On Sat, Jun 25, 2011 at 02:04:32AM +0800, Shawn Guo wrote:
> 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@xxxxxxxxxx>
> Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
Hey Shawn,
Comments below, but I've gone ahead and fixed them because I'm keen to
get this patch merged. I just wanted to let you know what I changed.
I'll post the modified version so you can test it.
> ---
> drivers/of/base.c | 181 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> drivers/of/fdt.c | 6 ++
> include/linux/of.h | 7 ++
> 3 files changed, 194 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 632ebae..89efd10 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -17,14 +17,38 @@
> * as published by the Free Software Foundation; either version
> * 2 of the License, or (at your option) any later version.
> */
> +#include <linux/bootmem.h>
> +#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
> + * @alias_id: Alias id decoded from alias
> + * @alias_stem: Alias stem name decoded from alias
> + *
> + * 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 alias_id;
> + char alias_stem[0];
> +};
> +
> +static LIST_HEAD(aliases_lookup);
> +
> struct device_node *allnodes;
> struct device_node *of_chosen;
> +struct device_node *of_aliases;
>
> /* use when traversing tree through the allnext, child, sibling,
> * or parent members of struct device_node.
> @@ -922,3 +946,160 @@ out_unlock:
> }
> #endif /* defined(CONFIG_OF_DYNAMIC) */
>
> +/*
> + * of_alias_find_available_id - Find an available id for the given device_node
Nit: kerneldoc format is "/**" to start the comment, and function
names should have '()' on it.
> + * @np: Pointer to the given device_node
> + * @stem: Alias stem of the given device_node
> + *
> + * The function travels the lookup table to find an available id for the
> + * given device_node with given alias stem. It returns the id found.
> + */
> +static int of_alias_find_available_id(struct device_node *np, const char *stem)
> +{
> + struct alias_prop *app;
> + int id = 0;
> +
> + while (1) {
> + bool used = false;
> + list_for_each_entry(app, &aliases_lookup, link) {
> + if (!strcmp(app->alias_stem, stem) &&
> + app->alias_id == id) {
> + used = true;
> + break;
> + }
> + }
> +
> + if (used)
> + id++;
> + else
> + return id;
> + }
> +}
I've simplified this somewhat to do the list_for_each_entry() only
once, and to bump up the id to +1 the largest entry:
list_for_each_entry(app, &aliases_lookup, link)
if ((strcmp(app->stem, stem) == 0) && id <= app->id)
id = app->id + 1;
.... actually, after looking further, I've rolled this code into the
of_alias_get_id() function.
> +
> +/**
> + * of_alias_lookup_add - Add alias into lookup table
> + * @alias: Alias name
> + * @id: Alias id
> + * @stem: Alias stem name
> + * @np: Pointer to device_node
> + *
> + * The function adds one alias into the lookup table and populate it
> + * with the info passed in. It returns 0 in sucess, or error code.
> + */
> +static int of_alias_lookup_add(char *alias, int id, const char *stem,
> + struct device_node *np)
> +{
> + struct alias_prop *app;
> + size_t sz = sizeof(*app) + strlen(stem) + 1;
> +
> + app = kzalloc(sz, GFP_KERNEL);
> + if (!app) {
> + /*
> + * It may fail due to being called by boot code,
> + * so try alloc_bootmem before return error.
> + */
> + app = alloc_bootmem(sz);
> + if (!app)
> + return -ENOMEM;
> + }
I'm not too fond of this since we *know* when this is going to be
called from early boot. So, instead, I've changed the code to use the
already existing dt_alloc functions as an argument to of_alias_lookup_add().
Also, alloc_bootmem() doesn't work on all platforms.
early_init_dt_alloc_memory_arch() needs to be used instead.
> +
> + app->np = np;
> + app->alias = alias;
> + app->alias_id = id;
> + strcpy(app->alias_stem, stem);
> + list_add_tail(&app->link, &aliases_lookup);
> +
> + return 0;
> +}
> +
> +/**
> + * of_alias_decode - Decode alias stem and id from alias name
> + * @alias: Alias name to be decoded
> + * @stem: Pointer used to return stem name
> + *
> + * The function decodes alias stem name and alias id from the given
> + * alias name. It returns stem name via parameter 'stem', and stem id
> + * via the return value. If no id is found in alias name, it returns 0
> + * as the default.
> + */
> +static int of_alias_decode(char *alias, char *stem)
> +{
> + int len = strlen(alias);
> + char *end = alias + len;
> +
> + while (isdigit(*--end))
> + len--;
Need to protect against len < 0
> +
> + strncpy(stem, alias, len);
> + stem[len] = '\0';
> +
> + return strlen(++end) ? simple_strtoul(end, NULL, 10) : 0;
> +}
> +
> +/**
> + * 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.
> + */
> +int of_alias_scan(void)
Changed to '__init void of_aliases_scan(void)'. There is no point in
returning an error code since it is never checked, and there is no
point in bailing on an error just in case it is a problem with only
one alias.
> +{
> + struct property *pp;
> + int ret, num = 0;
> +
> + if (!of_aliases)
> + return -ENODEV;
> +
> + for_each_property(pp, of_aliases->properties) {
> + char stem[32];
> + int id = of_alias_decode(pp->name, stem);
> +
> + /* Skip those we do not want to proceed */
> + if (!strcmp(pp->name, "name") ||
> + !strcmp(pp->name, "phandle") ||
> + !strcmp(pp->name, "linux,phandle"))
> + continue;
> +
> + ret = of_alias_lookup_add(pp->name, id, stem,
> + of_find_node_by_path(pp->value));
> + if (ret < 0)
> + return ret;
> + else
> + num++;
> + }
> +
> + return num;
> +}
> +
> +/**
> + * 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 = -1;
> +
> + list_for_each_entry(app, &aliases_lookup, link) {
> + if (np == app->np) {
> + id = app->alias_id;
> + break;
> + }
> + }
> +
> + if (id == -1) {
> + id = of_alias_find_available_id(np, stem);
> + if (of_alias_lookup_add(NULL, id, stem, np) < 0)
> + return -ENODEV;
> + }
> +
> + return id;
> +}
This whole function needs to be protected by a mutex.
> +EXPORT_SYMBOL_GPL(of_alias_get_id);
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 65200af..998dc63 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -711,6 +711,12 @@ void __init unflatten_device_tree(void)
> 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 == NULL)
> + of_aliases = of_find_node_by_path("/aliases@0");
I don't think the /aliases@0 variant is necessary. I've dropped it.
g.
> +
> + of_alias_scan();
> }
>
> #endif /* CONFIG_OF_EARLY_FLATTREE */
> diff --git a/include/linux/of.h b/include/linux/of.h
> index bfc0ed1..c35cc47 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)
> @@ -201,6 +202,9 @@ 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(
> @@ -213,6 +217,9 @@ 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 int 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);
> --
> 1.7.4.1
>
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
