+
+ 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 frameworkrequires 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 gunyahversion: %u. Currently
supported: %d\n",
+ gh_api_version(), GUNYAH_API_V1);
