[PATCHv3 resend 0/2] add DT endianness binding support.

[PATCHv3 resend 0/2] add DT endianness binding support.

[Xiubo Li]

Changes in V3 resend:
- Add arm list and rmk for review.
- Fix one comment from Markus Pargmann.

Changes in V3:
- Follow Mark Rutland's advice.
- Document common case of the endianess usage.

Changes in V2:
- Namespace the properties using the prefix sring.
- Add one binding ducomentation off regmap.



Xiubo Li (2):
  dt/bindings: Add the DT binding documentation for endianness
  regmap: add DT endianness binding support.

 .../devicetree/bindings/endianness/endianness.txt  |  47 +++++++
 drivers/base/regmap/regmap-i2c.c                   |   2 +
 drivers/base/regmap/regmap-spi.c                   |   2 +
 drivers/base/regmap/regmap.c                       | 147 +++++++++++++++++++--
 4 files changed, 187 insertions(+), 11 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/endianness/endianness.txt

-- 
1.8.4

[PATCHv3 resend 1/2] dt/bindings: Add the DT binding documentation for endianness

[Xiubo Li]

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
---
 .../devicetree/bindings/endianness/endianness.txt  | 47 ++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/endianness/endianness.txt

diff --git a/Documentation/devicetree/bindings/endianness/endianness.txt b/Documentation/devicetree/bindings/endianness/endianness.txt
new file mode 100644
index 0000000..49458a1
--- /dev/null
+++ b/Documentation/devicetree/bindings/endianness/endianness.txt
@@ -0,0 +1,47 @@
+Device-Tree binding for device endianness
+
+The endianness mode of CPU & Device scenarios:
+Index    CPU       Device     Endianess flag for DT bool property
+------------------------------------------------------------
+1        LE        LE         -
+2        LE        BE         'big-endian{,-*}'
+3        BE        BE         -
+4        BE        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{,-*}: this is one boolean property.
+
+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{,-*};
+};
-- 
1.8.4

[PATCHv3 resend 2/2] regmap: add DT endianness binding support.

[Xiubo Li]

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@freescale.com>
---
 drivers/base/regmap/regmap-i2c.c |   2 +
 drivers/base/regmap/regmap-spi.c |   2 +
 drivers/base/regmap/regmap.c     | 147 ++++++++++++++++++++++++++++++++++++---
 3 files changed, 140 insertions(+), 11 deletions(-)

diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index fa6bf52..1f603a6 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -96,6 +96,8 @@ 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 37f12ae..377fa29 100644
--- a/drivers/base/regmap/regmap-spi.c
+++ b/drivers/base/regmap/regmap-spi.c
@@ -110,6 +110,8 @@ 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 8e8cea1..91faf7d 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>
 
@@ -422,6 +423,132 @@ static void regmap_range_exit(struct regmap *map)
 	kfree(map->selector_work_buf);
 }
 
+enum regmap_endian_type {
+	REGMAP_ENDIAN_REG,
+	REGMAP_ENDIAN_VAL,
+};
+
+/**
+ * of_regmap_endian_by_type() - Parse and lookup the endian referenced
+ * by a device node
+ * @np: pointer to clock consumer node
+ * @type: type of endian for values or registers
+ *
+ * This function parses the device endian property, and uses them to
+ * determine the endian of the 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 endian from driver's config,
+	 * this is to be compatible with the none DT or the old drivers.
+	 * From the driver's config the endian 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 endian parsing from driver's config is REGMAP_ENDIAN_DEFAULT,
+	 * that means maybe we are using the DT node to specify the endianness.
+	 */
+	if (*endian != REGMAP_ENDIAN_DEFAULT)
+		return 0;
+
+	/*
+	 * Secondly, try to parse the endian from DT node if the
+	 * driver config does not specify it.
+	 * From the DT node the endian 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 endian parsing 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 endianess.
+	 */
+	if (*endian != REGMAP_ENDIAN_NATIVE)
+		return 0;
+
+	/*
+	 * Finally, try to parse the endian from regmap bus config
+	 * if in device's DT node the endian 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
  *
@@ -518,17 +645,15 @@ 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

Re: [PATCHv3 resend 1/2] dt/bindings: Add the DT binding documentation for endianness

[Kumar Gala]

On Apr 30, 2014, at 1:52 AM, Xiubo Li <Li.Xiubo@freescale.com> wrote:

> Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
> ---
> .../devicetree/bindings/endianness/endianness.txt  | 47 ++++++++++++++++++++++
> 1 file changed, 47 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/endianness/endianness.txt
> 
> diff --git a/Documentation/devicetree/bindings/endianness/endianness.txt b/Documentation/devicetree/bindings/endianness/endianness.txt
> new file mode 100644
> index 0000000..49458a1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/endianness/endianness.txt
> @@ -0,0 +1,47 @@
> +Device-Tree binding for device endianness
> +
> +The endianness mode of CPU & Device scenarios:
> +Index    CPU       Device     Endianess flag for DT bool property
> +------------------------------------------------------------
> +1        LE        LE         -
> +2        LE        BE         'big-endian{,-*}'
> +3        BE        BE         -
> +4        BE        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{,-*}: this is one boolean property.
> +

what is the {,-*} all about?

> +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{,-*};
> +};
> -- 
> 1.8.4
> 

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