i2c/chips: Remove deprecated pcf8574 driver (e7c5c49e) · Commits · e / devices / android_kernel_oneplus_sm8150

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);