Message-ID: <78491489-6b31-c741-8c69-8d52fb614a6c@linaro.org>
Date:   Tue, 28 Dec 2021 16:09:32 +0300
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Subject: Re: [PATCH 3/8] device property: Helper to match multiple connections
Content-Language: en-GB
To:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Vinod Koul <vkoul@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Hans de Goede <hdegoede@redhat.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-usb@vger.kernel.org
References: <20211228052116.1748443-1-bjorn.andersson@linaro.org>
 <20211228052116.1748443-4-bjorn.andersson@linaro.org>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
In-Reply-To: <20211228052116.1748443-4-bjorn.andersson@linaro.org>
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Precedence: bulk

On 28/12/2021 08:21, Bjorn Andersson wrote:
> In some cases multiple connections with the same connection id
> needs to be resolved from a fwnode graph.
> 
> One such example is when separate hardware is used for performing muxing and/or
> orientation switching of the SuperSpeed and SBU lines in a USB-C
> connector. In this case the connector needs to belong to a graph with
> multiple matching remote endpoints, and the TypeC controller needs to be
> able to resolve them both.
> 
> Add a new API that allows this kind of lookup.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
>   drivers/base/property.c  | 94 ++++++++++++++++++++++++++++++++++++++++
>   include/linux/property.h |  5 +++
>   2 files changed, 99 insertions(+)
> 
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index cbe4fa298413..0aa0296fd991 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -1180,6 +1180,36 @@ fwnode_graph_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
>   	return NULL;
>   }
>   
> +static unsigned int fwnode_graph_devcon_matches(struct fwnode_handle *fwnode,
> +						const char *con_id, void *data,
> +						devcon_match_fn_t match,
> +						void **matches,
> +						unsigned int matches_len)
> +{
> +	struct fwnode_handle *node;
> +	struct fwnode_handle *ep;
> +	unsigned int count = 0;
> +	void *ret;
> +
> +	fwnode_graph_for_each_endpoint(fwnode, ep) {
> +		if (count >= matches_len) {
> +			fwnode_handle_put(ep);
> +			return count;
> +		}
> +
> +		node = fwnode_graph_get_remote_port_parent(ep);
> +		if (!fwnode_device_is_available(node))
> +			continue;
> +
> +		ret = match(node, con_id, data);
> +		fwnode_handle_put(node);
> +
> +		if (ret)
> +			matches[count++] = ret;
> +	}
> +	return count;
> +}

This API doesn't let it's user know if there are more matches found in 
the device tree or not. I'd suggest to add 'count' mode that would 
return the amount of found matches if (matches == NULL) && (matches_len 
== 0).

> +
>   static void *
>   fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
>   		    void *data, devcon_match_fn_t match)
> @@ -1202,6 +1232,35 @@ fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
>   	return NULL;
>   }
>   
> +static unsigned int fwnode_devcon_matches(struct fwnode_handle *fwnode,
> +					  const char *con_id, void *data,
> +					  devcon_match_fn_t match,
> +					  void **matches,
> +					  unsigned int matches_len)
> +{
> +	struct fwnode_handle *node;
> +	unsigned int count = 0;
> +	void *ret;
> +	int i;
> +
> +	for (i = 0; ; i++) {
> +		if (count >= matches_len)
> +			return count;
> +
> +		node = fwnode_find_reference(fwnode, con_id, i);
> +		if (IS_ERR(node))
> +			break;
> +
> +		ret = match(node, NULL, data);
> +		fwnode_handle_put(node);
> +
> +		if (ret)
> +			matches[count++] = ret;
> +	}
> +
> +	return count;
> +}
> +

Same comment applies.

>   /**
>    * fwnode_connection_find_match - Find connection from a device node
>    * @fwnode: Device node with the connection
> @@ -1229,3 +1288,38 @@ void *fwnode_connection_find_match(struct fwnode_handle *fwnode,
>   	return fwnode_devcon_match(fwnode, con_id, data, match);
>   }
>   EXPORT_SYMBOL_GPL(fwnode_connection_find_match);
> +
> +/**
> + * fwnode_connection_find_matches - Find connections from a device node
> + * @fwnode: Device node with the connection
> + * @con_id: Identifier for the connection
> + * @data: Data for the match function
> + * @match: Function to check and convert the connection description
> + * @matches: Array of pointers to fill with matches
> + * @matches_len: Length of @matches
> + *
> + * Find up to @matches_len connections with unique identifier @con_id between
> + * @fwnode and other device nodes. @match will be used to convert the
> + * connection description to data the caller is expecting to be returned
> + * through the @matches array.
> + *
> + * Return: Number of matches resolved, of negative errno.
> + */
> +int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
> +				   const char *con_id, void *data,
> +				   devcon_match_fn_t match,
> +				   void **matches, unsigned int matches_len)
> +{
> +	unsigned int count;
> +
> +	if (!fwnode || !match || !matches)
> +		return -EINVAL;
> +
> +	count = fwnode_graph_devcon_matches(fwnode, con_id, data, match,
> +					    matches, matches_len);
> +
> +	return count + fwnode_devcon_matches(fwnode, con_id, data, match,
> +					     matches + count,
> +					     matches_len - count);
> +}
> +EXPORT_SYMBOL_GPL(fwnode_connection_find_matches);
> diff --git a/include/linux/property.h b/include/linux/property.h
> index 16f736c698a2..59484ccb260e 100644
> --- a/include/linux/property.h
> +++ b/include/linux/property.h
> @@ -444,6 +444,11 @@ static inline void *device_connection_find_match(struct device *dev,
>   	return fwnode_connection_find_match(dev_fwnode(dev), con_id, data, match);
>   }
>   
> +int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
> +				   const char *con_id, void *data,
> +				   devcon_match_fn_t match,
> +				   void **matches, unsigned int matches_len);
> +
>   /* -------------------------------------------------------------------------- */
>   /* Software fwnode support - when HW description is incomplete or missing */
>   


-- 
With best wishes
Dmitry