Merge tag 'dt-endian' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap into asoc-fsl

regmap: Device tree endianness support

This adds generic support for specifying endianess for register map in
the DT.

4 files changed, 114 insertions, 11 deletions

diff --git a/Documentation/devicetree/bindings/regmap/regmap.txt b/Documentation/devicetree/bindings/regmap/regmap.txt
new file mode 100644
index 000000000000..b494f8b8ef72
--- /dev/null
+++ b/Documentation/devicetree/bindings/regmap/regmap.txt
@@ -0,0 +1,47 @@
+Device-Tree binding for regmap
+
+The endianness mode of CPU & Device scenarios:
+Index     Device     Endianness properties
+---------------------------------------------------
+1         BE         'big-endian'
+2         LE         'little-endian'
+
+For one device driver, which will run in different scenarios above
+on different SoCs using the devicetree, we need one way to simplify
+this.
+
+Required properties:
+- {big,little}-endian: these are boolean properties, if absent
+  meaning that the CPU and the Device are in the same endianness mode,
+  these properties are for register values and all the buffers only.
+
+Examples:
+Scenario 1 : CPU in LE mode & device in LE mode.
+dev: dev@40031000 {
+              compatible = "name";
+              reg = <0x40031000 0x1000>;
+              ...
+};
+
+Scenario 2 : CPU in LE mode & device in BE mode.
+dev: dev@40031000 {
+              compatible = "name";
+              reg = <0x40031000 0x1000>;
+              ...
+              big-endian;
+};
+
+Scenario 3 : CPU in BE mode & device in BE mode.
+dev: dev@40031000 {
+              compatible = "name";
+              reg = <0x40031000 0x1000>;
+              ...
+};
+
+Scenario 4 : CPU in BE mode & device in LE mode.
+dev: dev@40031000 {
+              compatible = "name";
+              reg = <0x40031000 0x1000>;
+              ...
+              little-endian;
+};
diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index ca193d1ef47c..053150a7f9f2 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -168,6 +168,8 @@ static struct regmap_bus regmap_i2c = {
         .write = regmap_i2c_write,
         .gather_write = regmap_i2c_gather_write,
         .read = regmap_i2c_read,
+        .reg_format_endian_default = REGMAP_ENDIAN_BIG,
+        .val_format_endian_default = REGMAP_ENDIAN_BIG,
 };
 
 static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
diff --git a/drivers/base/regmap/regmap-spi.c b/drivers/base/regmap/regmap-spi.c
index 0eb3097c0d76..53d1148e80a0 100644
--- a/drivers/base/regmap/regmap-spi.c
+++ b/drivers/base/regmap/regmap-spi.c
@@ -109,6 +109,8 @@ static struct regmap_bus regmap_spi = {
         .async_alloc = regmap_spi_async_alloc,
         .read = regmap_spi_read,
         .read_flag_mask = 0x80,
+        .reg_format_endian_default = REGMAP_ENDIAN_BIG,
+        .val_format_endian_default = REGMAP_ENDIAN_BIG,
 };
 
 /**
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 78f43fb2fe84..01ae4b829360 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -15,6 +15,7 @@
 #include <linux/export.h>
 #include <linux/mutex.h>
 #include <linux/err.h>
+#include <linux/of.h>
 #include <linux/rbtree.h>
 #include <linux/sched.h>
 
@@ -448,6 +449,66 @@ int regmap_attach_dev(struct device *dev, struct regmap *map,
 }
 EXPORT_SYMBOL_GPL(regmap_attach_dev);
 
+static enum regmap_endian regmap_get_reg_endian(const struct regmap_bus *bus,
+                                        const struct regmap_config *config)
+{
+        enum regmap_endian endian;
+
+        /* Retrieve the endianness specification from the regmap config */
+        endian = config->reg_format_endian;
+
+        /* If the regmap config specified a non-default value, use that */
+        if (endian != REGMAP_ENDIAN_DEFAULT)
+                return endian;
+
+        /* Retrieve the endianness specification from the bus config */
+        if (bus && bus->reg_format_endian_default)
+                endian = bus->reg_format_endian_default;
+
+        /* If the bus specified a non-default value, use that */
+        if (endian != REGMAP_ENDIAN_DEFAULT)
+                return endian;
+
+        /* Use this if no other value was found */
+        return REGMAP_ENDIAN_BIG;
+}
+
+static enum regmap_endian regmap_get_val_endian(struct device *dev,
+                                        const struct regmap_bus *bus,
+                                        const struct regmap_config *config)
+{
+        struct device_node *np = dev->of_node;
+        enum regmap_endian endian;
+
+        /* Retrieve the endianness specification from the regmap config */
+        endian = config->val_format_endian;
+
+        /* If the regmap config specified a non-default value, use that */
+        if (endian != REGMAP_ENDIAN_DEFAULT)
+                return endian;
+
+        /* Parse the device's DT node for an endianness specification */
+        if (of_property_read_bool(np, "big-endian"))
+                endian = REGMAP_ENDIAN_BIG;
+        else if (of_property_read_bool(np, "little-endian"))
+                endian = REGMAP_ENDIAN_LITTLE;
+
+        /* If the endianness was specified in DT, use that */
+        if (endian != REGMAP_ENDIAN_DEFAULT)
+                return endian;
+
+        /* Retrieve the endianness specification from the bus config */
+        if (bus && bus->val_format_endian_default)
+                endian = bus->val_format_endian_default;
+
+        /* If the bus specified a non-default value, use that */
+        if (endian != REGMAP_ENDIAN_DEFAULT)
+                return endian;
+
+        /* Use this if no other value was found */
+        return REGMAP_ENDIAN_BIG;
+}
+
 /**
  * regmap_init(): Initialise register map
  *
@@ -551,17 +612,8 @@ struct regmap *regmap_init(struct device *dev,
                 map->reg_read  = _regmap_bus_read;
         }
 
-        reg_endian = config->reg_format_endian;
-        if (reg_endian == REGMAP_ENDIAN_DEFAULT)
-                reg_endian = bus->reg_format_endian_default;
-        if (reg_endian == REGMAP_ENDIAN_DEFAULT)
-                reg_endian = REGMAP_ENDIAN_BIG;
-
-        val_endian = config->val_format_endian;
-        if (val_endian == REGMAP_ENDIAN_DEFAULT)
-                val_endian = bus->val_format_endian_default;
-        if (val_endian == REGMAP_ENDIAN_DEFAULT)
-                val_endian = REGMAP_ENDIAN_BIG;
+        reg_endian = regmap_get_reg_endian(bus, config);
+        val_endian = regmap_get_val_endian(dev, bus, config);
 
         switch (config->reg_bits + map->reg_shift) {
         case 2: