drivers/i2c/muxes/pca954x.c - maze/linux - Git at Google

 /*
  * I2C multiplexer
  *
  * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
  * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
  *
  * This module supports the PCA954x series of I2C multiplexer/switch chips
  * made by Philips Semiconductors.
  * This includes the:
  *	 PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
  *	 and PCA9548.
  *
  * These chips are all controlled via the I2C bus itself, and all have a
  * single 8-bit register. The upstream "parent" bus fans out to two,
  * four, or eight downstream busses or channels; which of these
  * are selected is determined by the chip type and register contents. A
  * mux can select only one sub-bus at a time; a switch can select any
  * combination simultaneously.
  *
  * Based on:
  *	pca954x.c from Kumar Gala <galak@kernel.crashing.org>
  * Copyright (C) 2006
  *
  * Based on:
  *	pca954x.c from Ken Harrenstien
  * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
  *
  * Based on:
  *	i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
  * and
  *	pca9540.c from Jean Delvare <khali@linux-fr.org>.
  *
  * 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/init.h>
 #include <linux/slab.h>
 #include <linux/device.h>
 #include <linux/i2c.h>
 #include <linux/i2c-mux.h>

 #include <linux/i2c/pca954x.h>

 #define PCA954X_MAX_NCHANS 8

 enum pca_type {
 	pca_9540,
 	pca_9542,
 	pca_9543,
 	pca_9544,
 	pca_9545,
 	pca_9546,
 	pca_9547,
 	pca_9548,
 };

 struct pca954x {
 	enum pca_type type;
 	struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];

 	u8 last_chan;		/* last register value */
 };

 struct chip_desc {
 	u8 nchans;
 	u8 enable;	/* used for muxes only */
 	enum muxtype {
 		pca954x_ismux = 0,
 		pca954x_isswi
 	} muxtype;
 };

 /* Provide specs for the PCA954x types we know about */
 static const struct chip_desc chips[] = {
 	[pca_9540] = {
 		.nchans = 2,
 		.enable = 0x4,
 		.muxtype = pca954x_ismux,
 	},
 	[pca_9543] = {
 		.nchans = 2,
 		.muxtype = pca954x_isswi,
 	},
 	[pca_9544] = {
 		.nchans = 4,
 		.enable = 0x4,
 		.muxtype = pca954x_ismux,
 	},
 	[pca_9545] = {
 		.nchans = 4,
 		.muxtype = pca954x_isswi,
 	},
 	[pca_9547] = {
 		.nchans = 8,
 		.enable = 0x8,
 		.muxtype = pca954x_ismux,
 	},
 	[pca_9548] = {
 		.nchans = 8,
 		.muxtype = pca954x_isswi,
 	},
 };

 static const struct i2c_device_id pca954x_id[] = {
 	{ "pca9540", pca_9540 },
 	{ "pca9542", pca_9540 },
 	{ "pca9543", pca_9543 },
 	{ "pca9544", pca_9544 },
 	{ "pca9545", pca_9545 },
 	{ "pca9546", pca_9545 },
 	{ "pca9547", pca_9547 },
 	{ "pca9548", pca_9548 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, pca954x_id);

 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
    for this as they will try to lock adapter a second time */
 static int pca954x_reg_write(struct i2c_adapter *adap,
 			     struct i2c_client *client, u8 val)
 {
 	int ret = -ENODEV;

 	if (adap->algo->master_xfer) {
 		struct i2c_msg msg;
 		char buf[1];

 		msg.addr = client->addr;
 		msg.flags = 0;
 		msg.len = 1;
 		buf[0] = val;
 		msg.buf = buf;
 		ret = adap->algo->master_xfer(adap, &msg, 1);
 	} else {
 		union i2c_smbus_data data;
 		ret = adap->algo->smbus_xfer(adap, client->addr,
 					     client->flags,
 					     I2C_SMBUS_WRITE,
 					     val, I2C_SMBUS_BYTE, &data);
 	}

 	return ret;
 }

 static int pca954x_select_chan(struct i2c_adapter *adap,
 			       void *client, u32 chan)
 {
 	struct pca954x *data = i2c_get_clientdata(client);
 	const struct chip_desc *chip = &chips[data->type];
 	u8 regval;
 	int ret = 0;

 	/* we make switches look like muxes, not sure how to be smarter */
 	if (chip->muxtype == pca954x_ismux)
 		regval = chan | chip->enable;
 	else
 		regval = 1 << chan;

 	/* Only select the channel if its different from the last channel */
 	if (data->last_chan != regval) {
 		ret = pca954x_reg_write(adap, client, regval);
 		data->last_chan = regval;
 	}

 	return ret;
 }

 static int pca954x_deselect_mux(struct i2c_adapter *adap,
 				void *client, u32 chan)
 {
 	struct pca954x *data = i2c_get_clientdata(client);

 	/* Deselect active channel */
 	data->last_chan = 0;
 	return pca954x_reg_write(adap, client, data->last_chan);
 }

 /*
  * I2C init/probing/exit functions
  */
 static int pca954x_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
 	struct pca954x_platform_data *pdata = client->dev.platform_data;
 	int num, force;
 	struct pca954x *data;
 	int ret = -ENODEV;

 	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
 		goto err;

 	data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
 	if (!data) {
 		ret = -ENOMEM;
 		goto err;
 	}

 	i2c_set_clientdata(client, data);

 	/* Read the mux register at addr to verify
 	 * that the mux is in fact present.
 	 */
 	if (i2c_smbus_read_byte(client) < 0) {
 		dev_warn(&client->dev, "probe failed\n");
 		goto exit_free;
 	}

 	data->type = id->driver_data;
 	data->last_chan = 0;		   /* force the first selection */

 	/* Now create an adapter for each channel */
 	for (num = 0; num < chips[data->type].nchans; num++) {
 		force = 0;			  /* dynamic adap number */
 		if (pdata) {
 			if (num < pdata->num_modes)
 				/* force static number */
 				force = pdata->modes[num].adap_id;
 			else
 				/* discard unconfigured channels */
 				break;
 		}

 		data->virt_adaps[num] =
 			i2c_add_mux_adapter(adap, client,
 				force, num, pca954x_select_chan,
 				(pdata && pdata->modes[num].deselect_on_exit)
 					? pca954x_deselect_mux : NULL);

 		if (data->virt_adaps[num] == NULL) {
 			ret = -ENODEV;
 			dev_err(&client->dev,
 				"failed to register multiplexed adapter"
 				" %d as bus %d\n", num, force);
 			goto virt_reg_failed;
 		}
 	}

 	dev_info(&client->dev,
 		 "registered %d multiplexed busses for I2C %s %s\n",
 		 num, chips[data->type].muxtype == pca954x_ismux
 				? "mux" : "switch", client->name);

 	return 0;

 virt_reg_failed:
 	for (num--; num >= 0; num--)
 		i2c_del_mux_adapter(data->virt_adaps[num]);
 exit_free:
 	kfree(data);
 err:
 	return ret;
 }

 static int pca954x_remove(struct i2c_client *client)
 {
 	struct pca954x *data = i2c_get_clientdata(client);
 	const struct chip_desc *chip = &chips[data->type];
 	int i, err;

 	for (i = 0; i < chip->nchans; ++i)
 		if (data->virt_adaps[i]) {
 			err = i2c_del_mux_adapter(data->virt_adaps[i]);
 			if (err)
 				return err;
 			data->virt_adaps[i] = NULL;
 		}

 	kfree(data);
 	return 0;
 }

 static struct i2c_driver pca954x_driver = {
 	.driver		= {
 		.name	= "pca954x",
 		.owner	= THIS_MODULE,
 	},
 	.probe		= pca954x_probe,
 	.remove		= pca954x_remove,
 	.id_table	= pca954x_id,
 };

 static int __init pca954x_init(void)
 {
 	return i2c_add_driver(&pca954x_driver);
 }

 static void __exit pca954x_exit(void)
 {
 	i2c_del_driver(&pca954x_driver);
 }

 module_init(pca954x_init);
 module_exit(pca954x_exit);

 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
 MODULE_LICENSE("GPL v2");
	/*
	* I2C multiplexer
	*
	* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
	* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
	*
	* This module supports the PCA954x series of I2C multiplexer/switch chips
	* made by Philips Semiconductors.
	* This includes the:
	* PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
	* and PCA9548.
	*
	* These chips are all controlled via the I2C bus itself, and all have a
	* single 8-bit register. The upstream "parent" bus fans out to two,
	* four, or eight downstream busses or channels; which of these
	* are selected is determined by the chip type and register contents. A
	* mux can select only one sub-bus at a time; a switch can select any
	* combination simultaneously.
	*
	* Based on:
	* pca954x.c from Kumar Gala <galak@kernel.crashing.org>
	* Copyright (C) 2006
	*
	* Based on:
	* pca954x.c from Ken Harrenstien
	* Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
	*
	* Based on:
	* i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
	* and
	* pca9540.c from Jean Delvare <khali@linux-fr.org>.
	*
	* 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/init.h>
	#include <linux/slab.h>
	#include <linux/device.h>
	#include <linux/i2c.h>
	#include <linux/i2c-mux.h>

	#include <linux/i2c/pca954x.h>

	#define PCA954X_MAX_NCHANS 8

	enum pca_type {
	pca_9540,
	pca_9542,
	pca_9543,
	pca_9544,
	pca_9545,
	pca_9546,
	pca_9547,
	pca_9548,
	};

	struct pca954x {
	enum pca_type type;
	struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];

	u8 last_chan; /* last register value */
	};

	struct chip_desc {
	u8 nchans;
	u8 enable; /* used for muxes only */
	enum muxtype {
	pca954x_ismux = 0,
	pca954x_isswi
	} muxtype;
	};

	/* Provide specs for the PCA954x types we know about */
	static const struct chip_desc chips[] = {
	[pca_9540] = {
	.nchans = 2,
	.enable = 0x4,
	.muxtype = pca954x_ismux,
	},
	[pca_9543] = {
	.nchans = 2,
	.muxtype = pca954x_isswi,
	},
	[pca_9544] = {
	.nchans = 4,
	.enable = 0x4,
	.muxtype = pca954x_ismux,
	},
	[pca_9545] = {
	.nchans = 4,
	.muxtype = pca954x_isswi,
	},
	[pca_9547] = {
	.nchans = 8,
	.enable = 0x8,
	.muxtype = pca954x_ismux,
	},
	[pca_9548] = {
	.nchans = 8,
	.muxtype = pca954x_isswi,
	},
	};

	static const struct i2c_device_id pca954x_id[] = {
	{ "pca9540", pca_9540 },
	{ "pca9542", pca_9540 },
	{ "pca9543", pca_9543 },
	{ "pca9544", pca_9544 },
	{ "pca9545", pca_9545 },
	{ "pca9546", pca_9545 },
	{ "pca9547", pca_9547 },
	{ "pca9548", pca_9548 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, pca954x_id);

	/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
	for this as they will try to lock adapter a second time */
	static int pca954x_reg_write(struct i2c_adapter *adap,
	struct i2c_client *client, u8 val)
	{
	int ret = -ENODEV;

	if (adap->algo->master_xfer) {
	struct i2c_msg msg;
	char buf[1];

	msg.addr = client->addr;
	msg.flags = 0;
	msg.len = 1;
	buf[0] = val;
	msg.buf = buf;
	ret = adap->algo->master_xfer(adap, &msg, 1);
	} else {
	union i2c_smbus_data data;
	ret = adap->algo->smbus_xfer(adap, client->addr,
	client->flags,
	I2C_SMBUS_WRITE,
	val, I2C_SMBUS_BYTE, &data);
	}

	return ret;
	}

	static int pca954x_select_chan(struct i2c_adapter *adap,
	void *client, u32 chan)
	{
	struct pca954x *data = i2c_get_clientdata(client);
	const struct chip_desc *chip = &chips[data->type];
	u8 regval;
	int ret = 0;

	/* we make switches look like muxes, not sure how to be smarter */
	if (chip->muxtype == pca954x_ismux)
	regval = chan \| chip->enable;
	else
	regval = 1 << chan;

	/* Only select the channel if its different from the last channel */
	if (data->last_chan != regval) {
	ret = pca954x_reg_write(adap, client, regval);
	data->last_chan = regval;
	}

	return ret;
	}

	static int pca954x_deselect_mux(struct i2c_adapter *adap,
	void *client, u32 chan)
	{
	struct pca954x *data = i2c_get_clientdata(client);

	/* Deselect active channel */
	data->last_chan = 0;
	return pca954x_reg_write(adap, client, data->last_chan);
	}

	/*
	* I2C init/probing/exit functions
	*/
	static int pca954x_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
	struct pca954x_platform_data *pdata = client->dev.platform_data;
	int num, force;
	struct pca954x *data;
	int ret = -ENODEV;

	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
	goto err;

	data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
	if (!data) {
	ret = -ENOMEM;
	goto err;
	}

	i2c_set_clientdata(client, data);

	/* Read the mux register at addr to verify
	* that the mux is in fact present.
	*/
	if (i2c_smbus_read_byte(client) < 0) {
	dev_warn(&client->dev, "probe failed\n");
	goto exit_free;
	}

	data->type = id->driver_data;
	data->last_chan = 0; /* force the first selection */

	/* Now create an adapter for each channel */
	for (num = 0; num < chips[data->type].nchans; num++) {
	force = 0; /* dynamic adap number */
	if (pdata) {
	if (num < pdata->num_modes)
	/* force static number */
	force = pdata->modes[num].adap_id;
	else
	/* discard unconfigured channels */
	break;
	}

	data->virt_adaps[num] =
	i2c_add_mux_adapter(adap, client,
	force, num, pca954x_select_chan,
	(pdata && pdata->modes[num].deselect_on_exit)
	? pca954x_deselect_mux : NULL);

	if (data->virt_adaps[num] == NULL) {
	ret = -ENODEV;
	dev_err(&client->dev,
	"failed to register multiplexed adapter"
	" %d as bus %d\n", num, force);
	goto virt_reg_failed;
	}
	}

	dev_info(&client->dev,
	"registered %d multiplexed busses for I2C %s %s\n",
	num, chips[data->type].muxtype == pca954x_ismux
	? "mux" : "switch", client->name);

	return 0;

	virt_reg_failed:
	for (num--; num >= 0; num--)
	i2c_del_mux_adapter(data->virt_adaps[num]);
	exit_free:
	kfree(data);
	err:
	return ret;
	}

	static int pca954x_remove(struct i2c_client *client)
	{
	struct pca954x *data = i2c_get_clientdata(client);
	const struct chip_desc *chip = &chips[data->type];
	int i, err;

	for (i = 0; i < chip->nchans; ++i)
	if (data->virt_adaps[i]) {
	err = i2c_del_mux_adapter(data->virt_adaps[i]);
	if (err)
	return err;
	data->virt_adaps[i] = NULL;
	}

	kfree(data);
	return 0;
	}

	static struct i2c_driver pca954x_driver = {
	.driver = {
	.name = "pca954x",
	.owner = THIS_MODULE,
	},
	.probe = pca954x_probe,
	.remove = pca954x_remove,
	.id_table = pca954x_id,
	};

	static int __init pca954x_init(void)
	{
	return i2c_add_driver(&pca954x_driver);
	}

	static void __exit pca954x_exit(void)
	{
	i2c_del_driver(&pca954x_driver);
	}

	module_init(pca954x_init);
	module_exit(pca954x_exit);

	MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
	MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
	MODULE_LICENSE("GPL v2");