[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>
#include <linux/of.h>

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

	struct i2c_adapter *parent;
	struct device *mux_dev;
	void *mux_priv;
	u32 chan_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 = __i2c_transfer(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);
}

/* Return all parent classes, merged */
static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
{
	unsigned int class = 0;

	do {
		class |= parent->class;
		parent = i2c_parent_is_i2c_adapter(parent);
	} while (parent);

	return class;
}

struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
				struct device *mux_dev,
				void *mux_priv, u32 force_nr, u32 chan_id,
				unsigned int class,
				int (*select) (struct i2c_adapter *,
					       void *, u32),
				int (*deselect) (struct i2c_adapter *,
						 void *, u32))
{
	struct i2c_mux_priv *priv;
	char symlink_name[20];
	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_dev = mux_dev;
	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;
	priv->adap.retries = parent->retries;
	priv->adap.timeout = parent->timeout;
	priv->adap.quirks = parent->quirks;

	/* Sanity check on class */
	if (i2c_mux_parent_classes(parent) & class)
		dev_err(&parent->dev,
			"Segment %d behind mux can't share classes with ancestors\n",
			chan_id);
	else
		priv->adap.class = class;

	/*
	 * 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;
	}

	WARN(sysfs_create_link(&priv->adap.dev.kobj, &mux_dev->kobj, "mux_device"),
			       "can't create symlink to mux device\n");

	snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);
	WARN(sysfs_create_link(&mux_dev->kobj, &priv->adap.dev.kobj, symlink_name),
			       "can't create symlink for channel %u\n", chan_id);
	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);

void i2c_del_mux_adapter(struct i2c_adapter *adap)
{
	struct i2c_mux_priv *priv = adap->algo_data;
	char symlink_name[20];

	snprintf(symlink_name, sizeof(symlink_name), "channel-%u", priv->chan_id);
	sysfs_remove_link(&priv->mux_dev->kobj, symlink_name);

	sysfs_remove_link(&priv->adap.dev.kobj, "mux_device");
	i2c_del_adapter(adap);
	kfree(priv);
}
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>
bc45449b	27	#include <linux/of.h>
0826374b ML	28
	29	/* multiplexer per channel data */
	30	struct i2c_mux_priv {
	31	struct i2c_adapter adap;
	32	struct i2c_algorithm algo;
	33
	34	struct i2c_adapter *parent;
13377848 WS	35	struct device *mux_dev;
	36	void *mux_priv;
	37	u32 chan_id;
0826374b	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	53	if (ret >= 0)
e766f338	54	ret = __i2c_transfer(parent, msgs, num);
0826374b	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
eee543e8 JD	91	/* Return all parent classes, merged */
	92	static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
	93	{
	94	unsigned int class = 0;
	95
	96	do {
	97	class \|= parent->class;
	98	parent = i2c_parent_is_i2c_adapter(parent);
	99	} while (parent);
	100
	101	return class;
	102	}
	103
0826374b	104	struct i2c_adapter i2c_add_mux_adapter(struct i2c_adapter parent,
5a3ecd5f DD	105	struct device *mux_dev,
5a3ecd5f DD	106	void *mux_priv, u32 force_nr, u32 chan_id,
eee543e8	107	unsigned int class,
0826374b ML	108	int (select) (struct i2c_adapter ,
	109	void *, u32),
	110	int (deselect) (struct i2c_adapter ,
	111	void *, u32))
	112	{
	113	struct i2c_mux_priv *priv;
c9449aff	114	char symlink_name[20];
0826374b ML	115	int ret;
	116
	117	priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
	118	if (!priv)
	119	return NULL;
	120
	121	/* Set up private adapter data */
	122	priv->parent = parent;
13377848	123	priv->mux_dev = mux_dev;
5a3ecd5f	124	priv->mux_priv = mux_priv;
0826374b ML	125	priv->chan_id = chan_id;
	126	priv->select = select;
	127	priv->deselect = deselect;
	128
	129	/* Need to do algo dynamically because we don't know ahead
	130	* of time what sort of physical adapter we'll be dealing with.
	131	*/
	132	if (parent->algo->master_xfer)
	133	priv->algo.master_xfer = i2c_mux_master_xfer;
	134	if (parent->algo->smbus_xfer)
	135	priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
	136	priv->algo.functionality = i2c_mux_functionality;
	137
	138	/* Now fill out new adapter structure */
	139	snprintf(priv->adap.name, sizeof(priv->adap.name),
	140	"i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
	141	priv->adap.owner = THIS_MODULE;
0826374b ML	142	priv->adap.algo = &priv->algo;
	143	priv->adap.algo_data = priv;
	144	priv->adap.dev.parent = &parent->dev;
2212a852 EDB	145	priv->adap.retries = parent->retries;
2212a852 EDB	146	priv->adap.timeout = parent->timeout;
dc362d50	147	priv->adap.quirks = parent->quirks;
0826374b	148
eee543e8 JD	149	/* Sanity check on class */
	150	if (i2c_mux_parent_classes(parent) & class)
	151	dev_err(&parent->dev,
	152	"Segment %d behind mux can't share classes with ancestors\n",
	153	chan_id);
	154	else
	155	priv->adap.class = class;
	156
bc45449b DD	157	/*
	158	* Try to populate the mux adapter's of_node, expands to
	159	* nothing if !CONFIG_OF.
	160	*/
	161	if (mux_dev->of_node) {
	162	struct device_node *child;
	163	u32 reg;
	164
	165	for_each_child_of_node(mux_dev->of_node, child) {
	166	ret = of_property_read_u32(child, "reg", &reg);
	167	if (ret)
	168	continue;
	169	if (chan_id == reg) {
	170	priv->adap.dev.of_node = child;
	171	break;
	172	}
	173	}
	174	}
	175
0826374b ML	176	if (force_nr) {
	177	priv->adap.nr = force_nr;
	178	ret = i2c_add_numbered_adapter(&priv->adap);
	179	} else {
	180	ret = i2c_add_adapter(&priv->adap);
	181	}
	182	if (ret < 0) {
	183	dev_err(&parent->dev,
	184	"failed to add mux-adapter (error=%d)\n",
	185	ret);
	186	kfree(priv);
	187	return NULL;
	188	}
	189
51cf3b0e WS	190	WARN(sysfs_create_link(&priv->adap.dev.kobj, &mux_dev->kobj, "mux_device"),
	191	"can't create symlink to mux device\n");
	192
c9449aff GF	193	snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);
	194	WARN(sysfs_create_link(&mux_dev->kobj, &priv->adap.dev.kobj, symlink_name),
	195	"can't create symlink for channel %u\n", chan_id);
0826374b ML	196	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
	197	i2c_adapter_id(&priv->adap));
	198
	199	return &priv->adap;
	200	}
	201	EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
	202
51d95709	203	void i2c_del_mux_adapter(struct i2c_adapter *adap)
0826374b ML	204	{
0826374b ML	205	struct i2c_mux_priv *priv = adap->algo_data;
c9449aff GF	206	char symlink_name[20];
	207
	208	snprintf(symlink_name, sizeof(symlink_name), "channel-%u", priv->chan_id);
13377848	209	sysfs_remove_link(&priv->mux_dev->kobj, symlink_name);
0826374b	210
51cf3b0e	211	sysfs_remove_link(&priv->adap.dev.kobj, "mux_device");
bf51a8c5	212	i2c_del_adapter(adap);
0826374b	213	kfree(priv);
0826374b ML	214	}
	215	EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
	216
	217	MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
	218	MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
	219	MODULE_LICENSE("GPL v2");