On 5/8/25 23:23, Johannes Krottmayer wrote:
> Add new assembly function 'arch_very_early_init'
>
> This functions setups the power supply for STM32H7 SoC's to
> direct SMPS mode, which is required for some boards like
> the STM32H747I-DISCO in the default configuration.
>
> If this isn't done in an early stage it cause a deadlock and
> also the SoC is running in a limited mode according to the
> TRM from the SoC.
>
> Signed-off-by: Johannes Krottmayer <[email protected]>
> Cc: Patrick Delaunay <[email protected]>
> Cc: Patrice Chotard <[email protected]>
> ---
> arch/arm/mach-stm32/stm32h7/lowlevel.S | 45 ++++++++++++++++++++++++++
> 1 file changed, 45 insertions(+)
> create mode 100644 arch/arm/mach-stm32/stm32h7/lowlevel.S
>
> diff --git a/arch/arm/mach-stm32/stm32h7/lowlevel.S
> b/arch/arm/mach-stm32/stm32h7/lowlevel.S
> new file mode 100644
> index 00000000000..97f4e383e3b
> --- /dev/null
> +++ b/arch/arm/mach-stm32/stm32h7/lowlevel.S
> @@ -0,0 +1,45 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Copyright (C) 2025, Johannes Krottmayer <[email protected]>
> + */
> +
> +#include <linux/linkage.h>
> +
> +/*
> + * STM32H7 PWR registers
> + */
> +#define PWR_CR3 0x5802480C
> +#define PWR_CR3_LDOEN 1
> +
> +#define PWR_CSR1 0x58024804
> +#define PWR_CSR1_ACTVOSRDY 13
> +
> +ENTRY(arch_very_early_init)
> + /*
> + * Setup power supply for STM32H7 to direct SMPS mode.
> + * This is the default configuration from some boards
> + * like the SMT32H747i-DISCO.
> + *
> + * If these steps will not be done, this cause a deadlock.
> + */
> + ldr r6, =PWR_CR3
> + /* Disable LDO */
> + movs r0, #1
> + lsl r1, r0, #PWR_CR3_LDOEN
> + mvn r2, r1
> + ldr r3, [r6]
> + and r3, r2
> + str r3, [r6]
> + lsl r1, r0, #PWR_CSR1_ACTVOSRDY
> +
> + /* Loop until ACTVOSRDY is valid */
> +1:
> + ldr r6, =PWR_CSR1
> + ldr r3, [r6]
> + and r3, r1
> + cmp r3, r1
> + bne 1b
> +
> + /* Jump back to C runtime setup */
> + bx lr
> +ENDPROC(arch_very_early_init)
Hi Johannes
Reviewed-by: Patrice Chotard <[email protected]>
Thanks
Patrice
