arm: stm32mp: Implement support for TZC 400 controller

The purpose of this change is to allow configuring TrustZone (TZC)
memory permissions. For example, OP-TEE expects TZC regions to be
configured in a very particular way. The API presented here is
intended to allow exactly that.

UCLASS support is not implemented, because it would not be too useful.
Changing TZC permissions needs to be done with care, so as not to cut
off access to memory we are currently using. One place where we can
use this is at the end of SPL, right before jumping to OP-TEE.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/arch/arm/mach-stm32mp/include/mach/tzc.h b/arch/arm/mach-stm32mp/include/mach/tzc.h
new file mode 100644
index 0000000..16db55c
--- /dev/null
+++ b/arch/arm/mach-stm32mp/include/mach/tzc.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Simple API for configuring TrustZone memory regions
+ *
+ * The premise is that the desired TZC layout is known beforehand, and it can
+ * be configured in one step. tzc_configure() provides this functionality.
+ */
+#ifndef MACH_TZC_H
+#define MACH_TZC_H
+
+#include <linux/types.h>
+
+enum tzc_sec_mode {
+	TZC_ATTR_SEC_NONE = 0,
+	TZC_ATTR_SEC_R = 1,
+	TZC_ATTR_SEC_W = 2,
+	TZC_ATTR_SEC_RW	 = 3
+};
+
+struct tzc_region {
+	uintptr_t base;
+	uintptr_t top;
+	enum tzc_sec_mode sec_mode;
+	uint16_t nsec_id;
+	uint16_t filters_mask;
+};
+
+int tzc_configure(uintptr_t tzc, const struct tzc_region *cfg);
+int tzc_disable_filters(uintptr_t tzc, uint16_t filters_mask);
+int tzc_enable_filters(uintptr_t tzc, uint16_t filters_mask);
+void tzc_dump_config(uintptr_t tzc);
+
+#endif /* MACH_TZC_H */