Re: [PATCH v10 07/26] mailbox: Add Gunyah message queue mailbox

From: Srinivas Kandagatla
Date: Mon Feb 20 2023 - 08:59:40 EST



On 14/02/2023 21:23, 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@xxxxxxxxxxx>
---
Documentation/virt/gunyah/message-queue.rst | 8 +
drivers/mailbox/Makefile | 2 +
drivers/mailbox/gunyah-msgq.c | 214 ++++++++++++++++++++
include/linux/gunyah.h | 56 +++++
4 files changed, 280 insertions(+)
create mode 100644 drivers/mailbox/gunyah-msgq.c

diff --git a/Documentation/virt/gunyah/message-queue.rst b/Documentation/virt/gunyah/message-queue.rst
index 0667b3eb1ff9..082085e981e0 100644
--- a/Documentation/virt/gunyah/message-queue.rst
+++ b/Documentation/virt/gunyah/message-queue.rst
@@ -59,3 +59,11 @@ vIRQ: two TX message queues will have two vIRQs (and two capability IDs).
| | | | | |
| | | | | |
+---------------+ +-----------------+ +---------------+
+
+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/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

Why are we reusing CONFIG_GUNYAH Kconfig symbol for mailbox, why not CONFIG_GUNYAH_MBOX?

+
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..03ffaa30ce9b
--- /dev/null
+++ b/drivers/mailbox/gunyah-msgq.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2023 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>

...

+/* Fired when message queue transitions from "full" to "space available" to send messages */
+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;
+}
+
+/* Fired after sending message and hypercall told us there was more space available. */
+static void gh_msgq_txdone_tasklet(struct tasklet_struct *tasklet)

Tasklets have been long deprecated, consider using workqueues in this particular case.


+{
+ struct gh_msgq *msgq = container_of(tasklet, struct gh_msgq, txdone_tasklet);
+
+ mbox_chan_txdone(gh_msgq_chan(msgq), msgq->last_ret);
+}
+
+static int gh_msgq_send_data(struct mbox_chan *chan, void *data)
+{
..

+ tasklet_schedule(&msgq->txdone_tasklet);
+
+ return 0;
+}
+
+static 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 facilitate 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;
+
+ if (gh_api_version() != GUNYAH_API_V1) {
+ pr_err("Unrecognized gunyah version: %u. Currently supported: %d\n",
dev_err(parent

would make this more useful

+ gh_api_version(), GUNYAH_API_V1);
+ return -EOPNOTSUPP;
+ }
+
+ if (!gh_api_has_feature(GH_API_FEATURE_MSGQUEUE))
+ return -EOPNOTSUPP;
+
+ msgq->tx_ghrsc = tx_ghrsc;
+ msgq->rx_ghrsc = rx_ghrsc;
+
+ msgq->mbox.dev = parent;
+ msgq->mbox.ops = &gh_msgq_ops;
+ msgq->mbox.num_chans = 1;
+ msgq->mbox.txdone_irq = true;
+ msgq->mbox.chans = kcalloc(msgq->mbox.num_chans, sizeof(*msgq->mbox.chans), GFP_KERNEL);
+ if (!msgq->mbox.chans)
+ return -ENOMEM;
+
+ if (msgq->tx_ghrsc) {
+ ret = request_irq(msgq->tx_ghrsc->irq, gh_msgq_tx_irq_handler, 0, "gh_msgq_tx",
+ msgq);
+ if (ret)
+ goto err_chans;
+ }
+
+ if (msgq->rx_ghrsc) {
+ 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_setup(&msgq->txdone_tasklet, gh_msgq_txdone_tasklet);
+
+ 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 (msgq->rx_ghrsc)
+ free_irq(msgq->rx_ghrsc->irq, msgq);
+err_tx_irq:
+ if (msgq->tx_ghrsc)
+ 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)
+{
+ mbox_controller_unregister(&msgq->mbox);
+
+ if (msgq->rx_ghrsc)
+ free_irq(msgq->rx_ghrsc->irq, msgq);
+
+ if (msgq->tx_ghrsc)
+ free_irq(msgq->tx_ghrsc->irq, msgq);
+
+ kfree(msgq->mbox.chans);
+}
+EXPORT_SYMBOL_GPL(gh_msgq_remove);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Gunyah Message Queue Driver");