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Message-Id: <20120320163504.628033E2834@localhost>
Date: Tue, 20 Mar 2012 16:35:04 +0000
From: Grant Likely <grant.likely@...retlab.ca>
To: Stephen Warren <swarren@...dotorg.org>,
Linus Walleij <linus.walleij@...aro.org>,
Rob Herring <rob.herring@...xeda.com>
Cc: Linus Walleij <linus.walleij@...ricsson.com>, B29396@...escale.com,
s.hauer@...gutronix.de, dongas86@...il.com, shawn.guo@...aro.org,
thomas.abraham@...aro.org, tony@...mide.com,
linux-kernel@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
linux-tegra@...r.kernel.org, Stephen Warren <swarren@...dotorg.org>
Subject: Re: [PATCH 1/8] dt: add property iteration helpers
On Fri, 16 Mar 2012 14:54:22 -0600, Stephen Warren <swarren@...dotorg.org> wrote:
> This patch adds macros for_each_u32_property_value and
> for_each_string_property_value, which iterate over an array of values
> within a device-tree property. Usage is for example:
>
> struct of_iter_string_prop iter;
> for_each_string_property_value(iter, np, "pins")
> printk("Got value %s\n", iter.value);
>
> Signed-off-by: Stephen Warren <swarren@...dotorg.org>
Remind me about this one after the merge window.
That said, I'm not very happy about the state of dt property parsing
because a lot of code needs to be written to do a very simple thing.
I've got a prototype patch I'm working on which allows a parsing
'spec' to be passed into an "of_parse()" function that batch-decodes a
set of values and returns a single error code. That should simplify a
lot of things. That function might be a better solution if I pull in
parsing of multiple strings.
g.
> ---
> include/linux/of_iter_prop.h | 139 ++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 139 insertions(+), 0 deletions(-)
> create mode 100644 include/linux/of_iter_prop.h
>
> diff --git a/include/linux/of_iter_prop.h b/include/linux/of_iter_prop.h
> new file mode 100644
> index 0000000..57e9e6a
> --- /dev/null
> +++ b/include/linux/of_iter_prop.h
> @@ -0,0 +1,139 @@
> +/*
> + * Copyright (c) 2011-2012 NVIDIA CORPORATION. All rights reserved.
> + *
> + * Iterate over properties that store arrays.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +#ifndef __OF_ITER_PROP_H__
> +#define __OF_ITER_PROP_H__
> +
> +#include <linux/of.h>
> +
> +#ifdef CONFIG_OF
> +struct of_iter_u32_prop {
> + const struct property *prop;
> + int len;
> + const __be32 *pvalue;
> + u32 value;
> +};
> +
> +static inline void of_iter_u32_next(struct of_iter_u32_prop *iter)
> +{
> + if (!iter->len)
> + return;
> +
> + iter->len--;
> + if (iter->len)
> + iter->value = be32_to_cpup(iter->pvalue++);
> +}
> +
> +static inline void of_iter_u32_init(struct of_iter_u32_prop *iter,
> + const struct device_node *np,
> + const char *name)
> +{
> + iter->prop = of_find_property(np, name, &iter->len);
> + if (!iter->prop) {
> + iter->len = 0;
> + return;
> + }
> +
> + iter->pvalue = iter->prop->value;
> + if (!iter->pvalue) {
> + iter->len = 0;
> + return;
> + }
> +
> + iter->len /= sizeof(*iter->pvalue);
> +
> + if (iter->len)
> + iter->value = be32_to_cpup(iter->pvalue++);
> +}
> +
> +static inline bool of_iter_u32_test(struct of_iter_u32_prop *iter)
> +{
> + return iter->len > 0;
> +}
> +
> +#define for_each_u32_property_value(iter, np, prop_name) \
> + for (of_iter_u32_init(&iter, np, prop_name); \
> + of_iter_u32_test(&iter); \
> + of_iter_u32_next(&iter))
> +
> +struct of_iter_string_prop {
> + const struct property *prop;
> + int len;
> + const char *value;
> + const char *after;
> +};
> +
> +static inline void of_iter_string_init(struct of_iter_string_prop *iter,
> + const struct device_node *np,
> + const char *name)
> +{
> + iter->prop = of_find_property(np, name, &iter->len);
> + if (!iter->prop) {
> + iter->value = NULL;
> + return;
> + }
> +
> + iter->value = iter->prop->value;
> + if (!iter->value)
> + return;
> +
> + iter->after = iter->value + iter->len;
> +}
> +
> +static inline bool of_iter_string_test(struct of_iter_string_prop *iter)
> +{
> + if (!iter->value)
> + return false;
> +
> + return iter->value < iter->after;
> +}
> +
> +static inline void of_iter_string_next(struct of_iter_string_prop *iter)
> +{
> + int len;
> +
> + if (!iter->value)
> + return;
> +
> + len = strnlen(iter->value, iter->len);
> + iter->len -= len + 1;
> + iter->value += len + 1;
> +}
> +
> +#define for_each_string_property_value(iter, np, prop_name) \
> + for (of_iter_string_init(&iter, np, prop_name); \
> + of_iter_string_test(&iter); \
> + of_iter_string_next(&iter))
> +
> +#else
> +struct of_iter_u32_prop {
> + u32 value;
> +};
> +
> +#define for_each_u32_property_value(iter, np, prop_name) \
> + while (0)
> +
> +struct of_iter_string_prop {
> + const char *value;
> +};
> +
> +#define for_each_string_property_value(iter, np, prop_name) \
> + while (0)
> +
> +#endif /* CONFIG_OF */
> +
> +#endif /* __OF_ITER_PROP_H__ */
> --
> 1.7.0.4
>
--
Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies,Ltd.
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