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Subject: Re: [PATCH v4 2/7] MIPS: Loongson64: Distinguish firmware
 dependencies DTB/LEFI
To:     Qing Zhang <zhangqing@loongson.cn>,
        Huacai Chen <chenhuacai@kernel.org>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>
Cc:     linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, Ming Wang <wangming01@loongson.cn>
References: <20210310075639.20372-1-zhangqing@loongson.cn>
 <20210310075639.20372-3-zhangqing@loongson.cn>
From:   Oleksij Rempel <linux@rempel-privat.de>
Message-ID: <2484af69-13d1-09ff-3785-6c89cac4ffbd@rempel-privat.de>
Date:   Wed, 10 Mar 2021 11:57:23 +0100
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Hi,

Am 10.03.21 um 08:56 schrieb Qing Zhang:
> Add DTB boot support, only support Loongson-2K1000 processor
> for now, determine whether to use the built-in DTB or the DTB
> from the firmware by checking the range of CKSEG0 and XKPHYS.
> loongson_fw_interface will be used in the future.
>
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
> Tested-by: Ming Wang <wangming01@loongson.cn>
> ---
>
> v3-v4: Standard submission of information
>        Fix error handling
>
>  .../include/asm/mach-loongson64/boot_param.h     |  6 ++++++
>  arch/mips/include/asm/mach-loongson64/loongson.h |  3 ++-
>  arch/mips/loongson64/env.c                       | 13 ++++++++++++-
>  arch/mips/loongson64/init.c                      | 16 ++++++++++++++--
>  4 files changed, 34 insertions(+), 4 deletions(-)
>
> diff --git a/arch/mips/include/asm/mach-loongson64/boot_param.h b/arch/m=
ips/include/asm/mach-loongson64/boot_param.h
> index 4592841b6b0c..43737401dc06 100644
> --- a/arch/mips/include/asm/mach-loongson64/boot_param.h
> +++ b/arch/mips/include/asm/mach-loongson64/boot_param.h
> @@ -198,7 +198,13 @@ enum loongson_bridge_type {
>  	VIRTUAL =3D 3
>  };
>
> +enum loongson_fw_interface {
> +	LOONGSON_LEFI,
> +	LOONGSON_DTB,
> +};
> +
>  struct loongson_system_configuration {
> +	enum loongson_fw_interface fw_interface;
>  	u32 nr_cpus;
>  	u32 nr_nodes;
>  	int cores_per_node;
> diff --git a/arch/mips/include/asm/mach-loongson64/loongson.h b/arch/mip=
s/include/asm/mach-loongson64/loongson.h
> index ac1c20e172a2..3f885fa26ba6 100644
> --- a/arch/mips/include/asm/mach-loongson64/loongson.h
> +++ b/arch/mips/include/asm/mach-loongson64/loongson.h
> @@ -23,7 +23,8 @@ extern u32 memsize, highmemsize;
>  extern const struct plat_smp_ops loongson3_smp_ops;
>
>  /* loongson-specific command line, env and memory initialization */
> -extern void __init prom_init_env(void);
> +extern void __init prom_dtb_init_env(void);
> +extern void __init prom_lefi_init_env(void);
>  extern void __init szmem(unsigned int node);
>  extern void *loongson_fdt_blob;
>
> diff --git a/arch/mips/loongson64/env.c b/arch/mips/loongson64/env.c
> index 51a5d050a94c..e7d3a06175e3 100644
> --- a/arch/mips/loongson64/env.c
> +++ b/arch/mips/loongson64/env.c
> @@ -43,7 +43,18 @@ const char *get_system_type(void)
>  	return "Generic Loongson64 System";
>  }
>
> -void __init prom_init_env(void)
> +
> +void __init prom_dtb_init_env(void)
> +{
> +	if ((fw_arg2 < CKSEG0 || fw_arg2 > CKSEG1)
> +		&& (fw_arg2 < XKPHYS || fw_arg2 > XKSEG))
> +
> +		loongson_fdt_blob =3D __dtb_loongson64_2core_2k1000_begin;
> +	else
> +		loongson_fdt_blob =3D (void *)fw_arg2;
> +}
> +
> +void __init prom_lefi_init_env(void)
>  {
>  	struct boot_params *boot_p;
>  	struct loongson_params *loongson_p;
> diff --git a/arch/mips/loongson64/init.c b/arch/mips/loongson64/init.c
> index cfa788bca871..ed280b73bf89 100644
> --- a/arch/mips/loongson64/init.c
> +++ b/arch/mips/loongson64/init.c
> @@ -52,6 +52,10 @@ void __init szmem(unsigned int node)
>  	static unsigned long num_physpages;
>  	u64 node_id, node_psize, start_pfn, end_pfn, mem_start, mem_size;
>
> +	/* Otherwise come from DTB */
> +	if (loongson_sysconf.fw_interface !=3D LOONGSON_LEFI)
> +		return;
> +
>  	/* Parse memory information and activate */
>  	for (i =3D 0; i < loongson_memmap->nr_map; i++) {
>  		node_id =3D loongson_memmap->map[i].node_id;
> @@ -94,12 +98,20 @@ static void __init prom_init_memory(void)
>  void __init prom_init(void)
>  {
>  	fw_init_cmdline();
> -	prom_init_env();
> +
> +	if (fw_arg2 =3D=3D 0 || (fdt_magic(fw_arg2) =3D=3D FDT_MAGIC)) {
> +		loongson_sysconf.fw_interface =3D LOONGSON_DTB;
> +		prom_dtb_init_env();
> +	} else {
> +		loongson_sysconf.fw_interface =3D LOONGSON_LEFI;
> +		prom_lefi_init_env();
> +	}

Is it possible to make it compatible with MIPS UHI boot protocol? So boot =
loaders will be able to
handle Loongson kernel images as any other MIPS kernel images?

This protocol is described here on page 15, "3. Boot protocols"
https://docplayer.net/62444141-Unified-hosting-interface-md01069-reference=
-manual.html

According to this protocol, you should have:
fw_arg0 =3D -2
fw_arg1 =3D Virtual (kseg0) address of Device Tree Blob

This would made LS a first grade resident for many boot loaders and save a=
 lot of needles headaches.

=2D-
Regards,
Oleksij