Re: [PATCH v2] libfdt: add helpers to read address and size from reg

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Mon, Dec 05, 2016 at 05:11:30PM -0600, Benjamin Fair wrote:
> This patch extends the capability of libfdt to parse the contents of device
> trees in a similar manner to fdt_address_cells and fdt_size_cells.
> 
> It adds helper functions which read the address and size of a device from
> the reg property and performs basic sanity checks. Some functions also
> parse the values into integers in the host endianness.
> 
> The functions do not perform translation to a physical address using the
> ranges properties of parents, but this enhancement may be added as a
> separate function in the future.
> 
> Signed-off-by: Benjamin Fair <b-fair-l0cyMroinI0@public.gmane.org>
> ---
> 
> Changes since v1:
> 
>   * Split functions into smaller pieces
>     -> Also added wrapper functions to perform the full set of actions
>   * Changed types of addresses and sizes to uint64_t
>   * Removed unneeded constants
>   * Renamed and exported fdt_read_integer()
> 
>  libfdt/fdt_addresses.c | 118 ++++++++++++++++++++++++++++++++++++++++
>  libfdt/libfdt.h        | 145 +++++++++++++++++++++++++++++++++++++++++++++++++
>  libfdt/version.lds     |   5 ++
>  tests/.gitignore       |   1 +
>  tests/Makefile.tests   |   2 +-
>  tests/addr_size.c      | 130 ++++++++++++++++++++++++++++++++++++++++++++
>  tests/addresses.dts    |  11 ++++
>  tests/run_tests.sh     |   1 +
>  8 files changed, 412 insertions(+), 1 deletion(-)
>  create mode 100644 tests/addr_size.c
> 
> diff --git a/libfdt/fdt_addresses.c b/libfdt/fdt_addresses.c
> index eff4dbc..752f9ef 100644
> --- a/libfdt/fdt_addresses.c
> +++ b/libfdt/fdt_addresses.c
> @@ -94,3 +94,121 @@ int fdt_size_cells(const void *fdt, int nodeoffset)
>  
>  	return val;
>  }
> +
> +int fdt_read_integer(const fdt32_t *cells, int n, uint64_t *out)

I like this.

> +{
> +	int i;
> +
> +	/* Make sure the result will fit */
> +	if (n > sizeof(*out) / sizeof(*cells))
> +		return -FDT_ERR_BADNCELLS;
> +
> +	for (*out = 0, i = 0; i < n; i++) {
> +		*out <<= sizeof(*cells) * 8;
> +		*out |= fdt32_to_cpu(cells[i]);
> +	}
> +
> +	return 0;
> +}
> +
> +int fdt_addr_size(const void *fdt, int nodeoffset, int idx,
> +		  const fdt32_t **addrp, const fdt32_t **sizep)

> +{
> +	int parent;
> +	int ac, sc;
> +
> +	parent = fdt_parent_offset(fdt, nodeoffset);
> +	if (parent < 0)
> +		return parent;
> +
> +	ac = fdt_address_cells(fdt, parent);
> +	if (ac < 0)
> +		return ac;
> +
> +	sc = fdt_size_cells(fdt, parent);
> +	if (sc < 0)
> +		return sc;
> +
> +	return fdt_addr_size_cellcount(fdt, nodeoffset, idx,
> +				       ac, addrp, sc, sizep);
> +}
> +
> +int fdt_addr_size_cellcount(const void *fdt, int nodeoffset, int idx,
> +			    int ac, const fdt32_t **addrp,
> +			    int sc, const fdt32_t **sizep)

I think this is a reasonable interface, but I don't like the name.
It's just called "fdt_addr_size" but addr and size of what?  There are
plenty of things besides 'reg' that encode addresses and sizes.

I'd suggest fdt_reg_cellcount() for this.  Then
fdt_reg_cellcount_int() for the version that converts to integers
(when possible).

I'd then suggest an intermediate interface fdt_reg() and fdt_reg_int()
which takes a parent/bus node offset instead of explicit
#address-cells and #size-cells values.

Then, say, fdt_reg_simple() and fdt_reg_simple_int() for the expensive
versions using fdt_parent_offset().

As Simon Glass says, also put a note about the expense of the last in
libfdt.h

> +{
> +	int reg_stride;
> +	int res;
> +	const fdt32_t *reg;
> +
> +	reg = fdt_getprop(fdt, nodeoffset, "reg", &res);
> +	if (res < 0)
> +		return res;
> +
> +	reg_stride = ac + sc;
> +	/*
> +	 * res is the number of bytes read and must be an even multiple of the
> +	 * sum of ac and sc.
> +	 */
> +	if ((res % (reg_stride * sizeof(fdt32_t))) != 0)
> +		return -FDT_ERR_BADVALUE;
> +	/* Check that there are enough entries in reg */
> +	if (res < reg_stride * (idx + 1))
> +		return -FDT_ERR_BADVALUE;
> +
> +	if (addrp)
> +		*addrp = &reg[reg_stride * idx];
> +	if (sizep)
> +		*sizep = &reg[ac + reg_stride * idx];
> +
> +	return 0;
> +}
> +
> +int fdt_integer_addr_size(const void *fdt, int nodeoffset, int idx,
> +			  uint64_t *addrp, uint64_t *sizep)
> +{
> +	int parent;
> +	int ac, sc;
> +
> +	parent = fdt_parent_offset(fdt, nodeoffset);
> +	if (parent < 0)
> +		return parent;
> +
> +	ac = fdt_address_cells(fdt, parent);
> +	if (ac < 0)
> +		return ac;
> +
> +	sc = fdt_size_cells(fdt, parent);
> +	if (sc < 0)
> +		return sc;
> +
> +	return fdt_integer_addr_size_cellcount(fdt, nodeoffset, idx,
> +					       ac, addrp, sc, sizep);
> +}
> +
> +int fdt_integer_addr_size_cellcount(const void *fdt, int nodeoffset, int idx,
> +				    int ac, uint64_t *addr,
> +				    int sc, uint64_t *size)
> +{
> +	const fdt32_t *fdt_addr, *fdt_size;
> +	int res;
> +
> +	res = fdt_addr_size_cellcount(fdt, nodeoffset, idx,
> +				      ac, &fdt_addr, sc, &fdt_size);
> +	if (res < 0)
> +		return res;
> +
> +	if (addr) {
> +		res = fdt_read_integer(fdt_addr, ac, addr);
> +		if (res < 0)
> +			return res;
> +	}
> +
> +	if (size) {
> +		res = fdt_read_integer(fdt_size, sc, size);
> +		if (res < 0)
> +			return res;
> +	}
> +
> +	return 0;
> +}
> diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> index c69e918..9eaf790 100644
> --- a/libfdt/libfdt.h
> +++ b/libfdt/libfdt.h
> @@ -1085,6 +1085,151 @@ int fdt_address_cells(const void *fdt, int nodeoffset);
>   */
>  int fdt_size_cells(const void *fdt, int nodeoffset);
>  
> +/**
> + * fdt_read_integer - parse an array of cells into an integer
> + * @cells: pointer to an array of cells
> + * @n: number of cells to parse
> + * @out: pointer to where the value should be stored (will be overwritten)
> + *
> + * Given an array of cells from a property, convert the first n of them into a
> + * single integer in the host's endianness.
> + *
> + * returns:
> + *	0, on success
> + *	-FDT_ERR_BADNCELLS, if n is greater than 2
> + */
> +int fdt_read_integer(const fdt32_t *cells, int n, uint64_t *out);
> +
> +/**
> + * fdt_addr_size - get pointers to the address and/or size values from the reg
> + *                 property of a device node.
> + * @fdt: pointer to the device tree blob
> + * @nodeoffset: offset of the node to find the address and/or size from
> + * @idx: which address/size pair to read
> + * @addrp: pointer to where address pointer will be stored (will be
> + *         overwritten) or NULL
> + * @sizep: pointer to where size pointer will be stored (will be overwritten)
> + *         or NULL
> + *
> + * When the node has a valid reg property, returns pointers to the address
> + * and/or size values stored there. It does not parse the cell arrays into a
> + * single integer or covert them to host endianness.
> + *
> + * returns:
> + *	0, on success
> + *	-FDT_ERR_BADVALUE, if there is an unexpected number of entries in the
> + *		reg property
> + *	-FDT_ERR_NOTFOUND, if the node does not have a reg property
> + *	-FDT_ERR_BADNCELLS, if the number of address or size cells is invalid
> + *	-FDT_ERR_BADMAGIC,
> + *	-FDT_ERR_BADSTATE,
> + *	-FDT_ERR_BADSTRUCTURE,
> + *	-FDT_ERR_BADVERSION,
> + *	-FDT_ERR_TRUNCATED, standard meanings
> + */
> +int fdt_addr_size(const void *fdt, int nodeoffset, int idx,
> +		  const fdt32_t **addrp, const fdt32_t **sizep);
> +
> +/**
> + * fdt_addr_size_cellcount - get pointers to the address and/or size values
> + *                           from the reg property of a device node given the
> + *                           number of address and size cells.
> + * @fdt: pointer to the device tree blob
> + * @nodeoffset: offset of the node to find the address and/or size from
> + * @idx: which address/size pair to read
> + * @ac: number of address cells
> + * @addrp: pointer to where address pointer will be stored (will be
> + *         overwritten) or NULL
> + * @sc: number of size cells
> + * @sizep: pointer to where size pointer will be stored (will be overwritten)
> + *         or NULL
> + *
> + * When the node has a valid reg property, returns pointers to the address
> + * and/or size values stored there. It does not parse the cell arrays into a
> + * single integer or covert them to host endianness. This version uses values
> + * for #address-cells and #size-cells which are passed in as arguments, rather
> + * than reading them from the parent node. Therefore, this version is much
> + * faster if these values are already known.
> + *
> + * returns:
> + *	0, on success
> + *	-FDT_ERR_BADVALUE, if there is an unexpected number of entries in the
> + *		reg property
> + *	-FDT_ERR_NOTFOUND, if the node does not have a reg property
> + *	-FDT_ERR_BADMAGIC,
> + *	-FDT_ERR_BADSTATE,
> + *	-FDT_ERR_BADSTRUCTURE,
> + *	-FDT_ERR_BADVERSION,
> + *	-FDT_ERR_TRUNCATED, standard meanings
> + */
> +int fdt_addr_size_cellcount(const void *fdt, int nodeoffset, int idx,
> +			    int ac, const fdt32_t **addrp,
> +			    int sc, const fdt32_t **sizep);
> +
> +/**
> + * fdt_integer_addr_size - find address and/or size from the reg property of a
> + *                         device node and return them as integers.
> + * @fdt: pointer to the device tree blob
> + * @nodeoffset: offset of the node to find the address and/or size from
> + * @idx: which address/size pair to read
> + * @addrp: pointer to where address will be stored (will be overwritten) or NULL
> + * @sizep: pointer to where size will be stored (will be overwritten) or NULL
> + *
> + * When the node has a valid reg property, returns the address and/or size
> + * values stored there as integers in the host endianness. It does not perform
> + * any type of translation based on the parent bus(es).
> + *
> + * returns:
> + *	0, on success
> + *	-FDT_ERR_BADVALUE, if there is an unexpected number of entries in the
> + *		reg property
> + *	-FDT_ERR_NOTFOUND, if the node does not have a reg property
> + *	-FDT_ERR_BADNCELLS, if the number of address or size cells is invalid
> + *		or greater than 2 (which is the maximum currently supported)
> + *	-FDT_ERR_BADMAGIC,
> + *	-FDT_ERR_BADSTATE,
> + *	-FDT_ERR_BADSTRUCTURE,
> + *	-FDT_ERR_BADVERSION,
> + *	-FDT_ERR_TRUNCATED, standard meanings
> + */
> +int fdt_integer_addr_size(const void *fdt, int nodeoffset, int idx,
> +			  uint64_t *addrp, size_t *sizep);
> +
> +/**
> + * fdt_integer_addr_size_cellcount - find address and/or size from the reg
> + *                                   property of a device node and return them
> + *                                   as integers.
> + * @fdt: pointer to the device tree blob
> + * @nodeoffset: offset of the node to find the address and/or size from
> + * @idx: which address/size pair to read
> + * @ac: number of address cells
> + * @addrp: pointer to where address will be stored (will be overwritten) or NULL
> + * @sc: number of size cells
> + * @sizep: pointer to where size will be stored (will be overwritten) or NULL
> + *
> + * When the node has a valid reg property, returns the address and/or size
> + * values stored there as integers in the host endianness. It does not perform
> + * any type of translation based on the parent bus(es). This version uses
> + * values for #address-cells and #size-cells which are passed in as arguments,
> + * rather than reading them from the parent node. Therefore, this version is
> + * much faster if these values are already known.
> + *
> + * returns:
> + *	0, on success
> + *	-FDT_ERR_BADVALUE, if there is an unexpected number of entries in the
> + *		reg property
> + *	-FDT_ERR_NOTFOUND, if the node does not have a reg property
> + *	-FDT_ERR_BADNCELLS, if the number of address or size cells is invalid
> + *		or greater than 2 (which is the maximum currently supported)
> + *	-FDT_ERR_BADMAGIC,
> + *	-FDT_ERR_BADSTATE,
> + *	-FDT_ERR_BADSTRUCTURE,
> + *	-FDT_ERR_BADVERSION,
> + *	-FDT_ERR_TRUNCATED, standard meanings
> + */
> +int fdt_integer_addr_size_cellcount(const void *fdt, int nodeoffset, int idx,
> +				    int ac, uint64_t *addr,
> +				    int sc, uint64_t *size);
>  
>  /**********************************************************************/
>  /* Write-in-place functions                                           */
> diff --git a/libfdt/version.lds b/libfdt/version.lds
> index cff0358..0106f9d 100644
> --- a/libfdt/version.lds
> +++ b/libfdt/version.lds
> @@ -59,6 +59,11 @@ LIBFDT_1.2 {
>  		fdt_next_subnode;
>  		fdt_address_cells;
>  		fdt_size_cells;
> +		fdt_read_integer;
> +		fdt_addr_size;
> +		fdt_addr_size_cellcount;
> +		fdt_integer_addr_size;
> +		fdt_integer_addr_size_cellcount;
>  		fdt_stringlist_contains;
>  		fdt_resize;
>  		fdt_overlay_apply;
> diff --git a/tests/.gitignore b/tests/.gitignore
> index 354b565..9018414 100644
> --- a/tests/.gitignore
> +++ b/tests/.gitignore
> @@ -42,6 +42,7 @@ tmp.*
>  /path_offset
>  /path_offset_aliases
>  /phandle_format
> +/addr_size
>  /property_iterate
>  /propname_escapes
>  /references
> diff --git a/tests/Makefile.tests b/tests/Makefile.tests
> index eb039c5..c715421 100644
> --- a/tests/Makefile.tests
> +++ b/tests/Makefile.tests
> @@ -8,7 +8,7 @@ LIB_TESTS_L = get_mem_rsv \
>  	char_literal \
>  	sized_cells \
>  	notfound \
> -	addr_size_cells \
> +	addr_size_cells addr_size \
>  	stringlist \
>  	setprop_inplace nop_property nop_node \
>  	sw_tree1 \
> diff --git a/tests/addr_size.c b/tests/addr_size.c
> new file mode 100644
> index 0000000..4ee4c1b
> --- /dev/null
> +++ b/tests/addr_size.c
> @@ -0,0 +1,130 @@
> +/*
> + * libfdt - Flat Device Tree manipulation
> + *	Testcase for address and size handling
> + * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
> + *
> + * Based on addr_size_cells.c by David Gibson, <david-xT8FGy+AXnRB3Ne2BGzF6ryscVyMRj84@public.gmane.org.au>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU Lesser General Public License as published by
> + * the Free Software Foundation; either version 2.1 of the License, or (at
> + * your option) any later version.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
> + * whether express or implied; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + */
> +
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <stdint.h>
> +
> +#include <libfdt.h>
> +
> +#include "tests.h"
> +#include "testdata.h"
> +
> +static void check_node_integer(const void *fdt, const char *path, int idx,
> +			       uint64_t addr, uint64_t size)
> +{
> +	int offset, res;
> +	uint64_t xaddr, xsize;
> +
> +	offset = fdt_path_offset(fdt, path);
> +	if (offset < 0)
> +		FAIL("Couldn't find path %s", path);
> +
> +	res = fdt_integer_addr_size(fdt, offset, idx, &xaddr, &xsize);
> +	if (res < 0)
> +		FAIL("fdt_integer_addr_size gave error: %s", fdt_strerror(res));
> +
> +	if (xaddr != addr)
> +		FAIL("Physical address for %s is %lx instead of %lx\n", path,
> +		     xaddr, addr);
> +
> +	if (xsize != size)
> +		FAIL("Size for %s is %lx instead of %lx\n", path,
> +		     xsize, size);
> +}
> +
> +static void check_node(const void *fdt, const char *path, int idx,
> +		       uint64_t addr, uint64_t size)
> +{
> +	int offset, parent, res;
> +	int ac, sc;
> +	const fdt32_t *xaddr_fdt, *xsize_fdt;
> +	uint64_t xaddr, xsize;
> +
> +	offset = fdt_path_offset(fdt, path);
> +	if (offset < 0)
> +		FAIL("Couldn't find path %s", path);
> +
> +	parent = fdt_parent_offset(fdt, offset);
> +	if (parent < 0)
> +		FAIL("Couldn't get parent: %s", fdt_strerror(parent));
> +
> +	ac = fdt_address_cells(fdt, parent);
> +	if (ac < 0)
> +		FAIL("Couldn't read #address-cells: %s", fdt_strerror(ac));
> +
> +	sc = fdt_size_cells(fdt, parent);
> +	if (sc < 0)
> +		FAIL("Couldn't read #size-cells: %s", fdt_strerror(sc));
> +
> +	res = fdt_addr_size_cellcount(fdt, offset, idx, ac, &xaddr_fdt, sc,
> +				      &xsize_fdt);
> +	if (res < 0)
> +		FAIL("Couldn't find entries in reg: %s", fdt_strerror(res));
> +
> +	res = fdt_read_integer(xaddr_fdt, ac, &xaddr);
> +	if (res < 0)
> +		FAIL("Couldn't parse entries in reg: %s", fdt_strerror(res));
> +
> +	res = fdt_read_integer(xsize_fdt, sc, &xsize);
> +	if (res < 0)
> +		FAIL("Couldn't parse entries in reg: %s", fdt_strerror(res));
> +
> +	if (xaddr != addr)
> +		FAIL("Physical address for %s is %lx instead of %lx\n", path,
> +		     xaddr, addr);
> +
> +	if (xsize != size)
> +		FAIL("Size for %s is %lx instead of %lx\n", path,
> +		     xsize, size);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	void *fdt;
> +
> +	if (argc != 2)
> +		CONFIG("Usage: %s <dtb file>\n", argv[0]);
> +
> +	test_init(argc, argv);
> +	fdt = load_blob(argv[1]);
> +
> +	check_node(fdt, "/identity-bus@0/id-device@400", 0,
> +		   0x400, 0x100);
> +	check_node(fdt, "/simple-bus@1000000/sb-device@8000000800", 0,
> +		   0x8000000800, 0x200);
> +	check_node(fdt, "/identity-bus@0/id-device@400", 1,
> +		   0x400000000, 0x100000030);
> +	check_node(fdt, "/simple-bus@1000000/sb-device@8000000800", 1,
> +		   0x70000000, 0x700);
> +	check_node(fdt, "/simple-bus@1000000/sb-device@8000000800", 2,
> +		   0x1050000000, 0x20);
> +
> +	check_node_integer(fdt, "/identity-bus@0/id-device@400", 0,
> +			   0x400, 0x100);
> +	check_node_integer(fdt, "/simple-bus@1000000/sb-device@8000000800", 0,
> +			   0x8000000800, 0x200);
> +	check_node_integer(fdt, "/identity-bus@0/id-device@400", 1,
> +			   0x400000000, 0x100000030);
> +	check_node_integer(fdt, "/simple-bus@1000000/sb-device@8000000800", 1,
> +			   0x70000000, 0x700);
> +	check_node_integer(fdt, "/simple-bus@1000000/sb-device@8000000800", 2,
> +			   0x1050000000, 0x20);
> +	PASS();
> +}
> diff --git a/tests/addresses.dts b/tests/addresses.dts
> index a2faaf5..32c4379 100644
> --- a/tests/addresses.dts
> +++ b/tests/addresses.dts
> @@ -6,10 +6,21 @@
>  	#size-cells = <2>;
>  
>  	identity-bus@0 {
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		id-device@400 {
> +			reg = <0x0 0x00000400 0x0 0x00000100>,
> +			      <0x4 0x00000000 0x1 0x00000030>;
> +		};
>  	};
>  
>  	simple-bus@1000000 {
>  		#address-cells = <2>;
>  		#size-cells = <1>;
> +		sb-device@8000000800 {
> +			reg = <0x80 0x00000800 0x200>,
> +			      <0x00 0x70000000 0x700>,
> +			      <0x10 0x50000000 0x020>;
> +		};
>  	};
>  };
> diff --git a/tests/run_tests.sh b/tests/run_tests.sh
> index e4139dd..96aca48 100755
> --- a/tests/run_tests.sh
> +++ b/tests/run_tests.sh
> @@ -243,6 +243,7 @@ libfdt_tests () {
>  
>      run_dtc_test -I dts -O dtb -o addresses.test.dtb addresses.dts
>      run_test addr_size_cells addresses.test.dtb
> +    run_test addr_size addresses.test.dtb
>  
>      run_dtc_test -I dts -O dtb -o stringlist.test.dtb stringlist.dts
>      run_test stringlist stringlist.test.dtb

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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