[PATCH v2] dt: add of_alias_scan and of_alias_get_id
Shawn Guo
shawn.guo at freescale.com
Sat Jul 16 02:39:32 EDT 2011
On Fri, Jul 15, 2011 at 12:37:27PM -0600, Grant Likely wrote:
> From: Shawn Guo <shawn.guo at linaro.org>
>
> 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.
>
> Signed-off-by: Shawn Guo <shawn.guo at linaro.org>
> [grant.likey: add locking and rework parse loop]
> Signed-off-by: Grant Likely <grant.likely at secretlab.ca>
> ---
>
> Hi Shawn,
>
> I've reworked as discussed on the ML. Please test and let me know if
> it still works for you.
>
Grant, please see comments below.
> g.
>
> drivers/of/base.c | 130 ++++++++++++++++++++++++++++++++++++++++++++++++
> drivers/of/fdt.c | 4 +
> include/linux/of.h | 8 +++
> include/linux/of_fdt.h | 1
> 4 files changed, 141 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index b8b65fd..6d9adc6 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -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.
> @@ -980,3 +1005,108 @@ 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->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);
> +}
We need to do "ap->np = np;" in this function, otherwise the match of
(np == app->np) in function of_alias_get_id() will always fail.
Nit: I initially name pointer (struct alias_prop *) as 'app', while
the codes you add name it as 'ap'. You may want to get them consistent.
> +
> +/**
> + * 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
There is an extra "the". I did this :)
> + * number of alias_prop found, or error code in error case.
> + */
> +__init void of_alias_scan(void)
> +{
> + struct property *pp;
> +
> + 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 */
/*
* bla
*/
> + while (isdigit(*(end-1)) && end > start)
> + end--;
> + len = end - start;
> + id = strlen(end) ? simple_strtoul(end, NULL, 10) : -1;
> +
> + /* Allocate an alias_prop with enough space for the stem */
> + ap = early_init_dt_alloc_memory_arch(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.
> + * If not, dynamically creates one in the lookup table and returns it,
> + * or returns error code if fail to create.
> + */
> +int of_alias_get_id(struct device_node *np, const char *stem)
> +{
> + struct alias_prop *app;
> + int id = 0;
> + bool found = false;
> +
> + mutex_lock(&of_aliases_mutex);
> + list_for_each_entry(app, &aliases_lookup, link) {
> + if (strcmp(app->stem, stem) != 0)
> + continue;
> +
> + if (np == app->np) {
> + found = true;
> + id = app->id;
> + break;
> + }
> +
> + if (id <= app->id)
> + id = app->id + 1;
> + }
> +
> + /* If an id is not found, then allocate a new one */
> + if (!found) {
> + app = kzalloc(sizeof(*app) + strlen(stem) + 1, 4);
> + if (!app) {
> + id = -ENODEV;
> + goto out;
> + }
> + of_alias_add(app, np, id, stem, strlen(stem));
> + }
> +
> + out:
> + mutex_unlock(&of_aliases_mutex);
> +
> + return id;
> +}
> +EXPORT_SYMBOL_GPL(of_alias_get_id);
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 65200af..13d6d3a 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -707,10 +707,12 @@ 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 */
> + /* Get pointer to "/chosen" and "/aliasas" nodes for use everywhere */
> of_chosen = of_find_node_by_path("/chosen");
> if (of_chosen == NULL)
> of_chosen = of_find_node_by_path("/chosen at 0");
> + of_aliases = of_find_node_by_path("/aliases");
> + of_alias_scan();
> }
>
> #endif /* CONFIG_OF_EARLY_FLATTREE */
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 4fc4c1b..e334c11 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -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)
> @@ -205,6 +206,9 @@ 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(
> @@ -217,6 +221,10 @@ 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 *early_init_dt_alloc_memory_arch(u64 size, u64 align);
> +extern void of_alias_scan(void);
> +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);
> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
> index c84d900..b74b74f 100644
> --- a/include/linux/of_fdt.h
> +++ b/include/linux/of_fdt.h
> @@ -97,7 +97,6 @@ extern void early_init_dt_check_for_initrd(unsigned long node);
> extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
> int depth, void *data);
> extern void early_init_dt_add_memory_arch(u64 base, u64 size);
> -extern void * early_init_dt_alloc_memory_arch(u64 size, u64 align);
> extern u64 dt_mem_next_cell(int s, __be32 **cellp);
>
> /*
>
> _______________________________________________
> devicetree-discuss mailing list
> devicetree-discuss at lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/devicetree-discuss
>
--
Regards,
Shawn
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