From 21a99150a566b69edc7f3b9bc369bb4525e04acd Mon Sep 17 00:00:00 2001
From: Sam Shih <sam.shih@mediatek.com>
Date: Fri, 2 Jun 2023 13:06:17 +0800
Subject: [PATCH] 
 [spi-and-storage][999-2350-nvmem-core-Add-functions-to-make-number-reading-easy.patch]

---
 drivers/nvmem/core.c           | 161 +++++++++++++++++++++++++++------
 include/linux/nvmem-consumer.h |  15 +++
 2 files changed, 150 insertions(+), 26 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 19ac0d055..f65305b6d 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1102,16 +1102,8 @@ 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)
+static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
+				  void *val, size_t count)
 {
 	struct nvmem_cell *cell;
 	void *buf;
@@ -1126,21 +1118,50 @@ int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
 		nvmem_cell_put(cell);
 		return PTR_ERR(buf);
 	}
-	if (len != sizeof(*val)) {
+	if (len != count) {
 		kfree(buf);
 		nvmem_cell_put(cell);
 		return -EINVAL;
 	}
-	memcpy(val, buf, sizeof(*val));
+	memcpy(val, buf, count);
 	kfree(buf);
 	nvmem_cell_put(cell);
 
 	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
+ *
+ * @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)
+{
+	return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
+}
 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
 
 /**
- * nvmem_cell_read_u32() - Read a cell value as an u32
+ * nvmem_cell_read_u32() - Read a cell value as a u32
  *
  * @dev: Device that requests the nvmem cell.
  * @cell_id: Name of nvmem cell to read.
@@ -1149,32 +1170,120 @@ EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
  * Return: 0 on success or negative errno.
  */
 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
+{
+	return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
+
+/**
+ * nvmem_cell_read_u64() - Read a cell value as a u64
+ *
+ * @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_u64(struct device *dev, const char *cell_id, u64 *val)
+{
+	return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
+
+static const void *nvmem_cell_read_variable_common(struct device *dev,
+						   const char *cell_id,
+						   size_t max_len, size_t *len)
 {
 	struct nvmem_cell *cell;
+	int nbits;
 	void *buf;
-	size_t len;
 
 	cell = nvmem_cell_get(dev, cell_id);
 	if (IS_ERR(cell))
-		return PTR_ERR(cell);
+		return cell;
 
-	buf = nvmem_cell_read(cell, &len);
-	if (IS_ERR(buf)) {
-		nvmem_cell_put(cell);
-		return PTR_ERR(buf);
-	}
-	if (len != sizeof(*val)) {
+	nbits = cell->nbits;
+	buf = nvmem_cell_read(cell, len);
+	nvmem_cell_put(cell);
+	if (IS_ERR(buf))
+		return buf;
+
+	/*
+	 * If nbits is set then nvmem_cell_read() can significantly exaggerate
+	 * the length of the real data. Throw away the extra junk.
+	 */
+	if (nbits)
+		*len = DIV_ROUND_UP(nbits, 8);
+
+	if (*len > max_len) {
 		kfree(buf);
-		nvmem_cell_put(cell);
-		return -EINVAL;
+		return ERR_PTR(-ERANGE);
 	}
-	memcpy(val, buf, sizeof(*val));
+
+	return buf;
+}
+
+/**
+ * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
+ *
+ * @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_variable_le_u32(struct device *dev, const char *cell_id,
+				    u32 *val)
+{
+	size_t len;
+	const u8 *buf;
+	int i;
+
+	buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	/* Copy w/ implicit endian conversion */
+	*val = 0;
+	for (i = 0; i < len; i++)
+		*val |= buf[i] << (8 * i);
 
 	kfree(buf);
-	nvmem_cell_put(cell);
+
 	return 0;
 }
-EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
+EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
+
+/**
+ * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
+ *
+ * @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_variable_le_u64(struct device *dev, const char *cell_id,
+				    u64 *val)
+{
+	size_t len;
+	const u8 *buf;
+	int i;
+
+	buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	/* Copy w/ implicit endian conversion */
+	*val = 0;
+	for (i = 0; i < len; i++)
+		*val |= (uint64_t)buf[i] << (8 * i);
+
+	kfree(buf);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
 
 /**
  * nvmem_device_cell_read() - Read a given nvmem device and cell
diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
index 0f490b288..227b93158 100644
--- a/include/linux/nvmem-consumer.h
+++ b/include/linux/nvmem-consumer.h
@@ -64,6 +64,10 @@ 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);
+int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
+				    u32 *val);
+int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
+				    u64 *val);
 
 /* direct nvmem device read/write interface */
 struct nvmem_device *nvmem_device_get(struct device *dev, const char *name);
@@ -135,6 +139,17 @@ static inline int nvmem_cell_read_u32(struct device *dev,
 {
 	return -EOPNOTSUPP;
 }
+static inline int nvmem_cell_read_variable_le_u32(struct device *dev,
+						const char *cell_id, u32 *val)
+{
+	return -ENOSYS;
+}
+
+static inline int nvmem_cell_read_variable_le_u64(struct device *dev,
+						const char *cell_id, u64 *val);
+{
+	return -ENOSYS;
+}
 
 static inline struct nvmem_device *nvmem_device_get(struct device *dev,
 						    const char *name)
-- 
2.34.1