[PATCH v4 3/6] riscv: Provide a mechanism to fix DT for reserved memory

[Heinrich Schuchardt]

On 3/24/20 5:16 AM, Atish Patra wrote:
> In RISC-V, M-mode software can reserve physical memory regions
> by setting appropriate physical memory protection (PMP) csr. As the
> PMP csr are accessible only in M-mode, S-mode U-Boot can not read
> this configuration directly. However, M-mode software can pass this
> information via reserved-memory node in device tree so that S-mode
> software can access this information.
>
> This patch provides a framework to copy to the reserved-memory node
> from one DT to another. This will be used to update the DT used by
> U-Boot and the DT passed to the next stage OS.
>
> Signed-off-by: Atish Patra <atish.patra at wdc.com>
> ---
>   arch/riscv/cpu/start.S                |  1 +
>   arch/riscv/include/asm/global_data.h  |  1 +
>   arch/riscv/include/asm/u-boot-riscv.h |  2 +
>   arch/riscv/lib/Makefile               |  1 +
>   arch/riscv/lib/asm-offsets.c          |  1 +
>   arch/riscv/lib/fdt_fixup.c            | 80 +++++++++++++++++++++++++++
>   6 files changed, 86 insertions(+)
>   create mode 100644 arch/riscv/lib/fdt_fixup.c
>
> diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S
> index 6b3ff99c3882..0282685c2906 100644
> --- a/arch/riscv/cpu/start.S
> +++ b/arch/riscv/cpu/start.S
> @@ -121,6 +121,7 @@ call_board_init_f_0:
>
>   	jal	board_init_f_init_reserve
>
> +	SREG	s1, GD_FIRMWARE_FDT_ADDR(gp)
>   	/* save the boot hart id to global_data */
>   	SREG	tp, GD_BOOT_HART(gp)
>
> diff --git a/arch/riscv/include/asm/global_data.h b/arch/riscv/include/asm/global_data.h
> index b74bd7e738bb..51ac8d1c98e2 100644
> --- a/arch/riscv/include/asm/global_data.h
> +++ b/arch/riscv/include/asm/global_data.h
> @@ -15,6 +15,7 @@
>   /* Architecture-specific global data */
>   struct arch_global_data {
>   	long boot_hart;		/* boot hart id */
> +	phys_addr_t firmware_fdt_addr;
>   #ifdef CONFIG_SIFIVE_CLINT
>   	void __iomem *clint;	/* clint base address */
>   #endif
> diff --git a/arch/riscv/include/asm/u-boot-riscv.h b/arch/riscv/include/asm/u-boot-riscv.h
> index 49febd588102..543a1688db8f 100644
> --- a/arch/riscv/include/asm/u-boot-riscv.h
> +++ b/arch/riscv/include/asm/u-boot-riscv.h
> @@ -17,5 +17,7 @@ int cleanup_before_linux(void);
>   /* board/.../... */
>   int board_init(void);
>   void board_quiesce_devices(void);
> +int riscv_board_reserved_mem_fixup(void *fdt);
> +int riscv_fdt_copy_resv_mem_node(const void *src_fdt, void *dest_fdt);
>
>   #endif	/* _U_BOOT_RISCV_H_ */
> diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
> index adadbf4bcbef..d132b59ce32c 100644
> --- a/arch/riscv/lib/Makefile
> +++ b/arch/riscv/lib/Makefile
> @@ -24,6 +24,7 @@ obj-y	+= reset.o
>   obj-y   += setjmp.o
>   obj-$(CONFIG_SMP) += smp.o
>   obj-$(CONFIG_SPL_BUILD)	+= spl.o
> +obj-y   += fdt_fixup.o
>
>   # For building EFI apps
>   CFLAGS_$(EFI_CRT0) := $(CFLAGS_EFI)
> diff --git a/arch/riscv/lib/asm-offsets.c b/arch/riscv/lib/asm-offsets.c
> index 4fa4fd371473..7301c1b98e23 100644
> --- a/arch/riscv/lib/asm-offsets.c
> +++ b/arch/riscv/lib/asm-offsets.c
> @@ -14,6 +14,7 @@
>   int main(void)
>   {
>   	DEFINE(GD_BOOT_HART, offsetof(gd_t, arch.boot_hart));
> +	DEFINE(GD_FIRMWARE_FDT_ADDR, offsetof(gd_t, arch.firmware_fdt_addr));
>   #ifndef CONFIG_XIP
>   	DEFINE(GD_AVAILABLE_HARTS, offsetof(gd_t, arch.available_harts));
>   #endif
> diff --git a/arch/riscv/lib/fdt_fixup.c b/arch/riscv/lib/fdt_fixup.c
> new file mode 100644
> index 000000000000..f3d1ec5c5d02
> --- /dev/null
> +++ b/arch/riscv/lib/fdt_fixup.c
> @@ -0,0 +1,80 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) 2020 Western Digital Corporation or its affiliates
> + *
> + */
> +
> +#include <common.h>
> +#include <fdt_support.h>
> +#include <mapmem.h>
> +
> +DECLARE_GLOBAL_DATA_PTR;
> +

Please, provide Sphinx style comments for new functions. Cf.
https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html.

> +int riscv_fdt_copy_resv_mem_node(const void *src, void *dst)
> +{
> +	u32 phandle;
> +	struct fdt_memory pmp_mem;
> +	fdt_addr_t addr;
> +	fdt_size_t size;
> +	int offset, node, err, rmem_offset;
> +	bool nomap = true;
> +	char basename[32] = {0};
> +	int bname_len;
> +	int max_len = sizeof(basename);
> +	const char *name;
> +	char *temp;
> +
> +	offset = fdt_path_offset(src, "/reserved-memory");
> +	if (offset < 0) {
> +		printf("No reserved memory region found in source FDT\n");
> +		return 0;
> +	}
> +
> +	fdt_for_each_subnode(node, src, offset) {
> +		name = fdt_get_name(src, node, NULL);
> +
> +		addr = fdtdec_get_addr_size_auto_noparent(src, node,
> +							  "reg", 0, &size,
> +							  false);
> +		if (addr == FDT_ADDR_T_NONE) {
> +			debug("failed to read address/size for %s\n", name);
> +			continue;
> +		}
> +		strncpy(basename, name, max_len);
> +		temp = strchr(basename, '@');
> +		if (temp) {
> +			bname_len = strnlen(basename, max_len) - strnlen(temp,
> +								       max_len);
> +			*(basename + bname_len) = '\0';
> +		}
> +		pmp_mem.start = addr;
> +		pmp_mem.end = addr + size - 1;
> +		err = fdtdec_add_reserved_memory(dst, basename, &pmp_mem,
> +						 &phandle);
> +		if (err < 0) {
> +			printf("failed to add reserved memory: %d\n", err);
> +			return err;
> +		}
> +		if (!fdt_getprop(src, node, "no-map", NULL))
> +			nomap = false;
> +		if (nomap) {
> +			rmem_offset = fdt_node_offset_by_phandle(dst, phandle);
> +			fdt_setprop_empty(dst, rmem_offset, "no-map");
> +		}
> +	}
> +
> +	return 0;
> +}
> +

Same here.

Best regards

Heinrich

> +int riscv_board_reserved_mem_fixup(void *fdt)
> +{
> +	int err;
> +	void *src_fdt_addr;
> +
> +	src_fdt_addr = map_sysmem(gd->arch.firmware_fdt_addr, 0);
> +	err = riscv_fdt_copy_resv_mem_node(src_fdt_addr, fdt);
> +	if (err < 0)
> +		return err;
> +
> +	return 0;
> +}
>