Tegra: memctrl_v1: disable AHB redirection after cold boot

During boot, USB3 and flash media (SDMMC/SATA) devices need access to
IRAM. Because these clients connect to the MC and do not have a direct
path to the IRAM, the MC implements AHB redirection during boot to allow
path to IRAM. In this mode, accesses to a programmed memory address aperture
are directed to the AHB bus, allowing access to the IRAM. The AHB aperture
is defined by the IRAM_BASE_LO and IRAM_BASE_HI registers, which are
initialized to disable this aperture. Once bootup is complete, we must
program IRAM base/top, thus disabling access to IRAM.

This patch provides functionality to disable this access. The tegra port
calls this new function before jumping to the non-secure world during
cold boot.
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

plat/nvidia/tegra/common/drivers/memctrl/memctrl_v1.c

@@ -218,3 +218,29 @@ done:
 	video_mem_base = phys_base;
 	video_mem_size = size_in_bytes >> 20;
 }
+
+/*
+ * During boot, USB3 and flash media (SDMMC/SATA) devices need access to
+ * IRAM. Because these clients connect to the MC and do not have a direct
+ * path to the IRAM, the MC implements AHB redirection during boot to allow
+ * path to IRAM. In this mode, accesses to a programmed memory address aperture
+ * are directed to the AHB bus, allowing access to the IRAM. The AHB aperture
+ * is defined by the IRAM_BASE_LO and IRAM_BASE_HI registers, which are
+ * initialized to disable this aperture.
+ *
+ * Once bootup is complete, we must program IRAM base to 0xffffffff and
+ * IRAM top to 0x00000000, thus disabling access to IRAM. DRAM is then
+ * potentially accessible in this address range. These aperture registers
+ * also have an access_control/lock bit. After disabling the aperture, the
+ * access_control register should be programmed to lock the registers.
+ */
+void tegra_memctrl_disable_ahb_redirection(void)
+{
+	/* program the aperture registers */
+	tegra_mc_write_32(MC_IRAM_BASE_LO, 0xFFFFFFFF);
+	tegra_mc_write_32(MC_IRAM_TOP_LO, 0);
+	tegra_mc_write_32(MC_IRAM_BASE_TOP_HI, 0);
+
+	/* lock the aperture registers */
+	tegra_mc_write_32(MC_IRAM_REG_CTRL, MC_DISABLE_IRAM_CFG_WRITES);
+}

plat/nvidia/tegra/common/drivers/memctrl/memctrl_v2.c

@@ -581,3 +581,11 @@ void tegra_memctrl_videomem_setup(uint64_t phys_base, uint32_t size_in_bytes)
 	 */
 	mce_update_gsc_videomem();
 }
+
+/*
+ * This feature exists only for v1 of the Tegra Memory Controller.
+ */
+void tegra_memctrl_disable_ahb_redirection(void)
+{
+	; /* do nothing */
+}

plat/nvidia/tegra/common/tegra_bl31_setup.c

@@ -299,7 +299,16 @@ void bl31_platform_setup(void)
  ******************************************************************************/
 void bl31_plat_runtime_setup(void)
 {
-	; /* do nothing */
+	/*
+	 * During boot, USB3 and flash media (SDMMC/SATA) devices need
+	 * access to IRAM. Because these clients connect to the MC and
+	 * do not have a direct path to the IRAM, the MC implements AHB
+	 * redirection during boot to allow path to IRAM. In this mode
+	 * accesses to a programmed memory address aperture are directed
+	 * to the AHB bus, allowing access to the IRAM. This mode must be
+	 * disabled before we jump to the non-secure world.
+	 */
+	tegra_memctrl_disable_ahb_redirection();
 }
 
 /*******************************************************************************

plat/nvidia/tegra/include/drivers/memctrl.h

 /*
- * Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -36,5 +36,6 @@ void tegra_memctrl_restore_settings(void);
 void tegra_memctrl_tzdram_setup(uint64_t phys_base, uint32_t size_in_bytes);
 void tegra_memctrl_tzram_setup(uint64_t phys_base, uint32_t size_in_bytes);
 void tegra_memctrl_videomem_setup(uint64_t phys_base, uint32_t size_in_bytes);
+void tegra_memctrl_disable_ahb_redirection(void);
 
 #endif /* __MEMCTRL_H__ */

plat/nvidia/tegra/include/drivers/memctrl_v1.h

@@ -60,6 +60,13 @@
 #define MC_SMMU_TRANSLATION_ENABLE_4_0		0xb98
 #define  MC_SMMU_TRANSLATION_ENABLE		(~0)
 
+/* MC IRAM aperture registers */
+#define MC_IRAM_BASE_LO				0x65CU
+#define MC_IRAM_TOP_LO				0x660U
+#define MC_IRAM_BASE_TOP_HI			0x980U
+#define MC_IRAM_REG_CTRL			0x964U
+#define  MC_DISABLE_IRAM_CFG_WRITES		1U
+
 static inline uint32_t tegra_mc_read_32(uint32_t off)
 {
 	return mmio_read_32(TEGRA_MC_BASE + off);