[PATCH v2] of: Output devicetree alias names in uevent

[Grant Likely]

On Wed,  5 Dec 2012 23:49:25 -0800, Stepan Moskovchenko <stepanm at codeaurora.org> wrote:
> In some situations, userspace may want to resolve a
> device by function and logical number (ie, "serial0")
> rather than by the base address or full device path. Being
> able to resolve a device by alias frees userspace from the
> burden of otherwise having to maintain a mapping between
> device addresses and their logical assignments on each
> platform when multiple instances of the same hardware block
> are present in the system.
> 
> Although the uevent device attribute contains devicetree
> compatible information and the full device path, the uevent
> does not list the alises that may have been defined for the
> device.
> 
> Signed-off-by: Stepan Moskovchenko <stepanm at codeaurora.org>
> ---
> v2: Create of_private.h and move struct alias_prop there
>     Add alias uevent variables from of_device_uevent
>     Use app->alias instead of app->stem / app->id directly
>     Expose alias_lookup and of_alias_mutex
> 
>  drivers/of/base.c       |   23 +++--------------------
>  drivers/of/device.c     |   17 +++++++++++++++++
>  drivers/of/of_private.h |   33 +++++++++++++++++++++++++++++++++
>  3 files changed, 53 insertions(+), 20 deletions(-)
>  create mode 100644 drivers/of/of_private.h
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 5806449..715aef2 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -24,32 +24,15 @@
>  #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];
> -};
> +#include "of_private.h"
> 
> -static LIST_HEAD(aliases_lookup);
> +LIST_HEAD(aliases_lookup);
> 
>  struct device_node *allnodes;
>  struct device_node *of_chosen;
>  struct device_node *of_aliases;
> 
> -static DEFINE_MUTEX(of_aliases_mutex);
> +DEFINE_MUTEX(of_aliases_mutex);
> 
>  /* use when traversing tree through the allnext, child, sibling,
>   * or parent members of struct device_node.
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index 4c74e4f..b8d31db 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -8,6 +8,7 @@
>  #include <linux/slab.h>
> 
>  #include <asm/errno.h>
> +#include "of_private.h"
> 
>  /**
>   * of_match_device - Tell if a struct device matches an of_device_id list
> @@ -131,6 +132,7 @@ ssize_t of_device_get_modalias(struct device *dev, char *str, ssize_t len)
>  void of_device_uevent(struct device *dev, struct kobj_uevent_env *env)
>  {
>  	const char *compat;
> +	struct alias_prop *app;
>  	int seen = 0, cplen, sl;
> 
>  	if ((!dev) || (!dev->of_node))
> @@ -153,6 +155,21 @@ void of_device_uevent(struct device *dev, struct kobj_uevent_env *env)
>  		seen++;
>  	}
>  	add_uevent_var(env, "OF_COMPATIBLE_N=%d", seen);
> +
> +	seen = 0;
> +	mutex_lock(&of_aliases_mutex);
> +	list_for_each_entry(app, &aliases_lookup, link) {
> +		if (dev->of_node == app->np) {
> +			add_uevent_var(env, "OF_ALIAS_%d=%s", seen,
> +				       app->alias);
> +			seen++;
> +		}
> +	}
> +
> +	if (seen)
> +		add_uevent_var(env, "OF_ALIAS_N=%d", seen);
> +
> +	mutex_unlock(&of_aliases_mutex);
>  }
> 
>  int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env)
> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> new file mode 100644
> index 0000000..031608f
> --- /dev/null
> +++ b/drivers/of/of_private.h
> @@ -0,0 +1,33 @@
> +/* Copyright (c) 2012, The Linux Foundation. All rights reserved.

Oops, that doesn't look right. You need to preserve the copyright
messages from the file this came from. You didn't write this code, you
only moved it about.

Otherwise the patch looks good. Can you please respin with that change?

g.