Commit e7c5c49e authored by Wolfram Sang's avatar Wolfram Sang Committed by Jean Delvare
Browse files

i2c/chips: Remove deprecated pcf8574 driver 



The pcf8574 driver in drivers/i2c/chips which just exports its register to
sysfs is superseded by drivers/gpio/pcf857x.c which properly uses the gpiolib.
As this driver has been deprecated for more than a year, finally remove it.

Signed-off-by: default avatarWolfram Sang <w.sang@pengutronix.de>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 732d4811

Documentation/i2c/chips/pcf8574

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Kernel driver pcf8574

=====================



Supported chips:

  * Philips PCF8574

    Prefix: 'pcf8574'

    Addresses scanned: none

    Datasheet: Publicly available at the Philips Semiconductors website

               http://www.semiconductors.philips.com/pip/PCF8574P.html



 * Philips PCF8574A

    Prefix: 'pcf8574a'

    Addresses scanned: none

    Datasheet: Publicly available at the Philips Semiconductors website

               http://www.semiconductors.philips.com/pip/PCF8574P.html



Authors:

        Frodo Looijaard <frodol@dds.nl>,

        Philip Edelbrock <phil@netroedge.com>,

        Dan Eaton <dan.eaton@rocketlogix.com>,

        Aurelien Jarno <aurelien@aurel32.net>,

        Jean Delvare <khali@linux-fr.org>,





Description

-----------

The PCF8574(A) is an 8-bit I/O expander for the I2C bus produced by Philips

Semiconductors. It is designed to provide a byte I2C interface to up to 16

separate devices (8 x PCF8574 and 8 x PCF8574A).



This device consists of a quasi-bidirectional port. Each of the eight I/Os

can be independently used as an input or output. To setup an I/O as an

input, you have to write a 1 to the corresponding output.



For more informations see the datasheet.





Accessing PCF8574(A) via /sys interface

-------------------------------------



The PCF8574(A) is plainly impossible to detect ! Stupid chip.

So, you have to pass the I2C bus and address of the installed PCF857A

and PCF8574A devices explicitly to the driver at load time via the

force=... parameter.



On detection (i.e. insmod, modprobe et al.), directories are being

created for each detected PCF8574(A):



/sys/bus/i2c/devices/<0>-<1>/

where <0> is the bus the chip was detected on (e. g. i2c-0)

and <1> the chip address ([20..27] or [38..3f]):



(example: /sys/bus/i2c/devices/1-0020/)



Inside these directories, there are two files each:

read and write (and one file with chip name).



The read file is read-only. Reading gives you the current I/O input

if the corresponding output is set as 1, otherwise the current output

value, that is to say 0.



The write file is read/write. Writing a value outputs it on the I/O

port. Reading returns the last written value. As it is not possible

to read this value from the chip, you need to write at least once to

this file before you can read back from it.

drivers/i2c/chips/Kconfig

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@@ -16,23 +16,6 @@ config DS1682 
	  This driver can also be built as a module.  If so, the module

	  will be called ds1682.



config SENSORS_PCF8574

	tristate "Philips PCF8574 and PCF8574A (DEPRECATED)"

	depends on EXPERIMENTAL && GPIO_PCF857X = "n"

	default n

	help

	  If you say yes here you get support for Philips PCF8574 and 

	  PCF8574A chips. These chips are 8-bit I/O expanders for the I2C bus.



	  This driver can also be built as a module.  If so, the module

	  will be called pcf8574.



	  This driver is deprecated and will be dropped soon. Use

	  drivers/gpio/pcf857x.c instead.



	  These devices are hard to detect and rarely found on mainstream

	  hardware.  If unsure, say N.



config SENSORS_TSL2550

	tristate "Taos TSL2550 ambient light sensor"

	depends on EXPERIMENTAL

drivers/i2c/chips/Makefile

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@@ -11,7 +11,6 @@ 
#



obj-$(CONFIG_DS1682)		+= ds1682.o

obj-$(CONFIG_SENSORS_PCF8574)	+= pcf8574.o

obj-$(CONFIG_SENSORS_TSL2550)	+= tsl2550.o



ifeq ($(CONFIG_I2C_DEBUG_CHIP),y)

drivers/i2c/chips/pcf8574.c

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/*

    Copyright (c) 2000  Frodo Looijaard <frodol@dds.nl>, 

                        Philip Edelbrock <phil@netroedge.com>,

                        Dan Eaton <dan.eaton@rocketlogix.com>

    Ported to Linux 2.6 by Aurelien Jarno <aurel32@debian.org> with 

    the help of Jean Delvare <khali@linux-fr.org>



    This program is free software; you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation; either version 2 of the License, or

    (at your option) any later version.

    

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    GNU General Public License for more details.



    You should have received a copy of the GNU General Public License

    along with this program; if not, write to the Free Software

    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/



/* A few notes about the PCF8574:



* The PCF8574 is an 8-bit I/O expander for the I2C bus produced by

  Philips Semiconductors.  It is designed to provide a byte I2C

  interface to up to 8 separate devices.

  

* The PCF8574 appears as a very simple SMBus device which can be

  read from or written to with SMBUS byte read/write accesses.



  --Dan



*/



#include <linux/module.h>

#include <linux/init.h>

#include <linux/slab.h>

#include <linux/i2c.h>



/* Addresses to scan: none, device can't be detected */

static const unsigned short normal_i2c[] = { I2C_CLIENT_END };



/* Insmod parameters */

I2C_CLIENT_INSMOD_2(pcf8574, pcf8574a);



/* Each client has this additional data */

struct pcf8574_data {

	int write;			/* Remember last written value */

};



static void pcf8574_init_client(struct i2c_client *client);



/* following are the sysfs callback functions */

static ssize_t show_read(struct device *dev, struct device_attribute *attr, char *buf)

{

	struct i2c_client *client = to_i2c_client(dev);

	return sprintf(buf, "%u\n", i2c_smbus_read_byte(client));

}



static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);



static ssize_t show_write(struct device *dev, struct device_attribute *attr, char *buf)

{

	struct pcf8574_data *data = i2c_get_clientdata(to_i2c_client(dev));



	if (data->write < 0)

		return data->write;



	return sprintf(buf, "%d\n", data->write);

}



static ssize_t set_write(struct device *dev, struct device_attribute *attr, const char *buf,

			 size_t count)

{

	struct i2c_client *client = to_i2c_client(dev);

	struct pcf8574_data *data = i2c_get_clientdata(client);

	unsigned long val = simple_strtoul(buf, NULL, 10);



	if (val > 0xff)

		return -EINVAL;



	data->write = val;

	i2c_smbus_write_byte(client, data->write);

	return count;

}



static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write);



static struct attribute *pcf8574_attributes[] = {

	&dev_attr_read.attr,

	&dev_attr_write.attr,

	NULL

};



static const struct attribute_group pcf8574_attr_group = {

	.attrs = pcf8574_attributes,

};



/*

 * Real code

 */



/* Return 0 if detection is successful, -ENODEV otherwise */

static int pcf8574_detect(struct i2c_client *client, int kind,

			  struct i2c_board_info *info)

{

	struct i2c_adapter *adapter = client->adapter;

	const char *client_name;



	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))

		return -ENODEV;



	/* Now, we would do the remaining detection. But the PCF8574 is plainly

	   impossible to detect! Stupid chip. */



	/* Determine the chip type */

	if (kind <= 0) {

		if (client->addr >= 0x38 && client->addr <= 0x3f)

			kind = pcf8574a;

		else

			kind = pcf8574;

	}



	if (kind == pcf8574a)

		client_name = "pcf8574a";

	else

		client_name = "pcf8574";

	strlcpy(info->type, client_name, I2C_NAME_SIZE);



	return 0;

}



static int pcf8574_probe(struct i2c_client *client,

			 const struct i2c_device_id *id)

{

	struct pcf8574_data *data;

	int err;



	data = kzalloc(sizeof(struct pcf8574_data), GFP_KERNEL);

	if (!data) {

		err = -ENOMEM;

		goto exit;

	}



	i2c_set_clientdata(client, data);



	/* Initialize the PCF8574 chip */

	pcf8574_init_client(client);



	/* Register sysfs hooks */

	err = sysfs_create_group(&client->dev.kobj, &pcf8574_attr_group);

	if (err)

		goto exit_free;

	return 0;



      exit_free:

	kfree(data);

      exit:

	return err;

}



static int pcf8574_remove(struct i2c_client *client)

{

	sysfs_remove_group(&client->dev.kobj, &pcf8574_attr_group);

	kfree(i2c_get_clientdata(client));

	return 0;

}



/* Called when we have found a new PCF8574. */

static void pcf8574_init_client(struct i2c_client *client)

{

	struct pcf8574_data *data = i2c_get_clientdata(client);

	data->write = -EAGAIN;

}



static const struct i2c_device_id pcf8574_id[] = {

	{ "pcf8574", 0 },

	{ "pcf8574a", 0 },

	{ }

};



static struct i2c_driver pcf8574_driver = {

	.driver = {

		.name	= "pcf8574",

	},

	.probe		= pcf8574_probe,

	.remove		= pcf8574_remove,

	.id_table	= pcf8574_id,



	.detect		= pcf8574_detect,

	.address_data	= &addr_data,

};



static int __init pcf8574_init(void)

{

	return i2c_add_driver(&pcf8574_driver);

}



static void __exit pcf8574_exit(void)

{

	i2c_del_driver(&pcf8574_driver);

}





MODULE_AUTHOR

    ("Frodo Looijaard <frodol@dds.nl>, "

     "Philip Edelbrock <phil@netroedge.com>, "

     "Dan Eaton <dan.eaton@rocketlogix.com> "

     "and Aurelien Jarno <aurelien@aurel32.net>");

MODULE_DESCRIPTION("PCF8574 driver");

MODULE_LICENSE("GPL");



module_init(pcf8574_init);

module_exit(pcf8574_exit);

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