[PATCH] crypto: caam - skip RNG selftest when i.MX6 is in normal world

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On an i.MX6 running under OP-TEE, the CAAM selftest fails as it needs to
run in the secure world[1].

We can detect that barebox is running in the normal world on an i.MX6,
so use that info to gracefully skip the test.

This is not enough to get the CAAM working (The DECO registers may not
be accessible to barebox), but that is arguably a more useful error
message than an -EBUSY.

[1]: Scroll down to "Job Ring TZ assignment issue"
https://community.nxp.com/t5/i-MX-Security/RNG-self-test-errors-on-select-i-MX-device-revisions/ta-p/1102970

Reported-by: Fabian Pflug <f.pflug@pengutronix.de>
Cc: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/arm/mach-imx/imx6.c            |  2 +-
 drivers/crypto/caam/rng_self_test.c | 13 ++++++++++++-
 include/mach/imx/imx6.h             |  2 ++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-imx/imx6.c b/arch/arm/mach-imx/imx6.c
index 0cf2c17d6b90..29a56de56293 100644
--- a/arch/arm/mach-imx/imx6.c
+++ b/arch/arm/mach-imx/imx6.c
@@ -254,7 +254,7 @@ int imx6_devices_init(void)
 	return 0;
 }
 
-static bool imx6_cannot_write_l2x0(void)
+bool imx6_cannot_write_l2x0(void)
 {
 	void __iomem *l2x0_base = IOMEM(0x00a02000);
 	u32 val;
diff --git a/drivers/crypto/caam/rng_self_test.c b/drivers/crypto/caam/rng_self_test.c
index 5216ecef4451..a42d9cad1639 100644
--- a/drivers/crypto/caam/rng_self_test.c
+++ b/drivers/crypto/caam/rng_self_test.c
@@ -47,6 +47,8 @@
 #include <dma.h>
 #include <common.h>
 #include <linux/kernel.h>
+#include <mach/imx/generic.h>
+#include <mach/imx/imx6.h>
 
 #include "error.h"
 #include "regs.h"
@@ -143,7 +145,7 @@ static void rng_self_test_done(struct device *dev, u32 *desc, u32 err,
  * * i.MX6DLS silicon revision 1.4
  * * i.MX6SX silicon revision 1.4
  * * i.MX6UL silicon revision 1.2
- * * i.MX67SD silicon revision 1.3
+ * * i.MX7SD silicon revision 1.3
  *
  */
 int caam_rng_self_test(struct device *dev, const u8 caam_era, const u8 rngvid,
@@ -176,6 +178,15 @@ int caam_rng_self_test(struct device *dev, const u8 caam_era, const u8 rngvid,
 		return -EINVAL;
 	}
 
+	if (cpu_is_mx6() && imx6_cannot_write_l2x0()) {
+		/* If we enter this if clause, we are likely running
+		 * under OP-TEE, so there is no point in continuing
+		 * and getting -EBUSY waiting for job completion
+		 */
+		pr_info("skipping test in normal world\n");
+		return 0;
+	}
+
 	result = dma_alloc(sizeof(*result) * result_size);
 	desc = dma_alloc(sizeof(*desc) * desc_size);
 
diff --git a/include/mach/imx/imx6.h b/include/mach/imx/imx6.h
index 109df9b811c5..7b3cedd80f66 100644
--- a/include/mach/imx/imx6.h
+++ b/include/mach/imx/imx6.h
@@ -135,4 +135,6 @@ int imx6_cpu_revision(void);
 
 u64 imx6_uid(void);
 
+bool imx6_cannot_write_l2x0(void);
+
 #endif /* __MACH_IMX6_H */
-- 
2.47.3