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Commit 611cad72 authored by Shawn Guo's avatar Shawn Guo Committed by Grant Likely
Browse files

dt: add of_alias_scan and of_alias_get_id 



The patch adds function of_alias_scan to populate a global lookup
table with the properties of 'aliases' node and function
of_alias_get_id for drivers to find alias id from the lookup table.

v3: Split out automatic addition of aliases on id lookup so that it can be
    debated separately from the core functionality.
v2: - Add of_chosen/of_aliases populating and of_alias_scan() invocation
    for OF_PROMTREE.
    - Add locking
    - rework parse loop

Signed-off-by: default avatarShawn Guo <shawn.guo@linaro.org>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent a81dd364

drivers/of/base.c

+121 −0
Original line number Diff line number Diff line
@@ -17,14 +17,39 @@ 
 *      as published by the Free Software Foundation; either version

 *      2 of the License, or (at your option) any later version.

 */

#include <linux/ctype.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/spinlock.h>

#include <linux/slab.h>

#include <linux/proc_fs.h>



/**

 * struct alias_prop - Alias property in 'aliases' node

 * @link:	List node to link the structure in aliases_lookup list

 * @alias:	Alias property name

 * @np:		Pointer to device_node that the alias stands for

 * @id:		Index value from end of alias name

 * @stem:	Alias string without the index

 *

 * The structure represents one alias property of 'aliases' node as

 * an entry in aliases_lookup list.

 */

struct alias_prop {

	struct list_head link;

	const char *alias;

	struct device_node *np;

	int id;

	char stem[0];

};



static LIST_HEAD(aliases_lookup);



struct device_node *allnodes;

struct device_node *of_chosen;

struct device_node *of_aliases;



static DEFINE_MUTEX(of_aliases_mutex);



/* use when traversing tree through the allnext, child, sibling,

 * or parent members of struct device_node.
@@ -988,3 +1013,99 @@ void of_detach_node(struct device_node *np) 
}

#endif /* defined(CONFIG_OF_DYNAMIC) */



static void of_alias_add(struct alias_prop *ap, struct device_node *np,

			 int id, const char *stem, int stem_len)

{

	ap->np = np;

	ap->id = id;

	strncpy(ap->stem, stem, stem_len);

	ap->stem[stem_len] = 0;

	list_add_tail(&ap->link, &aliases_lookup);

	pr_debug("adding DT alias:%s: stem=%s id=%i node=%s\n",

		 ap->alias, ap->stem, ap->id, np ? np->full_name : NULL);

}



/**

 * of_alias_scan - Scan all properties of 'aliases' node

 *

 * The function scans all the properties of 'aliases' node and populate

 * the the global lookup table with the properties.  It returns the

 * number of alias_prop found, or error code in error case.

 *

 * @dt_alloc:	An allocator that provides a virtual address to memory

 *		for the resulting tree

 */

void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))

{

	struct property *pp;



	of_chosen = of_find_node_by_path("/chosen");

	if (of_chosen == NULL)

		of_chosen = of_find_node_by_path("/chosen@0");

	of_aliases = of_find_node_by_path("/aliases");

	if (!of_aliases)

		return;



	for_each_property(pp, of_aliases->properties) {

		const char *start = pp->name;

		const char *end = start + strlen(start);

		struct device_node *np;

		struct alias_prop *ap;

		int id, len;



		/* Skip those we do not want to proceed */

		if (!strcmp(pp->name, "name") ||

		    !strcmp(pp->name, "phandle") ||

		    !strcmp(pp->name, "linux,phandle"))

			continue;



		np = of_find_node_by_path(pp->value);

		if (!np)

			continue;



		/* walk the alias backwards to extract the id and work out

		 * the 'stem' string */

		while (isdigit(*(end-1)) && end > start)

			end--;

		len = end - start;



		if (kstrtoint(end, 10, &id) < 0)

			continue;



		/* Allocate an alias_prop with enough space for the stem */

		ap = dt_alloc(sizeof(*ap) + len + 1, 4);

		if (!ap)

			continue;

		ap->alias = start;

		of_alias_add(ap, np, id, start, len);

	}

}



/**

 * of_alias_get_id - Get alias id for the given device_node

 * @np:		Pointer to the given device_node

 * @stem:	Alias stem of the given device_node

 *

 * The function travels the lookup table to get alias id for the given

 * device_node and alias stem.  It returns the alias id if find it.

 */

int of_alias_get_id(struct device_node *np, const char *stem)

{

	struct alias_prop *app;

	int id = -ENODEV;



	mutex_lock(&of_aliases_mutex);

	list_for_each_entry(app, &aliases_lookup, link) {

		if (strcmp(app->stem, stem) != 0)

			continue;



		if (np == app->np) {

			id = app->id;

			break;

		}

	}

	mutex_unlock(&of_aliases_mutex);



	return id;

}

EXPORT_SYMBOL_GPL(of_alias_get_id);

drivers/of/fdt.c

+2 −4
Original line number Diff line number Diff line
@@ -707,10 +707,8 @@ void __init unflatten_device_tree(void) 
	__unflatten_device_tree(initial_boot_params, &allnodes,

				early_init_dt_alloc_memory_arch);



	/* Get pointer to OF "/chosen" node for use everywhere */

	of_chosen = of_find_node_by_path("/chosen");

	if (of_chosen == NULL)

		of_chosen = of_find_node_by_path("/chosen@0");

	/* Get pointer to "/chosen" and "/aliasas" nodes for use everywhere */

	of_alias_scan(early_init_dt_alloc_memory_arch);

}



#endif /* CONFIG_OF_EARLY_FLATTREE */

drivers/of/pdt.c

+8 −0
Original line number Diff line number Diff line
@@ -229,6 +229,11 @@ static struct device_node * __init of_pdt_build_tree(struct device_node *parent, 
	return ret;

}



static void *kernel_tree_alloc(u64 size, u64 align)

{

	return prom_early_alloc(size);

}



void __init of_pdt_build_devicetree(phandle root_node, struct of_pdt_ops *ops)

{

	struct device_node **nextp;
@@ -245,4 +250,7 @@ void __init of_pdt_build_devicetree(phandle root_node, struct of_pdt_ops *ops) 
	nextp = &allnodes->allnext;

	allnodes->child = of_pdt_build_tree(allnodes,

			of_pdt_prom_ops->getchild(allnodes->phandle), &nextp);



	/* Get pointer to "/chosen" and "/aliasas" nodes for use everywhere */

	of_alias_scan(kernel_tree_alloc);

}

include/linux/of.h

+7 −0
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ struct device_node { 
/* Pointer for first entry in chain of all nodes. */

extern struct device_node *allnodes;

extern struct device_node *of_chosen;

extern struct device_node *of_aliases;

extern rwlock_t devtree_lock;



static inline bool of_have_populated_dt(void)
@@ -209,6 +210,9 @@ extern int of_device_is_available(const struct device_node *device); 
extern const void *of_get_property(const struct device_node *node,

				const char *name,

				int *lenp);

#define for_each_property(pp, properties) \

	for (pp = properties; pp != NULL; pp = pp->next)



extern int of_n_addr_cells(struct device_node *np);

extern int of_n_size_cells(struct device_node *np);

extern const struct of_device_id *of_match_node(
@@ -221,6 +225,9 @@ extern int of_parse_phandles_with_args(struct device_node *np, 
	const char *list_name, const char *cells_name, int index,

	struct device_node **out_node, const void **out_args);



extern void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align));

extern int of_alias_get_id(struct device_node *np, const char *stem);



extern int of_machine_is_compatible(const char *compat);



extern int prom_add_property(struct device_node* np, struct property* prop);