[PATCH v8 04/12] mach-snapdragon: boot0.h: split out msm8916_boot0.h

Mon May 18 10:41:07 CEST 2026


On 16/05/2026 20:19, michael.srba at seznam.cz wrote:
> From: Michael Srba <Michael.Srba at seznam.cz>
> 
> Prepare for supporting alternative boot0.h per-SoC by splitting out
> the existing msm8916-specific code.
> 
> There is now a selection mechanism to choose a specific boot0.h
> in the Kconfig. BOOT0_MSM8916_PSCI_WORKAROUND is the only option
> right now, but more can be added. The toplevel boot0.h additionally
> enables conditionally performing the include only in u-boot proper,
> or only in SPL.
> 
> Signed-off-by: Michael Srba <Michael.Srba at seznam.cz>
> Reviewed-by: Simon Glass <sjg at chromium.org>

Reviewed-by: Casey Connolly <casey.connolly at linaro.org>

> ---
>  arch/arm/mach-snapdragon/Kconfig                   | 16 ++++++
>  arch/arm/mach-snapdragon/include/mach/boot0.h      | 60 +++-------------------
>  .../mach-snapdragon/include/mach/msm8916_boot0.h   | 54 +++++++++++++++++++
>  configs/dragonboard410c_defconfig                  |  1 +
>  configs/hmibsc_defconfig                           |  1 +
>  5 files changed, 80 insertions(+), 52 deletions(-)
> 
> diff --git a/arch/arm/mach-snapdragon/Kconfig b/arch/arm/mach-snapdragon/Kconfig
> index d3de8693b5a..f863daf6bb9 100644
> --- a/arch/arm/mach-snapdragon/Kconfig
> +++ b/arch/arm/mach-snapdragon/Kconfig
> @@ -42,4 +42,20 @@ config SYS_CONFIG_NAME
>  	  Based on this option include/configs/<CONFIG_SYS_CONFIG_NAME>.h header
>  	  will be used for board configuration.
>  
> +choice
> +	prompt "Qualcomm boot0.h workaround"
> +	optional
> +	help
> +	  While U-Boot on Qualcomm platforms doesn't generally need compile-time
> +	  adjustments based on the target SoC, workarounds in boot0.h can't
> +	  practically detect the SoC at runtime. Enable one of these workarounds
> +	  if you know you need it.
> +
> +config BOOT0_MSM8916_PSCI_WORKAROUND
> +	bool "boot0.h workaround for buggy PSCI on the msm8916 SoC"
> +	help
> +	  Select this if you are building U-Boot proper for an msm8916 board that
> +	  uses the buggy PSCI implementation.
> +endchoice
> +
>  endif
> diff --git a/arch/arm/mach-snapdragon/include/mach/boot0.h b/arch/arm/mach-snapdragon/include/mach/boot0.h
> index 953cccad790..b3c76d6d97d 100644
> --- a/arch/arm/mach-snapdragon/include/mach/boot0.h
> +++ b/arch/arm/mach-snapdragon/include/mach/boot0.h
> @@ -1,54 +1,10 @@
>  /* SPDX-License-Identifier: GPL-2.0+ */
> -/*
> - * Workaround for "PSCI bug" on DragonBoard 410c
> - * Copyright (C) 2021 Stephan Gerhold <stephan at gerhold.net>
> - *
> - * Syscall parameters taken from Qualcomm's LK fork (scm.h):
> - * Copyright (c) 2011-2015, The Linux Foundation. All rights reserved.
> - *
> - * The PSCI implementation in the TrustZone/tz firmware on DragonBoard 410c has
> - * a bug that starts all other CPU cores in 32-bit mode unless the TZ syscall
> - * that switches from 32-bit to 64-bit mode is executed at least once.
> - *
> - * Normally this happens inside Qualcomm's LK bootloader which runs in 32-bit
> - * mode and uses the TZ syscall to boot a kernel in 64-bit mode. However, if
> - * U-Boot is installed to the "aboot" partition (replacing LK) the switch to
> - * 64-bit mode never happens since U-Boot is already running in 64-bit mode.
> - *
> - * A workaround for this "PSCI bug" is to execute the TZ syscall when entering
> - * U-Boot. That way PSCI is made aware of the 64-bit switch and starts all other
> - * CPU cores in 64-bit mode as well.
> - */
> -#include <linux/arm-smccc.h>
> -
> -#define ARM_SMCCC_SIP32_FAST_CALL \
> -	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, ARM_SMCCC_OWNER_SIP, 0)
> -
> -	/*
> -	 * U-Boot might be started in EL2 or EL3 with custom firmware.
> -	 * In that case, we assume that the workaround is not necessary or is
> -	 * handled already by the alternative firmware. Using the syscall in EL2
> -	 * would demote U-Boot to EL1; in EL3 it would probably just crash.
> -	 */
> -	mrs	x0, CurrentEL
> -	cmp	x0, #(1 << 2)	/* EL1 */
> -	bne	reset
> -
> -	/* Prepare TZ syscall parameters */
> -	mov	x0, #ARM_SMCCC_SIP32_FAST_CALL
> -	movk	x0, #0x10f	/* SCM_SVC_MILESTONE_CMD_ID */
> -	mov	x1, #0x12	/* MAKE_SCM_ARGS(0x2, SMC_PARAM_TYPE_BUFFER_READ) */
> -	adr	x2, el1_system_param
> -	mov	x3, el1_system_param_end - el1_system_param
> -
> -	/* Switch PSCI to 64-bit mode. Resets CPU and returns at el1_elr */
> -	smc	#0
> -
> -	/* Something went wrong, perhaps PSCI is already in 64-bit mode? */
> +#if defined(CONFIG_SPL_BUILD)
>  	b	reset
> -
> -	.align	3
> -el1_system_param:
> -	.quad	0, 0, 0, 0, 0, 0, 0, 0, 0	/* el1_x0-x8 */
> -	.quad	reset				/* el1_elr */
> -el1_system_param_end:
> +#else
> +#if defined(CONFIG_BOOT0_MSM8916_PSCI_WORKAROUND)
> +#include "msm8916_boot0.h"
> +#else
> +	b	reset
> +#endif
> +#endif
> diff --git a/arch/arm/mach-snapdragon/include/mach/msm8916_boot0.h b/arch/arm/mach-snapdragon/include/mach/msm8916_boot0.h
> new file mode 100644
> index 00000000000..953cccad790
> --- /dev/null
> +++ b/arch/arm/mach-snapdragon/include/mach/msm8916_boot0.h
> @@ -0,0 +1,54 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Workaround for "PSCI bug" on DragonBoard 410c
> + * Copyright (C) 2021 Stephan Gerhold <stephan at gerhold.net>
> + *
> + * Syscall parameters taken from Qualcomm's LK fork (scm.h):
> + * Copyright (c) 2011-2015, The Linux Foundation. All rights reserved.
> + *
> + * The PSCI implementation in the TrustZone/tz firmware on DragonBoard 410c has
> + * a bug that starts all other CPU cores in 32-bit mode unless the TZ syscall
> + * that switches from 32-bit to 64-bit mode is executed at least once.
> + *
> + * Normally this happens inside Qualcomm's LK bootloader which runs in 32-bit
> + * mode and uses the TZ syscall to boot a kernel in 64-bit mode. However, if
> + * U-Boot is installed to the "aboot" partition (replacing LK) the switch to
> + * 64-bit mode never happens since U-Boot is already running in 64-bit mode.
> + *
> + * A workaround for this "PSCI bug" is to execute the TZ syscall when entering
> + * U-Boot. That way PSCI is made aware of the 64-bit switch and starts all other
> + * CPU cores in 64-bit mode as well.
> + */
> +#include <linux/arm-smccc.h>
> +
> +#define ARM_SMCCC_SIP32_FAST_CALL \
> +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, ARM_SMCCC_OWNER_SIP, 0)
> +
> +	/*
> +	 * U-Boot might be started in EL2 or EL3 with custom firmware.
> +	 * In that case, we assume that the workaround is not necessary or is
> +	 * handled already by the alternative firmware. Using the syscall in EL2
> +	 * would demote U-Boot to EL1; in EL3 it would probably just crash.
> +	 */
> +	mrs	x0, CurrentEL
> +	cmp	x0, #(1 << 2)	/* EL1 */
> +	bne	reset
> +
> +	/* Prepare TZ syscall parameters */
> +	mov	x0, #ARM_SMCCC_SIP32_FAST_CALL
> +	movk	x0, #0x10f	/* SCM_SVC_MILESTONE_CMD_ID */
> +	mov	x1, #0x12	/* MAKE_SCM_ARGS(0x2, SMC_PARAM_TYPE_BUFFER_READ) */
> +	adr	x2, el1_system_param
> +	mov	x3, el1_system_param_end - el1_system_param
> +
> +	/* Switch PSCI to 64-bit mode. Resets CPU and returns at el1_elr */
> +	smc	#0
> +
> +	/* Something went wrong, perhaps PSCI is already in 64-bit mode? */
> +	b	reset
> +
> +	.align	3
> +el1_system_param:
> +	.quad	0, 0, 0, 0, 0, 0, 0, 0, 0	/* el1_x0-x8 */
> +	.quad	reset				/* el1_elr */
> +el1_system_param_end:
> diff --git a/configs/dragonboard410c_defconfig b/configs/dragonboard410c_defconfig
> index 51ad265688c..645f0816701 100644
> --- a/configs/dragonboard410c_defconfig
> +++ b/configs/dragonboard410c_defconfig
> @@ -11,6 +11,7 @@ CONFIG_ENV_OFFSET=0x0
>  CONFIG_DEFAULT_DEVICE_TREE="qcom/apq8016-sbc"
>  CONFIG_OF_LIBFDT_OVERLAY=y
>  CONFIG_SYS_LOAD_ADDR=0x80080000
> +CONFIG_BOOT0_MSM8916_PSCI_WORKAROUND=y
>  CONFIG_IDENT_STRING="\nQualcomm-DragonBoard 410C"
>  CONFIG_REMAKE_ELF=y
>  CONFIG_BUTTON_CMD=y
> diff --git a/configs/hmibsc_defconfig b/configs/hmibsc_defconfig
> index 1e3d744193d..358b13aac77 100644
> --- a/configs/hmibsc_defconfig
> +++ b/configs/hmibsc_defconfig
> @@ -12,6 +12,7 @@ CONFIG_ENV_OFFSET=0x0
>  CONFIG_DEFAULT_DEVICE_TREE="apq8016-schneider-hmibsc"
>  CONFIG_OF_LIBFDT_OVERLAY=y
>  CONFIG_SYS_LOAD_ADDR=0x80080000
> +CONFIG_BOOT0_MSM8916_PSCI_WORKAROUND=y
>  CONFIG_IDENT_STRING="\nSchneider Electric-HMIBSC"
>  CONFIG_REMAKE_ELF=y
>  # CONFIG_ANDROID_BOOT_IMAGE is not set
> 

-- 
// Casey (she/her)