regmap: implement LE formatting/parsing for 16/32-bit values.

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@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

---
This patch is pulled back from upstream:
commit 4aa8c0694c731e03eb660b92a3afe14859142381

Change-Id: I8ac391476c8be6e59fd38493baa1f8afe03fd3fc
Reviewed-on: http://git.am.freescale.net:8181/19854
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Zhengxiong Jin <Jason.Jin@freescale.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 7d689a1..022f596 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -201,6 +201,13 @@ 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)
 {
@@ -225,6 +232,13 @@ 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)
 {
@@ -249,6 +263,13 @@ 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;
@@ -256,6 +277,13 @@ 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;
@@ -278,6 +306,13 @@ 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;
@@ -285,6 +320,13 @@ 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;
@@ -593,6 +635,11 @@ 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;
@@ -614,6 +661,11 @@ 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;