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>

1 files changed, 52 insertions, 0 deletions

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 63e30ef096e2..a1beffb4b066 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;
@@ -608,6 +650,11 @@ 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;
@@ -629,6 +676,11 @@ 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;