messages. Mailbox framework requires that tx done
>> +	 * happens asynchronously to sending the message. Gunyah message queues
>> +	 * tell us right away on the hypercall return whether we can send more
>> +	 * messages. To work around this, defer the txdone to a tasklet.
>> +	 */
>> +	tasklet_schedule(&msgq->txdone_tasklet);
>> +
> 
> Nice comments.
> 
> irq_work would be a better choice.
> 
>> +	return 0;
>> +}
>> +
>> +struct mbox_chan_ops gh_msgq_ops = {
>> +	.send_data = gh_msgq_send_data,
>> +};
>> +
>> +/**
>> + * gh_msgq_init() - Initialize a Gunyah message queue with an mbox_client
>> + * @parent: optional, device parent used for the mailbox controller
>> + * @msgq: Pointer to the gh_msgq to initialize
>> + * @cl: A mailbox client to bind to the mailbox channel that the message queue creates
>> + * @tx_ghrsc: optional, the transmission side of the message queue
>> + * @rx_ghrsc: optional, the receiving side of the message queue
>> + *
>> + * At least one of tx_ghrsc and rx_ghrsc should be not NULL. Most message queue use cases come with
>> + * a pair of message queues to facilitiate bidirectional communication. When tx_ghrsc is set,
>> + * the client can send messages with mbox_send_message(gh_msgq_chan(msgq), msg). When rx_ghrsc
>> + * is set, the mbox_client should register an .rx_callback() and the message queue driver will
>> + * push all available messages upon receiving the RX ready interrupt. The messages should be
>> + * consumed or copied by the client right away as the gh_msgq_rx_data will be replaced/destroyed
>> + * after the callback.
>> + *
>> + * Returns - 0 on success, negative otherwise
>> + */
>> +int gh_msgq_init(struct device *parent, struct gh_msgq *msgq, struct mbox_client *cl,
>> +		     struct gunyah_resource *tx_ghrsc, struct gunyah_resource *rx_ghrsc)
>> +{
>> +	int ret;
>> +
>> +	/* Must have at least a tx_ghrsc or rx_ghrsc and that they are the right device types */
>> +	if ((!tx_ghrsc && !rx_ghrsc) ||
>> +	    (tx_ghrsc && tx_ghrsc->type != GUNYAH_RESOURCE_TYPE_MSGQ_TX) ||
>> +	    (rx_ghrsc && rx_ghrsc->type != GUNYAH_RESOURCE_TYPE_MSGQ_RX))
>> +		return -EINVAL;
>> +
>> +	msgq->tx_ghrsc = tx_ghrsc;
>> +	msgq->rx_ghrsc = rx_ghrsc;
>> +
>> +	msgq->mbox.dev = parent;
>> +	msgq->mbox.ops = &gh_msgq_ops;
>> +	msgq->mbox.chans = kcalloc(1, sizeof(*msgq->mbox.chans), GFP_KERNEL);
> 
> Error handling missing.
> 
> minor nit pick:
> 
> If you initialize num_chans to 1 before, then you can use that as the first
> argument to kcalloc() which makes it more readable since you opted for kcalloc()
> instead of kzalloc() there.
> 
>> +	msgq->mbox.num_chans = 1;
>> +	msgq->mbox.txdone_irq = true;
>> +
>> +	if (gh_msgq_has_tx(msgq)) {
>> +		ret = request_irq(msgq->tx_ghrsc->irq, gh_msgq_tx_irq_handler, 0, "gh_msgq_tx",
>> +				msgq);
>> +		if (ret)
>> +			goto err_chans;
>> +	}
>> +
>> +	if (gh_msgq_has_rx(msgq)) {
>> +		ret = request_threaded_irq(msgq->rx_ghrsc->irq, NULL, gh_msgq_rx_irq_handler,
>> +						IRQF_ONESHOT, "gh_msgq_rx", msgq);
>> +		if (ret)
>> +			goto err_tx_irq;
>> +	}
>> +
>> +	tasklet_init(&msgq->txdone_tasklet, gh_msgq_txdone_tasklet, (unsigned long)msgq);
> 
> If you wish to use tasklets, use tasklet_setup().
> 
>> +
>> +	ret = mbox_controller_register(&msgq->mbox);
>> +	if (ret)
>> +		goto err_rx_irq;
>> +
>> +	ret = mbox_bind_client(gh_msgq_chan(msgq), cl);
>> +	if (ret)
>> +		goto err_mbox;
>> +
>> +	return 0;
>> +err_mbox:
>> +	mbox_controller_unregister(&msgq->mbox);
>> +err_rx_irq:
>> +	if (gh_msgq_has_rx(msgq))
>> +		free_irq(msgq->rx_ghrsc->irq, msgq);
>> +err_tx_irq:
>> +	if (gh_msgq_has_tx(msgq))
>> +		free_irq(msgq->tx_ghrsc->irq, msgq);
>> +err_chans:
>> +	kfree(msgq->mbox.chans);
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(gh_msgq_init);
>> +
>> +void gh_msgq_remove(struct gh_msgq *msgq)
>> +{
>> +	if (gh_msgq_has_rx(msgq))
>> +		free_irq(msgq->rx_ghrsc->irq, msgq);
>> +
>> +	if (gh_msgq_has_tx(msgq))
>> +		free_irq(msgq->tx_ghrsc->irq, msgq);
>> +
>> +	kfree(msgq->mbox.chans);
>> +}
>> +EXPORT_SYMBOL_GPL(gh_msgq_remove);
>> +
> 
> Is gh_msgq_remove() supposed to undo every thing done in gh_msgq_init()?
> ex: mbox controller and channel are not unregistered.
> 

Ah thanks for catching, updated this as well as rest of your comments.
diff mbox series

Patch

diff --git a/Documentation/virt/gunyah/message-queue.rst b/Documentation/virt/gunyah/message-queue.rst
index c9f4d75e2291..7324fc616684 100644
--- a/Documentation/virt/gunyah/message-queue.rst
+++ b/Documentation/virt/gunyah/message-queue.rst
@@ -53,3 +53,11 @@  reference message queue 2's capability ID.
       |               |         |                 |         |               |
       |               |         |                 |         |               |
       +---------------+         +-----------------+         +---------------+
+
+Gunyah message queues are exposed as mailboxes. To create the mailbox, create
+a mbox_client and call `gh_msgq_init`. On receipt of the RX_READY interrupt,
+all messages in the RX message queue are read and pushed via the `rx_callback`
+of the registered mbox_client.
+
+.. kernel-doc:: drivers/mailbox/gunyah-msgq.c
+   :identifiers: gh_msgq_init
diff --git a/MAINTAINERS b/MAINTAINERS
index 211977dc344b..586539eadd3b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8943,6 +8943,7 @@  S:	Supported
 F:	Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
 F:	Documentation/virt/gunyah/
 F:	arch/arm64/gunyah/
+F:	drivers/mailbox/gunyah-msgq.c
 F:	drivers/virt/gunyah/
 F:	include/linux/gunyah.h
 
diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 05d6fae800e3..baf9451c5f04 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -41,6 +41,16 @@  config IMX_MBOX
 	help
 	  Mailbox implementation for i.MX Messaging Unit (MU).
 
+config GUNYAH_MESSAGE_QUEUES
+	tristate "Gunyah Message Queue Mailbox"
+	depends on GUNYAH
+	help
+	  Mailbox implementation for Gunyah Message Queues. Gunyah message queues
+	  are an IPC mechanism to pass short messages between virtual machines
+	  running under the Gunyah hypervisor.
+
+	  Say Y here if you run Linux as a Gunyah virtual machine.
+
 config PLATFORM_MHU
 	tristate "Platform MHU Mailbox"
 	depends on OF
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index fc9376117111..5f929bb55e9a 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -55,6 +55,8 @@  obj-$(CONFIG_MTK_CMDQ_MBOX)	+= mtk-cmdq-mailbox.o
 
 obj-$(CONFIG_ZYNQMP_IPI_MBOX)	+= zynqmp-ipi-mailbox.o
 
+obj-$(CONFIG_GUNYAH)		+= gunyah-msgq.o
+
 obj-$(CONFIG_SUN6I_MSGBOX)	+= sun6i-msgbox.o
 
 obj-$(CONFIG_SPRD_MBOX)		+= sprd-mailbox.o
diff --git a/drivers/mailbox/gunyah-msgq.c b/drivers/mailbox/gunyah-msgq.c
new file mode 100644
index 000000000000..c4d2ede9334f
--- /dev/null
+++ b/drivers/mailbox/gunyah-msgq.c
@@ -0,0 +1,225 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/gunyah.h>
+#include <linux/printk.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/wait.h>
+
+#define mbox_chan_to_msgq(chan) (container_of(chan->mbox, struct gh_msgq, mbox))
+
+static inline bool gh_msgq_has_tx(struct gh_msgq *msgq)
+{
+	return msgq->tx_ghrsc->type == GUNYAH_RESOURCE_TYPE_MSGQ_TX;
+}
+
+static inline bool gh_msgq_has_rx(struct gh_msgq *msgq)
+{
+	return msgq->rx_ghrsc->type == GUNYAH_RESOURCE_TYPE_MSGQ_RX;
+}
+
+static irqreturn_t gh_msgq_rx_irq_handler(int irq, void *data)
+{
+	struct gh_msgq *msgq = data;
+	struct gh_msgq_rx_data rx_data;
+	unsigned long gh_err;
+	ssize_t ret;
+	bool ready = false;
+
+	do {
+		gh_err = gh_hypercall_msgq_recv(msgq->rx_ghrsc->capid,
+				(uintptr_t)&rx_data.data, sizeof(rx_data.data),
+				&rx_data.length, &ready);
+		if (gh_err == GH_ERROR_OK) {
+			mbox_chan_received_data(gh_msgq_chan(msgq), &rx_data);
+		} else if (GH_ERROR_MSGQUEUE_EMPTY) {
+			break;
+		} else {
+			pr_warn("Failed to receive data from msgq for %s: %ld\n",
+				msgq->mbox.dev ? dev_name(msgq->mbox.dev) : "", ret);
+			break;
+		}
+	} while (ready);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t gh_msgq_tx_irq_handler(int irq, void *data)
+{
+	struct gh_msgq *msgq = data;
+
+	mbox_chan_txdone(gh_msgq_chan(msgq), 0);
+
+	return IRQ_HANDLED;
+}
+
+static void gh_msgq_txdone_tasklet(unsigned long data)
+{
+	struct gh_msgq *msgq = (struct gh_msgq *)data;
+
+	mbox_chan_txdone(gh_msgq_chan(msgq), msgq->last_status);
+}
+
+static int gh_msgq_send_data(struct mbox_chan *chan, void *data)
+{
+	struct gh_msgq *msgq = mbox_chan_to_msgq(chan);
+	struct gh_msgq_tx_data *msgq_data = data;
+	u64 tx_flags = 0;
+	unsigned long ret;
+	bool ready;
+
+	if (msgq_data->push)
+		tx_flags |= GH_HYPERCALL_MSGQ_TX_FLAGS_PUSH;
+
+	ret = gh_hypercall_msgq_send(msgq->tx_ghrsc->capid, msgq_data->length,
+					(uintptr_t)msgq_data->data, tx_flags, &ready);
+
+	/**
+	 * unlikely because Linux tracks state of msgq and should not try to
+	 * send message when msgq is full.
+	 */
+	if (unlikely(ret == GH_ERROR_MSGQUEUE_FULL))
+		return -EAGAIN;
+
+	/**
+	 * Propagate all other errors to client. If we return error to mailbox
+	 * framework, then no other messages can be sent and nobody will know
+	 * to retry this message.
+	 */
+	msgq->last_status = gh_remap_error(ret);
+
+	/**
+	 * This message was successfully sent, but message queue isn't ready to
+	 * receive more messages because it's now full. Mailbox framework
+	 * requires that we only report that message was transmitted only when
+	 * we're ready to transmit another message. We'll get that in the form
+	 * of tx IRQ once the other side starts to drain the msgq.
+	 */
+	if (ret == GH_ERROR_OK && !ready)
+		return 0;
+
+	/**
+	 * We can send more messages. Mailbox framework requires that tx done
+	 * happens asynchronously to sending the message. Gunyah message queues
+	 * tell us right away on the hypercall return whether we can send more
+	 * messages. To work around this, defer the txdone to a tasklet.
+	 */
+	tasklet_schedule(&msgq->txdone_tasklet);
+
+	return 0;
+}
+
+struct mbox_chan_ops gh_msgq_ops = {
+	.send_data = gh_msgq_send_data,
+};
+
+/**
+ * gh_msgq_init() - Initialize a Gunyah message queue with an mbox_client
+ * @parent: optional, device parent used for the mailbox controller
+ * @msgq: Pointer to the gh_msgq to initialize
+ * @cl: A mailbox client to bind to the mailbox channel that the message queue creates
+ * @tx_ghrsc: optional, the transmission side of the message queue
+ * @rx_ghrsc: optional, the receiving side of the message queue
+ *
+ * At least one of tx_ghrsc and rx_ghrsc should be not NULL. Most message queue use cases come with
+ * a pair of message queues to facilitiate bidirectional communication. When tx_ghrsc is set,
+ * the client can send messages with mbox_send_message(gh_msgq_chan(msgq), msg). When rx_ghrsc
+ * is set, the mbox_client should register an .rx_callback() and the message queue driver will
+ * push all available messages upon receiving the RX ready interrupt. The messages should be
+ * consumed or copied by the client right away as the gh_msgq_rx_data will be replaced/destroyed
+ * after the callback.
+ *
+ * Returns - 0 on success, negative otherwise
+ */
+int gh_msgq_init(struct device *parent, struct gh_msgq *msgq, struct mbox_client *cl,
+		     struct gunyah_resource *tx_ghrsc, struct gunyah_resource *rx_ghrsc)
+{
+	int ret;
+
+	/* Must have at least a tx_ghrsc or rx_ghrsc and that they are the right device types */
+	if ((!tx_ghrsc && !rx_ghrsc) ||
+	    (tx_ghrsc && tx_ghrsc->type != GUNYAH_RESOURCE_TYPE_MSGQ_TX) ||
+	    (rx_ghrsc && rx_ghrsc->type != GUNYAH_RESOURCE_TYPE_MSGQ_RX))
+		return -EINVAL;
+
+	msgq->tx_ghrsc = tx_ghrsc;
+	msgq->rx_ghrsc = rx_ghrsc;
+
+	msgq->mbox.dev = parent;
+	msgq->mbox.ops = &gh_msgq_ops;
+	msgq->mbox.chans = kcalloc(1, sizeof(*msgq->mbox.chans), GFP_KERNEL);
+	msgq->mbox.num_chans = 1;
+	msgq->mbox.txdone_irq = true;
+
+	if (gh_msgq_has_tx(msgq)) {
+		ret = request_irq(msgq->tx_ghrsc->irq, gh_msgq_tx_irq_handler, 0, "gh_msgq_tx",
+				msgq);
+		if (ret)
+			goto err_chans;
+	}
+
+	if (gh_msgq_has_rx(msgq)) {
+		ret = request_threaded_irq(msgq->rx_ghrsc->irq, NULL, gh_msgq_rx_irq_handler,
+						IRQF_ONESHOT, "gh_msgq_rx", msgq);
+		if (ret)
+			goto err_tx_irq;
+	}
+
+	tasklet_init(&msgq->txdone_tasklet, gh_msgq_txdone_tasklet, (unsigned long)msgq);
+
+	ret = mbox_controller_register(&msgq->mbox);
+	if (ret)
+		goto err_rx_irq;
+
+	ret = mbox_bind_client(gh_msgq_chan(msgq), cl);
+	if (ret)
+		goto err_mbox;
+
+	return 0;
+err_mbox:
+	mbox_controller_unregister(&msgq->mbox);
+err_rx_irq:
+	if (gh_msgq_has_rx(msgq))
+		free_irq(msgq->rx_ghrsc->irq, msgq);
+err_tx_irq:
+	if (gh_msgq_has_tx(msgq))
+		free_irq(msgq->tx_ghrsc->irq, msgq);
+err_chans:
+	kfree(msgq->mbox.chans);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gh_msgq_init);
+
+void gh_msgq_remove(struct gh_msgq *msgq)
+{
+	if (gh_msgq_has_rx(msgq))
+		free_irq(msgq->rx_ghrsc->irq, msgq);
+
+	if (gh_msgq_has_tx(msgq))
+		free_irq(msgq->tx_ghrsc->irq, msgq);
+
+	kfree(msgq->mbox.chans);
+}
+EXPORT_SYMBOL_GPL(gh_msgq_remove);
+
+
+static int __init gh_msgq_init_module(void)
+{
+	if (gh_api_version() != GUNYAH_API_V1) {
+		pr_warn("Unrecognized gunyah version: %u. Currently supported: %d\n",
+			gh_api_version(), GUNYAH_API_V1);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+module_init(gh_msgq_init_module);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Gunyah Message Queue Driver");
diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
index c863cac4a3cf..e317d7ac938f 100644
--- a/include/linux/gunyah.h
+++ b/include/linux/gunyah.h
@@ -7,10 +7,67 @@ 
 #define _GUNYAH_H
 
 #include <linux/bitfield.h>
-#include <linux/types.h>
 #include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
+#include <linux/types.h>
+
+/* Follows resource manager's resource types for VM_GET_HYP_RESOURCES */
+enum gunyah_resource_type {
+	GUNYAH_RESOURCE_TYPE_BELL_TX	= 0,
+	GUNYAH_RESOURCE_TYPE_BELL_RX	= 1,
+	GUNYAH_RESOURCE_TYPE_MSGQ_TX	= 2,
+	GUNYAH_RESOURCE_TYPE_MSGQ_RX	= 3,
+	GUNYAH_RESOURCE_TYPE_VCPU	= 4,
+};
+
+struct gunyah_resource {
+	enum gunyah_resource_type type;
+	u64 capid;
+	int irq;
+};
+
+/**
+ * Gunyah Message Queues
+ */
+
+#define GH_MSGQ_MAX_MSG_SIZE	240
+
+struct gh_msgq_tx_data {
+	size_t length;
+	bool push;
+	char data[];
+};
+
+struct gh_msgq_rx_data {
+	size_t length;
+	char data[GH_MSGQ_MAX_MSG_SIZE];
+};
+
+struct gh_msgq {
+	struct gunyah_resource *tx_ghrsc;
+	struct gunyah_resource *rx_ghrsc;
+
+	/* msgq private */
+	int last_status;
+	struct mbox_controller mbox;
+	struct tasklet_struct txdone_tasklet;
+};
+
+
+int gh_msgq_init(struct device *parent, struct gh_msgq *msgq, struct mbox_client *cl,
+		     struct gunyah_resource *tx_ghrsc, struct gunyah_resource *rx_ghrsc);
+void gh_msgq_remove(struct gh_msgq *msgq);
+
+static inline struct mbox_chan *gh_msgq_chan(struct gh_msgq *msgq)
+{
+	return &msgq->mbox.chans[0];
+}
+
+/******************************************************************************/
+/* Common arch-independent macros and definitions for Gunyah hypercalls */
 
-/* Common Gunyah macros */
 #define GH_CAPID_INVAL	U64_MAX
 #define GH_VMID_ROOT_VM	0xff