Re: [PATCH V7 1/2] mtd: partitions: add of_match_table parser matching

[Boris Brezillon <boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>]

On Thu,  4 Jan 2018 08:05:33 +0100
Rafał Miłecki <zajec5-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> From: Brian Norris <computersforpeace-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> 
> Partition parsers can now provide an of_match_table to enable
> flash<-->parser matching via device tree as documented in the
> mtd/partition.txt.
> 
> It works by looking for a matching parser for every string in the
> "compatibility" property (starting with the most specific one).
> 
> This support is currently limited to built-in parsers as it uses
> request_module() and friends. This should be sufficient for most cases
> though as compiling parsers as modules isn't a common choice.
> 

Applied both patches.

Thanks,

Boris

> Signed-off-by: Brian Norris <computersforpeace-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Signed-off-by: Rafał Miłecki <rafal-g1n6cQUeyibVItvQsEIGlw@public.gmane.org>
> ---
> This is based on Brian's patches:
> [RFC PATCH 4/7] mtd: add of_match_mtd_parser() and of_mtd_match_mtd_parser() helpers
> [RFC PATCH 6/7] RFC: mtd: partitions: enable of_match_table matching
> 
> V1: Put helpers in mtdpart.c instead of drivers/of/of_mtd.c
>     Merge helpers into a single of_mtd_match_mtd_parser
> V3: Add a simple comment to note we will need the best match in the future
> V4: Rework new functions to pick parser with the best match
>     Move new code in parse_mtd_partitions up so it has precedence over flash
>     driver defaults and MTD defaults
> V5: Rework matching code to start checking with the most specific string in the
>     "compatibility" property.
> V6: Initialize "ret" variable in mtd_part_get_parser_by_cp to NULL
> V7: Rename function "mtd_part_get_parser_by_cp" to use "_compatible_"
>     Rename "cp" variable to "compat"
>     Drop unneeded if (np) check from the parse_mtd_partitions
> ---
>  drivers/mtd/mtdpart.c          | 59 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mtd/partitions.h |  1 +
>  2 files changed, 60 insertions(+)
> 
> diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
> index be088bccd593..76e12fb81563 100644
> --- a/drivers/mtd/mtdpart.c
> +++ b/drivers/mtd/mtdpart.c
> @@ -30,6 +30,7 @@
>  #include <linux/mtd/mtd.h>
>  #include <linux/mtd/partitions.h>
>  #include <linux/err.h>
> +#include <linux/of.h>
>  
>  #include "mtdcore.h"
>  
> @@ -880,6 +881,45 @@ static int mtd_part_do_parse(struct mtd_part_parser *parser,
>  }
>  
>  /**
> + * mtd_part_get_compatible_parser - find MTD parser by a compatible string
> + *
> + * @compat: compatible string describing partitions in a device tree
> + *
> + * MTD parsers can specify supported partitions by providing a table of
> + * compatibility strings. This function finds a parser that advertises support
> + * for a passed value of "compatible".
> + */
> +static struct mtd_part_parser *mtd_part_get_compatible_parser(const char *compat)
> +{
> +	struct mtd_part_parser *p, *ret = NULL;
> +
> +	spin_lock(&part_parser_lock);
> +
> +	list_for_each_entry(p, &part_parsers, list) {
> +		const struct of_device_id *matches;
> +
> +		matches = p->of_match_table;
> +		if (!matches)
> +			continue;
> +
> +		for (; matches->compatible[0]; matches++) {
> +			if (!strcmp(matches->compatible, compat) &&
> +			    try_module_get(p->owner)) {
> +				ret = p;
> +				break;
> +			}
> +		}
> +
> +		if (ret)
> +			break;
> +	}
> +
> +	spin_unlock(&part_parser_lock);
> +
> +	return ret;
> +}
> +
> +/**
>   * parse_mtd_partitions - parse MTD partitions
>   * @master: the master partition (describes whole MTD device)
>   * @types: names of partition parsers to try or %NULL
> @@ -905,8 +945,27 @@ int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
>  			 struct mtd_part_parser_data *data)
>  {
>  	struct mtd_part_parser *parser;
> +	struct device_node *np;
> +	struct property *prop;
> +	const char *compat;
>  	int ret, err = 0;
>  
> +	np = of_get_child_by_name(mtd_get_of_node(master), "partitions");
> +	of_property_for_each_string(np, "compatible", prop, compat) {
> +		parser = mtd_part_get_compatible_parser(compat);
> +		if (!parser)
> +			continue;
> +		ret = mtd_part_do_parse(parser, master, pparts, data);
> +		if (ret > 0) {
> +			of_node_put(np);
> +			return 0;
> +		}
> +		mtd_part_parser_put(parser);
> +		if (ret < 0 && !err)
> +			err = ret;
> +	}
> +	of_node_put(np);
> +
>  	if (!types)
>  		types = default_mtd_part_types;
>  
> diff --git a/include/linux/mtd/partitions.h b/include/linux/mtd/partitions.h
> index c4beb70dacbd..11cb0c50cd84 100644
> --- a/include/linux/mtd/partitions.h
> +++ b/include/linux/mtd/partitions.h
> @@ -77,6 +77,7 @@ struct mtd_part_parser {
>  	struct list_head list;
>  	struct module *owner;
>  	const char *name;
> +	const struct of_device_id *of_match_table;
>  	int (*parse_fn)(struct mtd_info *, const struct mtd_partition **,
>  			struct mtd_part_parser_data *);
>  	void (*cleanup)(const struct mtd_partition *pparts, int nr_parts);

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