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[RESEND RFC 1/3] nvmem: Add 'of_nvmem_cell_from_device_node()'

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  [RESEND RFC 1/3] nvmem: Add 'of_nvmem_cell_from_device_node()' Andrey Smirnov <andrew.smirnov@gmail.com> - 2016-03-01 18:00 +0100
    Re: [RESEND RFC 1/3] nvmem: Add 'of_nvmem_cell_from_device_node()' Srinivas Kandagatla <srinivas.kandagatla@linaro.org> - 2016-03-02 15:00 +0100
      Re: [RESEND RFC 1/3] nvmem: Add 'of_nvmem_cell_from_device_node()' Andrey Smirnov <andrew.smirnov@gmail.com> - 2016-03-02 19:20 +0100

#1346756 — [RESEND RFC 1/3] nvmem: Add 'of_nvmem_cell_from_device_node()'

Add 'of_nvmem_cell_from_device_node()' -- a function that allows to
obtain 'struct nvmem_cell' from a device tree node representing it. One
use-case for such a function would be to access nvmem cells with known
phandles.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 drivers/nvmem/core.c           | 44 +++++++++++++++++++++++++++++-------------
 include/linux/nvmem-consumer.h |  7 +++++++
 2 files changed, 38 insertions(+), 13 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 6fd4e5a..08550dd 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -601,29 +601,21 @@ static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
 
 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
 /**
- * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
+ * of_nvmem_cell_from_device_node() - Get a nvmem cell from device node representation
  *
- * @dev node: Device tree node that uses the nvmem cell
- * @id: nvmem cell name from nvmem-cell-names property.
+ * @np node: Device tree node representing NVMEM cell
  *
  * Return: Will be an ERR_PTR() on error or a valid pointer
  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
  * nvmem_cell_put().
  */
-struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
-					    const char *name)
+struct nvmem_cell *of_nvmem_cell_from_device_node(struct device_node *cell_np)
 {
-	struct device_node *cell_np, *nvmem_np;
+	struct device_node *nvmem_np;
 	struct nvmem_cell *cell;
 	struct nvmem_device *nvmem;
 	const __be32 *addr;
-	int rval, len, index;
-
-	index = of_property_match_string(np, "nvmem-cell-names", name);
-
-	cell_np = of_parse_phandle(np, "nvmem-cells", index);
-	if (!cell_np)
-		return ERR_PTR(-EINVAL);
+	int rval, len;
 
 	nvmem_np = of_get_next_parent(cell_np);
 	if (!nvmem_np)
@@ -682,6 +674,32 @@ err_mem:
 
 	return ERR_PTR(rval);
 }
+EXPORT_SYMBOL_GPL(of_nvmem_cell_from_device_node);
+
+/**
+ * of_nvmem_cell_get() - Get a nvmem cell from given device node referencing it and cell id
+ *
+ * @dev node: Device tree node that uses the nvmem cell
+ * @id: nvmem cell name from nvmem-cell-names property.
+ *
+ * Return: Will be an ERR_PTR() on error or a valid pointer
+ * to a struct nvmem_cell.  The nvmem_cell will be freed by the
+ * nvmem_cell_put().
+ */
+struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
+					    const char *name)
+{
+	struct device_node *cell_np;
+	int index;
+
+	index = of_property_match_string(np, "nvmem-cell-names", name);
+
+	cell_np = of_parse_phandle(np, "nvmem-cells", index);
+	if (!cell_np)
+		return ERR_PTR(-EINVAL);
+
+	return of_nvmem_cell_from_device_node(cell_np);
+}
 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
 #endif
 
diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
index 9bb77d3..ff0abb0 100644
--- a/include/linux/nvmem-consumer.h
+++ b/include/linux/nvmem-consumer.h
@@ -136,11 +136,18 @@ static inline int nvmem_device_write(struct nvmem_device *nvmem,
 #endif /* CONFIG_NVMEM */
 
 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
+struct nvmem_cell *of_nvmem_cell_from_device_node(struct device_node *np);
 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
 				     const char *name);
 struct nvmem_device *of_nvmem_device_get(struct device_node *np,
 					 const char *name);
 #else
+
+static inline struct nvmem_cell *
+of_nvmem_cell_from_device_node(struct device_node *np)
+{
+	return ERR_PTR(-ENOSYS);
+}
 static inline struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
 				     const char *name)
 {
-- 
2.5.0

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#1348044

Sorry for so late review comments,


On 01/03/16 16:59, Andrey Smirnov wrote:
> Add 'of_nvmem_cell_from_device_node()' -- a function that allows to
> obtain 'struct nvmem_cell' from a device tree node representing it. One
> use-case for such a function would be to access nvmem cells with known
> phandles.

Totally missing the purpose of this new API, Why is of_nvmem_cell_get() 
not useful, its exactly doing same thing.

Unless you randomly want to handle phandles without proper dt bindings.

Thanks
srini

>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
>   drivers/nvmem/core.c           | 44 +++++++++++++++++++++++++++++-------------
>   include/linux/nvmem-consumer.h |  7 +++++++
>   2 files changed, 38 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index 6fd4e5a..08550dd 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -601,29 +601,21 @@ static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
>
>   #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
>   /**
> - * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
> + * of_nvmem_cell_from_device_node() - Get a nvmem cell from device node representation
>    *
> - * @dev node: Device tree node that uses the nvmem cell
> - * @id: nvmem cell name from nvmem-cell-names property.
> + * @np node: Device tree node representing NVMEM cell
>    *
>    * Return: Will be an ERR_PTR() on error or a valid pointer
>    * to a struct nvmem_cell.  The nvmem_cell will be freed by the
>    * nvmem_cell_put().
>    */
> -struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
> -					    const char *name)
> +struct nvmem_cell *of_nvmem_cell_from_device_node(struct device_node *cell_np)
>   {
> -	struct device_node *cell_np, *nvmem_np;
> +	struct device_node *nvmem_np;
>   	struct nvmem_cell *cell;
>   	struct nvmem_device *nvmem;
>   	const __be32 *addr;
> -	int rval, len, index;
> -
> -	index = of_property_match_string(np, "nvmem-cell-names", name);
> -
> -	cell_np = of_parse_phandle(np, "nvmem-cells", index);
> -	if (!cell_np)
> -		return ERR_PTR(-EINVAL);
> +	int rval, len;
>
>   	nvmem_np = of_get_next_parent(cell_np);
>   	if (!nvmem_np)
> @@ -682,6 +674,32 @@ err_mem:
>
>   	return ERR_PTR(rval);
>   }
> +EXPORT_SYMBOL_GPL(of_nvmem_cell_from_device_node);
> +
> +/**
> + * of_nvmem_cell_get() - Get a nvmem cell from given device node referencing it and cell id
> + *
> + * @dev node: Device tree node that uses the nvmem cell
> + * @id: nvmem cell name from nvmem-cell-names property.
> + *
> + * Return: Will be an ERR_PTR() on error or a valid pointer
> + * to a struct nvmem_cell.  The nvmem_cell will be freed by the
> + * nvmem_cell_put().
> + */
> +struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
> +					    const char *name)
> +{
> +	struct device_node *cell_np;
> +	int index;
> +
> +	index = of_property_match_string(np, "nvmem-cell-names", name);
> +
> +	cell_np = of_parse_phandle(np, "nvmem-cells", index);
> +	if (!cell_np)
> +		return ERR_PTR(-EINVAL);
> +
> +	return of_nvmem_cell_from_device_node(cell_np);
> +}
>   EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
>   #endif
>
> diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
> index 9bb77d3..ff0abb0 100644
> --- a/include/linux/nvmem-consumer.h
> +++ b/include/linux/nvmem-consumer.h
> @@ -136,11 +136,18 @@ static inline int nvmem_device_write(struct nvmem_device *nvmem,
>   #endif /* CONFIG_NVMEM */
>
>   #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
> +struct nvmem_cell *of_nvmem_cell_from_device_node(struct device_node *np);
>   struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
>   				     const char *name);
>   struct nvmem_device *of_nvmem_device_get(struct device_node *np,
>   					 const char *name);
>   #else
> +
> +static inline struct nvmem_cell *
> +of_nvmem_cell_from_device_node(struct device_node *np)
> +{
> +	return ERR_PTR(-ENOSYS);
> +}
>   static inline struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
>   				     const char *name)
>   {
>

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#1348376

On Wed, Mar 2, 2016 at 5:58 AM, Srinivas Kandagatla
<srinivas.kandagatla@linaro.org> wrote:
> Sorry for so late review comments,
>
>
> On 01/03/16 16:59, Andrey Smirnov wrote:
>>
>> Add 'of_nvmem_cell_from_device_node()' -- a function that allows to
>> obtain 'struct nvmem_cell' from a device tree node representing it. One
>> use-case for such a function would be to access nvmem cells with known
>> phandles.
>
>
> Totally missing the purpose of this new API, Why is of_nvmem_cell_get() not
> useful, its exactly doing same thing.
>
> Unless you randomly want to handle phandles without proper dt bindings.

That about sums up what I was trying to do. In my "composite" driver,
the way the layout of the cell is specified is a 3-element tuple
containing a phandle to nvmem cell, offset within that cell and the
size of the chunk to use, so in order to be able to use that phandle I
introduced this function.

Andrey

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