[PATCHv4 2/2] regmap: add DT endianness binding support.

From: Xiubo Li
Date: Thu May 08 2014 - 22:50:58 EST

For many drivers which will support rich endianness of CPU<-->Dev
need define DT properties by itself without the binding support.

The endianness using regmap:
Index CPU Device Endianess flag for DT bool property
------------------------------------------------------------
1 LE LE -
2 LE BE 'big-endian-{val,reg}'
3 BE BE -
4 BE LE 'little-endian-{val,reg}'

Please see the following documetation for detail:
Documentation/devicetree/bindings/endianness/endianness.txt

Signed-off-by: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>
---
drivers/base/regmap/regmap-i2c.c | 2 +
drivers/base/regmap/regmap-spi.c | 2 +
drivers/base/regmap/regmap.c | 148 ++++++++++++++++++++++++++++++++++++---
3 files changed, 141 insertions(+), 11 deletions(-)

diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index ebd1895..9b0fbf9 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -95,6 +95,8 @@ 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,
};

/**
diff --git a/drivers/base/regmap/regmap-spi.c b/drivers/base/regmap/regmap-spi.c
index 0eb3097..53d1148 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 63e30ef..4805246 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>

@@ -402,6 +403,133 @@ int regmap_attach_dev(struct device *dev, struct regmap *map,
}
EXPORT_SYMBOL_GPL(regmap_attach_dev);

+enum regmap_endian_type {
+ REGMAP_ENDIAN_REG,
+ REGMAP_ENDIAN_VAL,
+};
+
+/**
+ * of_regmap_endian_by_type() - Parses and lookups the endianness referenced
+ * by a device node
+ * @np: pointer to the consumer device node
+ * @type: endianness type for values or registers
+ *
+ * This function parses the device endianness properties, and uses them to
+ * determine the endianness of the device's registers and values.
+ */
+static int of_regmap_endian_by_type(struct device_node *np,
+ enum regmap_endian_type type,
+ enum regmap_endian *endian)
+{
+ if (!endian)
+ return -EINVAL;
+
+ switch (type) {
+ case REGMAP_ENDIAN_REG:
+ if (of_property_read_bool(np, "big-endian-reg"))
+ *endian = REGMAP_ENDIAN_BIG;
+ else if (of_property_read_bool(np, "little-endian-reg"))
+ *endian = REGMAP_ENDIAN_LITTLE;
+ else
+ *endian = REGMAP_ENDIAN_NATIVE;
+ break;
+ case REGMAP_ENDIAN_VAL:
+ if (of_property_read_bool(np, "big-endian-val"))
+ *endian = REGMAP_ENDIAN_BIG;
+ else if (of_property_read_bool(np, "little-endian-val"))
+ *endian = REGMAP_ENDIAN_LITTLE;
+ else
+ *endian = REGMAP_ENDIAN_NATIVE;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int of_regmap_get_endian(struct device *dev,
+ const struct regmap_bus *bus,
+ const struct regmap_config *config,
+ enum regmap_endian_type type,
+ enum regmap_endian *endian)
+{
+ int ret;
+
+ if (!endian || !config)
+ return -EINVAL;
+
+ /*
+ * Firstly, try to parse the endianness from driver's config,
+ * this is to be compatible with the none DT or the old drivers.
+ * From the driver's config the endianness value maybe:
+ * REGMAP_ENDIAN_BIG,
+ * REGMAP_ENDIAN_LITTLE,
+ * REGMAP_ENDIAN_NATIVE,
+ * REGMAP_ENDIAN_DEFAULT.
+ */
+ switch (type) {
+ case REGMAP_ENDIAN_REG:
+ *endian = config->reg_format_endian;
+ break;
+ case REGMAP_ENDIAN_VAL:
+ *endian = config->val_format_endian;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /*
+ * If the endianness parsed from driver config is
+ * REGMAP_ENDIAN_DEFAULT, that means maybe we are using the DT
+ * node to specify the endianness information.
+ */
+ if (*endian != REGMAP_ENDIAN_DEFAULT)
+ return 0;
+
+ /*
+ * Secondly, try to parse the endianness from DT node if the
+ * driver config does not specify it.
+ * From the DT node the endianness value maybe:
+ * REGMAP_ENDIAN_BIG,
+ * REGMAP_ENDIAN_LITTLE,
+ * REGMAP_ENDIAN_NATIVE,
+ */
+ if (dev) {
+ ret = of_regmap_endian_by_type(dev->of_node, type, endian);
+ if (ret < 0)
+ return ret;
+ }
+
+ /*
+ * If the endianness parsed from DT node is REGMAP_ENDIAN_NATIVE, that
+ * maybe means the DT does not care the endianness or it should use
+ * the regmap bus's default endianness, then we should try to check
+ * whether the regmap bus has specified the default endianness.
+ */
+ if (*endian != REGMAP_ENDIAN_NATIVE)
+ return 0;
+
+ /*
+ * Finally, try to parse the endianness from regmap bus config
+ * if in device's DT node the endianness property is absent.
+ */
+ switch (type) {
+ case REGMAP_ENDIAN_REG:
+ if (bus && bus->reg_format_endian_default)
+ *endian = bus->reg_format_endian_default;
+ break;
+ case REGMAP_ENDIAN_VAL:
+ if (bus && bus->val_format_endian_default)
+ *endian = bus->val_format_endian_default;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
/**
* regmap_init(): Initialise register map
*
@@ -499,17 +627,15 @@ 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;
+ ret = of_regmap_get_endian(dev, bus, config, REGMAP_ENDIAN_REG,
+ &reg_endian);
+ if (ret)
+ return ERR_PTR(ret);
+
+ ret = of_regmap_get_endian(dev, bus, config, REGMAP_ENDIAN_VAL,
+ &val_endian);
+ if (ret)
+ return ERR_PTR(ret);

switch (config->reg_bits + map->reg_shift) {
case 2:
--
1.8.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/