[PATCHv2 1/3] regmap: implement LE formatting/parsing for 16/32-bit values.

[Xiubo Li]

Allow busses to request little endianness formatting and
parsing for 16- and 32-bit values. This will be useful to
support regmap-mmio.

For the following the scenarios using the regmap-mmio,
for example:

Index    CPU       Device     Endianess flag for values
----------------------------------------------------------
1        LE        LE         REGMAP_ENDIAN_DEFAULT/NATIVE
2        LE        BE         REGMAP_ENDIAN_BIG
3        BE        BE         REGMAP_ENDIAN_DEFAULT/NATIVE
4        BE        LE         REGMAP_ENDIAN_LITTLE

For one device driver, which will support all the cases above,
needs two boolean properties in DT node like: 'big-endian'
for case 2 and 'little-endian' for case 4, and for cases 1
and 3 they all will be absent.

Signed-off-by: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>
---
 drivers/base/regmap/regmap.c | 52 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 6a19515..8e8cea1 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -192,6 +192,13 @@ static void regmap_format_16_be(void *buf, unsigned int val, unsigned int shift)
 	b[0] = cpu_to_be16(val << shift);
 }
 
+static void regmap_format_16_le(void *buf, unsigned int val, unsigned int shift)
+{
+	__le16 *b = buf;
+
+	b[0] = cpu_to_le16(val << shift);
+}
+
 static void regmap_format_16_native(void *buf, unsigned int val,
 				    unsigned int shift)
 {
@@ -216,6 +223,13 @@ static void regmap_format_32_be(void *buf, unsigned int val, unsigned int shift)
 	b[0] = cpu_to_be32(val << shift);
 }
 
+static void regmap_format_32_le(void *buf, unsigned int val, unsigned int shift)
+{
+	__le32 *b = buf;
+
+	b[0] = cpu_to_le32(val << shift);
+}
+
 static void regmap_format_32_native(void *buf, unsigned int val,
 				    unsigned int shift)
 {
@@ -240,6 +254,13 @@ static unsigned int regmap_parse_16_be(const void *buf)
 	return be16_to_cpu(b[0]);
 }
 
+static unsigned int regmap_parse_16_le(const void *buf)
+{
+	const __le16 *b = buf;
+
+	return le16_to_cpu(b[0]);
+}
+
 static void regmap_parse_16_be_inplace(void *buf)
 {
 	__be16 *b = buf;
@@ -247,6 +268,13 @@ static void regmap_parse_16_be_inplace(void *buf)
 	b[0] = be16_to_cpu(b[0]);
 }
 
+static void regmap_parse_16_le_inplace(void *buf)
+{
+	__le16 *b = buf;
+
+	b[0] = le16_to_cpu(b[0]);
+}
+
 static unsigned int regmap_parse_16_native(const void *buf)
 {
 	return *(u16 *)buf;
@@ -269,6 +297,13 @@ static unsigned int regmap_parse_32_be(const void *buf)
 	return be32_to_cpu(b[0]);
 }
 
+static unsigned int regmap_parse_32_le(const void *buf)
+{
+	const __le32 *b = buf;
+
+	return le32_to_cpu(b[0]);
+}
+
 static void regmap_parse_32_be_inplace(void *buf)
 {
 	__be32 *b = buf;
@@ -276,6 +311,13 @@ static void regmap_parse_32_be_inplace(void *buf)
 	b[0] = be32_to_cpu(b[0]);
 }
 
+static void regmap_parse_32_le_inplace(void *buf)
+{
+	__le32 *b = buf;
+
+	b[0] = le32_to_cpu(b[0]);
+}
+
 static unsigned int regmap_parse_32_native(const void *buf)
 {
 	return *(u32 *)buf;
@@ -585,6 +627,11 @@ struct regmap *regmap_init(struct device *dev,
 			map->format.parse_val = regmap_parse_16_be;
 			map->format.parse_inplace = regmap_parse_16_be_inplace;
 			break;
+		case REGMAP_ENDIAN_LITTLE:
+			map->format.format_val = regmap_format_16_le;
+			map->format.parse_val = regmap_parse_16_le;
+			map->format.parse_inplace = regmap_parse_16_le_inplace;
+			break;
 		case REGMAP_ENDIAN_NATIVE:
 			map->format.format_val = regmap_format_16_native;
 			map->format.parse_val = regmap_parse_16_native;
@@ -606,6 +653,11 @@ struct regmap *regmap_init(struct device *dev,
 			map->format.parse_val = regmap_parse_32_be;
 			map->format.parse_inplace = regmap_parse_32_be_inplace;
 			break;
+		case REGMAP_ENDIAN_LITTLE:
+			map->format.format_val = regmap_format_32_le;
+			map->format.parse_val = regmap_parse_32_le;
+			map->format.parse_inplace = regmap_parse_32_le_inplace;
+			break;
 		case REGMAP_ENDIAN_NATIVE:
 			map->format.format_val = regmap_format_32_native;
 			map->format.parse_val = regmap_parse_32_native;
-- 
1.8.4


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