[PATCH] regmap: Add REGMAP_ENDIAN_SWAP support for values.

[Xiubo Li]

For the following cases of the SoCs using regmap-mmio:

Index   CPU mode   Device mode   Need Bytes Swap ?
--------------------------------------------------
1       LE         LE            No
2       LE         BE            Yes
3       BE         BE            No
4       BE         LE            Yes

And possiblly one Device will be used in all the endianness modes
above with the same device driver, then for the 1 and 3 cases the
REGMAP_ENDIAN_NATIVE is okey, but for the 2 and 4 cases, the
REGMAP_ENDIAN_SWAP is needed.

For the DT node, just one property like 'endian-swap' will be okey
for cases 2 and 4.

----

Certainly, for the 2 case, we can just use REGMAP_ENDIAN_BIG
instead of REGMAP_ENDIAN_SWAP, and then we should add one DT node
property like 'big-endian'.

While for the 4 case, we can just use REGMAP_ENDIAN_LITTLE instead
of REGMAP_ENDIAN_SWAP, and then we should add one DT node property
like 'little-endian'. Another question is that the
REGMAP_ENDIAN_LITTLE hasn't support by regmap core yet.

And using the REGMAP_ENDIAN_BIG and REGMAP_ENDIAN_LITTLE will make
the driver a bit more complex, and also the usage of it.

Thus using the REGMAP_ENDIAN_SWAP and one DT node property like
'endian-swap' will make the driver more easy to develop and to use
for all the above possible cases.

Signed-off-by: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>
---
 drivers/base/regmap/regmap.c | 56 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/regmap.h       |  1 +
 2 files changed, 57 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 6a19515..71e0a0d 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -192,6 +192,14 @@ 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_swap(void *buf, unsigned int val,
+				  unsigned int shift)
+{
+	__u16 *b = buf;
+
+	b[0] = __swab16(val << shift);
+}
+
 static void regmap_format_16_native(void *buf, unsigned int val,
 				    unsigned int shift)
 {
@@ -216,6 +224,14 @@ 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_swap(void *buf, unsigned int val,
+				  unsigned int shift)
+{
+	__u32 *b = buf;
+
+	b[0] = __swab32(val << shift);
+}
+
 static void regmap_format_32_native(void *buf, unsigned int val,
 				    unsigned int shift)
 {
@@ -240,6 +256,13 @@ static unsigned int regmap_parse_16_be(const void *buf)
 	return be16_to_cpu(b[0]);
 }
 
+static unsigned int regmap_parse_16_swap(const void *buf)
+{
+	const __u16 *b = buf;
+
+	return __swab16(b[0]);
+}
+
 static void regmap_parse_16_be_inplace(void *buf)
 {
 	__be16 *b = buf;
@@ -247,6 +270,13 @@ static void regmap_parse_16_be_inplace(void *buf)
 	b[0] = be16_to_cpu(b[0]);
 }
 
+static void regmap_parse_16_swap_inplace(void *buf)
+{
+	__u16 *b = buf;
+
+	b[0] = __swab16(b[0]);
+}
+
 static unsigned int regmap_parse_16_native(const void *buf)
 {
 	return *(u16 *)buf;
@@ -269,6 +299,13 @@ static unsigned int regmap_parse_32_be(const void *buf)
 	return be32_to_cpu(b[0]);
 }
 
+static unsigned int regmap_parse_32_swap(const void *buf)
+{
+	const __u32 *b = buf;
+
+	return __swab32((b[0]));
+}
+
 static void regmap_parse_32_be_inplace(void *buf)
 {
 	__be32 *b = buf;
@@ -276,6 +313,13 @@ static void regmap_parse_32_be_inplace(void *buf)
 	b[0] = be32_to_cpu(b[0]);
 }
 
+static void regmap_parse_32_swap_inplace(void *buf)
+{
+	__u32 *b = buf;
+
+	b[0] = __swab32(b[0]);
+}
+
 static unsigned int regmap_parse_32_native(const void *buf)
 {
 	return *(u32 *)buf;
@@ -585,6 +629,12 @@ 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_SWAP:
+			map->format.format_val = regmap_format_16_swap;
+			map->format.parse_val = regmap_parse_16_swap;
+			map->format.parse_inplace =
+					regmap_parse_16_swap_inplace;
+			break;
 		case REGMAP_ENDIAN_NATIVE:
 			map->format.format_val = regmap_format_16_native;
 			map->format.parse_val = regmap_parse_16_native;
@@ -606,6 +656,12 @@ 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_SWAP:
+			map->format.format_val = regmap_format_32_swap;
+			map->format.parse_val = regmap_parse_32_swap;
+			map->format.parse_inplace =
+					regmap_parse_32_swap_inplace;
+			break;
 		case REGMAP_ENDIAN_NATIVE:
 			map->format.format_val = regmap_format_32_native;
 			map->format.parse_val = regmap_parse_32_native;
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 4149f1a..a2e68f3 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -56,6 +56,7 @@ enum regmap_endian {
 	REGMAP_ENDIAN_DEFAULT = 0,
 	REGMAP_ENDIAN_BIG,
 	REGMAP_ENDIAN_LITTLE,
+	REGMAP_ENDIAN_SWAP,
 	REGMAP_ENDIAN_NATIVE,
 };
 
-- 
1.8.4


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