[PATCH 1/2] OF: update stdout-path parsing

[grant.likely@secretlab.ca (Grant Likely)]

On Sat,  8 Feb 2014 12:53:52 +0100, Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com> wrote:
> Today we only check if the linux,stdout-path property is present and retreive
> the node. But the DT specification allow to pass the serial options too as
> this
> 	linux,stdout-path = &UART0;
> 
> or with options
> 
> 	inux,stdout-path = "/plb at 0/serial at 84000000:115200";

typo.  :-)

> 
> So update the parsing to support and also the backward compatible stdout-path
> property.

Looks reasonable to me. Comment below, but otherwise:

Acked-by: Grant Likely <grant.likely@linaro.org>

> 
> Cc: linux-serial at vger.kernel.org
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
> ---
>  drivers/of/base.c  | 57 +++++++++++++++++++++++++++++++++++++++++++++---------
>  include/linux/of.h |  4 ++--
>  2 files changed, 50 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index ff85450..ab9ff2f 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -34,6 +34,7 @@ EXPORT_SYMBOL(of_allnodes);
>  struct device_node *of_chosen;
>  struct device_node *of_aliases;
>  static struct device_node *of_stdout;
> +static char *of_stdout_option;
>  
>  DEFINE_MUTEX(of_aliases_mutex);
>  
> @@ -1783,6 +1784,45 @@ static void of_alias_add(struct alias_prop *ap, struct device_node *np,
>  }
>  
>  /**
> + * of_stdout_path_scan - check if a device node matches the
> + *                           linux,stdout-path property and parse it
> + */
> +static void of_stdout_path_scan(void)
> +{
> +	const char *name;
> +	const char *tmp;
> +	const char *tmp_option;
> +
> +	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
> +	if (!name)
> +		name = of_get_property(of_chosen, "stdout-path", NULL);

Should protect against unterminated strings. Use of_property_read_string()

> +
> +	if (!name)
> +		return;
> +
> +	tmp_option = strchr(name, ':');
> +
> +	if (!tmp_option) {
> +		of_stdout = of_find_node_by_path(name);
> +		return;
> +	}
> +
> +	tmp = kstrndup(name, strlen(name) - strlen(tmp_option), GFP_KERNEL);
> +	if (!tmp)
> +		return;

Having to do a strdup is kind of ugly and expensive when the only
problem is the terminating colon. I would rather see
of_find_node_by_path modified to do the right thing by ignoring the
colon which is illegal in path names anyway.

> +
> +	of_stdout = of_find_node_by_path(tmp);
> +	if (!of_stdout)
> +		goto out;
> +
> +	tmp_option++;
> +	of_stdout_option = kstrdup(tmp_option, GFP_KERNEL);

The strdup is unnecessary. tmp_option is already null terminated, is
immutable, and contains the data you need.

> +
> +out:
> +	kfree(tmp);

Please reverse the to eliminate the non-error goto:
	of_stdout = of_find_node_by_path(tmp);
	if (of_stdout)
		of_stdout_option = tmp_option++;
	kfree(tmp);

> +}
> +
> +/**
>   * of_alias_scan - Scan all properties of 'aliases' node
>   *
>   * The function scans all the properties of 'aliases' node and populate
> @@ -1800,13 +1840,8 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
>  	if (of_chosen == NULL)
>  		of_chosen = of_find_node_by_path("/chosen at 0");
>  
> -	if (of_chosen) {
> -		const char *name;
> -
> -		name = of_get_property(of_chosen, "linux,stdout-path", NULL);
> -		if (name)
> -			of_stdout = of_find_node_by_path(name);
> -	}
> +	if (of_chosen)
> +		of_stdout_path_scan();

Move the of_chosen check directly into the function.

>  
>  	of_aliases = of_find_node_by_path("/aliases");
>  	if (!of_aliases)
> @@ -1923,13 +1958,17 @@ EXPORT_SYMBOL_GPL(of_prop_next_string);
>   *                            linux,stdout-path property
>   *
>   * Check if this device node matches the linux,stdout-path property
> - * in the chosen node. return true if yes, false otherwise.
> + * in the chosen node. return true if yes, false otherwise with the option if
> + * requested.
>   */
> -int of_device_is_stdout_path(struct device_node *dn)
> +int of_device_is_stdout_path(struct device_node *dn, char** option)
>  {
>  	if (!of_stdout)
>  		return false;
>  
> +	if (option)
> +		*option = of_stdout_option;
> +
>  	return of_stdout == dn;
>  }
>  EXPORT_SYMBOL_GPL(of_device_is_stdout_path);
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 70c64ba..a8afe44 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -352,7 +352,7 @@ const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
>   */
>  const char *of_prop_next_string(struct property *prop, const char *cur);
>  
> -int of_device_is_stdout_path(struct device_node *dn);
> +int of_device_is_stdout_path(struct device_node *dn, char** option);
>  
>  #else /* CONFIG_OF */
>  
> @@ -542,7 +542,7 @@ static inline int of_machine_is_compatible(const char *compat)
>  	return 0;
>  }
>  
> -static inline int of_device_is_stdout_path(struct device_node *dn)
> +static inline int of_device_is_stdout_path(struct device_node *dn, char** option)
>  {
>  	return 0;
>  }
> -- 
> 1.9.rc1
> 
> 
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