[PATCH v9 08/27] mailbox: Add Gunyah message queue mailbox

Elliot Berman
2023-01-20T22:48:32Z

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/Makefile | 2 +
drivers/mailbox/gunyah-msgq.c | 214 ++++++++++++++++++++
include/linux/gunyah.h | 59 +++++-
5 files changed, 283 insertions(+), 1 deletion(-)
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/MAINTAINERS b/MAINTAINERS
index fe19e71efc6d..d02e8abe6457 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9049,6 +9049,7 @@ 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/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..caa283f7248b
--- /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>
+
+#define mbox_chan_to_msgq(chan) (container_of(chan->mbox, struct gh_msgq, mbox))
+
+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;
+ bool ready = true;
+
+ while (ready) {
+ 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_err == GH_ERROR_MSGQUEUE_EMPTY) {
+ break;
+ } else {
+ pr_warn("Failed to receive data from msgq for %s: %zd\n",
+ msgq->mbox.dev ? dev_name(msgq->mbox.dev) : "", gh_err);
+ break;
+ }
+ }
+
+ 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(struct tasklet_struct *tasklet)
+{
+ 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)
+{
+ 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_ret = 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 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;
+}
+
+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_warn("Unrecognized gunyah version: %u. Currently supported: %d\n",
+ gh_api_version(), GUNYAH_API_V1);
+ return -ENODEV;
+ }
+
+ 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.chans = kcalloc(msgq->mbox.num_chans, sizeof(*msgq->mbox.chans), GFP_KERNEL);
+ if (!msgq->mbox.chans)
+ return -ENOMEM;
+ msgq->mbox.txdone_irq = true;
+
+ 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");
diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
index b5f61c14ec1e..5d6fc9f88718 100644
--- a/include/linux/gunyah.h
+++ b/include/linux/gunyah.h
@@ -8,10 +8,67 @@

#include <linux/bitfield.h>
#include <linux/errno.h>
+#include <linux/interrupt.h>
#include <linux/limits.h>
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
#include <linux/types.h>

-/* Common Gunyah macros */
+/* 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_ret; /* Linux error, not GH_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 */
+
#define GH_CAPID_INVAL U64_MAX
#define GH_VMID_ROOT_VM 0xff

--
2.39.0