[U-Boot] [PATCH v2 5/7] armv8: layerscape: Eanble falcon boot
Łukasz Majewski
lukma at denx.de
Mon Sep 25 14:17:22 UTC 2017
Hi York,
If you don't mind, I would like to ask you for some help and
clarification regarding your work.
> Add jump_to_image_linux() for arm64. Add "noreturn" flag to
> armv8_switch_to_el2(). Add hooks to fsl-layerscape to enable falcon
> boot.
I'm trying to do the same on imx6q board (armv7).
>
> Signed-off-by: York Sun <york.sun at nxp.com>
>
> ---
>
> Changes in v2:
> Relace getenv_f() with env_get_f() after rebasing to latet master.
>
> .../arm/cpu/armv8/fsl-layerscape/doc/README.falcon | 140 +++++++++++++++++++++
> arch/arm/cpu/armv8/fsl-layerscape/spl.c | 29 +++++
> arch/arm/include/asm/system.h | 2 +-
> arch/arm/lib/spl.c | 11 ++
> 4 files changed, 181 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm/cpu/armv8/fsl-layerscape/doc/README.falcon
>
> diff --git a/arch/arm/cpu/armv8/fsl-layerscape/doc/README.falcon b/arch/arm/cpu/armv8/fsl-layerscape/doc/README.falcon
> new file mode 100644
> index 0000000..282b19f
> --- /dev/null
> +++ b/arch/arm/cpu/armv8/fsl-layerscape/doc/README.falcon
> @@ -0,0 +1,140 @@
> +Falcon boot option
> +------------------
> +Falcon boot is a short cut boot method for SD/eMMC targets. It skips loading the
> +RAM version U-Boot. Instead, it loads FIT image and boot directly to Linux.
> +CONFIG_SPL_OS_BOOT enables falcon boot. CONFIG_SPL_LOAD_FIT enables the FIT
^^^^^^ - this is a bit cumbersome, since it requires some stub
for dtb creation (but this can be fixed for boards not yet supporting
dts u-boot configuration).
> +image support (also need CONFIG_SPL_OF_LIBFDT, CONFIG_SPL_FIT and optionally
> +CONFIG_SPL_GZIP).
> +
> +To enable falcon boot, a hook function spl_start_uboot() returns 0 to indicate
> +booting U-Boot is not the first choice. The kernel FIT image needs to be put
> +at CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR. SPL mmc driver reads the header to
> +determine if this is a FIT image. If true, FIT image components are parsed and
> +copied or decompressed (if applicable) to their desitinations. If FIT image is
> +not found, normal U-Boot flow will follow.
This part is similar to the one for old, venerable uImage.
> +
> +An important part of falcon boot is to prepare the device tree. A normal U-Boot
> +does FDT fixups when booting Linux. For falcon boot, Linux boots directly from
> +SPL, skipping the normal U-Boot. The device tree has to be prepared in advance.
> +A command "spl export" should be called under the normal RAM version U-Boot.
> +It is equivalent to go through "bootm" step-by-step until device tree fixup is
> +done. The device tree in memory is the one needed for falcon boot. Falcon boot
> +flow suggests to save this image to SD/eMMC at the location pointed by macro
> +CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR, with maximum size specified by macro
> +CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS. However, when FIT image is used for
> +Linux, the device tree stored in FIT image overwrites the memory loaded by spl
> +driver from these sectors. We could change this loading order to favor the
> +stored sectors. But when secure boot is enabled, these sectors are used for
> +signature header and needs to be loaded before the FIT image. So it is important
> +to understand the device tree in FIT image should be the one actually used, or
> +leave it abscent to favor the stored sectors. It is easier to deploy the FIT
> +image with embedded static device tree to multiple boards.
> +
> +Macro CONFIG_SYS_SPL_ARGS_ADDR serves two purposes. One is the pointer to load
> +the stored sectors to. Normally this is the static device tree. The second
> +purpose is the memory location of signature header for secure boot. After the
> +FIT image is loaded into memory, it is validated against the signature header
> +before individual components are extracted (and optionally decompressed) into
> +their final memory locations, respectivelly. After the validation, the header
> +is no longer used. The static device tree is copied into this location. So
> +this macro is passed as the location of device tree when booting Linux.
I've not yet go to this point -> Please look into below comments.
I'm just curious - how can I specify the DTBs precedence? I mean how to
decide if one from FIT or from eMMC sector are used?
> +components. Otherwise U-Boot cannot load them correctly.
> +
> +Generate FIT image with static device tree
> +------------------------------------------
> +Example:
> +
> +/dts-v1/;
I'm trying to load fitImage (with kernel + 2 dtbs) from eMMC directly by
SPL. The fitImage has been generated with OE-core recipe. The same
results are with one generated with mkimage.
> +
> +/ {
> + description = "Image file for the LS1043A Linux Kernel";
> + #address-cells = <1>;
> +
> + images {
> + kernel at 1 {
> + description = "ARM64 Linux kernel";
> + data = /incbin/("./arch/arm64/boot/Image.gz");
> + type = "kernel";
> + arch = "arm64";
> + os = "linux";
> + compression = "gzip";
> + load = <0x80080000>;
> + entry = <0x80080000>;
^^^^ common/spl/spl_fit.c - function spl_load_fit_image()
requires "data-offset" and "data-size" properties to be defined -
otherwise we exit with -ENOENT.
Even when creating my fitImage with u-boot's mkimage those properties
haven't been added.
> + };
> + fdt at 1 {
> + description = "Flattened Device Tree blob";
> + data = /incbin/("./fsl-ls1043ardb-static.dtb");
> + type = "flat_dt";
> + arch = "arm64";
> + compression = "none";
> + load = <0x90000000>;
> + };
> + ramdisk at 1 {
> + description = "LS1043 Ramdisk";
> + data = /incbin/("./rootfs.cpio.gz");
> + type = "ramdisk";
> + arch = "arm64";
> + os = "linux";
> + compression = "gzip";
> + load = <0xa0000000>;
> + };
> + };
> +
> + configurations {
> + default = "config at 1";
> + config at 1 {
> + description = "Boot Linux kernel";
> + kernel = "kernel at 1";
> + fdt = "fdt at 1";
> + ramdisk = "ramdisk at 1";
> + loadables = "fdt", "ramdisk";
^^^
Isn't here loadables require "kernel", "fdt", "ramdisk" ?
Could you share how have you managed to load fitImage from SPL? Maybe
I'm missing some patches? Is there any "reference" repo, so I could see
the "complete" work?
> + };
> + };
> +};
> +
> +The "loadables" is not optional. It tells SPL which images to load into memory.
> +
> +Other things to consider
> +-----------------------
> +Falcon boot skips a lot of initialization in U-Boot. If Linux expects the
> +hardware to be initialized by U-Boot, the related code should be ported to SPL
> +build. For example, if Linux expect Ethernet PHY to be initialized in U-Boot
> +(which is not a common case), the PHY initialization has to be included in
> +falcon boot. This increases the SPL image size and should be handled carefully.
> +If Linux has PHY driver enabled, it still depends on the correct MDIO bus setup
> +in U-Boot. Normal U-Boot sets the MDC ratio to generate a proper clock signal.
> diff --git a/arch/arm/cpu/armv8/fsl-layerscape/spl.c b/arch/arm/cpu/armv8/fsl-layerscape/spl.c
> index 2776240..30b5432 100644
> --- a/arch/arm/cpu/armv8/fsl-layerscape/spl.c
> +++ b/arch/arm/cpu/armv8/fsl-layerscape/spl.c
> @@ -116,4 +116,33 @@ void board_init_f(ulong dummy)
> gd->arch.tlb_allocated = gd->arch.tlb_addr;
> #endif /* CONFIG_SPL_FSL_LS_PPA */
> }
> +
> +#ifdef CONFIG_SPL_OS_BOOT
> +/*
> + * Return
> + * 0 if booting into OS is selected
> + * 1 if booting into U-Boot is selected
> + */
> +int spl_start_uboot(void)
> +{
> + char s[8];
> +
> + env_init();
> + env_get_f("boot_os", s, sizeof(s));
> + if ((s != NULL) && (*s != '0' && *s != 'n' && *s != 'N' &&
> + *s != 'f' && *s != 'F'))
> + return 0;
> +
> + return 1;
> +}
> +#endif /* CONFIG_SPL_OS_BOOT */
> +#ifdef CONFIG_SPL_LOAD_FIT
> +int board_fit_config_name_match(const char *name)
> +{
> + /* Just empty function now - can't decide what to choose */
> + debug("%s: %s\n", __func__, name);
> +
> + return 0;
> +}
> +#endif
> #endif /* CONFIG_SPL_BUILD */
> diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
> index 79bd19a..7d8dc44 100644
> --- a/arch/arm/include/asm/system.h
> +++ b/arch/arm/include/asm/system.h
> @@ -215,7 +215,7 @@ void __asm_switch_ttbr(u64 new_ttbr);
> * @entry_point: kernel entry point
> * @es_flag: execution state flag, ES_TO_AARCH64 or ES_TO_AARCH32
> */
> -void armv8_switch_to_el2(u64 args, u64 mach_nr, u64 fdt_addr,
> +void __noreturn armv8_switch_to_el2(u64 args, u64 mach_nr, u64 fdt_addr,
> u64 arg4, u64 entry_point, u64 es_flag);
> /*
> * Switch from EL2 to EL1 for ARMv8
> diff --git a/arch/arm/lib/spl.c b/arch/arm/lib/spl.c
> index 27d6682..ab5d227 100644
> --- a/arch/arm/lib/spl.c
> +++ b/arch/arm/lib/spl.c
> @@ -7,6 +7,7 @@
> *
> * SPDX-License-Identifier: GPL-2.0+
> */
> +
> #include <common.h>
> #include <config.h>
> #include <spl.h>
> @@ -47,6 +48,15 @@ void __weak board_init_f(ulong dummy)
> * image.
> */
> #ifdef CONFIG_SPL_OS_BOOT
> +#ifdef CONFIG_ARM64
> +void __noreturn jump_to_image_linux(struct spl_image_info *spl_image)
> +{
> + debug("Entering kernel arg pointer: 0x%p\n", spl_image->arg);
> + cleanup_before_linux();
> + armv8_switch_to_el2((u64)spl_image->arg, 0, 0, 0,
> + spl_image->entry_point, ES_TO_AARCH64);
> +}
> +#else
> void __noreturn jump_to_image_linux(struct spl_image_info *spl_image)
> {
> unsigned long machid = 0xffffffff;
> @@ -62,4 +72,5 @@ void __noreturn jump_to_image_linux(struct spl_image_info *spl_image)
> cleanup_before_linux();
> image_entry(0, machid, spl_image->arg);
> }
> +#endif /* CONFIG_ARM64 */
> #endif
>
--
Best regards,
Lukasz Majewski
--
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