1 files changed, 33 insertions, 101 deletions

diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index cc0cdd7e9de3..baeea0c2e619 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -73,14 +73,16 @@ static int cxl_pci_mbox_wait_for_doorbell(struct cxl_dev_state *cxlds)
 	return 0;
 }
 
-static void cxl_pci_mbox_timeout(struct cxl_dev_state *cxlds,
-				 struct cxl_mbox_cmd *mbox_cmd)
-{
-	struct device *dev = cxlds->dev;
+#define cxl_err(dev, status, msg)                                        \
+	dev_err_ratelimited(dev, msg ", device state %s%s\n",                  \
+			    status & CXLMDEV_DEV_FATAL ? " fatal" : "",        \
+			    status & CXLMDEV_FW_HALT ? " firmware-halt" : "")
 
-	dev_dbg(dev, "Mailbox command (opcode: %#x size: %zub) timed out\n",
-		mbox_cmd->opcode, mbox_cmd->size_in);
-}
+#define cxl_cmd_err(dev, cmd, status, msg)                               \
+	dev_err_ratelimited(dev, msg " (opcode: %#x), device state %s%s\n",    \
+			    (cmd)->opcode,                                     \
+			    status & CXLMDEV_DEV_FATAL ? " fatal" : "",        \
+			    status & CXLMDEV_FW_HALT ? " firmware-halt" : "")
 
 /**
  * __cxl_pci_mbox_send_cmd() - Execute a mailbox command
@@ -134,7 +136,11 @@ static int __cxl_pci_mbox_send_cmd(struct cxl_dev_state *cxlds,
 
 	/* #1 */
 	if (cxl_doorbell_busy(cxlds)) {
-		dev_err_ratelimited(dev, "Mailbox re-busy after acquiring\n");
+		u64 md_status =
+			readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);
+
+		cxl_cmd_err(cxlds->dev, mbox_cmd, md_status,
+			    "mailbox queue busy");
 		return -EBUSY;
 	}
 
@@ -160,7 +166,9 @@ static int __cxl_pci_mbox_send_cmd(struct cxl_dev_state *cxlds,
 	/* #5 */
 	rc = cxl_pci_mbox_wait_for_doorbell(cxlds);
 	if (rc == -ETIMEDOUT) {
-		cxl_pci_mbox_timeout(cxlds, mbox_cmd);
+		u64 md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);
+
+		cxl_cmd_err(cxlds->dev, mbox_cmd, md_status, "mailbox timeout");
 		return rc;
 	}
 
@@ -198,98 +206,13 @@ static int __cxl_pci_mbox_send_cmd(struct cxl_dev_state *cxlds,
 	return 0;
 }
 
-/**
- * cxl_pci_mbox_get() - Acquire exclusive access to the mailbox.
- * @cxlds: The device state to gain access to.
- *
- * Context: Any context. Takes the mbox_mutex.
- * Return: 0 if exclusive access was acquired.
- */
-static int cxl_pci_mbox_get(struct cxl_dev_state *cxlds)
-{
-	struct device *dev = cxlds->dev;
-	u64 md_status;
-	int rc;
-
-	mutex_lock_io(&cxlds->mbox_mutex);
-
-	/*
-	 * XXX: There is some amount of ambiguity in the 2.0 version of the spec
-	 * around the mailbox interface ready (8.2.8.5.1.1).  The purpose of the
-	 * bit is to allow firmware running on the device to notify the driver
-	 * that it's ready to receive commands. It is unclear if the bit needs
-	 * to be read for each transaction mailbox, ie. the firmware can switch
-	 * it on and off as needed. Second, there is no defined timeout for
-	 * mailbox ready, like there is for the doorbell interface.
-	 *
-	 * Assumptions:
-	 * 1. The firmware might toggle the Mailbox Interface Ready bit, check
-	 *    it for every command.
-	 *
-	 * 2. If the doorbell is clear, the firmware should have first set the
-	 *    Mailbox Interface Ready bit. Therefore, waiting for the doorbell
-	 *    to be ready is sufficient.
-	 */
-	rc = cxl_pci_mbox_wait_for_doorbell(cxlds);
-	if (rc) {
-		dev_warn(dev, "Mailbox interface not ready\n");
-		goto out;
-	}
-
-	md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);
-	if (!(md_status & CXLMDEV_MBOX_IF_READY && CXLMDEV_READY(md_status))) {
-		dev_err(dev, "mbox: reported doorbell ready, but not mbox ready\n");
-		rc = -EBUSY;
-		goto out;
-	}
-
-	/*
-	 * Hardware shouldn't allow a ready status but also have failure bits
-	 * set. Spit out an error, this should be a bug report
-	 */
-	rc = -EFAULT;
-	if (md_status & CXLMDEV_DEV_FATAL) {
-		dev_err(dev, "mbox: reported ready, but fatal\n");
-		goto out;
-	}
-	if (md_status & CXLMDEV_FW_HALT) {
-		dev_err(dev, "mbox: reported ready, but halted\n");
-		goto out;
-	}
-	if (CXLMDEV_RESET_NEEDED(md_status)) {
-		dev_err(dev, "mbox: reported ready, but reset needed\n");
-		goto out;
-	}
-
-	/* with lock held */
-	return 0;
-
-out:
-	mutex_unlock(&cxlds->mbox_mutex);
-	return rc;
-}
-
-/**
- * cxl_pci_mbox_put() - Release exclusive access to the mailbox.
- * @cxlds: The device state to communicate with.
- *
- * Context: Any context. Expects mbox_mutex to be held.
- */
-static void cxl_pci_mbox_put(struct cxl_dev_state *cxlds)
-{
-	mutex_unlock(&cxlds->mbox_mutex);
-}
-
 static int cxl_pci_mbox_send(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *cmd)
 {
 	int rc;
 
-	rc = cxl_pci_mbox_get(cxlds);
-	if (rc)
-		return rc;
-
+	mutex_lock_io(&cxlds->mbox_mutex);
 	rc = __cxl_pci_mbox_send_cmd(cxlds, cmd);
-	cxl_pci_mbox_put(cxlds);
+	mutex_unlock(&cxlds->mbox_mutex);
 
 	return rc;
 }
@@ -310,11 +233,20 @@ static int cxl_pci_setup_mailbox(struct cxl_dev_state *cxlds)
 	} while (!time_after(jiffies, timeout));
 
 	if (!(md_status & CXLMDEV_MBOX_IF_READY)) {
-		dev_err(cxlds->dev,
-			"timeout awaiting mailbox ready, device state:%s%s\n",
-			md_status & CXLMDEV_DEV_FATAL ? " fatal" : "",
-			md_status & CXLMDEV_FW_HALT ? " firmware-halt" : "");
-		return -EIO;
+		cxl_err(cxlds->dev, md_status,
+			"timeout awaiting mailbox ready");
+		return -ETIMEDOUT;
+	}
+
+	/*
+	 * A command may be in flight from a previous driver instance,
+	 * think kexec, do one doorbell wait so that
+	 * __cxl_pci_mbox_send_cmd() can assume that it is the only
+	 * source for future doorbell busy events.
+	 */
+	if (cxl_pci_mbox_wait_for_doorbell(cxlds) != 0) {
+		cxl_err(cxlds->dev, md_status, "timeout awaiting mailbox idle");
+		return -ETIMEDOUT;
 	}
 
 	cxlds->mbox_send = cxl_pci_mbox_send;