From 73c38934daa10b518b20f2d21298fc8a8226843b Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Mon, 19 Jan 2015 16:25:52 -0700 Subject: ARM: tegra: support running in non-secure mode When the CPU is in non-secure (NS) mode (when running U-Boot under a secure monitor), certain actions cannot be taken, since they would need to write to secure-only registers. One example is configuring the ARM architectural timer's CNTFRQ register. We could support this in one of two ways: 1) Compile twice, once for secure mode (in which case anything goes) and once for non-secure mode (in which case certain actions are disabled). This complicates things, since everyone needs to keep track of different U-Boot binaries for different situations. 2) Detect NS mode at run-time, and optionally skip any impossible actions. This has the advantage of a single U-Boot binary working in all cases. (2) is not possible on ARM in general, since there's no architectural way to detect secure-vs-non-secure. However, there is a Tegra-specific way to detect this. This patches uses that feature to detect secure vs. NS mode on Tegra, and uses that to: * Skip the ARM arch timer initialization. * Set/clear an environment variable so that boot scripts can take different action depending on which mode the CPU is in. This might be something like: if CPU is secure: load secure monitor code into RAM. boot secure monitor. secure monitor will restart (a new copy of) U-Boot in NS mode. else: execute normal boot process Signed-off-by: Stephen Warren Signed-off-by: Tom Warren --- board/nvidia/common/board.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'board') diff --git a/board/nvidia/common/board.c b/board/nvidia/common/board.c index 80ef8fd..018dddb 100644 --- a/board/nvidia/common/board.c +++ b/board/nvidia/common/board.c @@ -21,6 +21,7 @@ #include #endif #include +#include #include #include #include @@ -180,6 +181,14 @@ int board_late_init(void) /* Make sure we finish initing the LCD */ tegra_lcd_check_next_stage(gd->fdt_blob, 1); #endif +#if defined(CONFIG_TEGRA_SUPPORT_NON_SECURE) + if (tegra_cpu_is_non_secure()) { + printf("CPU is in NS mode\n"); + setenv("cpu_ns_mode", "1"); + } else { + setenv("cpu_ns_mode", ""); + } +#endif return 0; } -- cgit v1.1