[PATCH v2 4/5] ARM: mach-imx: test PL310 write access

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If OP-TEE early loading is performed, OP-TEE will configure the PL210
and lock write access to the controller from the normal world. Test this
by trying to write the same value back and do not configure if we can
not write to the PL310.

Signed-off-by: Rouven Czerwinski <r.czerwinski@xxxxxxxxxxxxxx>
---
 arch/arm/mach-imx/imx6.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm/mach-imx/imx6.c b/arch/arm/mach-imx/imx6.c
index 41e0066add..c6fd862379 100644
--- a/arch/arm/mach-imx/imx6.c
+++ b/arch/arm/mach-imx/imx6.c
@@ -11,6 +11,7 @@
  *
  */
 
+#include <abort.h>
 #include <init.h>
 #include <common.h>
 #include <io.h>
@@ -273,6 +274,22 @@ int imx6_devices_init(void)
 	return 0;
 }
 
+static bool imx6_can_write_l2x0(void)
+{
+	void __iomem *l2x0_base = IOMEM(0x00a02000);
+	u32 val;
+	/*
+	 * Mask data aborts and try to access the PL210. If OP-TEE is running we
+	 * will receive a data-abort and assume barebox is running in the normal
+	 * world.
+	 */
+	val = readl(l2x0_base + L2X0_PREFETCH_CTRL);
+
+	data_abort_mask();
+	writel(val, l2x0_base + L2X0_PREFETCH_CTRL);
+	return data_abort_unmask();
+}
+
 static int imx6_mmu_init(void)
 {
 	void __iomem *l2x0_base = IOMEM(0x00a02000);
@@ -281,6 +298,9 @@ static int imx6_mmu_init(void)
 	if (!cpu_is_mx6())
 		return 0;
 
+	if (imx6_can_write_l2x0())
+		return 0;
+
 	val = readl(l2x0_base + L2X0_CACHE_ID);
 	cache_part = val & L2X0_CACHE_ID_PART_MASK;
 	cache_rtl  = val & L2X0_CACHE_ID_RTL_MASK;
-- 
2.25.0


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