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SubjectRe: [PATCH v8 07/28] mailbox: Allow direct registration to a channel
From
On 12/19/22 4:58 PM, Elliot Berman wrote:
> Support virtual mailbox controllers and clients which are not platform
> devices or come from the devicetree by allowing them to match client to
> channel via some other mechanism.

The new function behaves very much like mbox_request_channel()
did before.

The new function differs from omap_mbox_request_channel() in that
it can change the if chan->txdone_method is TXDONE_BY_POLL, it
is changed to TXDONE_BY_ACK if the client's knows_txdone field is
set. Is this OK? Why?

It also assumes chan->mbox->ops->startup us non-null (though that
isn't really a problem).

>
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> ---
> drivers/mailbox/mailbox.c | 96 ++++++++++++++++++++++++----------
> drivers/mailbox/omap-mailbox.c | 18 ++-----
> drivers/mailbox/pcc.c | 18 ++-----
> include/linux/mailbox_client.h | 1 +
> 4 files changed, 76 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
> index 4229b9b5da98..adf36c05fa43 100644
> --- a/drivers/mailbox/mailbox.c
> +++ b/drivers/mailbox/mailbox.c
> @@ -317,6 +317,71 @@ int mbox_flush(struct mbox_chan *chan, unsigned long timeout)
> }
> EXPORT_SYMBOL_GPL(mbox_flush);
>
> +static int __mbox_bind_client(struct mbox_chan *chan, struct mbox_client *cl)

There should be an unbind_client() call. At a minimum, you are
calling try_module_get(), and the matching module_put() call
would belong there. And even though one might just call
module_put() elsewhere for this, it would be cleaner to have
a function that similarly encapsulates the shutdown call
as well.

-Alex

> +{
> + struct device *dev = cl->dev;
> + unsigned long flags;
> + int ret;
> +
> + if (chan->cl || !try_module_get(chan->mbox->dev->driver->owner)) {
> + dev_dbg(dev, "%s: mailbox not free\n", __func__);
> + return -EBUSY;
> + }
> +
> + spin_lock_irqsave(&chan->lock, flags);
> + chan->msg_free = 0;
> + chan->msg_count = 0;
> + chan->active_req = NULL;
> + chan->cl = cl;
> + init_completion(&chan->tx_complete);
> +
> + if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
> + chan->txdone_method = TXDONE_BY_ACK;
> +
> + spin_unlock_irqrestore(&chan->lock, flags);
> +
> + if (chan->mbox->ops->startup) {
> + ret = chan->mbox->ops->startup(chan);
> +
> + if (ret) {
> + dev_err(dev, "Unable to startup the chan (%d)\n", ret);
> + mbox_free_channel(chan);
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * mbox_bind_client - Request a mailbox channel.
> + * @chan: The mailbox channel to bind the client to.
> + * @cl: Identity of the client requesting the channel.
> + *
> + * The Client specifies its requirements and capabilities while asking for
> + * a mailbox channel. It can't be called from atomic context.
> + * The channel is exclusively allocated and can't be used by another
> + * client before the owner calls mbox_free_channel.
> + * After assignment, any packet received on this channel will be
> + * handed over to the client via the 'rx_callback'.
> + * The framework holds reference to the client, so the mbox_client
> + * structure shouldn't be modified until the mbox_free_channel returns.
> + *
> + * Return: 0 if the channel was assigned to the client successfully.
> + * <0 for request failure.
> + */
> +int mbox_bind_client(struct mbox_chan *chan, struct mbox_client *cl)
> +{
> + int ret;
> +
> + mutex_lock(&con_mutex);
> + ret = __mbox_bind_client(chan, cl);
> + mutex_unlock(&con_mutex);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(mbox_bind_client);
> +
> /**
> * mbox_request_channel - Request a mailbox channel.
> * @cl: Identity of the client requesting the channel.
> @@ -340,7 +405,6 @@ struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
> struct mbox_controller *mbox;
> struct of_phandle_args spec;
> struct mbox_chan *chan;
> - unsigned long flags;
> int ret;
>
> if (!dev || !dev->of_node) {
> @@ -372,33 +436,9 @@ struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
> return chan;
> }
>
> - if (chan->cl || !try_module_get(mbox->dev->driver->owner)) {
> - dev_dbg(dev, "%s: mailbox not free\n", __func__);
> - mutex_unlock(&con_mutex);
> - return ERR_PTR(-EBUSY);
> - }
> -
> - spin_lock_irqsave(&chan->lock, flags);
> - chan->msg_free = 0;
> - chan->msg_count = 0;
> - chan->active_req = NULL;
> - chan->cl = cl;
> - init_completion(&chan->tx_complete);
> -
> - if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
> - chan->txdone_method = TXDONE_BY_ACK;
> -
> - spin_unlock_irqrestore(&chan->lock, flags);
> -
> - if (chan->mbox->ops->startup) {
> - ret = chan->mbox->ops->startup(chan);
> -
> - if (ret) {
> - dev_err(dev, "Unable to startup the chan (%d)\n", ret);
> - mbox_free_channel(chan);
> - chan = ERR_PTR(ret);
> - }
> - }
> + ret = __mbox_bind_client(chan, cl);
> + if (ret)
> + chan = ERR_PTR(ret);
>
> mutex_unlock(&con_mutex);
> return chan;
> diff --git a/drivers/mailbox/omap-mailbox.c b/drivers/mailbox/omap-mailbox.c
> index 098c82d87137..711a56ec8592 100644
> --- a/drivers/mailbox/omap-mailbox.c
> +++ b/drivers/mailbox/omap-mailbox.c
> @@ -441,21 +441,9 @@ struct mbox_chan *omap_mbox_request_channel(struct mbox_client *cl,
> if (!mbox || !mbox->chan)
> return ERR_PTR(-ENOENT);
>
> - chan = mbox->chan;
> - spin_lock_irqsave(&chan->lock, flags);
> - chan->msg_free = 0;
> - chan->msg_count = 0;
> - chan->active_req = NULL;
> - chan->cl = cl;
> - init_completion(&chan->tx_complete);
> - spin_unlock_irqrestore(&chan->lock, flags);
> -
> - ret = chan->mbox->ops->startup(chan);
> - if (ret) {
> - pr_err("Unable to startup the chan (%d)\n", ret);
> - mbox_free_channel(chan);
> - chan = ERR_PTR(ret);
> - }
> + ret = mbox_bind_client(mbox->chan, cl);
> + if (ret)
> + return ERR_PTR(ret);
>
> return chan;
> }
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 3c2bc0ca454c..f655be083369 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -283,7 +283,7 @@ pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
> struct pcc_chan_info *pchan;
> struct mbox_chan *chan;
> struct device *dev;
> - unsigned long flags;
> + int rc;
>
> if (subspace_id < 0 || subspace_id >= pcc_chan_count)
> return ERR_PTR(-ENOENT);
> @@ -296,21 +296,11 @@ pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
> }
> dev = chan->mbox->dev;
>
> - spin_lock_irqsave(&chan->lock, flags);
> - chan->msg_free = 0;
> - chan->msg_count = 0;
> - chan->active_req = NULL;
> - chan->cl = cl;
> - init_completion(&chan->tx_complete);
> -
> - if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
> - chan->txdone_method = TXDONE_BY_ACK;
> -
> - spin_unlock_irqrestore(&chan->lock, flags);
> + rc = mbox_bind_client(chan, cl);
> + if (rc)
> + return ERR_PTR(rc);
>
> if (pchan->plat_irq > 0) {
> - int rc;
> -
> rc = devm_request_irq(dev, pchan->plat_irq, pcc_mbox_irq, 0,
> MBOX_IRQ_NAME, chan);
> if (unlikely(rc)) {
> diff --git a/include/linux/mailbox_client.h b/include/linux/mailbox_client.h
> index 65229a45590f..734694912ef7 100644
> --- a/include/linux/mailbox_client.h
> +++ b/include/linux/mailbox_client.h
> @@ -37,6 +37,7 @@ struct mbox_client {
> void (*tx_done)(struct mbox_client *cl, void *mssg, int r);
> };
>
> +int mbox_bind_client(struct mbox_chan *chan, struct mbox_client *cl);
> struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
> const char *name);
> struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index);

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