[PATCH v4 3/5] nvmem: core: Add consumer API to get nvmem cell from node

[Sanchayan Maity <maitysanchayan@gmail.com>]

From: Stefan Agner <stefan@agner.ch>

The existing NVMEM consumer API's do not allow to get a
NVMEM cell directly given a device tree node. This patch
adds a function to provide this functionality.

Assuming the nvmem cell id name is known, this can be used
as follows

struct device_node *cell_np;
struct nvmem_cell *foo_cell;

cell_np = of_find_node_by_name(parent, "foo");
foo_cell = of_nvmem_cell_get_direct(cell_np);

Parent node can also be the of_node of the main SoC device
node.

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
 drivers/nvmem/core.c           | 44 +++++++++++++++++++++++++++++-------------
 include/linux/nvmem-consumer.h |  1 +
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 965911d..470abee 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -743,29 +743,21 @@ 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_get_direct() - Get a nvmem cell from given device node
  *
- * @dev node: Device tree node that uses the nvmem cell
- * @id: nvmem cell name from nvmem-cell-names property.
+ * @dev node: Device tree node that uses 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_get_direct(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)
@@ -824,6 +816,32 @@ err_mem:
 
 	return ERR_PTR(rval);
 }
+EXPORT_SYMBOL_GPL(of_nvmem_cell_get_direct);
+
+/**
+ * of_nvmem_cell_get() - Get a nvmem cell from given device node 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_get_direct(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..bf879fc 100644
--- a/include/linux/nvmem-consumer.h
+++ b/include/linux/nvmem-consumer.h
@@ -136,6 +136,7 @@ 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_get_direct(struct device_node *cell_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,
-- 
2.9.0