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stm32mp2: update register used by BL31 for boot parameter

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Use the ARM64 kernel booting register settings, defined in Linux
documentation Documentation/arch/arm64/booting.rst:

 x0 = physical address of device tree blob (dtb) in system RAM.

so kernel can replace U-Boot in FIP without modification of BL31.

Use x0 for future TF-A version and keep x2 as fallback to be compatible
with previous version of TF-A BL31.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
This commit is contained in:
Patrick Delaunay
2025-09-17 14:31:30 +02:00
committed by Patrice Chotard
parent d1afa66504
commit 8a2e75e6a1
1 changed files with 12 additions and 4 deletions
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16
arch/arm/mach-stm32mp/stm32mp2/cpu.c
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@@ -92,13 +92,21 @@ uintptr_t get_stm32mp_bl2_dtb(void)
}
/*
* Save the FDT address provided by TF-A in r2 at boot time
* Save the FDT address provided by TF-A at boot time
* This function is called from start.S
*/
void save_boot_params(unsigned long r0, unsigned long r1, unsigned long r2,
unsigned long r3)
void save_boot_params(unsigned long x0, unsigned long x1, unsigned long x2,
unsigned long x3)
{
nt_fw_dtb = r2;
/* use the ARM64 kernel booting register settings:
* x0 = physical address of device tree blob (dtb) in system RAM.
* so kernel can replace U-Boot in FIP wihtout BL31 modification
* else falback to x2 used in previous TF-A version
*/
if (x0)
nt_fw_dtb = x0;
else
nt_fw_dtb = x2;
save_boot_params_ret();
}