linux-kernel - [PATCH v2 28/29] nvmem: core: Add nvmem_cell_read

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Date:   Tue, 23 Jun 2020 04:51:05 +0200
From:   Andreas Färber <afaerber@...e.de>
To:     linux-realtek-soc@...ts.infradead.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        James Tai [戴志峰] 
        <james.tai@...ltek.com>,
        Stanley Chang [昌育德] 
        <stanley_chang@...ltek.com>, Edgar Lee <cylee12@...ltek.com>,
        Andreas Färber <afaerber@...e.de>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH v2 28/29] 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@...e.de>
---
 v2: New
 
 drivers/nvmem/core.c           | 15 +++++++++++++++
 include/linux/nvmem-consumer.h |  1 +
 2 files changed, 16 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 95bed31391cd..d6bacc878500 100644
--- 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 1b311d27c9b8..052293f4cbdb 100644
--- 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);
-- 
2.26.2