[PATCH] crypto: caam: map job ring registers without claiming region

[Rosen Penev <rosenp@gmail.com>]

devm_platform_ioremap_resource() ends up calling request_mem_region(),
which fails with -EBUSY on i.MX SoCs:

There the job rings are modelled as sub-regions of their parent
fsl,sec-v4.0 register window, and caam_probe() already reserves the
whole window exclusively via devm_of_iomap() before the children are
populated.  Every job ring therefore collides with its own parent and
fails to probe, taking the hardware RNG offline (seen on i.MX6, i.MX7
and i.MX8 boards such as colibri-imx7 and verdin-imx8mp).

Map the job ring registers with devm_ioremap() instead, which does not
claim the (already owned) region.

Fixes: 9a955c0a7d11 ("crypto: caam - simplify probe resource and IRQ handling")
Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/crypto/caam/jr.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/caam/jr.c b/drivers/crypto/caam/jr.c
index f9e029945b51..2ed8229d4733 100644
--- a/drivers/crypto/caam/jr.c
+++ b/drivers/crypto/caam/jr.c
@@ -583,12 +583,29 @@ static int caam_jr_probe(struct platform_device *pdev)
 	struct caam_drv_private_jr *jrpriv;
 	static int total_jobrs;
 	void __iomem *ctrl;
+	struct resource *r;
 	int error;
 	int irq;
 
-	ctrl = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(ctrl))
-		return PTR_ERR(ctrl);
+	/*
+	 * The job rings live inside the register window of their parent
+	 * fsl,sec-v4.0 node, which caam_probe() already reserves (and maps)
+	 * via devm_of_iomap().  A requested region that overlaps that
+	 * reservation, e.g. from devm_platform_ioremap_resource(), would
+	 * therefore fail with -EBUSY, so map the registers without claiming
+	 * the region here.
+	 */
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!r) {
+		dev_err(&pdev->dev, "platform_get_resource() failed\n");
+		return -EINVAL;
+	}
+
+	ctrl = devm_ioremap(&pdev->dev, r->start, resource_size(r));
+	if (!ctrl) {
+		dev_err(&pdev->dev, "devm_ioremap() failed\n");
+		return -ENOMEM;
+	}
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
-- 
2.55.0