nvmem: core: add nvmem_add_one_cell()

Add a new function to add exactly one cell. This will be used by the
nvmem layout drivers to add custom cells. In contrast to the
nvmem_add_cells(), this has the advantage that we don't have to assemble
a list of cells on runtime.
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230206134356.839737-16-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/core.c

@@ -501,6 +501,36 @@ static int nvmem_cell_info_to_nvmem_cell_entry(struct nvmem_device *nvmem,
 	return 0;
 }
 
+/**
+ * nvmem_add_one_cell() - Add one cell information to an nvmem device
+ *
+ * @nvmem: nvmem device to add cells to.
+ * @info: nvmem cell info to add to the device
+ *
+ * Return: 0 or negative error code on failure.
+ */
+int nvmem_add_one_cell(struct nvmem_device *nvmem,
+		       const struct nvmem_cell_info *info)
+{
+	struct nvmem_cell_entry *cell;
+	int rval;
+
+	cell = kzalloc(sizeof(*cell), GFP_KERNEL);
+	if (!cell)
+		return -ENOMEM;
+
+	rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
+	if (rval) {
+		kfree(cell);
+		return rval;
+	}
+
+	nvmem_cell_entry_add(cell);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nvmem_add_one_cell);
+
 /**
  * nvmem_add_cells() - Add cell information to an nvmem device
  *
@@ -514,34 +544,15 @@ static int nvmem_add_cells(struct nvmem_device *nvmem,
 		    const struct nvmem_cell_info *info,
 		    int ncells)
 {
-	struct nvmem_cell_entry **cells;
-	int i, rval = 0;
-
-	cells = kcalloc(ncells, sizeof(*cells), GFP_KERNEL);
-	if (!cells)
-		return -ENOMEM;
+	int i, rval;
 
 	for (i = 0; i < ncells; i++) {
-		cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
-		if (!cells[i]) {
-			rval = -ENOMEM;
-			goto out;
-		}
-
-		rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, &info[i], cells[i]);
-		if (rval) {
-			kfree(cells[i]);
-			goto out;
-		}
-
-		nvmem_cell_entry_add(cells[i]);
+		rval = nvmem_add_one_cell(nvmem, &info[i]);
+		if (rval)
+			return rval;
 	}
 
-out:
-	/* remove tmp array */
-	kfree(cells);
-
-	return rval;
+	return 0;
 }
 
 /**

include/linux/nvmem-provider.h

@@ -153,6 +153,9 @@ struct nvmem_device *devm_nvmem_register(struct device *dev,
 void nvmem_add_cell_table(struct nvmem_cell_table *table);
 void nvmem_del_cell_table(struct nvmem_cell_table *table);
 
+int nvmem_add_one_cell(struct nvmem_device *nvmem,
+		       const struct nvmem_cell_info *info);
+
 #else
 
 static inline struct nvmem_device *nvmem_register(const struct nvmem_config *c)
@@ -170,6 +173,11 @@ devm_nvmem_register(struct device *dev, const struct nvmem_config *c)
 
 static inline void nvmem_add_cell_table(struct nvmem_cell_table *table) {}
 static inline void nvmem_del_cell_table(struct nvmem_cell_table *table) {}
+static inline int nvmem_add_one_cell(struct nvmem_device *nvmem,
+				     const struct nvmem_cell_info *info)
+{
+	return -EOPNOTSUPP;
+}
 
 #endif /* CONFIG_NVMEM */
 #endif  /* ifndef _LINUX_NVMEM_PROVIDER_H */