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: Shawn Guo <shawn.guo@linaro.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Shawn Guo 2011-08-15 15:28:14 +08:00 committed by Grant Likely
parent a81dd364de
commit 611cad7201
4 changed files with 138 additions and 4 deletions

View File

@ -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 @@ out_unlock:
}
#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);

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@ -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 */

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@ -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);
}

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@ -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);