diff mbox

[2/3] i2c: mux: Add dt support to i2c-mux-gpio driver

Message ID 1348241535-27754-3-git-send-email-maxime.ripard@free-electrons.com (mailing list archive)
State New, archived
Headers show

Commit Message

Maxime Ripard Sept. 21, 2012, 3:32 p.m. UTC 
Allow the i2c-mux-gpio to be used by a device tree enabled device. The
bindings are inspired by the one found in the i2c-mux-pinctrl driver.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
 .../devicetree/bindings/i2c/i2c-mux-gpio.txt       |   86 +++++++++++
 drivers/i2c/muxes/i2c-mux-gpio.c                   |  158 +++++++++++++++-----
 2 files changed, 208 insertions(+), 36 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt

Comments

Stephen Warren Sept. 21, 2012, 4:37 p.m. UTC | #1 
On 09/21/2012 09:32 AM, Maxime Ripard wrote:
> Allow the i2c-mux-gpio to be used by a device tree enabled device. The
> bindings are inspired by the one found in the i2c-mux-pinctrl driver.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

> +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt
> @@ -0,0 +1,86 @@
> +GPIO-based I2C Bus Mux
> +
> +This binding describes an I2C bus multiplexer that uses GPIOs to
> +route the I2C signals.
> +
> +                                 +-----+  +-----+
> +                                 | dev |  | dev |
> +    +------------------------+   +-----+  +-----+
> +    | SoC                    |      |        |
> +    |                   /----|------+--------+
> +    |   +---+   +------+     | child bus A, on GPIO value set to 0
> +    |   |I2C|---| Mux  |     |
> +    |   +---+   +--+---+     | child bus B, on GPIO value set to 1
> +    |              |    \----|------+--------+--------+
> +    |   +------+   |         |      |        |        |
> +    |   | GPIO |---+         |  +-----+  +-----+  +-----+
> +    |   +------+             |  | dev |  | dev |  | dev |
> +    +------------------------+  +-----+  +-----+  +-----+

The "Mux" box should be outside the SoC, since it isn't part of the SoC
itself but something external.

> +Required properties:
> +- compatible: i2c-mux-gpio
> +- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
> +  port is connected to.
> +
> +Also required are:
> +
> +- muxer-gpios: list of gpios to use to control the muxer

Perhaps just "mux-gpios"? Bikeshedding, I know...

> +* Standard I2C mux properties. See mux.txt in this directory.
> +
> +* I2C child bus nodes. See mux.txt in this directory.
> +
> +For each i2c child nodes, an I2C child bus will be created. They will
> +be numbered based on the reg property of each nodes.

s/nodes/node/ in both of the two lines above.

> +Whenever an access is made to a device on a child bus, the value set
> +in the revelant node's reg property will be outputed using the list of

s/outputed/output/

> +GPIOs, the first in the list holding the most-significant value.
> +
> +If an idle state is defined, using the idle-state (optional) property,

The idle-state property isn't documented in the list of properties above.

> +whenever an access is not being made to a device on a child bus, the
> +idle value will be programmed into the GPIOs.
> +
> +If an idle state is not defined, the most recently used value will be
> +left programmed into hardware whenever no access is being made of a
> +device on a child bus.
> +
> +Example:
> +	i2cmux {
> +		compatible = "i2c-mux-gpio";
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		muxer-gpios = <&gpio1 22 0 &gpio1 23 0>;
> +		i2c-parent = <&i2c1>;
> +
> +		i2c@0 {
> +			reg = <0>;
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +		};
> +
> +		i2c@1 {
> +		      reg = <1>;
> +		      #address-cells = <1>;
> +		      #size-cells = <0>;
> +		};

The indentation above is a mix of TABs and spaces, and is inconsistent
between nodes; just TABs would be best.

> +
> +		i2c@2 {
> +			reg = <2>;
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +		};

I'm not sure it's a good idea to have example bus nodes that are empty;
why not leave out two of the options, and put some device on each of the
buses that is defined?


> +		i2c@3 {
> +			reg = <3>;
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			pca9555: pca9555@20 {
> +				compatible = "nxp,pca9555";
> +				gpio-controller;
> +				#gpio-cells = <2>;
> +				reg = <0x20>;
> +			};
> +		};
> +	};

> diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c

> +#ifdef CONFIG_OF
> +static int __devinit i2c_mux_gpio_probe_dt(struct gpiomux *mux,
> +					struct platform_device *pdev)

> +	mux->data->n_values = of_get_child_count(np);
> +
> +	values = devm_kzalloc(&pdev->dev, sizeof(*mux->data->values), GFP_KERNEL);

Don't you need to multiply the size by mux->data->n_values?

> +	gpios = devm_kzalloc(&pdev->dev, mux->data->n_gpios, GFP_KERNEL);

Don't you need to multiple the size by sizeof(*gpios) here?
diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt
new file mode 100644
index 0000000..f2bd120
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt
@@ -0,0 +1,86 @@ 
+GPIO-based I2C Bus Mux
+
+This binding describes an I2C bus multiplexer that uses GPIOs to
+route the I2C signals.
+
+                                 +-----+  +-----+
+                                 | dev |  | dev |
+    +------------------------+   +-----+  +-----+
+    | SoC                    |      |        |
+    |                   /----|------+--------+
+    |   +---+   +------+     | child bus A, on GPIO value set to 0
+    |   |I2C|---| Mux  |     |
+    |   +---+   +--+---+     | child bus B, on GPIO value set to 1
+    |              |    \----|------+--------+--------+
+    |   +------+   |         |      |        |        |
+    |   | GPIO |---+         |  +-----+  +-----+  +-----+
+    |   +------+             |  | dev |  | dev |  | dev |
+    +------------------------+  +-----+  +-----+  +-----+
+
+Required properties:
+- compatible: i2c-mux-gpio
+- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
+  port is connected to.
+
+Also required are:
+
+- muxer-gpios: list of gpios to use to control the muxer
+
+* Standard I2C mux properties. See mux.txt in this directory.
+
+* I2C child bus nodes. See mux.txt in this directory.
+
+For each i2c child nodes, an I2C child bus will be created. They will
+be numbered based on the reg property of each nodes.
+
+Whenever an access is made to a device on a child bus, the value set
+in the revelant node's reg property will be outputed using the list of
+GPIOs, the first in the list holding the most-significant value.
+
+If an idle state is defined, using the idle-state (optional) property,
+whenever an access is not being made to a device on a child bus, the
+idle value will be programmed into the GPIOs.
+
+If an idle state is not defined, the most recently used value will be
+left programmed into hardware whenever no access is being made of a
+device on a child bus.
+
+Example:
+	i2cmux {
+		compatible = "i2c-mux-gpio";
+		#address-cells = <1>;
+		#size-cells = <0>;
+		muxer-gpios = <&gpio1 22 0 &gpio1 23 0>;
+		i2c-parent = <&i2c1>;
+
+		i2c@0 {
+			reg = <0>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+		};
+
+		i2c@1 {
+		      reg = <1>;
+		      #address-cells = <1>;
+		      #size-cells = <0>;
+		};
+
+		i2c@2 {
+			reg = <2>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+		};
+
+		i2c@3 {
+			reg = <3>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			pca9555: pca9555@20 {
+				compatible = "nxp,pca9555";
+				gpio-controller;
+				#gpio-cells = <2>;
+				reg = <0x20>;
+			};
+		};
+	};
diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
index fbc400b..108caaa 100644
--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -16,26 +16,28 @@ 
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/gpio.h>
+#include <linux/of_i2c.h>
+#include <linux/of_gpio.h>
 
 struct gpiomux {
 	struct i2c_adapter *parent;
 	struct i2c_adapter **adap; /* child busses */
-	struct i2c_mux_gpio_platform_data data;
+	struct i2c_mux_gpio_platform_data *data;
 };
 
 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
 {
 	int i;
 
-	for (i = 0; i < mux->data.n_gpios; i++)
-		gpio_set_value(mux->data.gpios[i], val & (1 << i));
+	for (i = 0; i < mux->data->n_gpios; i++)
+		gpio_set_value(mux->data->gpios[i], val & (1 << i));
 }
 
 static int i2c_mux_gpio_select(struct i2c_adapter *adap, void *data, u32 chan)
 {
 	struct gpiomux *mux = data;
 
-	i2c_mux_gpio_set(mux, mux->data.values[chan]);
+	i2c_mux_gpio_set(mux, mux->data->values[chan]);
 
 	return 0;
 }
@@ -44,67 +46,146 @@  static int i2c_mux_gpio_deselect(struct i2c_adapter *adap, void *data, u32 chan)
 {
 	struct gpiomux *mux = data;
 
-	i2c_mux_gpio_set(mux, mux->data.idle);
+	i2c_mux_gpio_set(mux, mux->data->idle);
 
 	return 0;
 }
 
+#ifdef CONFIG_OF
+static int __devinit i2c_mux_gpio_probe_dt(struct gpiomux *mux,
+					struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device_node *adapter_np, *child;
+	struct i2c_adapter *adapter;
+	unsigned *values, *gpios;
+	int i = 0;
+
+	if (!np)
+		return 0;
+
+	mux->data = devm_kzalloc(&pdev->dev, sizeof(*mux->data),
+				GFP_KERNEL);
+	if (!mux->data) {
+		dev_err(&pdev->dev, "Cannot allocate platform_data");
+		return -ENOMEM;
+	}
+
+	adapter_np = of_parse_phandle(np, "i2c-parent", 0);
+	if (!adapter_np) {
+		dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
+		return -ENODEV;
+	}
+	adapter = of_find_i2c_adapter_by_node(adapter_np);
+	if (!adapter) {
+		dev_err(&pdev->dev, "Cannot find parent bus\n");
+		return -ENODEV;
+	}
+	mux->data->parent = i2c_adapter_id(adapter);
+	put_device(&adapter->dev);
+
+	mux->data->n_values = of_get_child_count(np);
+
+	values = devm_kzalloc(&pdev->dev, sizeof(*mux->data->values), GFP_KERNEL);
+	if (!values) {
+		dev_err(&pdev->dev, "Cannot allocate values array");
+		return -ENOMEM;
+	}
+
+	for_each_child_of_node(np, child) {
+		of_property_read_u32(child, "reg", values + i);
+		i++;
+	}
+	mux->data->values = values;
+
+	if (of_property_read_u32(np, "idle-state", &mux->data->idle))
+		mux->data->idle = I2C_MUX_GPIO_NO_IDLE;
+
+	mux->data->n_gpios = of_gpio_named_count(np, "muxer-gpios");
+	if (mux->data->n_gpios < 0) {
+		dev_err(&pdev->dev, "Missing muxer-gpios property in the DT.\n");
+		return -EINVAL;
+	}
+
+	gpios = devm_kzalloc(&pdev->dev, mux->data->n_gpios, GFP_KERNEL);
+	if (!gpios) {
+		dev_err(&pdev->dev, "Cannot allocate gpios array");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < mux->data->n_gpios; i++)
+		gpios[i] = of_get_named_gpio(np, "muxer-gpios", i);
+
+	mux->data->gpios = gpios;
+
+	return 0;
+}
+#else
+static int __devinit i2c_mux_gpio_probe_dt(struct gpiomux *mux,
+					struct platform_device *pdev)
+{
+	return 0;
+}
+#endif
+
 static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
 {
 	struct gpiomux *mux;
-	struct i2c_mux_gpio_platform_data *pdata;
 	struct i2c_adapter *parent;
 	int (*deselect) (struct i2c_adapter *, void *, u32);
 	unsigned initial_state;
 	int i, ret;
 
-	pdata = pdev->dev.platform_data;
-	if (!pdata) {
-		dev_err(&pdev->dev, "Missing platform data\n");
-		return -ENODEV;
+	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+	if (!mux) {
+		dev_err(&pdev->dev, "Cannot allocate gpiomux structure");
+		return -ENOMEM;
 	}
 
-	parent = i2c_get_adapter(pdata->parent);
+	platform_set_drvdata(pdev, mux);
+
+	mux->data = pdev->dev.platform_data;
+	if (!mux->data) {
+		ret = i2c_mux_gpio_probe_dt(mux, pdev);
+		if (ret < 0)
+			return ret;
+	}
+
+	parent = i2c_get_adapter(mux->data->parent);
 	if (!parent) {
 		dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
-			pdata->parent);
+			mux->data->parent);
 		return -ENODEV;
 	}
 
-	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
-	if (!mux) {
-		ret = -ENOMEM;
-		goto alloc_failed;
-	}
-
 	mux->parent = parent;
-	mux->data = *pdata;
 	mux->adap = devm_kzalloc(&pdev->dev,
-				sizeof(struct i2c_adapter *) * pdata->n_values,
+				sizeof(struct i2c_adapter *) * mux->data->n_values,
 				GFP_KERNEL);
 	if (!mux->adap) {
+		dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
 		ret = -ENOMEM;
 		goto alloc_failed;
 	}
 
-	if (pdata->idle != I2C_MUX_GPIO_NO_IDLE) {
-		initial_state = pdata->idle;
+	if (mux->data->idle != I2C_MUX_GPIO_NO_IDLE) {
+		initial_state = mux->data->idle;
 		deselect = i2c_mux_gpio_deselect;
 	} else {
-		initial_state = pdata->values[0];
+		initial_state = mux->data->values[0];
 		deselect = NULL;
 	}
 
-	for (i = 0; i < pdata->n_gpios; i++) {
-		ret = gpio_request(pdata->gpios[i], "i2c-mux-gpio");
+	for (i = 0; i < mux->data->n_gpios; i++) {
+		ret = gpio_request(mux->data->gpios[i], "i2c-mux-gpio");
 		if (ret)
 			goto err_request_gpio;
-		gpio_direction_output(pdata->gpios[i],
+		gpio_direction_output(mux->data->gpios[i],
 				      initial_state & (1 << i));
 	}
 
-	for (i = 0; i < pdata->n_values; i++) {
-		u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
+	for (i = 0; i < mux->data->n_values; i++) {
+		u32 nr = mux->data->base_nr ? (mux->data->base_nr + i) : 0;
 
 		mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr, i,
 						   i2c_mux_gpio_select, deselect);
@@ -116,19 +197,17 @@  static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
 	}
 
 	dev_info(&pdev->dev, "%d port mux on %s adapter\n",
-		 pdata->n_values, parent->name);
-
-	platform_set_drvdata(pdev, mux);
+		 mux->data->n_values, parent->name);
 
 	return 0;
 
 add_adapter_failed:
 	for (; i > 0; i--)
 		i2c_del_mux_adapter(mux->adap[i - 1]);
-	i = pdata->n_gpios;
+	i = mux->data->n_gpios;
 err_request_gpio:
 	for (; i > 0; i--)
-		gpio_free(pdata->gpios[i - 1]);
+		gpio_free(mux->data->gpios[i - 1]);
 alloc_failed:
 	i2c_put_adapter(parent);
 
@@ -140,11 +219,11 @@  static int __devexit i2c_mux_gpio_remove(struct platform_device *pdev)
 	struct gpiomux *mux = platform_get_drvdata(pdev);
 	int i;
 
-	for (i = 0; i < mux->data.n_values; i++)
+	for (i = 0; i < mux->data->n_values; i++)
 		i2c_del_mux_adapter(mux->adap[i]);
 
-	for (i = 0; i < mux->data.n_gpios; i++)
-		gpio_free(mux->data.gpios[i]);
+	for (i = 0; i < mux->data->n_gpios; i++)
+		gpio_free(mux->data->gpios[i]);
 
 	platform_set_drvdata(pdev, NULL);
 	i2c_put_adapter(mux->parent);
@@ -152,12 +231,19 @@  static int __devexit i2c_mux_gpio_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct of_device_id i2c_mux_gpio_of_match[] __devinitconst = {
+	{ .compatible = "i2c-mux-gpio", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
+
 static struct platform_driver i2c_mux_gpio_driver = {
 	.probe	= i2c_mux_gpio_probe,
 	.remove	= __devexit_p(i2c_mux_gpio_remove),
 	.driver	= {
 		.owner	= THIS_MODULE,
 		.name	= "i2c-mux-gpio",
+		.of_match_table = of_match_ptr(i2c_mux_gpio_of_match),
 	},
 };