[PATCH] ARM: i.MX6: configure AIPS registers only if trusted

[Philipp Zabel]

Bail out of AIPS configuration if OP-TEE has cleared the MTW
("master trusted for write access") bit for the ARM core master
to lock down AIPS configuration.

Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
---
 arch/arm/mach-imx/imx6.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm/mach-imx/imx6.c b/arch/arm/mach-imx/imx6.c
index ed6cde801ec7..0cf2c17d6b90 100644
--- a/arch/arm/mach-imx/imx6.c
+++ b/arch/arm/mach-imx/imx6.c
@@ -31,8 +31,16 @@
 #define MX6_OCOTP_CFG0			0x410
 #define MX6_OCOTP_CFG1			0x420
 
+#define BM_MPR_MPROT1_MTW		(0x1 << 25)
+
 static void imx6_configure_aips(void __iomem *aips)
 {
+	u32 mpr = readl(aips);
+
+	/* Bail if CPU ist not trusted for write accesses. */
+	if (!(mpr & BM_MPR_MPROT1_MTW))
+		return;
+
 	/*
 	 * Set all MPROTx to be non-bufferable, trusted for R/W,
 	 * not forced to user-mode.
-- 
2.47.3