[PATCH v2 10/14] ARM: i.MX: add imx6_can_access_tzasc()

[Sascha Hauer <s.hauer@pengutronix.de>]

On ARMv7 there is no direct way to detect if we are in the secure or non
secure world. Add a imx6_can_access_tzasc() for this purpose. When
accessing the TZASC triggers a data abort then we are in the non secure
world, because OP-TEE configures the CSU to forbid accesses to the TZASC
from the normal world. This function can be used later to detect if we
have to load OP-TEE or not.

We'll need CONFIG_ARM_EXCEPTIONS_PBL for this functionality, so select
this symbol in Kconfig.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 arch/arm/mach-imx/Kconfig |  1 +
 arch/arm/mach-imx/tzasc.c | 13 +++++++++++++
 include/mach/imx/tzasc.h  |  1 +
 3 files changed, 15 insertions(+)

diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
index bb6bad169831b03879527ef9f676ff99b955a6fd..38ef55727678855591bf41cecca76947434381e8 100644
--- a/arch/arm/mach-imx/Kconfig
+++ b/arch/arm/mach-imx/Kconfig
@@ -50,6 +50,7 @@ config ARCH_IMX_TZASC
 	bool
 	depends on ARCH_IMX6 || ARCH_IMX8M
 	default y if PBL_OPTEE
+	select ARM_EXCEPTIONS_PBL
 
 #
 # PMIC configuration found on i.MX51 Babbadge board
diff --git a/arch/arm/mach-imx/tzasc.c b/arch/arm/mach-imx/tzasc.c
index ed20ad8803a2e91b67b5d8c3ab1a4265c4228ec7..0fe7f6eb7f4ac67b6db63ee78b5fc867d17df9cc 100644
--- a/arch/arm/mach-imx/tzasc.c
+++ b/arch/arm/mach-imx/tzasc.c
@@ -13,6 +13,8 @@
 #include <linux/sizes.h>
 #include <mach/imx/imx8m-regs.h>
 #include <io.h>
+#include <abort.h>
+#include <asm/barebox-arm.h>
 
 /*******************************************************************************
  *                         TZC380 defines
@@ -329,6 +331,17 @@ bool imx6ul_tzc380_is_bypassed(void)
 	return !(readl(&gpr[9]) & MX6_GPR_TZASC1_EN);
 }
 
+bool imx6_can_access_tzasc(void)
+{
+	arm_pbl_init_exceptions();
+
+	data_abort_mask();
+
+	readl(IOMEM(MX6_TZASC1_BASE));
+
+	return !data_abort_unmask();
+}
+
 void imx8m_tzc380_init(void)
 {
 	u32 __iomem *gpr = IOMEM(MX8M_IOMUXC_GPR_BASE_ADDR);
diff --git a/include/mach/imx/tzasc.h b/include/mach/imx/tzasc.h
index 0fbcdc2150e63864366a8dddeed2d1b97685903d..ca85704a8f459ab6e0cdc975940d855929f3d6f7 100644
--- a/include/mach/imx/tzasc.h
+++ b/include/mach/imx/tzasc.h
@@ -10,6 +10,7 @@ void imx6q_tzc380_early_ns_region1(void);
 void imx6ul_tzc380_early_ns_region1(void);
 bool imx6q_tzc380_is_bypassed(void);
 bool imx6ul_tzc380_is_bypassed(void);
+bool imx6_can_access_tzasc(void);
 void imx8m_tzc380_init(void);
 bool imx8m_tzc380_is_enabled(void);
 

-- 
2.39.5