linux-kernel - [PATCH 3/4] iommu/pamu: WARN when fsl_pamu

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Date:   Wed,  9 Aug 2017 16:46:53 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     iommu@...ts.linux-foundation.org
Cc:     Varun.Sethi@...escale.com, linux-kernel@...r.kernel.org,
        Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 3/4] iommu/pamu: WARN when fsl_pamu_probe() is called more than once

From: Joerg Roedel <jroedel@...e.de>

The function probes the PAMU hardware from device-tree
specifications. It initializes global variables and can thus
be only safely called once.

Add a check that that prints a warning when its called more
than once.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 drivers/iommu/fsl_pamu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iommu/fsl_pamu.c b/drivers/iommu/fsl_pamu.c
index a34355f..9ee8e9e 100644
--- a/drivers/iommu/fsl_pamu.c
+++ b/drivers/iommu/fsl_pamu.c
@@ -42,6 +42,8 @@ struct pamu_isr_data {
 static struct paace *ppaact;
 static struct paace *spaact;
 
+static bool probed;			/* Has PAMU been probed? */
+
 /*
  * Table for matching compatible strings, for device tree
  * guts node, for QorIQ SOCs.
@@ -1033,6 +1035,9 @@ static int fsl_pamu_probe(struct platform_device *pdev)
 	 * NOTE : All PAMUs share the same LIODN tables.
 	 */
 
+	if (WARN_ON(probed))
+		return -EBUSY;
+
 	pamu_regs = of_iomap(dev->of_node, 0);
 	if (!pamu_regs) {
 		dev_err(dev, "ioremap of PAMU node failed\n");
@@ -1172,6 +1177,8 @@ static int fsl_pamu_probe(struct platform_device *pdev)
 
 	setup_liodns();
 
+	probed = true;
+
 	return 0;
 
 error_genpool:
-- 
2.7.4