[PATCH v2 5/6] mailbox: Add generic mechanism for testing Mailbox Controllers

On Thu, Aug 13, 2015 at 3:53 PM, Lee Jones [off-list ref] wrote:

On Thu, 13 Aug 2015, Jassi Brar wrote:

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On Thu, Aug 13, 2015 at 2:49 PM, Lee Jones [off-list ref] wrote:

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On Thu, 13 Aug 2015, Jassi Brar wrote:

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+
+static void mbox_test_prepare_message(struct mbox_client *client, void *message)
+{
+       struct mbox_test_device *tdev = dev_get_drvdata(client->dev);
+
+       if (tdev->mmio)
+               memcpy(tdev->mmio, message, MBOX_MAX_MSG_LEN);

This is unlikely to work. Those platforms that need to send a 2 part
message, they do :
(a) Signal/Command/Target code via some controller register (via
mbox_send_message).
(b) Setup the payload in Shared-Memory (via tx_prepare).

This test driver assumes both are the same. I think you have to
declare something like

This driver assumes that the framework will call client->tx_prepare()
first, which satisfies (b).  It then assumes controller->send_data()
will be invoked, which will send the platform specific
signal/command/target code, which then satisfies (a).

Yeah, but what would be that code? Who provides that?

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In what way does it assume they are the same?

notice the 'message' pointer in
mbox_send_message(tdev->tx_channel, message);
    and
memcpy(tdev->mmio, message, MBOX_MAX_MSG_LEN);

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struct mbox_test_message { /* same for TX and RX */
          unsigned sig_len;
          void *signal;               /* rx/tx via mailbox api */
          unsigned pl_len;
          void *payload;           /* rx/tx via shared-memory */
};

How do you think this should be set and use these?

The userspace would want to specify the command code (32bits or not)
that would be passed via the fifo/register of the controller. So we
need signal[]

The data to be passed via share-memory could be provided by userspace
via the payload[] array.

Okay, so would the solution be two userspace files 'signal' and
'message', so in the case of a client specified signal we can write it
into there first.

echo 255  > signal
echo test > message

... or in the case where no signal is required, or the controller
driver taking care of it, we just don't write anything to signal?

file_operations.write() should parse signal and message, coming from
userspace, into a local structure before routing them via
mbox_send_message and tx_prepare respectively.

Okay.  So before I code this up we should agree on syntax.

How would you like to represent the break between signal and message?
Obviously ' ' would be a bad idea, as some clients may want to send
messages with white space contained.  How about '\t' or '\n'?

Yeah, I am not a fan of markers and flags either.

Maybe we should share with userspace
  struct mbox_test_message { /* same for TX and RX */
           unsigned sig_len;
           void __user *signal;        /* rx/tx via mailbox api */
           unsigned pl_len;
           void __user *payload;    /* rx/tx via shared-memory */
  };

First copy_from_user the structure of length sizof(struct
mbox_test_message) and then copy_from_user length sig_len and pl_len
from signal[] and payload[] respectively (usually ioctls would carry
such data).