nvmem: core: Add nvmem_cell_read_u8()

Complement the u16, u32 and u64 helpers with a u8 variant to ease
accessing byte-sized values.

This helper will be useful for Realtek Digital Home Center platforms,
which store some byte and sub-byte sized values in non-volatile memory.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20200722100705.7772-7-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 95bed31391cd1c50057c7e4ac8f6017c551557d2..d6bacc8785009f74523a2c52226545dfa91630cd 100644 (file)
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1374,6 +1374,21 @@ static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
        return 0;
 }
 
+/**
+ * nvmem_cell_read_u8() - Read a cell value as a u8
+ *
+ * @dev: Device that requests the nvmem cell.
+ * @cell_id: Name of nvmem cell to read.
+ * @val: pointer to output value.
+ *
+ * Return: 0 on success or negative errno.
+ */
+int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
+{
+       return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
+
 /**
  * nvmem_cell_read_u16() - Read a cell value as a u16
  *

diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
index 1b311d27c9b86d8d8b23efc5b6b847eec69a88d8..052293f4cbdb0a64d95884aee645778e9a63c511 100644 (file)
--- a/include/linux/nvmem-consumer.h
+++ b/include/linux/nvmem-consumer.h
@@ -61,6 +61,7 @@ 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_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);
 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val);