Re: [PATCH 1/2] i2c: mux: add device tree support

[Wolfram Sang]

On Tue, Apr 17, 2012 at 12:49:04PM -0600, Stephen Warren wrote:
> From: Stephen Warren <swarren@xxxxxxxxxx>
> 
> * Define core portions of the DT binding for I2C bus muxes.
> * Enhance i2c_add_mux_adapter():
> ** Add parameters required for DT support. Update all callers.
> ** Set the appropriate adap->dev.of_node for the child bus.
> ** Call of_i2c_register_devices() for the child bus.
> 
> Signed-off-by: Stephen Warren <swarren@xxxxxxxxxx>

David Daney (CCed) posted another variant [1]. Just looking at the
patches (and not really using them), I tend to like the approach using
<reg> better. But I am open for discussion, so I'd appreciate your
feedback.

Regards,

   Wolfram

[1] http://lkml.org/lkml/2012/4/12/423

> ---
> Note: This series depends on the 3 patches I just sent that affect
> of_find_i2c_device_by_node and implement of_find_i2c_adapter_by_node.
> It might be useful to put this patch (and the others I sent) in
> a separate tree so it can be merged into any SoC trees that wish to use
> this new feature.
> 
>  Documentation/devicetree/bindings/i2c/i2cmux.txt |   45 ++++++++++++++++++++++
>  drivers/i2c/i2c-mux.c                            |   23 +++++++++++-
>  drivers/i2c/muxes/gpio-i2cmux.c                  |    5 +-
>  drivers/i2c/muxes/pca9541.c                      |    4 +-
>  drivers/i2c/muxes/pca954x.c                      |    4 +-
>  include/linux/i2c-mux.h                          |    4 +-
>  6 files changed, 77 insertions(+), 8 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/i2c/i2cmux.txt
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2cmux.txt b/Documentation/devicetree/bindings/i2c/i2cmux.txt
> new file mode 100644
> index 0000000..1e4e2bc
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2cmux.txt
> @@ -0,0 +1,45 @@
> +Common I2C mux bindings
> +
> +An I2C mux is a device that connects a master I2C bus to one of a number of
> +child I2C busses, under programmatic control.
> +
> +Each I2C mux may define the set of child busses it supports in a different
> +way. Some devices may have a hard-coded set of child ports, whereas others may
> +support a varying set of child busses (especially when the bus mux is
> +implemented using GPIOs or pin muxing). Any bindings required to represent
> +this are the domain of the individual mux device.
> +
> +For each child bus, there shall be a node within the I2C mux's own node for
> +that bus. This node will contain all the I2C devices on that bus, just like
> +any other I2C bus. Each child bus shall be identified by some name. The set
> +of child bus names is defined by the individual I2C mux's bindings. Bus names
> +are used to construct the name of the bus's child node using the format
> +i2c-bus-%s. Each child bus node needs the usual #address-cells and #size-cells
> +properties.
> +
> +Example:
> +
> +	i2cmux {
> +		// properties here omitted from the example.
> +
> +		i2c-bus-0 {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			eeprom {
> +				compatible = "eeprom";
> +				reg = <0x50>;
> +			};
> +		};
> +
> +		i2c-bus-1 {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			eeprom {
> +				compatible = "eeprom";
> +				reg = <0x50>;
> +			};
> +		};
> +	};
> +
> diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
> index d7a4833..8adeeec 100644
> --- a/drivers/i2c/i2c-mux.c
> +++ b/drivers/i2c/i2c-mux.c
> @@ -24,6 +24,7 @@
>  #include <linux/slab.h>
>  #include <linux/i2c.h>
>  #include <linux/i2c-mux.h>
> +#include <linux/of_i2c.h>
>  
>  /* multiplexer per channel data */
>  struct i2c_mux_priv {
> @@ -86,8 +87,10 @@ static u32 i2c_mux_functionality(struct i2c_adapter *adap)
>  	return parent->algo->functionality(parent);
>  }
>  
> -struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
> +struct i2c_adapter *i2c_add_mux_adapter(struct device *dev,
> +				struct i2c_adapter *parent,
>  				void *mux_dev, u32 force_nr, u32 chan_id,
> +				const char *chan_name,
>  				int (*select) (struct i2c_adapter *,
>  					       void *, u32),
>  				int (*deselect) (struct i2c_adapter *,
> @@ -124,6 +127,22 @@ struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
>  	priv->adap.algo_data = priv;
>  	priv->adap.dev.parent = &parent->dev;
>  
> +	if (dev->of_node) {
> +		const char *name;
> +
> +		if (chan_name)
> +			name = kasprintf(GFP_KERNEL, "i2c-bus-%s",
> +					     chan_name);
> +		else
> +			name = kasprintf(GFP_KERNEL, "i2c-bus-%d",
> +					     chan_id);
> +
> +		priv->adap.dev.of_node = of_find_node_by_name(dev->of_node,
> +							      name);
> +
> +		kfree(name);
> +	}
> +
>  	if (force_nr) {
>  		priv->adap.nr = force_nr;
>  		ret = i2c_add_numbered_adapter(&priv->adap);
> @@ -141,6 +160,8 @@ struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
>  	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
>  		 i2c_adapter_id(&priv->adap));
>  
> +	of_i2c_register_devices(&priv->adap);
> +
>  	return &priv->adap;
>  }
>  EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
> diff --git a/drivers/i2c/muxes/gpio-i2cmux.c b/drivers/i2c/muxes/gpio-i2cmux.c
> index e5fa695..7284c70 100644
> --- a/drivers/i2c/muxes/gpio-i2cmux.c
> +++ b/drivers/i2c/muxes/gpio-i2cmux.c
> @@ -105,8 +105,9 @@ static int __devinit gpiomux_probe(struct platform_device *pdev)
>  	for (i = 0; i < pdata->n_values; i++) {
>  		u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
>  
> -		mux->adap[i] = i2c_add_mux_adapter(parent, mux, nr, i,
> -						   gpiomux_select, deselect);
> +		mux->adap[i] = i2c_add_mux_adapter(&pdev->dev, parent, mux, nr,
> +						   i, NULL, gpiomux_select,
> +						   deselect);
>  		if (!mux->adap[i]) {
>  			ret = -ENODEV;
>  			dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
> diff --git a/drivers/i2c/muxes/pca9541.c b/drivers/i2c/muxes/pca9541.c
> index e0df9b6..e1777fb 100644
> --- a/drivers/i2c/muxes/pca9541.c
> +++ b/drivers/i2c/muxes/pca9541.c
> @@ -353,8 +353,8 @@ static int pca9541_probe(struct i2c_client *client,
>  	force = 0;
>  	if (pdata)
>  		force = pdata->modes[0].adap_id;
> -	data->mux_adap = i2c_add_mux_adapter(adap, client, force, 0,
> -					     pca9541_select_chan,
> +	data->mux_adap = i2c_add_mux_adapter(&client->dev, adap, client, force,
> +					     0, NULL, pca9541_select_chan,
>  					     pca9541_release_chan);
>  
>  	if (data->mux_adap == NULL) {
> diff --git a/drivers/i2c/muxes/pca954x.c b/drivers/i2c/muxes/pca954x.c
> index 0e37ef2..736a803 100644
> --- a/drivers/i2c/muxes/pca954x.c
> +++ b/drivers/i2c/muxes/pca954x.c
> @@ -226,8 +226,8 @@ static int pca954x_probe(struct i2c_client *client,
>  		}
>  
>  		data->virt_adaps[num] =
> -			i2c_add_mux_adapter(adap, client,
> -				force, num, pca954x_select_chan,
> +			i2c_add_mux_adapter(&client->dev, adap, client,
> +				force, num, NULL, pca954x_select_chan,
>  				(pdata && pdata->modes[num].deselect_on_exit)
>  					? pca954x_deselect_mux : NULL);
>  
> diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
> index 747f0cd..43fb11a 100644
> --- a/include/linux/i2c-mux.h
> +++ b/include/linux/i2c-mux.h
> @@ -33,8 +33,10 @@
>   * and deselect callback functions to perform hardware-specific
>   * mux control.
>   */
> -struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
> +struct i2c_adapter *i2c_add_mux_adapter(struct device *dev,
> +				struct i2c_adapter *parent,
>  				void *mux_dev, u32 force_nr, u32 chan_id,
> +				const char *chan_name,
>  				int (*select) (struct i2c_adapter *,
>  					       void *mux_dev, u32 chan_id),
>  				int (*deselect) (struct i2c_adapter *,
> -- 
> 1.7.0.4
> 

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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