linux-kernel - Re: [PATCH v16 06/16] lib: fdt: add a helper function for handling memory range property

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Message-ID: <20181130132106.GD9000@arm.com>
Date:   Fri, 30 Nov 2018 13:21:07 +0000
From:   Will Deacon <will.deacon@....com>
To:     AKASHI Takahiro <takahiro.akashi@...aro.org>, mark.rutland@....com,
        robh+dt@...nel.org, frowand.list@...il.com
Cc:     catalin.marinas@....com, dhowells@...hat.com, vgoyal@...hat.com,
        herbert@...dor.apana.org.au, davem@...emloft.net,
        dyoung@...hat.com, bhe@...hat.com, arnd@...db.de,
        schwidefsky@...ibm.com, heiko.carstens@...ibm.com,
        prudo@...ux.ibm.com, ard.biesheuvel@...aro.org,
        james.morse@....com, bhsharma@...hat.com,
        kexec@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v16 06/16] lib: fdt: add a helper function for handling
 memory range property

[moving some DT people to TO:]

On Thu, Nov 15, 2018 at 02:52:45PM +0900, AKASHI Takahiro wrote:
> Added function, fdt_setprop_reg(), will be used later to handle
> kexec-specific property in arm64's kexec_file implementation.
> It will possibly be merged into libfdt in the future.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Frank Rowand <frowand.list@...il.com>
> Cc: devicetree@...r.kernel.org
> ---
>  include/linux/libfdt.h | 26 ++++++++++++++++++++
>  lib/Makefile           |  2 +-
>  lib/fdt_addresses.c    | 56 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 83 insertions(+), 1 deletion(-)
>  create mode 100644 lib/fdt_addresses.c

We need an ack from the DT side before we can merge this series, please.

Will

> diff --git a/include/linux/libfdt.h b/include/linux/libfdt.h
> index 90ed4ebfa692..47c4dc9e135c 100644
> --- a/include/linux/libfdt.h
> +++ b/include/linux/libfdt.h
> @@ -5,4 +5,30 @@
>  #include <linux/libfdt_env.h>
>  #include "../../scripts/dtc/libfdt/libfdt.h"
>  
> +/**
> + * fdt_setprop_reg - add/set a memory region property
> + * @fdt: pointer to the device tree blob
> + * @nodeoffset: offset of the node to add a property at
> + * @name: name of property
> + * @addr: physical start address
> + * @size: size of region
> + *
> + * returns:
> + *	0, on success
> + *      -FDT_ERR_BADLAYOUT,
> + *	-FDT_ERR_BADMAGIC,
> + *	-FDT_ERR_BADNCELLS, if the node has a badly formatted or invalid
> + *		#address-cells property
> + *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
> + *	-FDT_ERR_BADSTATE,
> + *	-FDT_ERR_BADSTRUCTURE,
> + *	-FDT_ERR_BADVERSION,
> + *	-FDT_ERR_BADVALUE, addr or size doesn't fit to respective cells size
> + *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
> + *              contain a new property
> + *	-FDT_ERR_TRUNCATED, standard meanings
> + */
> +int fdt_setprop_reg(void *fdt, int nodeoffset, const char *name,
> +					       u64 addr, u64 size);
> +
>  #endif /* _INCLUDE_LIBFDT_H_ */
> diff --git a/lib/Makefile b/lib/Makefile
> index db06d1237898..2a96cb05e15d 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -205,7 +205,7 @@ KASAN_SANITIZE_stackdepot.o := n
>  KCOV_INSTRUMENT_stackdepot.o := n
>  
>  libfdt_files = fdt.o fdt_ro.o fdt_wip.o fdt_rw.o fdt_sw.o fdt_strerror.o \
> -	       fdt_empty_tree.o
> +	       fdt_empty_tree.o fdt_addresses.o
>  $(foreach file, $(libfdt_files), \
>  	$(eval CFLAGS_$(file) = -I$(src)/../scripts/dtc/libfdt))
>  lib-$(CONFIG_LIBFDT) += $(libfdt_files)
> diff --git a/lib/fdt_addresses.c b/lib/fdt_addresses.c
> new file mode 100644
> index 000000000000..97ddd5a5cc10
> --- /dev/null
> +++ b/lib/fdt_addresses.c
> @@ -0,0 +1,56 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/libfdt_env.h>
> +#include <linux/types.h>
> +#include "../scripts/dtc/libfdt/fdt_addresses.c"
> +
> +/*
> + * helper functions for arm64 kexec
> + * Those functions may be merged into libfdt in the future.
> + */
> +
> +/* This function assumes that cells is 1 or 2 */
> +static void cpu64_to_fdt_cells(void *buf, u64 val64, int cells)
> +{
> +	__be32 val32;
> +
> +	while (cells) {
> +		val32 = cpu_to_fdt32(val64 >> (32 * (--cells)));
> +		memcpy(buf, &val32, sizeof(val32));
> +		buf += sizeof(val32);
> +	}
> +}
> +
> +int fdt_setprop_reg(void *fdt, int nodeoffset, const char *name,
> +						u64 addr, u64 size)
> +{
> +	int addr_cells, size_cells;
> +	char buf[sizeof(__be32) * 2 * 2];
> +		/* assume dt_root_[addr|size]_cells <= 2 */
> +	void *prop;
> +	size_t buf_size;
> +
> +	addr_cells = fdt_address_cells(fdt, 0);
> +	if (addr_cells < 0)
> +		return addr_cells;
> +	size_cells = fdt_size_cells(fdt, 0);
> +	if (size_cells < 0)
> +		return size_cells;
> +
> +	/* if *_cells >= 2, cells can hold 64-bit values anyway */
> +	if ((addr_cells == 1) && ((addr > U32_MAX) ||
> +				  ((addr + size) > U32_MAX)))
> +		return -FDT_ERR_BADVALUE;
> +
> +	if ((size_cells == 1) && (size > U32_MAX))
> +		return -FDT_ERR_BADVALUE;
> +
> +	buf_size = (addr_cells + size_cells) * sizeof(u32);
> +	prop = buf;
> +
> +	cpu64_to_fdt_cells(prop, addr, addr_cells);
> +	prop += addr_cells * sizeof(u32);
> +
> +	cpu64_to_fdt_cells(prop, size, size_cells);
> +
> +	return fdt_setprop(fdt, nodeoffset, name, buf, buf_size);
> +}
> -- 
> 2.19.0
>