mirror of
https://github.com/brain-hackers/u-boot-brain
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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 <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
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| .. | ||
| tegra20 | ||
| tegra30 | ||
| tegra114 | ||
| tegra124 | ||
| ap.c | ||
| board.c | ||
| cache.c | ||
| clock.c | ||
| cmd_enterrcm.c | ||
| cpu.c | ||
| cpu.h | ||
| Kconfig | ||
| lowlevel_init.S | ||
| Makefile | ||
| pinmux-common.c | ||
| powergate.c | ||
| spl.c | ||
| sys_info.c | ||
| vpr.c | ||
| xusb-padctl.c | ||