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@xxxxxxxxxxx>
<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.
