[PATCH V3] i2c: Add generic I2C multiplexer using pinctrl API

Rob Herring robherring2 at gmail.com
Fri May 18 10:13:09 EST 2012


On 05/01/2012 12:23 PM, Stephen Warren wrote:
> From: Stephen Warren <swarren at nvidia.com>
> 
> This is useful for SoCs whose I2C module's signals can be routed to
> different sets of pins at run-time, using the pinctrl API.
> 
>                                  +-----+  +-----+
>                                  | dev |  | dev |
>     +------------------------+   +-----+  +-----+
>     | SoC                    |      |        |
>     |                   /----|------+--------+
>     |   +---+   +------+     | child bus A, on first set of pins
>     |   |I2C|---|Pinmux|     |
>     |   +---+   +------+     | child bus B, on second set of pins
>     |                   \----|------+--------+--------+
>     |                        |      |        |        |
>     +------------------------+  +-----+  +-----+  +-----+
>                                 | dev |  | dev |  | dev |
>                                 +-----+  +-----+  +-----+
>

Such a pretty drawing, I think it deserves to be in the binding doc.

Otherwise, looks good to me:

Acked-by: Rob Herring <rob.herring at calxeda.com>

Sorry for the delayed response.

Rob

> Signed-off-by: Stephen Warren <swarren at nvidia.com>
> Acked-by: Linus Walleij <linus.walleij at linaro.org>
> ---
> v3: Renamed pinctrl-i2cmux.c to i2c-mux-pinctrl.c to match recent changes
>     to other I2C mux files.
> v2: Rebase onto David Daney's i2c-mux OF support, including slight binding
>     changes. Add more error messages.
> 
> squash pinctrl i2c mux
> ---
>  .../devicetree/bindings/i2c/i2c-mux-pinctrl.txt    |   79 ++++++
>  drivers/i2c/muxes/Kconfig                          |   12 +
>  drivers/i2c/muxes/Makefile                         |    1 +
>  drivers/i2c/muxes/i2c-mux-pinctrl.c                |  279 ++++++++++++++++++++
>  include/linux/i2c-mux-pinctrl.h                    |   41 +++
>  5 files changed, 412 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt
>  create mode 100644 drivers/i2c/muxes/i2c-mux-pinctrl.c
>  create mode 100644 include/linux/i2c-mux-pinctrl.h
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt
> new file mode 100644
> index 0000000..b10e268
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt
> @@ -0,0 +1,79 @@
> +Pinctrl-based I2C Bus Mux
> +
> +This binding describes an I2C bus multiplexer that uses pin multiplexing to
> +route the I2C signals, and represents the pin multiplexing configuration
> +using the pinctrl device tree bindings.
> +
> +Required properties:
> +- compatible: i2c-mux-pinctrl
> +- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
> +  port is connected to.
> +
> +Also required are:
> +
> +* Standard pinctrl properties that specify the pin mux state for each child
> +  bus. See ../pinctrl/pinctrl-bindings.txt.
> +
> +* Standard I2C mux properties. See mux.txt in this directory.
> +
> +* I2C child bus nodes. See mux.txt in this directory.
> +
> +For each named state defined in the pinctrl-names property, an I2C child bus
> +will be created. I2C child bus numbers are assigned based on the index into
> +the pinctrl-names property.
> +
> +The only exception is that no bus will be created for a state named "idle". If
> +such a state is defined, it must be the last entry in pinctrl-names. For
> +example:
> +
> +	pinctrl-names = "ddc", "pta", "idle"  ->  ddc = bus 0, pta = bus 1
> +	pinctrl-names = "ddc", "idle", "pta"  ->  Invalid ("idle" not last)
> +	pinctrl-names = "idle", "ddc", "pta"  ->  Invalid ("idle" not last)
> +
> +Whenever an access is made to a device on a child bus, the relevant pinctrl
> +state will be programmed into hardware.
> +
> +If an idle state is defined, whenever an access is not being made to a device
> +on a child bus, the idle pinctrl state will be programmed into hardware.
> +
> +If an idle state is not defined, the most recently used pinctrl state will be
> +left programmed into hardware whenever no access is being made of a device on
> +a child bus.
> +
> +Example:
> +
> +	i2cmux {
> +		compatible = "i2c-mux-pinctrl";
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		i2c-parent = <&i2c1>;
> +
> +		pinctrl-names = "ddc", "pta", "idle";
> +		pinctrl-0 = <&state_i2cmux_ddc>;
> +		pinctrl-1 = <&state_i2cmux_pta>;
> +		pinctrl-2 = <&state_i2cmux_idle>;
> +
> +		i2c at 0 {
> +			reg = <0>;
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			eeprom {
> +				compatible = "eeprom";
> +				reg = <0x50>;
> +			};
> +		};
> +
> +		i2c at 1 {
> +			reg = <1>;
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			eeprom {
> +				compatible = "eeprom";
> +				reg = <0x50>;
> +			};
> +		};
> +	};
> +
> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
> index e14a420..c237a1b 100644
> --- a/drivers/i2c/muxes/Kconfig
> +++ b/drivers/i2c/muxes/Kconfig
> @@ -37,4 +37,16 @@ config I2C_MUX_PCA954x
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called i2c-mux-pca954x.
>  
> +config I2C_MUX_PINCTRL
> +	tristate "pinctrl-based I2C multiplexer"
> +	depends on PINCTRL
> +	help
> +	  If you say yes to this option, support will be included for an I2C
> +	  multiplexer that uses the pinctrl subsystem, i.e. pin multiplexing.
> +	  This is useful for SoCs whose I2C module's signals can be routed to
> +	  different sets of pins at run-time.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called pinctrl-i2cmux.
> +
>  endmenu
> diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
> index 0868335..0e2a3cd 100644
> --- a/drivers/i2c/muxes/Makefile
> +++ b/drivers/i2c/muxes/Makefile
> @@ -4,5 +4,6 @@
>  obj-$(CONFIG_I2C_MUX_GPIO)	+= gpio-i2cmux.o
>  obj-$(CONFIG_I2C_MUX_PCA9541)	+= i2c-mux-pca9541.o
>  obj-$(CONFIG_I2C_MUX_PCA954x)	+= i2c-mux-pca954x.o
> +obj-$(CONFIG_I2C_MUX_PINCTRL)	+= i2c-mux-pinctrl.o
>  
>  ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
> diff --git a/drivers/i2c/muxes/i2c-mux-pinctrl.c b/drivers/i2c/muxes/i2c-mux-pinctrl.c
> new file mode 100644
> index 0000000..46a6697
> --- /dev/null
> +++ b/drivers/i2c/muxes/i2c-mux-pinctrl.c
> @@ -0,0 +1,279 @@
> +/*
> + * I2C multiplexer using pinctrl API
> + *
> + * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/i2c-mux.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/of_i2c.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/i2c-mux-pinctrl.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +struct i2c_mux_pinctrl {
> +	struct device *dev;
> +	struct i2c_mux_pinctrl_platform_data *pdata;
> +	struct pinctrl *pinctrl;
> +	struct pinctrl_state **states;
> +	struct pinctrl_state *state_idle;
> +	struct i2c_adapter *parent;
> +	struct i2c_adapter **busses;
> +};
> +
> +static int i2c_mux_pinctrl_select(struct i2c_adapter *adap, void *data,
> +				  u32 chan)
> +{
> +	struct i2c_mux_pinctrl *mux = data;
> +
> +	return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
> +}
> +
> +static int i2c_mux_pinctrl_deselect(struct i2c_adapter *adap, void *data,
> +				    u32 chan)
> +{
> +	struct i2c_mux_pinctrl *mux = data;
> +
> +	return pinctrl_select_state(mux->pinctrl, mux->state_idle);
> +}
> +
> +#ifdef CONFIG_OF
> +static int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
> +				struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	int num_names, i, ret;
> +	struct device_node *adapter_np;
> +	struct i2c_adapter *adapter;
> +
> +	if (!np)
> +		return 0;
> +
> +	mux->pdata = devm_kzalloc(&pdev->dev, sizeof(*mux->pdata), GFP_KERNEL);
> +	if (!mux->pdata) {
> +		dev_err(mux->dev,
> +			"Cannot allocate i2c_mux_pinctrl_platform_data\n");
> +		return -ENOMEM;
> +	}
> +
> +	num_names = of_property_count_strings(np, "pinctrl-names");
> +	if (num_names < 0) {
> +		dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n",
> +			num_names);
> +		return num_names;
> +	}
> +
> +	mux->pdata->pinctrl_states = devm_kzalloc(&pdev->dev,
> +		sizeof(*mux->pdata->pinctrl_states) * num_names,
> +		GFP_KERNEL);
> +	if (!mux->pdata->pinctrl_states) {
> +		dev_err(mux->dev, "Cannot allocate pinctrl_states\n");
> +		return -ENOMEM;
> +	}
> +
> +	for (i = 0; i < num_names; i++) {
> +		ret = of_property_read_string_index(np, "pinctrl-names", i,
> +			&mux->pdata->pinctrl_states[mux->pdata->bus_count]);
> +		if (ret < 0) {
> +			dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n",
> +				ret);
> +			return ret;
> +		}
> +		if (!strcmp(mux->pdata->pinctrl_states[mux->pdata->bus_count],
> +			    "idle")) {
> +			if (i != num_names - 1) {
> +				dev_err(mux->dev, "idle state must be last\n");
> +				return -EINVAL;
> +			}
> +			mux->pdata->pinctrl_state_idle = "idle";
> +		} else {
> +			mux->pdata->bus_count++;
> +		}
> +	}
> +
> +	adapter_np = of_parse_phandle(np, "i2c-parent", 0);
> +	if (!adapter_np) {
> +		dev_err(mux->dev, "Cannot parse i2c-parent\n");
> +		return -ENODEV;
> +	}
> +	adapter = of_find_i2c_adapter_by_node(adapter_np);
> +	if (!adapter) {
> +		dev_err(mux->dev, "Cannot find parent bus\n");
> +		return -ENODEV;
> +	}
> +	mux->pdata->parent_bus_num = i2c_adapter_id(adapter);
> +	put_device(&adapter->dev);
> +
> +	return 0;
> +}
> +#else
> +static inline int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
> +					   struct platform_device *pdev)
> +{
> +	return 0;
> +}
> +#endif
> +
> +static int __devinit i2c_mux_pinctrl_probe(struct platform_device *pdev)
> +{
> +	struct i2c_mux_pinctrl *mux;
> +	int (*deselect)(struct i2c_adapter *, void *, u32);
> +	int i, ret;
> +
> +	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
> +	if (!mux) {
> +		dev_err(&pdev->dev, "Cannot allocate i2c_mux_pinctrl\n");
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +	platform_set_drvdata(pdev, mux);
> +
> +	mux->dev = &pdev->dev;
> +
> +	mux->pdata = pdev->dev.platform_data;
> +	if (!mux->pdata) {
> +		ret = i2c_mux_pinctrl_parse_dt(mux, pdev);
> +		if (ret < 0)
> +			goto err;
> +	}
> +	if (!mux->pdata) {
> +		dev_err(&pdev->dev, "Missing platform data\n");
> +		ret = -ENODEV;
> +		goto err;
> +	}
> +
> +	mux->states = devm_kzalloc(&pdev->dev,
> +				   sizeof(*mux->states) * mux->pdata->bus_count,
> +				   GFP_KERNEL);
> +	if (!mux->states) {
> +		dev_err(&pdev->dev, "Cannot allocate states\n");
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	mux->busses = devm_kzalloc(&pdev->dev,
> +				   sizeof(mux->busses) * mux->pdata->bus_count,
> +				   GFP_KERNEL);
> +	if (!mux->states) {
> +		dev_err(&pdev->dev, "Cannot allocate busses\n");
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	mux->pinctrl = devm_pinctrl_get(&pdev->dev);
> +	if (IS_ERR(mux->pinctrl)) {
> +		ret = PTR_ERR(mux->pinctrl);
> +		dev_err(&pdev->dev, "Cannot get pinctrl: %d\n", ret);
> +		goto err;
> +	}
> +	for (i = 0; i < mux->pdata->bus_count; i++) {
> +		mux->states[i] = pinctrl_lookup_state(mux->pinctrl,
> +						mux->pdata->pinctrl_states[i]);
> +			if (IS_ERR(mux->states[i])) {
> +				ret = PTR_ERR(mux->states[i]);
> +				dev_err(&pdev->dev,
> +					"Cannot look up pinctrl state %s: %d\n",
> +					mux->pdata->pinctrl_states[i], ret);
> +				goto err;
> +			}
> +	}
> +	if (mux->pdata->pinctrl_state_idle) {
> +		mux->state_idle = pinctrl_lookup_state(mux->pinctrl,
> +						mux->pdata->pinctrl_state_idle);
> +		if (IS_ERR(mux->state_idle)) {
> +			ret = PTR_ERR(mux->state_idle);
> +			dev_err(&pdev->dev,
> +				"Cannot look up pinctrl state %s: %d\n",
> +				mux->pdata->pinctrl_state_idle, ret);
> +			goto err;
> +		}
> +
> +		deselect = i2c_mux_pinctrl_deselect;
> +	} else {
> +		deselect = NULL;
> +	}
> +
> +	mux->parent = i2c_get_adapter(mux->pdata->parent_bus_num);
> +	if (!mux->parent) {
> +		dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
> +			mux->pdata->parent_bus_num);
> +		ret = -ENODEV;
> +		goto err;
> +	}
> +
> +	for (i = 0; i < mux->pdata->bus_count; i++) {
> +		u32 bus = mux->pdata->base_bus_num ?
> +				(mux->pdata->base_bus_num + i) : 0;
> +
> +		mux->busses[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev,
> +						     mux, bus, i,
> +						     i2c_mux_pinctrl_select,
> +						     deselect);
> +		if (!mux->busses[i]) {
> +			ret = -ENODEV;
> +			dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
> +			goto err_del_adapter;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_del_adapter:
> +	for (; i > 0; i--)
> +		i2c_del_mux_adapter(mux->busses[i - 1]);
> +	i2c_put_adapter(mux->parent);
> +err:
> +	return ret;
> +}
> +
> +static int __devexit i2c_mux_pinctrl_remove(struct platform_device *pdev)
> +{
> +	struct i2c_mux_pinctrl *mux = platform_get_drvdata(pdev);
> +	int i;
> +
> +	for (i = 0; i < mux->pdata->bus_count; i++)
> +		i2c_del_mux_adapter(mux->busses[i]);
> +
> +	i2c_put_adapter(mux->parent);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id i2c_mux_pinctrl_of_match[] __devinitconst = {
> +	{ .compatible = "i2c-mux-pinctrl", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
> +#endif
> +
> +static struct platform_driver i2c_mux_pinctrl_driver = {
> +	.driver	= {
> +		.name	= "i2c-mux-pinctrl",
> +		.owner	= THIS_MODULE,
> +		.of_match_table = of_match_ptr(i2c_mux_pinctrl_of_match),
> +	},
> +	.probe	= i2c_mux_pinctrl_probe,
> +	.remove	= __devexit_p(i2c_mux_pinctrl_remove),
> +};
> +module_platform_driver(i2c_mux_pinctrl_driver);
> +
> +MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
> +MODULE_AUTHOR("Stephen Warren <swarren at nvidia.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:i2c-mux-pinctrl");
> diff --git a/include/linux/i2c-mux-pinctrl.h b/include/linux/i2c-mux-pinctrl.h
> new file mode 100644
> index 0000000..a65c864
> --- /dev/null
> +++ b/include/linux/i2c-mux-pinctrl.h
> @@ -0,0 +1,41 @@
> +/*
> + * i2c-mux-pinctrl platform data
> + *
> + * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef _LINUX_I2C_MUX_PINCTRL_H
> +#define _LINUX_I2C_MUX_PINCTRL_H
> +
> +/**
> + * struct i2c_mux_pinctrl_platform_data - Platform data for i2c-mux-pinctrl
> + * @parent_bus_num: Parent I2C bus number
> + * @base_bus_num: Base I2C bus number for the child busses. 0 for dynamic.
> + * @bus_count: Number of child busses. Also the number of elements in
> + *	@pinctrl_states
> + * @pinctrl_states: The names of the pinctrl state to select for each child bus
> + * @pinctrl_state_idle: The pinctrl state to select when no child bus is being
> + *	accessed. If NULL, the most recently used pinctrl state will be left
> + *	selected.
> + */
> +struct i2c_mux_pinctrl_platform_data {
> +	int parent_bus_num;
> +	int base_bus_num;
> +	int bus_count;
> +	const char **pinctrl_states;
> +	const char *pinctrl_state_idle;
> +};
> +
> +#endif



More information about the devicetree-discuss mailing list