linux-kernel - [PATCH v2 4/6] nvmem: core: add nvmem_cell_read

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Message-ID: <1551349196-8956-5-git-send-email-fabrice.gasnier@st.com>
Date:   Thu, 28 Feb 2019 11:19:54 +0100
From:   Fabrice Gasnier <fabrice.gasnier@...com>
To:     <srinivas.kandagatla@...aro.org>, <robh+dt@...nel.org>,
        <alexandre.torgue@...com>
CC:     <mark.rutland@....com>, <mcoquelin.stm32@...il.com>,
        <fabrice.gasnier@...com>, <lionel.debieve@...com>,
        <devicetree@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 4/6] nvmem: core: add nvmem_cell_read_u16

Add nvmem_cell_read_u16() helper to ease read of an u16 value on consumer
side. This is inspired by nvmem_cell_read_u32() function.
This helper is useful on stm32 that has 16 bits data cells stored in non
volatile memory.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...com>
---
 drivers/nvmem/core.c           | 37 +++++++++++++++++++++++++++++++++++++
 include/linux/nvmem-consumer.h |  7 +++++++
 2 files changed, 44 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index f7301bb..5bd48ed 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1331,6 +1331,43 @@ int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
 EXPORT_SYMBOL_GPL(nvmem_cell_write);
 
 /**
+ * nvmem_cell_read_u16() - Read a cell value as an u16
+ *
+ * @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_u16(struct device *dev, const char *cell_id, u16 *val)
+{
+	struct nvmem_cell *cell;
+	void *buf;
+	size_t len;
+
+	cell = nvmem_cell_get(dev, cell_id);
+	if (IS_ERR(cell))
+		return PTR_ERR(cell);
+
+	buf = nvmem_cell_read(cell, &len);
+	if (IS_ERR(buf)) {
+		nvmem_cell_put(cell);
+		return PTR_ERR(buf);
+	}
+	if (len != sizeof(*val)) {
+		kfree(buf);
+		nvmem_cell_put(cell);
+		return -EINVAL;
+	}
+	memcpy(val, buf, sizeof(*val));
+	kfree(buf);
+	nvmem_cell_put(cell);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
+
+/**
  * nvmem_cell_read_u32() - Read a cell value as an u32
  *
  * @dev: Device that requests the nvmem cell.
diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
index 312bfa5..8f8be5b 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_u16(struct device *dev, const char *cell_id, u16 *val);
 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val);
 
 /* direct nvmem device read/write interface */
@@ -122,6 +123,12 @@ static inline int nvmem_cell_write(struct nvmem_cell *cell,
 	return -EOPNOTSUPP;
 }
 
+static inline int nvmem_cell_read_u16(struct device *dev,
+				      const char *cell_id, u16 *val)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline int nvmem_cell_read_u32(struct device *dev,
 				      const char *cell_id, u32 *val)
 {
-- 
2.7.4