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

/*
 * Multiplexed I2C bus driver.
 *
 * Copyright (c) 2008-2009 Rodolfo Giometti <[email protected]>
 * Copyright (c) 2008-2009 Eurotech S.p.A. <[email protected]>
 * Copyright (c) 2009-2010 NSN GmbH & Co KG <[email protected]>
 *
 * 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 <[email protected]>
 *	i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
 *	i2c-virtual.c from Brian Kuschak <[email protected]>
 *
 * 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>
#include <linux/of.h>
#include <linux/of_i2c.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;

	/*
	 * Try to populate the mux adapter's of_node, expands to
	 * nothing if !CONFIG_OF.
	 */
	if (mux_dev->of_node) {
		struct device_node *child;
		u32 reg;

		for_each_child_of_node(mux_dev->of_node, child) {
			ret = of_property_read_u32(child, "reg", &reg);
			if (ret)
				continue;
			if (chan_id == reg) {
				priv->adap.dev.of_node = child;
				break;
			}
		}
	}

	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));

	of_i2c_register_devices(&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 <[email protected]>");
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 <[email protected]>
	5	* Copyright (c) 2008-2009 Eurotech S.p.A. <[email protected]>
	6	* Copyright (c) 2009-2010 NSN GmbH & Co KG <[email protected]>
	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 <[email protected]>
	14	* i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
	15	* i2c-virtual.c from Brian Kuschak <[email protected]>
	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>
bc45449b DD	27	#include <linux/of.h>
bc45449b DD	28	#include <linux/of_i2c.h>
0826374b ML	29
	30	/* multiplexer per channel data */
	31	struct i2c_mux_priv {
	32	struct i2c_adapter adap;
	33	struct i2c_algorithm algo;
	34
	35	struct i2c_adapter *parent;
5a3ecd5f	36	void mux_priv; / the mux chip/device */
0826374b ML	37	u32 chan_id; /* the channel id */
0826374b ML	38
5a3ecd5f DD	39	int (select)(struct i2c_adapter , void *mux_priv, u32 chan_id);
5a3ecd5f DD	40	int (deselect)(struct i2c_adapter , void *mux_priv, u32 chan_id);
0826374b ML	41	};
	42
	43	static int i2c_mux_master_xfer(struct i2c_adapter *adap,
	44	struct i2c_msg msgs[], int num)
	45	{
	46	struct i2c_mux_priv *priv = adap->algo_data;
	47	struct i2c_adapter *parent = priv->parent;
	48	int ret;
	49
	50	/* Switch to the right mux port and perform the transfer. */
	51
5a3ecd5f	52	ret = priv->select(parent, priv->mux_priv, priv->chan_id);
0826374b ML	53	if (ret >= 0)
	54	ret = parent->algo->master_xfer(parent, msgs, num);
	55	if (priv->deselect)
5a3ecd5f	56	priv->deselect(parent, priv->mux_priv, priv->chan_id);
0826374b ML	57
	58	return ret;
	59	}
	60
	61	static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
	62	u16 addr, unsigned short flags,
	63	char read_write, u8 command,
	64	int size, union i2c_smbus_data *data)
	65	{
	66	struct i2c_mux_priv *priv = adap->algo_data;
	67	struct i2c_adapter *parent = priv->parent;
	68	int ret;
	69
	70	/* Select the right mux port and perform the transfer. */
	71
5a3ecd5f	72	ret = priv->select(parent, priv->mux_priv, priv->chan_id);
0826374b ML	73	if (ret >= 0)
	74	ret = parent->algo->smbus_xfer(parent, addr, flags,
	75	read_write, command, size, data);
	76	if (priv->deselect)
5a3ecd5f	77	priv->deselect(parent, priv->mux_priv, priv->chan_id);
0826374b ML	78
	79	return ret;
	80	}
	81
	82	/* Return the parent's functionality */
	83	static u32 i2c_mux_functionality(struct i2c_adapter *adap)
	84	{
	85	struct i2c_mux_priv *priv = adap->algo_data;
	86	struct i2c_adapter *parent = priv->parent;
	87
	88	return parent->algo->functionality(parent);
	89	}
	90
	91	struct i2c_adapter i2c_add_mux_adapter(struct i2c_adapter parent,
5a3ecd5f DD	92	struct device *mux_dev,
5a3ecd5f DD	93	void *mux_priv, u32 force_nr, u32 chan_id,
0826374b ML	94	int (select) (struct i2c_adapter ,
	95	void *, u32),
	96	int (deselect) (struct i2c_adapter ,
	97	void *, u32))
	98	{
	99	struct i2c_mux_priv *priv;
	100	int ret;
	101
	102	priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
	103	if (!priv)
	104	return NULL;
	105
	106	/* Set up private adapter data */
	107	priv->parent = parent;
5a3ecd5f	108	priv->mux_priv = mux_priv;
0826374b ML	109	priv->chan_id = chan_id;
	110	priv->select = select;
	111	priv->deselect = deselect;
	112
	113	/* Need to do algo dynamically because we don't know ahead
	114	* of time what sort of physical adapter we'll be dealing with.
	115	*/
	116	if (parent->algo->master_xfer)
	117	priv->algo.master_xfer = i2c_mux_master_xfer;
	118	if (parent->algo->smbus_xfer)
	119	priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
	120	priv->algo.functionality = i2c_mux_functionality;
	121
	122	/* Now fill out new adapter structure */
	123	snprintf(priv->adap.name, sizeof(priv->adap.name),
	124	"i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
	125	priv->adap.owner = THIS_MODULE;
0826374b ML	126	priv->adap.algo = &priv->algo;
	127	priv->adap.algo_data = priv;
	128	priv->adap.dev.parent = &parent->dev;
	129
bc45449b DD	130	/*
	131	* Try to populate the mux adapter's of_node, expands to
	132	* nothing if !CONFIG_OF.
	133	*/
	134	if (mux_dev->of_node) {
	135	struct device_node *child;
	136	u32 reg;
	137
	138	for_each_child_of_node(mux_dev->of_node, child) {
	139	ret = of_property_read_u32(child, "reg", &reg);
	140	if (ret)
	141	continue;
	142	if (chan_id == reg) {
	143	priv->adap.dev.of_node = child;
	144	break;
	145	}
	146	}
	147	}
	148
0826374b ML	149	if (force_nr) {
	150	priv->adap.nr = force_nr;
	151	ret = i2c_add_numbered_adapter(&priv->adap);
	152	} else {
	153	ret = i2c_add_adapter(&priv->adap);
	154	}
	155	if (ret < 0) {
	156	dev_err(&parent->dev,
	157	"failed to add mux-adapter (error=%d)\n",
	158	ret);
	159	kfree(priv);
	160	return NULL;
	161	}
	162
	163	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
	164	i2c_adapter_id(&priv->adap));
	165
bc45449b DD	166	of_i2c_register_devices(&priv->adap);
bc45449b DD	167
0826374b ML	168	return &priv->adap;
	169	}
	170	EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
	171
	172	int i2c_del_mux_adapter(struct i2c_adapter *adap)
	173	{
	174	struct i2c_mux_priv *priv = adap->algo_data;
	175	int ret;
	176
	177	ret = i2c_del_adapter(adap);
	178	if (ret < 0)
	179	return ret;
	180	kfree(priv);
	181
	182	return 0;
	183	}
	184	EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
	185
	186	MODULE_AUTHOR("Rodolfo Giometti <[email protected]>");
	187	MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
	188	MODULE_LICENSE("GPL v2");