[PATCH v2 5/8] nvmem: provide consumer access to cell size metrics

[Oleksij Rempel <o.rempel@pengutronix.de>]

Add nvmem_cell_get_size() function to provide access to cell size
metrics. In some cases we may get cell size less as consumer would
expect it. So, nvmem_cell_write() would fail with incorrect buffer size.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/nvmem/core.c           | 25 +++++++++++++++++++++++++
 include/linux/nvmem-consumer.h |  7 +++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 980123fb4dde..a21e5649fcda 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1790,6 +1790,31 @@ int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
 
 EXPORT_SYMBOL_GPL(nvmem_cell_write);
 
+/**
+ * nvmem_cell_get_size() - Get the size of a given nvmem cell
+ * @cell: nvmem cell to be queried.
+ * @bytes: Pointer to store the size of the cell in bytes. Can be NULL.
+ * @bits: Pointer to store the size of the cell in bits. Can be NULL.
+ *
+ * Return: 0 on success or negative on failure.
+ */
+int nvmem_cell_get_size(struct nvmem_cell *cell, size_t *bytes, size_t *bits)
+{
+	struct nvmem_cell_entry *entry = cell->entry;
+
+	if (!entry->nvmem)
+		return -EINVAL;
+
+	if (bytes)
+		*bytes = entry->bytes;
+
+	if (bits)
+		*bits = entry->nbits;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_get_size);
+
 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
 				  void *val, size_t count)
 {
diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
index 34c0e58dfa26..bcb0e17e415d 100644
--- a/include/linux/nvmem-consumer.h
+++ b/include/linux/nvmem-consumer.h
@@ -56,6 +56,7 @@ void nvmem_cell_put(struct nvmem_cell *cell);
 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell);
 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len);
 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len);
+int nvmem_cell_get_size(struct nvmem_cell *cell, size_t *bytes, size_t *bits);
 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val);
 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val);
 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val);
@@ -128,6 +129,12 @@ static inline int nvmem_cell_write(struct nvmem_cell *cell,
 	return -EOPNOTSUPP;
 }
 
+static inline int nvmem_cell_get_size(struct nvmem_cell *cell, size_t *bytes,
+				      size_t *bits)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline int nvmem_cell_read_u8(struct device *dev,
 				     const char *cell_id, u8 *val)
 {
-- 
2.39.2