In preparation of better and latest documentation,
remove the current documentation.
Signed-off-by: anish kumar <yesanishhere@xxxxxxxxx>
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Documentation/driver-api/mailbox.rst | 129 ---------------------------
1 file changed, 129 deletions(-)
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-============================
-The Common Mailbox Framework
-============================
-
-:Author: Jassi Brar <jaswinder.singh@xxxxxxxxxx>
-
-This document aims to help developers write client and controller
-drivers for the API. But before we start, let us note that the
-client (especially) and controller drivers are likely going to be
-very platform specific because the remote firmware is likely to be
-proprietary and implement non-standard protocol. So even if two
-platforms employ, say, PL320 controller, the client drivers can't
-be shared across them. Even the PL320 driver might need to accommodate
-some platform specific quirks. So the API is meant mainly to avoid
-similar copies of code written for each platform. Having said that,
-nothing prevents the remote f/w to also be Linux based and use the
-same api there. However none of that helps us locally because we only
-ever deal at client's protocol level.
-
-Some of the choices made during implementation are the result of this
-peculiarity of this "common" framework.
-
-
-
-Controller Driver (See include/linux/mailbox_controller.h)
-==========================================================
-
-
-Allocate mbox_controller and the array of mbox_chan.
-Populate mbox_chan_ops, except peek_data() all are mandatory.
-The controller driver might know a message has been consumed
-by the remote by getting an IRQ or polling some hardware flag
-or it can never know (the client knows by way of the protocol).
-The method in order of preference is IRQ -> Poll -> None, which
-the controller driver should set via 'txdone_irq' or 'txdone_poll'
-or neither.
-
-
-Client Driver (See include/linux/mailbox_client.h)
-==================================================
-
-
-The client might want to operate in blocking mode (synchronously
-send a message through before returning) or non-blocking/async mode (submit
-a message and a callback function to the API and return immediately).
-
-::
-
- struct demo_client {
- struct mbox_client cl;
- struct mbox_chan *mbox;
- struct completion c;
- bool async;
- /* ... */
- };
-
- /*
- * This is the handler for data received from remote. The behaviour is purely
- * dependent upon the protocol. This is just an example.
- */
- static void message_from_remote(struct mbox_client *cl, void *mssg)
- {
- struct demo_client *dc = container_of(cl, struct demo_client, cl);
- if (dc->async) {
- if (is_an_ack(mssg)) {
- /* An ACK to our last sample sent */
- return; /* Or do something else here */
- } else { /* A new message from remote */
- queue_req(mssg);
- }
- } else {
- /* Remote f/w sends only ACK packets on this channel */
- return;
- }
- }
-
- static void sample_sent(struct mbox_client *cl, void *mssg, int r)
- {
- struct demo_client *dc = container_of(cl, struct demo_client, cl);
- complete(&dc->c);
- }
-
- static void client_demo(struct platform_device *pdev)
- {
- struct demo_client *dc_sync, *dc_async;
- /* The controller already knows async_pkt and sync_pkt */
- struct async_pkt ap;
- struct sync_pkt sp;
-
- dc_sync = kzalloc(sizeof(*dc_sync), GFP_KERNEL);
- dc_async = kzalloc(sizeof(*dc_async), GFP_KERNEL);
-
- /* Populate non-blocking mode client */
- dc_async->cl.dev = &pdev->dev;
- dc_async->cl.rx_callback = message_from_remote;
- dc_async->cl.tx_done = sample_sent;
- dc_async->cl.tx_block = false;
- dc_async->cl.tx_tout = 0; /* doesn't matter here */
- dc_async->cl.knows_txdone = false; /* depending upon protocol */
- dc_async->async = true;
- init_completion(&dc_async->c);
-
- /* Populate blocking mode client */
- dc_sync->cl.dev = &pdev->dev;
- dc_sync->cl.rx_callback = message_from_remote;
- dc_sync->cl.tx_done = NULL; /* operate in blocking mode */
- dc_sync->cl.tx_block = true;
- dc_sync->cl.tx_tout = 500; /* by half a second */
- dc_sync->cl.knows_txdone = false; /* depending upon protocol */
- dc_sync->async = false;
-
- /* ASync mailbox is listed second in 'mboxes' property */
- dc_async->mbox = mbox_request_channel(&dc_async->cl, 1);
- /* Populate data packet */
- /* ap.xxx = 123; etc */
- /* Send async message to remote */
- mbox_send_message(dc_async->mbox, &ap);
-
- /* Sync mailbox is listed first in 'mboxes' property */
- dc_sync->mbox = mbox_request_channel(&dc_sync->cl, 0);
- /* Populate data packet */
- /* sp.abc = 123; etc */
- /* Send message to remote in blocking mode */
- mbox_send_message(dc_sync->mbox, &sp);
- /* At this point 'sp' has been sent */
-
- /* Now wait for async chan to be done */
- wait_for_completion(&dc_async->c);
- }
--
2.39.3 (Apple Git-146)
