[PATCH v2 1/8] reset: modify the way reset lookup works for board files

[p.zabel@pengutronix.de (Philipp Zabel)]

Hi Bartosz,

On Fri, 2018-03-23 at 10:36 +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> Commit 7af1bb19f1d7 ("reset: add support for non-DT systems")
> introduced reset control lookup mechanism for boards that still use
> board files.
> 
> The routine used to register lookup entries takes the corresponding
> reset_controlled_dev structure as argument.
> 
> It's been determined however that for the first user of this new
> interface - davinci psc driver - it will be easier to register the
> lookup entries using the reset controller device name.

Thank you, this is what I expected in the first place.

> This patch changes the way lookup entries are added.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
>  drivers/reset/core.c             | 33 +++++++++++++++++++++++++++++----
>  include/linux/reset-controller.h |  8 +++++---
>  2 files changed, 34 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/reset/core.c b/drivers/reset/core.c
> index 06fa4907afc4..f37048e55336 100644
> --- a/drivers/reset/core.c
> +++ b/drivers/reset/core.c
> @@ -153,11 +153,11 @@ EXPORT_SYMBOL_GPL(devm_reset_controller_register);
>  
>  /**
>   * reset_controller_add_lookup - register a set of lookup entries
> - * @rcdev: initialized reset controller device owning the reset line
> + * @provider: name of the reset controller provider
>   * @lookup: array of reset lookup entries
>   * @num_entries: number of entries in the lookup array
>   */
> -void reset_controller_add_lookup(struct reset_controller_dev *rcdev,
> +void reset_controller_add_lookup(const char *provider,

Is there any reason not to drop the provider parameter completely?
I'd just let the user add the provider device id to the lookup, see
below.

>  				 struct reset_control_lookup *lookup,
>  				 unsigned int num_entries)
>  {
> @@ -174,7 +174,7 @@ void reset_controller_add_lookup(struct reset_controller_dev *rcdev,
>  			continue;
>  		}
>  
> -		entry->rcdev = rcdev;
> +		entry->provider = provider;
>  		list_add_tail(&entry->list, &reset_lookup_list);
>  	}
>  	mutex_unlock(&reset_lookup_mutex);
> @@ -526,11 +526,30 @@ struct reset_control *__of_reset_control_get(struct device_node *node,
>  }
>  EXPORT_SYMBOL_GPL(__of_reset_control_get);
>  
> +static struct reset_controller_dev *
> +__reset_controller_by_name(const char *name)
> +{
> +	struct reset_controller_dev *rcdev;
> +
> +	lockdep_assert_held(&reset_list_mutex);
> +
> +	list_for_each_entry(rcdev, &reset_controller_list, list) {
> +		if (!rcdev->dev)
> +			continue;
> +
> +		if (!strcmp(name, dev_name(rcdev->dev)))
> +			return rcdev;
> +	}
> +
> +	return NULL;
> +}
> +
>  static struct reset_control *
>  __reset_control_get_from_lookup(struct device *dev, const char *con_id,
>  				bool shared, bool optional)
>  {
>  	const struct reset_control_lookup *lookup;
> +	struct reset_controller_dev *rcdev;
>  	const char *dev_id = dev_name(dev);
>  	struct reset_control *rstc = NULL;
>  
> @@ -547,7 +566,13 @@ __reset_control_get_from_lookup(struct device *dev, const char *con_id,
>  		    ((con_id && lookup->con_id) &&
>  		     !strcmp(con_id, lookup->con_id))) {
>  			mutex_lock(&reset_list_mutex);
> -			rstc = __reset_control_get_internal(lookup->rcdev,
> +			rcdev = __reset_controller_by_name(lookup->provider);
> +			if (!rcdev) {
> +				mutex_unlock(&reset_list_mutex);
> +				continue;

What is the reason to continue here? If we've found a matching lookup
that contains a rcdev dev_id for which there is no reset controller,
shouldn't we just return an error?

> +			}
> +
> +			rstc = __reset_control_get_internal(rcdev,
>  							    lookup->index,
>  							    shared);
>  			mutex_unlock(&reset_list_mutex);
> diff --git a/include/linux/reset-controller.h b/include/linux/reset-controller.h
> index 25698f6c1fae..1a6c25d825d3 100644
> --- a/include/linux/reset-controller.h
> +++ b/include/linux/reset-controller.h
> @@ -30,14 +30,14 @@ struct of_phandle_args;
>   * struct reset_control_lookup - represents a single lookup entry
>   *
>   * @list: internal list of all reset lookup entries
> - * @rcdev: reset controller device controlling this reset line
> + * @provider: name of the reset controller device controlling this reset line
>   * @index: ID of the reset controller in the reset controller device
>   * @dev_id: name of the device associated with this reset line
>   * @con_id name of the reset line (can be NULL)
>   */
>  struct reset_control_lookup {
>  	struct list_head list;
> -	struct reset_controller_dev *rcdev;
> +	const char *provider;

Looks good to me, but I'd also extend RESET_LOOKUP to set the provider
instead of passing it to the reset_controller_add_lookup function,
similarly to PWM_LOOKUP:

#define RESET_LOOKUP(_provider, _index, _dev_id, _con_id)

>  	unsigned int index;
>  	const char *dev_id;
>  	const char *con_id;
> @@ -57,6 +57,7 @@ struct reset_control_lookup {
>   * @owner: kernel module of the reset controller driver
>   * @list: internal list of reset controller devices
>   * @reset_control_head: head of internal list of requested reset controls
> + * @dev: corresponding driver model device struct
>   * @of_node: corresponding device tree node as phandle target
>   * @of_reset_n_cells: number of cells in reset line specifiers
>   * @of_xlate: translation function to translate from specifier as found in the
> @@ -68,6 +69,7 @@ struct reset_controller_dev {
>  	struct module *owner;
>  	struct list_head list;
>  	struct list_head reset_control_head;
> +	struct device *dev;
>  	struct device_node *of_node;
>  	int of_reset_n_cells;
>  	int (*of_xlate)(struct reset_controller_dev *rcdev,
> @@ -82,7 +84,7 @@ struct device;
>  int devm_reset_controller_register(struct device *dev,
>  				   struct reset_controller_dev *rcdev);
>  
> -void reset_controller_add_lookup(struct reset_controller_dev *rcdev,
> +void reset_controller_add_lookup(const char *provider,
>  				 struct reset_control_lookup *lookup,
>  				 unsigned int num_entries);
>  

regards
Philipp