[deliverable/linux.git] / drivers / i2c / muxes / i2c-mux-pca9541.c

/*
 * I2C multiplexer driver for PCA9541 bus master selector
 *
 * Copyright (c) 2010 Ericsson AB.
 *
 * Author: Guenter Roeck <linux@roeck-us.net>
 *
 * Derived from:
 *  pca954x.c
 *
 *  Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
 *  Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
 *
 * 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/module.h>
#include <linux/jiffies.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/i2c-mux.h>

#include <linux/i2c/pca954x.h>

/*
 * The PCA9541 is a bus master selector. It supports two I2C masters connected
 * to a single slave bus.
 *
 * Before each bus transaction, a master has to acquire bus ownership. After the
 * transaction is complete, bus ownership has to be released. This fits well
 * into the I2C multiplexer framework, which provides select and release
 * functions for this purpose. For this reason, this driver is modeled as
 * single-channel I2C bus multiplexer.
 *
 * This driver assumes that the two bus masters are controlled by two different
 * hosts. If a single host controls both masters, platform code has to ensure
 * that only one of the masters is instantiated at any given time.
 */

#define PCA9541_CONTROL		0x01
#define PCA9541_ISTAT		0x02

#define PCA9541_CTL_MYBUS	(1 << 0)
#define PCA9541_CTL_NMYBUS	(1 << 1)
#define PCA9541_CTL_BUSON	(1 << 2)
#define PCA9541_CTL_NBUSON	(1 << 3)
#define PCA9541_CTL_BUSINIT	(1 << 4)
#define PCA9541_CTL_TESTON	(1 << 6)
#define PCA9541_CTL_NTESTON	(1 << 7)

#define PCA9541_ISTAT_INTIN	(1 << 0)
#define PCA9541_ISTAT_BUSINIT	(1 << 1)
#define PCA9541_ISTAT_BUSOK	(1 << 2)
#define PCA9541_ISTAT_BUSLOST	(1 << 3)
#define PCA9541_ISTAT_MYTEST	(1 << 6)
#define PCA9541_ISTAT_NMYTEST	(1 << 7)

#define BUSON		(PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)
#define MYBUS		(PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)
#define mybus(x)	(!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
#define busoff(x)	(!((x) & BUSON) || ((x) & BUSON) == BUSON)

/* arbitration timeouts, in jiffies */
#define ARB_TIMEOUT	(HZ / 8)	/* 125 ms until forcing bus ownership */
#define ARB2_TIMEOUT	(HZ / 4)	/* 250 ms until acquisition failure */

/* arbitration retry delays, in us */
#define SELECT_DELAY_SHORT	50
#define SELECT_DELAY_LONG	1000

struct pca9541 {
	struct i2c_client *client;
	unsigned long select_timeout;
	unsigned long arb_timeout;
};

static const struct i2c_device_id pca9541_id[] = {
	{"pca9541", 0},
	{}
};

MODULE_DEVICE_TABLE(i2c, pca9541_id);

#ifdef CONFIG_OF
static const struct of_device_id pca9541_of_match[] = {
	{ .compatible = "nxp,pca9541" },
	{}
};
#endif

/*
 * Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
 * as they will try to lock the adapter a second time.
 */
static int pca9541_reg_write(struct i2c_client *client, u8 command, u8 val)
{
	struct i2c_adapter *adap = client->adapter;
	int ret;

	if (adap->algo->master_xfer) {
		struct i2c_msg msg;
		char buf[2];

		msg.addr = client->addr;
		msg.flags = 0;
		msg.len = 2;
		buf[0] = command;
		buf[1] = val;
		msg.buf = buf;
		ret = __i2c_transfer(adap, &msg, 1);
	} else {
		union i2c_smbus_data data;

		data.byte = val;
		ret = adap->algo->smbus_xfer(adap, client->addr,
					     client->flags,
					     I2C_SMBUS_WRITE,
					     command,
					     I2C_SMBUS_BYTE_DATA, &data);
	}

	return ret;
}

/*
 * Read from chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
 * as they will try to lock adapter a second time.
 */
static int pca9541_reg_read(struct i2c_client *client, u8 command)
{
	struct i2c_adapter *adap = client->adapter;
	int ret;
	u8 val;

	if (adap->algo->master_xfer) {
		struct i2c_msg msg[2] = {
			{
				.addr = client->addr,
				.flags = 0,
				.len = 1,
				.buf = &command
			},
			{
				.addr = client->addr,
				.flags = I2C_M_RD,
				.len = 1,
				.buf = &val
			}
		};
		ret = __i2c_transfer(adap, msg, 2);
		if (ret == 2)
			ret = val;
		else if (ret >= 0)
			ret = -EIO;
	} else {
		union i2c_smbus_data data;

		ret = adap->algo->smbus_xfer(adap, client->addr,
					     client->flags,
					     I2C_SMBUS_READ,
					     command,
					     I2C_SMBUS_BYTE_DATA, &data);
		if (!ret)
			ret = data.byte;
	}
	return ret;
}

/*
 * Arbitration management functions
 */

/* Release bus. Also reset NTESTON and BUSINIT if it was set. */
static void pca9541_release_bus(struct i2c_client *client)
{
	int reg;

	reg = pca9541_reg_read(client, PCA9541_CONTROL);
	if (reg >= 0 && !busoff(reg) && mybus(reg))
		pca9541_reg_write(client, PCA9541_CONTROL,
				  (reg & PCA9541_CTL_NBUSON) >> 1);
}

/*
 * Arbitration is defined as a two-step process. A bus master can only activate
 * the slave bus if it owns it; otherwise it has to request ownership first.
 * This multi-step process ensures that access contention is resolved
 * gracefully.
 *
 * Bus	Ownership	Other master	Action
 * state		requested access
 * ----------------------------------------------------
 * off	-		yes		wait for arbitration timeout or
 *					for other master to drop request
 * off	no		no		take ownership
 * off	yes		no		turn on bus
 * on	yes		-		done
 * on	no		-		wait for arbitration timeout or
 *					for other master to release bus
 *
 * The main contention point occurs if the slave bus is off and both masters
 * request ownership at the same time. In this case, one master will turn on
 * the slave bus, believing that it owns it. The other master will request
 * bus ownership. Result is that the bus is turned on, and master which did
 * _not_ own the slave bus before ends up owning it.
 */

/* Control commands per PCA9541 datasheet */
static const u8 pca9541_control[16] = {
	4, 0, 1, 5, 4, 4, 5, 5, 0, 0, 1, 1, 0, 4, 5, 1
};

/*
 * Channel arbitration
 *
 * Return values:
 *  <0: error
 *  0 : bus not acquired
 *  1 : bus acquired
 */
static int pca9541_arbitrate(struct i2c_client *client)
{
	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
	struct pca9541 *data = i2c_mux_priv(muxc);
	int reg;

	reg = pca9541_reg_read(client, PCA9541_CONTROL);
	if (reg < 0)
		return reg;

	if (busoff(reg)) {
		int istat;
		/*
		 * Bus is off. Request ownership or turn it on unless
		 * other master requested ownership.
		 */
		istat = pca9541_reg_read(client, PCA9541_ISTAT);
		if (!(istat & PCA9541_ISTAT_NMYTEST)
		    || time_is_before_eq_jiffies(data->arb_timeout)) {
			/*
			 * Other master did not request ownership,
			 * or arbitration timeout expired. Take the bus.
			 */
			pca9541_reg_write(client,
					  PCA9541_CONTROL,
					  pca9541_control[reg & 0x0f]
					  | PCA9541_CTL_NTESTON);
			data->select_timeout = SELECT_DELAY_SHORT;
		} else {
			/*
			 * Other master requested ownership.
			 * Set extra long timeout to give it time to acquire it.
			 */
			data->select_timeout = SELECT_DELAY_LONG * 2;
		}
	} else if (mybus(reg)) {
		/*
		 * Bus is on, and we own it. We are done with acquisition.
		 * Reset NTESTON and BUSINIT, then return success.
		 */
		if (reg & (PCA9541_CTL_NTESTON | PCA9541_CTL_BUSINIT))
			pca9541_reg_write(client,
					  PCA9541_CONTROL,
					  reg & ~(PCA9541_CTL_NTESTON
						  | PCA9541_CTL_BUSINIT));
		return 1;
	} else {
		/*
		 * Other master owns the bus.
		 * If arbitration timeout has expired, force ownership.
		 * Otherwise request it.
		 */
		data->select_timeout = SELECT_DELAY_LONG;
		if (time_is_before_eq_jiffies(data->arb_timeout)) {
			/* Time is up, take the bus and reset it. */
			pca9541_reg_write(client,
					  PCA9541_CONTROL,
					  pca9541_control[reg & 0x0f]
					  | PCA9541_CTL_BUSINIT
					  | PCA9541_CTL_NTESTON);
		} else {
			/* Request bus ownership if needed */
			if (!(reg & PCA9541_CTL_NTESTON))
				pca9541_reg_write(client,
						  PCA9541_CONTROL,
						  reg | PCA9541_CTL_NTESTON);
		}
	}
	return 0;
}

static int pca9541_select_chan(struct i2c_mux_core *muxc, u32 chan)
{
	struct pca9541 *data = i2c_mux_priv(muxc);
	struct i2c_client *client = data->client;
	int ret;
	unsigned long timeout = jiffies + ARB2_TIMEOUT;
		/* give up after this time */

	data->arb_timeout = jiffies + ARB_TIMEOUT;
		/* force bus ownership after this time */

	do {
		ret = pca9541_arbitrate(client);
		if (ret)
			return ret < 0 ? ret : 0;

		if (data->select_timeout == SELECT_DELAY_SHORT)
			udelay(data->select_timeout);
		else
			msleep(data->select_timeout / 1000);
	} while (time_is_after_eq_jiffies(timeout));

	return -ETIMEDOUT;
}

static int pca9541_release_chan(struct i2c_mux_core *muxc, u32 chan)
{
	struct pca9541 *data = i2c_mux_priv(muxc);
	struct i2c_client *client = data->client;

	pca9541_release_bus(client);
	return 0;
}

/*
 * I2C init/probing/exit functions
 */
static int pca9541_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct i2c_adapter *adap = client->adapter;
	struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
	struct i2c_mux_core *muxc;
	struct pca9541 *data;
	int force;
	int ret;

	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE_DATA))
		return -ENODEV;

	/*
	 * I2C accesses are unprotected here.
	 * We have to lock the adapter before releasing the bus.
	 */
	i2c_lock_adapter(adap);
	pca9541_release_bus(client);
	i2c_unlock_adapter(adap);

	/* Create mux adapter */

	force = 0;
	if (pdata)
		force = pdata->modes[0].adap_id;
	muxc = i2c_mux_alloc(adap, &client->dev, 1, sizeof(*data),
			     I2C_MUX_ARBITRATOR,
			     pca9541_select_chan, pca9541_release_chan);
	if (!muxc)
		return -ENOMEM;

	data = i2c_mux_priv(muxc);
	data->client = client;

	i2c_set_clientdata(client, muxc);

	ret = i2c_mux_add_adapter(muxc, force, 0, 0);
	if (ret) {
		dev_err(&client->dev, "failed to register master selector\n");
		return ret;
	}

	dev_info(&client->dev, "registered master selector for I2C %s\n",
		 client->name);

	return 0;
}

static int pca9541_remove(struct i2c_client *client)
{
	struct i2c_mux_core *muxc = i2c_get_clientdata(client);

	i2c_mux_del_adapters(muxc);
	return 0;
}

static struct i2c_driver pca9541_driver = {
	.driver = {
		   .name = "pca9541",
		   .of_match_table = of_match_ptr(pca9541_of_match),
		   },
	.probe = pca9541_probe,
	.remove = pca9541_remove,
	.id_table = pca9541_id,
};

module_i2c_driver(pca9541_driver);

MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
MODULE_DESCRIPTION("PCA9541 I2C master selector driver");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
ae63b13b GR	1	/*
	2	* I2C multiplexer driver for PCA9541 bus master selector
	3	*
	4	* Copyright (c) 2010 Ericsson AB.
	5	*
b104153e	6	* Author: Guenter Roeck <linux@roeck-us.net>
ae63b13b GR	7	*
	8	* Derived from:
	9	* pca954x.c
	10	*
	11	* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
	12	* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
	13	*
	14	* This file is licensed under the terms of the GNU General Public
	15	* License version 2. This program is licensed "as is" without any
	16	* warranty of any kind, whether express or implied.
	17	*/
	18
	19	#include <linux/module.h>
ae63b13b GR	20	#include <linux/jiffies.h>
	21	#include <linux/delay.h>
	22	#include <linux/slab.h>
	23	#include <linux/device.h>
	24	#include <linux/i2c.h>
	25	#include <linux/i2c-mux.h>
	26
	27	#include <linux/i2c/pca954x.h>
	28
	29	/*
	30	* The PCA9541 is a bus master selector. It supports two I2C masters connected
	31	* to a single slave bus.
	32	*
	33	* Before each bus transaction, a master has to acquire bus ownership. After the
	34	* transaction is complete, bus ownership has to be released. This fits well
	35	* into the I2C multiplexer framework, which provides select and release
	36	* functions for this purpose. For this reason, this driver is modeled as
	37	* single-channel I2C bus multiplexer.
	38	*
	39	* This driver assumes that the two bus masters are controlled by two different
	40	* hosts. If a single host controls both masters, platform code has to ensure
	41	* that only one of the masters is instantiated at any given time.
	42	*/
	43
	44	#define PCA9541_CONTROL 0x01
	45	#define PCA9541_ISTAT 0x02
	46
	47	#define PCA9541_CTL_MYBUS (1 << 0)
	48	#define PCA9541_CTL_NMYBUS (1 << 1)
	49	#define PCA9541_CTL_BUSON (1 << 2)
	50	#define PCA9541_CTL_NBUSON (1 << 3)
	51	#define PCA9541_CTL_BUSINIT (1 << 4)
	52	#define PCA9541_CTL_TESTON (1 << 6)
	53	#define PCA9541_CTL_NTESTON (1 << 7)
	54
	55	#define PCA9541_ISTAT_INTIN (1 << 0)
	56	#define PCA9541_ISTAT_BUSINIT (1 << 1)
	57	#define PCA9541_ISTAT_BUSOK (1 << 2)
	58	#define PCA9541_ISTAT_BUSLOST (1 << 3)
	59	#define PCA9541_ISTAT_MYTEST (1 << 6)
	60	#define PCA9541_ISTAT_NMYTEST (1 << 7)
	61
	62	#define BUSON (PCA9541_CTL_BUSON \| PCA9541_CTL_NBUSON)
	63	#define MYBUS (PCA9541_CTL_MYBUS \| PCA9541_CTL_NMYBUS)
	64	#define mybus(x) (!((x) & MYBUS) \|\| ((x) & MYBUS) == MYBUS)
	65	#define busoff(x) (!((x) & BUSON) \|\| ((x) & BUSON) == BUSON)
	66
	67	/* arbitration timeouts, in jiffies */
	68	#define ARB_TIMEOUT (HZ / 8) /* 125 ms until forcing bus ownership */
	69	#define ARB2_TIMEOUT (HZ / 4) /* 250 ms until acquisition failure */
	70
	71	/* arbitration retry delays, in us */
	72	#define SELECT_DELAY_SHORT 50
	73	#define SELECT_DELAY_LONG 1000
	74
	75	struct pca9541 {
ab88b97c	76	struct i2c_client *client;
ae63b13b GR	77	unsigned long select_timeout;
	78	unsigned long arb_timeout;
	79	};
	80
	81	static const struct i2c_device_id pca9541_id[] = {
	82	{"pca9541", 0},
	83	{}
	84	};
	85
	86	MODULE_DEVICE_TABLE(i2c, pca9541_id);
	87
a1cbf338 PR	88	#ifdef CONFIG_OF
	89	static const struct of_device_id pca9541_of_match[] = {
	90	{ .compatible = "nxp,pca9541" },
	91	{}
	92	};
	93	#endif
	94
ae63b13b GR	95	/*
	96	* Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
	97	* as they will try to lock the adapter a second time.
	98	*/
	99	static int pca9541_reg_write(struct i2c_client *client, u8 command, u8 val)
	100	{
	101	struct i2c_adapter *adap = client->adapter;
	102	int ret;
	103
	104	if (adap->algo->master_xfer) {
	105	struct i2c_msg msg;
	106	char buf[2];
	107
	108	msg.addr = client->addr;
	109	msg.flags = 0;
	110	msg.len = 2;
	111	buf[0] = command;
	112	buf[1] = val;
	113	msg.buf = buf;
0a8237ae	114	ret = __i2c_transfer(adap, &msg, 1);
ae63b13b GR	115	} else {
	116	union i2c_smbus_data data;
	117
	118	data.byte = val;
	119	ret = adap->algo->smbus_xfer(adap, client->addr,
	120	client->flags,
	121	I2C_SMBUS_WRITE,
	122	command,
	123	I2C_SMBUS_BYTE_DATA, &data);
	124	}
	125
	126	return ret;
	127	}
	128
	129	/*
	130	* Read from chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
	131	* as they will try to lock adapter a second time.
	132	*/
	133	static int pca9541_reg_read(struct i2c_client *client, u8 command)
	134	{
	135	struct i2c_adapter *adap = client->adapter;
	136	int ret;
	137	u8 val;
	138
	139	if (adap->algo->master_xfer) {
	140	struct i2c_msg msg[2] = {
	141	{
	142	.addr = client->addr,
	143	.flags = 0,
	144	.len = 1,
	145	.buf = &command
	146	},
	147	{
	148	.addr = client->addr,
	149	.flags = I2C_M_RD,
	150	.len = 1,
	151	.buf = &val
	152	}
	153	};
0a8237ae	154	ret = __i2c_transfer(adap, msg, 2);
ae63b13b GR	155	if (ret == 2)
	156	ret = val;
	157	else if (ret >= 0)
	158	ret = -EIO;
	159	} else {
	160	union i2c_smbus_data data;
	161
	162	ret = adap->algo->smbus_xfer(adap, client->addr,
	163	client->flags,
	164	I2C_SMBUS_READ,
	165	command,
	166	I2C_SMBUS_BYTE_DATA, &data);
	167	if (!ret)
	168	ret = data.byte;
	169	}
	170	return ret;
	171	}
	172
	173	/*
	174	* Arbitration management functions
	175	*/
	176
	177	/* Release bus. Also reset NTESTON and BUSINIT if it was set. */
	178	static void pca9541_release_bus(struct i2c_client *client)
	179	{
	180	int reg;
	181
	182	reg = pca9541_reg_read(client, PCA9541_CONTROL);
	183	if (reg >= 0 && !busoff(reg) && mybus(reg))
	184	pca9541_reg_write(client, PCA9541_CONTROL,
	185	(reg & PCA9541_CTL_NBUSON) >> 1);
	186	}
	187
	188	/*
	189	* Arbitration is defined as a two-step process. A bus master can only activate
	190	* the slave bus if it owns it; otherwise it has to request ownership first.
	191	* This multi-step process ensures that access contention is resolved
	192	* gracefully.
	193	*
	194	* Bus Ownership Other master Action
	195	* state requested access
	196	* ----------------------------------------------------
	197	* off - yes wait for arbitration timeout or
	198	* for other master to drop request
	199	* off no no take ownership
	200	* off yes no turn on bus
	201	* on yes - done
	202	* on no - wait for arbitration timeout or
	203	* for other master to release bus
	204	*
	205	* The main contention point occurs if the slave bus is off and both masters
	206	* request ownership at the same time. In this case, one master will turn on
	207	* the slave bus, believing that it owns it. The other master will request
	208	* bus ownership. Result is that the bus is turned on, and master which did
	209	* _not_ own the slave bus before ends up owning it.
	210	*/
	211
	212	/* Control commands per PCA9541 datasheet */
	213	static const u8 pca9541_control[16] = {
	214	4, 0, 1, 5, 4, 4, 5, 5, 0, 0, 1, 1, 0, 4, 5, 1
	215	};
	216
	217	/*
	218	* Channel arbitration
219	*
220	* Return values:
221	* <0: error
222	* 0 : bus not acquired
223	* 1 : bus acquired
224	*/
225	static int pca9541_arbitrate(struct i2c_client *client)
226	{
ab88b97c PR	227	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
ab88b97c PR	228	struct pca9541 *data = i2c_mux_priv(muxc);
ae63b13b GR	229	int reg;
	230
	231	reg = pca9541_reg_read(client, PCA9541_CONTROL);
	232	if (reg < 0)
	233	return reg;
	234
	235	if (busoff(reg)) {
	236	int istat;
	237	/*
	238	* Bus is off. Request ownership or turn it on unless
	239	* other master requested ownership.
	240	*/
	241	istat = pca9541_reg_read(client, PCA9541_ISTAT);
	242	if (!(istat & PCA9541_ISTAT_NMYTEST)
	243	\|\| time_is_before_eq_jiffies(data->arb_timeout)) {
	244	/*
	245	* Other master did not request ownership,
	246	* or arbitration timeout expired. Take the bus.
	247	*/
	248	pca9541_reg_write(client,
	249	PCA9541_CONTROL,
	250	pca9541_control[reg & 0x0f]
	251	\| PCA9541_CTL_NTESTON);
	252	data->select_timeout = SELECT_DELAY_SHORT;
	253	} else {
	254	/*
	255	* Other master requested ownership.
	256	* Set extra long timeout to give it time to acquire it.
	257	*/
	258	data->select_timeout = SELECT_DELAY_LONG * 2;
	259	}
	260	} else if (mybus(reg)) {
	261	/*
	262	* Bus is on, and we own it. We are done with acquisition.
	263	* Reset NTESTON and BUSINIT, then return success.
	264	*/
	265	if (reg & (PCA9541_CTL_NTESTON \| PCA9541_CTL_BUSINIT))
	266	pca9541_reg_write(client,
	267	PCA9541_CONTROL,
	268	reg & ~(PCA9541_CTL_NTESTON
	269	\| PCA9541_CTL_BUSINIT));
	270	return 1;
	271	} else {
	272	/*
	273	* Other master owns the bus.
	274	* If arbitration timeout has expired, force ownership.
	275	* Otherwise request it.
	276	*/
	277	data->select_timeout = SELECT_DELAY_LONG;
	278	if (time_is_before_eq_jiffies(data->arb_timeout)) {
	279	/* Time is up, take the bus and reset it. */
	280	pca9541_reg_write(client,
	281	PCA9541_CONTROL,
	282	pca9541_control[reg & 0x0f]
	283	\| PCA9541_CTL_BUSINIT
	284	\| PCA9541_CTL_NTESTON);
	285	} else {
	286	/* Request bus ownership if needed */
	287	if (!(reg & PCA9541_CTL_NTESTON))
	288	pca9541_reg_write(client,
	289	PCA9541_CONTROL,
	290	reg \| PCA9541_CTL_NTESTON);
	291	}
	292	}
293	return 0;
294	}
295
ab88b97c	296	static int pca9541_select_chan(struct i2c_mux_core *muxc, u32 chan)
ae63b13b	297	{
ab88b97c PR	298	struct pca9541 *data = i2c_mux_priv(muxc);
ab88b97c PR	299	struct i2c_client *client = data->client;
ae63b13b GR	300	int ret;
	301	unsigned long timeout = jiffies + ARB2_TIMEOUT;
	302	/* give up after this time */
	303
	304	data->arb_timeout = jiffies + ARB_TIMEOUT;
	305	/* force bus ownership after this time */
	306
	307	do {
	308	ret = pca9541_arbitrate(client);
	309	if (ret)
	310	return ret < 0 ? ret : 0;
	311
	312	if (data->select_timeout == SELECT_DELAY_SHORT)
	313	udelay(data->select_timeout);
	314	else
	315	msleep(data->select_timeout / 1000);
	316	} while (time_is_after_eq_jiffies(timeout));
	317
	318	return -ETIMEDOUT;
	319	}
	320
ab88b97c	321	static int pca9541_release_chan(struct i2c_mux_core *muxc, u32 chan)
ae63b13b	322	{
ab88b97c PR	323	struct pca9541 *data = i2c_mux_priv(muxc);
	324	struct i2c_client *client = data->client;
	325
ae63b13b GR	326	pca9541_release_bus(client);
	327	return 0;
	328	}
	329
	330	/*
	331	* I2C init/probing/exit functions
	332	*/
	333	static int pca9541_probe(struct i2c_client *client,
	334	const struct i2c_device_id *id)
	335	{
	336	struct i2c_adapter *adap = client->adapter;
6d4028c6	337	struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
ab88b97c	338	struct i2c_mux_core *muxc;
ae63b13b GR	339	struct pca9541 *data;
ae63b13b GR	340	int force;
ab88b97c	341	int ret;
ae63b13b GR	342
ae63b13b GR	343	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE_DATA))
ab88b97c	344	return -ENODEV;
ae63b13b GR	345
	346	/*
	347	* I2C accesses are unprotected here.
	348	* We have to lock the adapter before releasing the bus.
	349	*/
	350	i2c_lock_adapter(adap);
	351	pca9541_release_bus(client);
	352	i2c_unlock_adapter(adap);
	353
	354	/* Create mux adapter */
	355
	356	force = 0;
	357	if (pdata)
	358	force = pdata->modes[0].adap_id;
40839590 PR	359	muxc = i2c_mux_alloc(adap, &client->dev, 1, sizeof(*data),
40839590 PR	360	I2C_MUX_ARBITRATOR,
ab88b97c PR	361	pca9541_select_chan, pca9541_release_chan);
	362	if (!muxc)
	363	return -ENOMEM;
ae63b13b	364
ab88b97c PR	365	data = i2c_mux_priv(muxc);
	366	data->client = client;
	367
	368	i2c_set_clientdata(client, muxc);
	369
	370	ret = i2c_mux_add_adapter(muxc, force, 0, 0);
	371	if (ret) {
ae63b13b	372	dev_err(&client->dev, "failed to register master selector\n");
ab88b97c	373	return ret;
ae63b13b GR	374	}
	375
	376	dev_info(&client->dev, "registered master selector for I2C %s\n",
	377	client->name);
	378
	379	return 0;
ae63b13b GR	380	}
	381
	382	static int pca9541_remove(struct i2c_client *client)
	383	{
ab88b97c	384	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
ae63b13b	385
ab88b97c	386	i2c_mux_del_adapters(muxc);
ae63b13b GR	387	return 0;
	388	}
	389
	390	static struct i2c_driver pca9541_driver = {
	391	.driver = {
	392	.name = "pca9541",
a1cbf338	393	.of_match_table = of_match_ptr(pca9541_of_match),
ae63b13b GR	394	},
	395	.probe = pca9541_probe,
	396	.remove = pca9541_remove,
	397	.id_table = pca9541_id,
	398	};
	399
de05497a	400	module_i2c_driver(pca9541_driver);
ae63b13b	401
83a638df	402	MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
ae63b13b GR	403	MODULE_DESCRIPTION("PCA9541 I2C master selector driver");
ae63b13b GR	404	MODULE_LICENSE("GPL v2");