[Skiboot] [PATCH v3 04/11] libflash/mbox-flash: Allow mbox-flash to tell the driver msg timeouts

[Cyril Bur]

Currently when mbox-flash decides that a message times out the driver
has no way of knowing to drop the message and will continue waiting for
a response indefinitely preventing more messages from ever being sent.

This is a problem if the BMC crashes or has some other issue where it
won't ever respond to our outstanding message.

This patch provides a method for mbox-flash to tell the driver how long
it should wait before it no longer needs to care about the response.

Signed-off-by: Cyril Bur <cyril.bur at au1.ibm.com>
---
 hw/lpc-mbox.c         | 12 +++++++++---
 include/lpc-mbox.h    |  2 +-
 libflash/mbox-flash.c | 17 +++++++++--------
 3 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/hw/lpc-mbox.c b/hw/lpc-mbox.c
index 74214938..f303f4d5 100644
--- a/hw/lpc-mbox.c
+++ b/hw/lpc-mbox.c
@@ -64,6 +64,7 @@ struct mbox {
 	struct lock lock; /* Protect in_flight */
 	struct bmc_mbox_msg *in_flight;
 	uint8_t sequence;
+	unsigned long timeout;
 };
 
 static struct mbox mbox;
@@ -115,7 +116,7 @@ static void bmc_mbox_send_message(struct bmc_mbox_msg *msg)
 	bmc_mbox_outb(MBOX_CTRL_INT_SEND, MBOX_HOST_CTRL);
 }
 
-int bmc_mbox_enqueue(struct bmc_mbox_msg *msg)
+int bmc_mbox_enqueue(struct bmc_mbox_msg *msg, unsigned int timeout_sec)
 {
 	if (!mbox.base) {
 		prlog(PR_CRIT, "Using MBOX without init!\n");
@@ -125,10 +126,15 @@ int bmc_mbox_enqueue(struct bmc_mbox_msg *msg)
 	lock(&mbox.lock);
 	if (mbox.in_flight) {
 		prlog(PR_DEBUG, "MBOX message already in flight\n");
-		unlock(&mbox.lock);
-		return OPAL_BUSY;
+		if (mftb() > mbox.timeout) {
+			prlog(PR_ERR, "In flight message dropped on the floor\n");
+		} else {
+			unlock(&mbox.lock);
+			return OPAL_BUSY;
+		}
 	}
 
+	mbox.timeout = mftb() + secs_to_tb(timeout_sec);
 	mbox.in_flight = msg;
 	unlock(&mbox.lock);
 	msg->seq = ++mbox.sequence;
diff --git a/include/lpc-mbox.h b/include/lpc-mbox.h
index c4b1015b..569f1f72 100644
--- a/include/lpc-mbox.h
+++ b/include/lpc-mbox.h
@@ -63,7 +63,7 @@ struct bmc_mbox_msg {
 	uint8_t bmc;
 };
 
-int bmc_mbox_enqueue(struct bmc_mbox_msg *msg);
+int bmc_mbox_enqueue(struct bmc_mbox_msg *msg, unsigned int timeout_sec);
 int bmc_mbox_register_callback(void (*callback)(struct bmc_mbox_msg *msg, void *priv),
 		void *drv_data);
 int bmc_mbox_register_attn(void (*callback)(uint8_t bits, void *priv),
diff --git a/libflash/mbox-flash.c b/libflash/mbox-flash.c
index 3615df78..7fd2e119 100644
--- a/libflash/mbox-flash.c
+++ b/libflash/mbox-flash.c
@@ -252,13 +252,14 @@ static bool is_reboot(struct mbox_flash_data *mbox_flash)
 	return mbox_flash->reboot;
 }
 
-static int msg_send(struct mbox_flash_data *mbox_flash, struct bmc_mbox_msg *msg)
+static int msg_send(struct mbox_flash_data *mbox_flash, struct bmc_mbox_msg *msg,
+		unsigned int timeout_sec)
 {
 	if (is_reboot(mbox_flash))
 		return FLASH_ERR_AGAIN;
 	mbox_flash->busy = true;
 	mbox_flash->rc = 0;
-	return bmc_mbox_enqueue(msg);
+	return bmc_mbox_enqueue(msg, timeout_sec);
 }
 
 static int wait_for_bmc(struct mbox_flash_data *mbox_flash, unsigned int timeout_sec)
@@ -307,7 +308,7 @@ static int mbox_flash_ack(struct mbox_flash_data *mbox_flash, uint8_t reg)
 	/* Clear this first so msg_send() doesn't freak out */
 	mbox_flash->reboot = false;
 
-	rc = msg_send(mbox_flash, msg);
+	rc = msg_send(mbox_flash, msg, MBOX_DEFAULT_TIMEOUT);
 
 	/* Still need to deal with it, we've only acked it now. */
 	mbox_flash->reboot = true;
@@ -499,7 +500,7 @@ static int mbox_flash_mark_write(struct mbox_flash_data *mbox_flash,
 		msg_put_u16(msg, 2, end - start); /* Total Length */
 	}
 
-	rc = msg_send(mbox_flash, msg);
+	rc = msg_send(mbox_flash, msg, MBOX_DEFAULT_TIMEOUT);
 	if (rc) {
 		prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
 		goto out;
@@ -554,7 +555,7 @@ static int mbox_flash_flush(struct mbox_flash_data *mbox_flash)
 	if (!msg)
 		return FLASH_ERR_MALLOC_FAILED;
 
-	rc = msg_send(mbox_flash, msg);
+	rc = msg_send(mbox_flash, msg, MBOX_DEFAULT_TIMEOUT);
 	if (rc) {
 		prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
 		goto out;
@@ -609,7 +610,7 @@ static int mbox_window_move(struct mbox_flash_data *mbox_flash,
 		return FLASH_ERR_MALLOC_FAILED;
 
 	msg_put_u16(msg, 0, bytes_to_blocks(mbox_flash, pos));
-	rc = msg_send(mbox_flash, msg);
+	rc = msg_send(mbox_flash, msg, MBOX_DEFAULT_TIMEOUT);
 	if (rc) {
 		prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
 		goto out;
@@ -772,7 +773,7 @@ static int mbox_flash_get_info(struct blocklevel_device *bl, const char **name,
 		*name = NULL;
 
 	mbox_flash->busy = true;
-	rc = msg_send(mbox_flash, msg);
+	rc = msg_send(mbox_flash, msg, MBOX_DEFAULT_TIMEOUT);
 	if (rc) {
 		prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
 		goto out;
@@ -965,7 +966,7 @@ static int protocol_init(struct mbox_flash_data *mbox_flash)
 		return FLASH_ERR_MALLOC_FAILED;
 
 	msg_put_u8(msg, 0, mbox_flash->version);
-	rc = msg_send(mbox_flash, msg);
+	rc = msg_send(mbox_flash, msg, MBOX_DEFAULT_TIMEOUT);
 	if (rc) {
 		prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
 		goto out;
-- 
2.15.1