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.
Thanks,
Pavan
