linux-kernel - [PATCH v4 1/2] nvmem: core: add nvmem_cell

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Message-ID: <20250228180326.256058-2-jberring@redhat.com>
Date: Fri, 28 Feb 2025 13:03:25 -0500
From: Jennifer Berringer <jberring@...hat.com>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
	Sebastian Reichel <sre@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	Jennifer Berringer <jberring@...hat.com>
Subject: [PATCH v4 1/2] nvmem: core: add nvmem_cell_size()

This function allows nvmem consumers to know the size of an nvmem cell
before calling nvmem_cell_write() or nvmem_cell_read(), which is helpful
for drivers that may need to handle devices with different cell sizes.

Signed-off-by: Jennifer Berringer <jberring@...hat.com>
---
 drivers/nvmem/core.c           | 18 ++++++++++++++++++
 include/linux/nvmem-consumer.h |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index d6494dfc20a7..4d0cbd20da48 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1624,6 +1624,24 @@ void nvmem_cell_put(struct nvmem_cell *cell)
 }
 EXPORT_SYMBOL_GPL(nvmem_cell_put);
 
+/**
+ * nvmem_cell_size() - Get nvmem cell size in bytes.
+ *
+ * @cell: nvmem cell.
+ *
+ * Return: size of the nvmem cell.
+ */
+size_t nvmem_cell_size(struct nvmem_cell *cell)
+{
+	struct nvmem_cell_entry *entry = cell->entry;
+
+	if (!entry)
+		return 0;
+
+	return entry->bytes;
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_size);
+
 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
 {
 	u8 *p, *b;
diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
index 34c0e58dfa26..a2020527d2d3 100644
--- a/include/linux/nvmem-consumer.h
+++ b/include/linux/nvmem-consumer.h
@@ -54,6 +54,7 @@ struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id);
 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id);
 void nvmem_cell_put(struct nvmem_cell *cell);
 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell);
+size_t nvmem_cell_size(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_read_u8(struct device *dev, const char *cell_id, u8 *val);
@@ -117,6 +118,11 @@ static inline void nvmem_cell_put(struct nvmem_cell *cell)
 {
 }
 
+static inline size_t nvmem_cell_size(struct nvmem_cell *cell)
+{
+	return 0;
+}
+
 static inline void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
 {
 	return ERR_PTR(-EOPNOTSUPP);
-- 
2.47.1