imx: imx_aips: Add initial AIPS support

This patch adds an initial AHB-to-IP TrustZone (AIPS-TZ) initialization
routine. Setting up the AIPSTZ controller is required to inform the SoC
interconnect fabric which bus-masters can read/write and if the read/writes
are buffered.

For our purposes the initial configuration is for everything to be open. We
can lock-down later on as necessary.
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>

plat/imx/common/imx_aips.c

+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <mmio.h>
+#include <utils_def.h>
+#include <imx_aips.h>
+#include <imx_regs.h>
+
+static void imx_aips_set_default_access(struct aipstz_regs *aips_regs)
+{
+	int i;
+	uintptr_t addr;
+
+	/*
+	 * See section 4.7.7.1 AIPSTZ_MPR field descriptions
+	 * i.MX 7Solo Applications Processor Reference Manual, Rev. 0.1, 08/2016
+	 * 0111 ->
+	 *	0: Write Access from master not buffered
+	 *	1: Master is trusted for read access
+	 *	1: Master is trsuted for write access
+	 *	1: Access from master is not forced to user mode
+	 */
+	addr = (uintptr_t)&aips_regs->aipstz_mpr;
+	mmio_write_32(addr, 0x77777777);
+
+	/*
+	 * Helpfully the OPACR registers have the logical inversion of the above
+	 * See section 4.7.7.1 AIPSTZ_MPR field descriptions
+	 * i.MX 7Solo Applications Processor Reference Manual, Rev. 0.1, 08/2016
+	 * 0000 ->
+	 *	0: Write Access to the peripheral is not buffered by AIPSTZ
+	 *	0: The peripheral does not require supervisor priv to access
+	 *	0: Master is trsuted for write access
+	 *	0: Access from master is not forced to user mode
+	 */
+	for (i = 0; i < AIPSTZ_OAPCR_COUNT; i++) {
+		addr = (uintptr_t)&aips_regs->aipstz_opacr[i];
+		mmio_write_32(addr, 0x00000000);
+	}
+}
+
+void imx_aips_init(void)
+{
+	int i;
+	struct aipstz_regs *aips_regs[] = {
+		(struct aipstz_regs *)(AIPS1_BASE + AIPSTZ_CONFIG_OFFSET),
+		(struct aipstz_regs *)(AIPS2_BASE + AIPSTZ_CONFIG_OFFSET),
+		(struct aipstz_regs *)(AIPS3_BASE + AIPSTZ_CONFIG_OFFSET),
+	};
+
+	for (i = 0; i < ARRAY_SIZE(aips_regs); i++)
+		imx_aips_set_default_access(aips_regs[i]);
+}

plat/imx/common/include/imx_aips.h

+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __IMX_AIPS_H__
+#define __IMX_AIPS_H__
+
+#include <stdint.h>
+
+#define AIPSTZ_OAPCR_COUNT	0x05
+
+struct aipstz_regs {
+	uint32_t aipstz_mpr;
+	uint32_t res[15];
+	uint32_t aipstz_opacr[AIPSTZ_OAPCR_COUNT];
+};
+
+void imx_aips_init(void);
+
+#endif /* __IMX_AIPS_H__ */