[PATCH 1/2] regmap: allow busses to request formatting with specific endianness

From: Stephen Warren <swarren@nvidia.com>

Add a field to struct regmap_bus that allows bus drivers to request that
register addresses and values be formatted with a specific endianness.

The default endianness is unchanged from current operation: Big.

Implement native endian formatting/parsing for 16- and 32-bit values.
This will be enough to support regmap-mmio.c.

Signed-off-by: Stephen Warren <swarren@nvidia.com>

I'm not 100% sure if this is the approach you had in mind. However, anything
more all-encompassing would require separating the concepts of endianness and
serialization that are coupled together in functions like
regmap_format_4_12_write, and I'm not sure how that would work conceptually.

drivers/base/regmap/regmap.c | 90 +++++++++++++++++++++++++++++++++++++--
include/linux/regmap.h | 9 ++++
2 files changed, 89 insertions(+), 10 deletions(-)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 2aa076e..33da8bd 100644
a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -119,13 +119,19 @@ static void regmap_format_8(void *buf, unsigned int val, unsigned int shift)
b[0] = val << shift;
}

-static void regmap_format_16(void *buf, unsigned int val, unsigned int shift)
+static void regmap_format_16_be(void *buf, unsigned int val, unsigned int shift)
{
__be16 *b = buf;

b[0] = cpu_to_be16(val << shift);
}

+static void regmap_format_16_native(void *buf, unsigned int val,
+ unsigned int shift)
+{
+ *(u16 *)buf = val << shift;
+}
+
static void regmap_format_24(void *buf, unsigned int val, unsigned int shift)
{
u8 *b = buf;
@@ -137,13 +143,19 @@ static void regmap_format_24(void *buf, unsigned int val, unsigned int shift)
b[2] = val;
}

-static void regmap_format_32(void *buf, unsigned int val, unsigned int shift)
+static void regmap_format_32_be(void *buf, unsigned int val, unsigned int shift)
{
__be32 *b = buf;

b[0] = cpu_to_be32(val << shift);
}

+static void regmap_format_32_native(void *buf, unsigned int val,
+ unsigned int shift)
+{
+ *(u32 *)buf = val << shift;
+}
+
static unsigned int regmap_parse_8(void *buf)
{
u8 *b = buf;
@@ -151,7 +163,7 @@ static unsigned int regmap_parse_8(void *buf)
return b[0];
}

-static unsigned int regmap_parse_16(void *buf)
+static unsigned int regmap_parse_16_be(void *buf)
{
__be16 *b = buf;

@@ -160,6 +172,11 @@ static unsigned int regmap_parse_16(void *buf)
return b[0];
}

+static unsigned int regmap_parse_16_native(void *buf)
+{
+ return *(u16 *)buf;
+}
+
static unsigned int regmap_parse_24(void *buf)
{
u8 *b = buf;
@@ -170,7 +187,7 @@ static unsigned int regmap_parse_24(void *buf)
return ret;
}

-static unsigned int regmap_parse_32(void *buf)
+static unsigned int regmap_parse_32_be(void *buf)
{
__be32 *b = buf;

@@ -179,6 +196,11 @@ static unsigned int regmap_parse_32(void *buf)
return b[0];
}

+static unsigned int regmap_parse_32_native(void *buf)
+{
+ return *(u32 *)buf;
+}
+
static void regmap_lock_mutex(struct regmap *map)
{
mutex_lock(&map->mutex);
@@ -279,6 +301,8 @@ struct regmap *regmap_init(struct device *dev,
case 2:
switch (config->val_bits) {
case 6:
+ if (bus->format_endian != REGMAP_ENDIAN_BIG)
+ goto err_map;
map->format.format_write = regmap_format_2_6_write;
break;
default:
@@ -289,6 +313,8 @@ struct regmap *regmap_init(struct device *dev,
case 4:
switch (config->val_bits) {
case 12:
+ if (bus->format_endian != REGMAP_ENDIAN_BIG)
+ goto err_map;
map->format.format_write = regmap_format_4_12_write;
break;
default:
@@ -299,6 +325,8 @@ struct regmap *regmap_init(struct device *dev,
case 7:
switch (config->val_bits) {
case 9:
+ if (bus->format_endian != REGMAP_ENDIAN_BIG)
+ goto err_map;
map->format.format_write = regmap_format_7_9_write;
break;
default:
@@ -309,6 +337,8 @@ struct regmap *regmap_init(struct device *dev,
case 10:
switch (config->val_bits) {
case 14:
+ if (bus->format_endian != REGMAP_ENDIAN_BIG)
+ goto err_map;
map->format.format_write = regmap_format_10_14_write;
break;
default:
@@ -321,11 +351,29 @@ struct regmap *regmap_init(struct device *dev,
break;

case 16:
- map->format.format_reg = regmap_format_16;
+ switch (bus->format_endian) {
+ case REGMAP_ENDIAN_BIG:
+ map->format.format_reg = regmap_format_16_be;
+ break;
+ case REGMAP_ENDIAN_NATIVE:
+ map->format.format_reg = regmap_format_16_native;
+ break;
+ default:
+ goto err_map;
+ }
break;

case 32:
- map->format.format_reg = regmap_format_32;
+ switch (bus->format_endian) {
+ case REGMAP_ENDIAN_BIG:
+ map->format.format_reg = regmap_format_32_be;
+ break;
+ case REGMAP_ENDIAN_NATIVE:
+ map->format.format_reg = regmap_format_32_native;
+ break;
+ default:
+ goto err_map;
+ }
break;

default:
@@ -338,16 +386,38 @@ struct regmap *regmap_init(struct device *dev,
map->format.parse_val = regmap_parse_8;
break;
case 16:
- map->format.format_val = regmap_format_16;
- map->format.parse_val = regmap_parse_16;
+ switch (bus->format_endian) {
+ case REGMAP_ENDIAN_BIG:
+ map->format.format_val = regmap_format_16_be;
+ map->format.parse_val = regmap_parse_16_be;
+ break;
+ case REGMAP_ENDIAN_NATIVE:
+ map->format.format_val = regmap_format_16_native;
+ map->format.parse_val = regmap_parse_16_native;
+ break;
+ default:
+ goto err_map;
+ }
break;
case 24:
+ if (bus->format_endian != REGMAP_ENDIAN_BIG)
+ goto err_map;
map->format.format_val = regmap_format_24;
map->format.parse_val = regmap_parse_24;
break;
case 32:
- map->format.format_val = regmap_format_32;
- map->format.parse_val = regmap_parse_32;
+ switch (bus->format_endian) {
+ case REGMAP_ENDIAN_BIG:
+ map->format.format_val = regmap_format_32_be;
+ map->format.parse_val = regmap_parse_32_be;
+ break;
+ case REGMAP_ENDIAN_NATIVE:
+ map->format.format_val = regmap_format_32_native;
+ map->format.parse_val = regmap_parse_32_native;
+ break;
+ default:
+ goto err_map;
+ }
break;
}

diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 56af22e..6452afd 100644
a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -121,6 +121,12 @@ typedef int (*regmap_hw_read)(void *context,
void *val_buf, size_t val_size);
typedef void (*regmap_hw_free_context)(void *context);

+enum regmap_endian {
+ REGMAP_ENDIAN_BIG = 0, /* Compatible default if unspecified */
+ REGMAP_ENDIAN_LITTLE,
+ REGMAP_ENDIAN_NATIVE,
+};
+
/**
* Description of a hardware bus for the register map infrastructure.
*
@@ -133,6 +139,8 @@ typedef void (*regmap_hw_free_context)(void *context);
* data.
* @read_flag_mask: Mask to be set in the top byte of the register when doing
* a read.
+ * @format_endian: Endianness for formatted register addresses, values, or
+ * serialized combinations thereof.
*/
struct regmap_bus {
bool fast_io;
@@ -141,6 +149,7 @@ struct regmap_bus {
regmap_hw_read read;
regmap_hw_free_context free_context;
u8 read_flag_mask;
+ enum regmap_endian format_endian;
};

struct regmap *regmap_init(struct device *dev,
1.7.0.4

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