Re: [PATCH v2] dt: add of_alias_scan and of_alias_get_id

[Shawn Guo]

On Mon, Aug 15, 2011 at 03:28:14PM +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>
> [grant.likey: add locking and rework parse loop]
> Signed-off-by: Grant Likely <grant.likely@xxxxxxxxxxxx>

Hi Grant,

Any comments on this patch?

Regards,
Shawn

> ---
> Changes since v1:
>  * Add of_chosen/of_aliases populating and of_alias_scan() invocation
>    for OF_PROMTREE (non-tested).
> 
>  drivers/of/base.c      |  136 ++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/of/fdt.c       |   12 +++--
>  drivers/of/pdt.c       |   12 ++++
>  include/linux/of.h     |    8 +++
>  include/linux/of_fdt.h |    1 -
>  5 files changed, 163 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 3ff22e3..5e6ce02 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.
> @@ -988,3 +1013,114 @@ 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;
> +
> +	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.
> + * 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..98b6fb1 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -404,6 +404,13 @@ static void __unflatten_device_tree(struct boot_param_header *blob,
>  			   be32_to_cpu(((__be32 *)mem)[size / 4]));
>  	*allnextp = NULL;
>  
> +	/* 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@0");
> +	of_aliases = of_find_node_by_path("/aliases");
> +	of_alias_scan(dt_alloc);
> +
>  	pr_debug(" <- unflatten_device_tree()\n");
>  }
>  
> @@ -706,11 +713,6 @@ 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");
>  }
>  
>  #endif /* CONFIG_OF_EARLY_FLATTREE */
> diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
> index 4d87b5d..686a4b3 100644
> --- a/drivers/of/pdt.c
> +++ b/drivers/of/pdt.c
> @@ -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 +250,11 @@ 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_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");
> +	of_alias_scan(kernel_tree_alloc);
>  }
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 9180dc5..4ea7d81 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)
> @@ -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 +225,10 @@ 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 * (*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);
> 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);
>  
>  /*
> -- 
> 1.7.4.1
> 
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