This is a note to let you know that I've just added the patch titled
mailbox: mpfs: read the system controller's status
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mailbox-mpfs-read-the-system-controller-s-status.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d261f609f3d05d20cc647346562f2e323be8db81
Author: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Date: Wed Nov 23 17:56:52 2022 +0000
mailbox: mpfs: read the system controller's status
[ Upstream commit ab47d0bfdf88faac0eb02749e5bfaa306e004300 ]
Some services explicitly return an error code in their response, but
others rely on the system controller to set a status in its status
register. The meaning of the bits varies based on what service is
requested, so pass it back up to the driver that requested the service
in the first place. The field in the message struct already existed, but
was unused until now.
If the system controller is busy, in which case we should never actually
be in the interrupt handler, or if the service fails the mailbox itself
should not be read. Callers should check the status before operating on
the response.
There's an existing, but unused, #define for the mailbox mask - but it
was incorrect. It was doing a GENMASK_ULL(32, 16) which should've just
been a GENMASK(31, 16), so fix that up and start using it.
Fixes: 83d7b1560810 ("mbox: add polarfire soc system controller mailbox")
Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Reviewed-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Jassi Brar <jaswinder.singh@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/mailbox/mailbox-mpfs.c b/drivers/mailbox/mailbox-mpfs.c
index cfacb3f320a6..853901acaeec 100644
--- a/drivers/mailbox/mailbox-mpfs.c
+++ b/drivers/mailbox/mailbox-mpfs.c
@@ -2,7 +2,7 @@
/*
* Microchip PolarFire SoC (MPFS) system controller/mailbox controller driver
*
- * Copyright (c) 2020 Microchip Corporation. All rights reserved.
+ * Copyright (c) 2020-2022 Microchip Corporation. All rights reserved.
*
* Author: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
*
@@ -56,7 +56,7 @@
#define SCB_STATUS_NOTIFY_MASK BIT(SCB_STATUS_NOTIFY)
#define SCB_STATUS_POS (16)
-#define SCB_STATUS_MASK GENMASK_ULL(SCB_STATUS_POS + SCB_MASK_WIDTH, SCB_STATUS_POS)
+#define SCB_STATUS_MASK GENMASK(SCB_STATUS_POS + SCB_MASK_WIDTH - 1, SCB_STATUS_POS)
struct mpfs_mbox {
struct mbox_controller controller;
@@ -130,13 +130,38 @@ static void mpfs_mbox_rx_data(struct mbox_chan *chan)
struct mpfs_mbox *mbox = (struct mpfs_mbox *)chan->con_priv;
struct mpfs_mss_response *response = mbox->response;
u16 num_words = ALIGN((response->resp_size), (4)) / 4U;
- u32 i;
+ u32 i, status;
if (!response->resp_msg) {
dev_err(mbox->dev, "failed to assign memory for response %d\n", -ENOMEM);
return;
}
+ /*
+ * The status is stored in bits 31:16 of the SERVICES_SR register.
+ * It is only valid when BUSY == 0.
+ * We should *never* get an interrupt while the controller is
+ * still in the busy state. If we do, something has gone badly
+ * wrong & the content of the mailbox would not be valid.
+ */
+ if (mpfs_mbox_busy(mbox)) {
+ dev_err(mbox->dev, "got an interrupt but system controller is busy\n");
+ response->resp_status = 0xDEAD;
+ return;
+ }
+
+ status = readl_relaxed(mbox->ctrl_base + SERVICES_SR_OFFSET);
+
+ /*
+ * If the status of the individual servers is non-zero, the service has
+ * failed. The contents of the mailbox at this point are not be valid,
+ * so don't bother reading them. Set the status so that the driver
+ * implementing the service can handle the result.
+ */
+ response->resp_status = (status & SCB_STATUS_MASK) >> SCB_STATUS_POS;
+ if (response->resp_status)
+ return;
+
if (!mpfs_mbox_busy(mbox)) {
for (i = 0; i < num_words; i++) {
response->resp_msg[i] =
