[deliverable/linux.git] / drivers / i2c / i2c-mux.c

/*
 * Multiplexed I2C bus driver.
 *
 * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
 * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
 * Copyright (c) 2009-2010 NSN GmbH & Co KG <michael.lawnick.ext@nsn.com>
 *
 * Simplifies access to complex multiplexed I2C bus topologies, by presenting
 * each multiplexed bus segment as an additional I2C adapter.
 * Supports multi-level mux'ing (mux behind a mux).
 *
 * Based on:
 *	i2c-virt.c from Kumar Gala <galak@kernel.crashing.org>
 *	i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
 *	i2c-virtual.c from Brian Kuschak <bkuschak@yahoo.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/i2c-mux.h>

/* multiplexer per channel data */
struct i2c_mux_priv {
	struct i2c_adapter adap;
	struct i2c_algorithm algo;

	struct i2c_adapter *parent;
	void *mux_priv;	/* the mux chip/device */
	u32  chan_id;	/* the channel id */

	int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
	int (*deselect)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
};

static int i2c_mux_master_xfer(struct i2c_adapter *adap,
			       struct i2c_msg msgs[], int num)
{
	struct i2c_mux_priv *priv = adap->algo_data;
	struct i2c_adapter *parent = priv->parent;
	int ret;

	/* Switch to the right mux port and perform the transfer. */

	ret = priv->select(parent, priv->mux_priv, priv->chan_id);
	if (ret >= 0)
		ret = parent->algo->master_xfer(parent, msgs, num);
	if (priv->deselect)
		priv->deselect(parent, priv->mux_priv, priv->chan_id);

	return ret;
}

static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
			      u16 addr, unsigned short flags,
			      char read_write, u8 command,
			      int size, union i2c_smbus_data *data)
{
	struct i2c_mux_priv *priv = adap->algo_data;
	struct i2c_adapter *parent = priv->parent;
	int ret;

	/* Select the right mux port and perform the transfer. */

	ret = priv->select(parent, priv->mux_priv, priv->chan_id);
	if (ret >= 0)
		ret = parent->algo->smbus_xfer(parent, addr, flags,
					read_write, command, size, data);
	if (priv->deselect)
		priv->deselect(parent, priv->mux_priv, priv->chan_id);

	return ret;
}

/* Return the parent's functionality */
static u32 i2c_mux_functionality(struct i2c_adapter *adap)
{
	struct i2c_mux_priv *priv = adap->algo_data;
	struct i2c_adapter *parent = priv->parent;

	return parent->algo->functionality(parent);
}

struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
				struct device *mux_dev,
				void *mux_priv, u32 force_nr, u32 chan_id,
				int (*select) (struct i2c_adapter *,
					       void *, u32),
				int (*deselect) (struct i2c_adapter *,
						 void *, u32))
{
	struct i2c_mux_priv *priv;
	int ret;

	priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
	if (!priv)
		return NULL;

	/* Set up private adapter data */
	priv->parent = parent;
	priv->mux_priv = mux_priv;
	priv->chan_id = chan_id;
	priv->select = select;
	priv->deselect = deselect;

	/* Need to do algo dynamically because we don't know ahead
	 * of time what sort of physical adapter we'll be dealing with.
	 */
	if (parent->algo->master_xfer)
		priv->algo.master_xfer = i2c_mux_master_xfer;
	if (parent->algo->smbus_xfer)
		priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
	priv->algo.functionality = i2c_mux_functionality;

	/* Now fill out new adapter structure */
	snprintf(priv->adap.name, sizeof(priv->adap.name),
		 "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
	priv->adap.owner = THIS_MODULE;
	priv->adap.algo = &priv->algo;
	priv->adap.algo_data = priv;
	priv->adap.dev.parent = &parent->dev;

	if (force_nr) {
		priv->adap.nr = force_nr;
		ret = i2c_add_numbered_adapter(&priv->adap);
	} else {
		ret = i2c_add_adapter(&priv->adap);
	}
	if (ret < 0) {
		dev_err(&parent->dev,
			"failed to add mux-adapter (error=%d)\n",
			ret);
		kfree(priv);
		return NULL;
	}

	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
		 i2c_adapter_id(&priv->adap));

	return &priv->adap;
}
EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);

int i2c_del_mux_adapter(struct i2c_adapter *adap)
{
	struct i2c_mux_priv *priv = adap->algo_data;
	int ret;

	ret = i2c_del_adapter(adap);
	if (ret < 0)
		return ret;
	kfree(priv);

	return 0;
}
EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);

MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
0826374b ML	1	/*
	2	* Multiplexed I2C bus driver.
	3	*
	4	* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
	5	* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
	6	* Copyright (c) 2009-2010 NSN GmbH & Co KG <michael.lawnick.ext@nsn.com>
	7	*
	8	* Simplifies access to complex multiplexed I2C bus topologies, by presenting
	9	* each multiplexed bus segment as an additional I2C adapter.
	10	* Supports multi-level mux'ing (mux behind a mux).
	11	*
	12	* Based on:
	13	* i2c-virt.c from Kumar Gala <galak@kernel.crashing.org>
	14	* i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
	15	* i2c-virtual.c from Brian Kuschak <bkuschak@yahoo.com>
	16	*
	17	* This file is licensed under the terms of the GNU General Public
	18	* License version 2. This program is licensed "as is" without any
	19	* warranty of any kind, whether express or implied.
	20	*/
	21
	22	#include <linux/kernel.h>
	23	#include <linux/module.h>
	24	#include <linux/slab.h>
	25	#include <linux/i2c.h>
	26	#include <linux/i2c-mux.h>
	27
	28	/* multiplexer per channel data */
	29	struct i2c_mux_priv {
	30	struct i2c_adapter adap;
	31	struct i2c_algorithm algo;
	32
	33	struct i2c_adapter *parent;
5a3ecd5f	34	void mux_priv; / the mux chip/device */
0826374b ML	35	u32 chan_id; /* the channel id */
0826374b ML	36
5a3ecd5f DD	37	int (select)(struct i2c_adapter , void *mux_priv, u32 chan_id);
5a3ecd5f DD	38	int (deselect)(struct i2c_adapter , void *mux_priv, u32 chan_id);
0826374b ML	39	};
	40
	41	static int i2c_mux_master_xfer(struct i2c_adapter *adap,
	42	struct i2c_msg msgs[], int num)
	43	{
	44	struct i2c_mux_priv *priv = adap->algo_data;
	45	struct i2c_adapter *parent = priv->parent;
	46	int ret;
	47
	48	/* Switch to the right mux port and perform the transfer. */
	49
5a3ecd5f	50	ret = priv->select(parent, priv->mux_priv, priv->chan_id);
0826374b ML	51	if (ret >= 0)
	52	ret = parent->algo->master_xfer(parent, msgs, num);
	53	if (priv->deselect)
5a3ecd5f	54	priv->deselect(parent, priv->mux_priv, priv->chan_id);
0826374b ML	55
	56	return ret;
	57	}
	58
	59	static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
	60	u16 addr, unsigned short flags,
	61	char read_write, u8 command,
	62	int size, union i2c_smbus_data *data)
	63	{
	64	struct i2c_mux_priv *priv = adap->algo_data;
	65	struct i2c_adapter *parent = priv->parent;
	66	int ret;
	67
	68	/* Select the right mux port and perform the transfer. */
	69
5a3ecd5f	70	ret = priv->select(parent, priv->mux_priv, priv->chan_id);
0826374b ML	71	if (ret >= 0)
	72	ret = parent->algo->smbus_xfer(parent, addr, flags,
	73	read_write, command, size, data);
	74	if (priv->deselect)
5a3ecd5f	75	priv->deselect(parent, priv->mux_priv, priv->chan_id);
0826374b ML	76
	77	return ret;
	78	}
	79
	80	/* Return the parent's functionality */
	81	static u32 i2c_mux_functionality(struct i2c_adapter *adap)
	82	{
	83	struct i2c_mux_priv *priv = adap->algo_data;
	84	struct i2c_adapter *parent = priv->parent;
	85
	86	return parent->algo->functionality(parent);
	87	}
	88
	89	struct i2c_adapter i2c_add_mux_adapter(struct i2c_adapter parent,
5a3ecd5f DD	90	struct device *mux_dev,
5a3ecd5f DD	91	void *mux_priv, u32 force_nr, u32 chan_id,
0826374b ML	92	int (select) (struct i2c_adapter ,
	93	void *, u32),
	94	int (deselect) (struct i2c_adapter ,
	95	void *, u32))
	96	{
	97	struct i2c_mux_priv *priv;
	98	int ret;
	99
	100	priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
	101	if (!priv)
	102	return NULL;
	103
	104	/* Set up private adapter data */
	105	priv->parent = parent;
5a3ecd5f	106	priv->mux_priv = mux_priv;
0826374b ML	107	priv->chan_id = chan_id;
	108	priv->select = select;
	109	priv->deselect = deselect;
	110
	111	/* Need to do algo dynamically because we don't know ahead
	112	* of time what sort of physical adapter we'll be dealing with.
	113	*/
	114	if (parent->algo->master_xfer)
	115	priv->algo.master_xfer = i2c_mux_master_xfer;
	116	if (parent->algo->smbus_xfer)
	117	priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
	118	priv->algo.functionality = i2c_mux_functionality;
	119
	120	/* Now fill out new adapter structure */
	121	snprintf(priv->adap.name, sizeof(priv->adap.name),
	122	"i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
	123	priv->adap.owner = THIS_MODULE;
0826374b ML	124	priv->adap.algo = &priv->algo;
	125	priv->adap.algo_data = priv;
	126	priv->adap.dev.parent = &parent->dev;
	127
	128	if (force_nr) {
	129	priv->adap.nr = force_nr;
	130	ret = i2c_add_numbered_adapter(&priv->adap);
	131	} else {
	132	ret = i2c_add_adapter(&priv->adap);
	133	}
	134	if (ret < 0) {
	135	dev_err(&parent->dev,
	136	"failed to add mux-adapter (error=%d)\n",
	137	ret);
	138	kfree(priv);
	139	return NULL;
	140	}
	141
	142	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
	143	i2c_adapter_id(&priv->adap));
	144
	145	return &priv->adap;
	146	}
	147	EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
	148
	149	int i2c_del_mux_adapter(struct i2c_adapter *adap)
	150	{
	151	struct i2c_mux_priv *priv = adap->algo_data;
	152	int ret;
	153
	154	ret = i2c_del_adapter(adap);
	155	if (ret < 0)
	156	return ret;
	157	kfree(priv);
	158
	159	return 0;
	160	}
	161	EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
	162
	163	MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
	164	MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
	165	MODULE_LICENSE("GPL v2");