mirror of
https://github.com/brain-hackers/u-boot-brain
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73c38934da
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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| .. | ||
| ap.h | ||
| apb_misc.h | ||
| board.h | ||
| clk_rst.h | ||
| clock.h | ||
| funcmux.h | ||
| fuse.h | ||
| gp_padctrl.h | ||
| gpio.h | ||
| mmc.h | ||
| pinmux.h | ||
| pmc.h | ||
| powergate.h | ||
| scu.h | ||
| sys_proto.h | ||
| tegra_i2c.h | ||
| tegra_mmc.h | ||
| tegra.h | ||
| timer.h | ||
| uart.h | ||
| usb.h | ||
| warmboot.h | ||
| xusb-padctl.h | ||