Oops, I send a patch to Greg KH and I forgot to copy the lm-sensors
list. Please find below the mail I sent to him.
Sorry for all.
----- Original Message -----
From: Aurelien Jarno <aurelien at aurel32.net>
To: Greg KH <greg at kroah.com>
Sent: Thu, 18 Mar 2004 23:37:37 +0100
Subject: [PATCH 2.6] New chip driver: pcf8574
Hi Greg,
Please find below a patch against kernel 2.6.5-rc1 to add the pcf8574
driver (an I/O expander for the I2C bus). I have ported it from the 2.4
version, and it includes some fixes and simplifications.
It has been reviewed by Jean Delvare on IRC.
Thanks,
Aurelien
diff -urN linux-2.6.5-rc1.orig/drivers/i2c/chips/Kconfig linux-2.6.5-rc1/drivers/i2c/chips/Kconfig
--- linux-2.6.5-rc1.orig/drivers/i2c/chips/Kconfig 2004-03-18 20:24:27.000000000 +0100
+++ linux-2.6.5-rc1/drivers/i2c/chips/Kconfig 2004-03-18 20:25:26.000000000 +0100
@@ -209,4 +209,15 @@
This driver can also be built as a module. If so, the module
will be called eeprom.
+config SENSORS_PCF8574
+ tristate "Philips PCF8574 and PCF8574A"
+ depends on I2C && EXPERIMENTAL
+ select I2C_SENSOR
+ help
+ If you say yes here you get support for Philips PCF8574 and
+ PCF8574A chips.
+
+ This driver can also be built as a module. If so, the module
+ will be called pcf8574.
+
endmenu
diff -urN linux-2.6.5-rc1.orig/drivers/i2c/chips/Makefile linux-2.6.5-rc1/drivers/i2c/chips/Makefile
--- linux-2.6.5-rc1.orig/drivers/i2c/chips/Makefile 2004-03-18 20:24:27.000000000 +0100
+++ linux-2.6.5-rc1/drivers/i2c/chips/Makefile 2004-03-18 20:25:26.000000000 +0100
@@ -19,6 +19,7 @@
obj-$(CONFIG_SENSORS_LM83) += lm83.o
obj-$(CONFIG_SENSORS_LM85) += lm85.o
obj-$(CONFIG_SENSORS_LM90) += lm90.o
+obj-$(CONFIG_SENSORS_PCF8574) += pcf8574.o
obj-$(CONFIG_SENSORS_VIA686A) += via686a.o
obj-$(CONFIG_SENSORS_W83L785TS) += w83l785ts.o
diff -urN linux-2.6.5-rc1.orig/drivers/i2c/chips/pcf8574.c linux-2.6.5-rc1/drivers/i2c/chips/pcf8574.c
--- linux-2.6.5-rc1.orig/drivers/i2c/chips/pcf8574.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.5-rc1/drivers/i2c/chips/pcf8574.c 2004-03-18 22:23:10.000000000 +0100
@@ -0,0 +1,245 @@
+/*
+ pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware
+ monitoring
+ Copyright (c) 2000 Frodo Looijaard <frodol at dds.nl>,
+ Philip Edelbrock <phil at netroedge.com>,
+ Dan Eaton <dan.eaton at rocketlogix.com>
+ Ported to Linux 2.6 by Aurelien Jarno <aurel32 at debian.org> with
+ the help of Jean Delvare <khali at 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>
+#include <linux/i2c-sensor.h>
+
+/* Addresses to scan */
+static unsigned short normal_i2c[] = { I2C_CLIENT_END };
+static unsigned short normal_i2c_range[] = { 0x20, 0x27, 0x38, 0x3f, I2C_CLIENT_END };
+static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END };
+static unsigned int normal_isa_range[] = { I2C_CLIENT_ISA_END };
+
+/* Insmod parameters */
+SENSORS_INSMOD_2(pcf8574, pcf8574a);
+
+/* Initial values */
+#define PCF8574_INIT 255 /* All outputs on (input mode) */
+
+/* Each client has this additional data */
+struct pcf8574_data {
+ struct semaphore update_lock;
+
+ u8 read, write; /* Register values */
+};
+
+static int pcf8574_attach_adapter(struct i2c_adapter *adapter);
+static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind);
+static int pcf8574_detach_client(struct i2c_client *client);
+static void pcf8574_init_client(struct i2c_client *client);
+static struct pcf8574_data *pcf8574_update_client(struct device *dev);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver pcf8574_driver = {
+ .owner = THIS_MODULE,
+ .name = "pcf8574",
+ .id = I2C_DRIVERID_PCF8574,
+ .flags = I2C_DF_NOTIFY,
+ .attach_adapter = pcf8574_attach_adapter,
+ .detach_client = pcf8574_detach_client,
+};
+
+static int pcf8574_id = 0;
+
+/* following are the sysfs callback functions */
+static ssize_t show_read(struct device *dev, char *buf)
+{
+ struct pcf8574_data *data = pcf8574_update_client(dev);
+ return sprintf(buf, "%u\n", data->read);
+}
+
+static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);
+
+static ssize_t show_write(struct device *dev, char *buf)
+{
+ struct pcf8574_data *data = i2c_get_clientdata(to_i2c_client(dev));
+ return sprintf(buf, "%u\n", data->write);
+}
+
+static ssize_t set_write(struct device *dev, const char *buf,
+ size_t count)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct pcf8574_data *data = i2c_get_clientdata(client);
+ data->write = simple_strtoul(buf, NULL, 10);
+ i2c_smbus_write_byte(client, data->write);
+ return count;
+}
+
+static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write);
+
+/*
+ * Real code
+ */
+
+static int pcf8574_attach_adapter(struct i2c_adapter *adapter)
+{
+ return i2c_detect(adapter, &addr_data, pcf8574_detect);
+}
+
+/* This function is called by i2c_detect */
+int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+ struct i2c_client *new_client;
+ struct pcf8574_data *data;
+ int err = 0;
+ const char *client_name = "";
+
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
+ goto exit;
+
+ /* OK. For now, we presume we have a valid client. We now create the
+ client structure, even though we cannot fill it completely yet. */
+ if (!(new_client = kmalloc(sizeof(struct i2c_client) +
+ sizeof(struct pcf8574_data),
+ GFP_KERNEL))) {
+ err = -ENOMEM;
+ goto exit;
+ }
+
+ memset(new_client, 0, sizeof(struct i2c_client) +
+ sizeof(struct pcf8574_data));
+
+ data = (struct pcf8574_data *) (new_client + 1);
+ i2c_set_clientdata(new_client, data);
+ new_client->addr = address;
+ new_client->adapter = adapter;
+ new_client->driver = &pcf8574_driver;
+ new_client->flags = 0;
+
+ /* 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 (address >= 0x38 && address <= 0x3f)
+ kind = pcf8574a;
+ else
+ kind = pcf8574;
+ }
+
+ if (kind == pcf8574a)
+ client_name = "pcf8574a";
+ else
+ client_name = "pcf8574";
+
+ /* Fill in the remaining client fields and put it into the global list */
+ strlcpy(new_client->name, client_name, I2C_NAME_SIZE);
+
+ new_client->id = pcf8574_id++;
+ init_MUTEX(&data->update_lock);
+
+ /* Tell the I2C layer a new client has arrived */
+ if ((err = i2c_attach_client(new_client)))
+ goto exit_free;
+
+ /* Initialize the PCF8574 chip */
+ pcf8574_init_client(new_client);
+
+ /* Register sysfs hooks */
+ device_create_file(&new_client->dev, &dev_attr_read);
+ device_create_file(&new_client->dev, &dev_attr_write);
+ return 0;
+
+/* OK, this is not exactly good programming practice, usually. But it is
+ very code-efficient in this case. */
+
+ exit_free:
+ kfree(new_client);
+ exit:
+ return err;
+}
+
+static int pcf8574_detach_client(struct i2c_client *client)
+{
+ int err;
+
+ if ((err = i2c_detach_client(client))) {
+ dev_err(&client->dev,
+ "Client deregistration failed, client not detached.\n");
+ return err;
+ }
+
+ kfree(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 = PCF8574_INIT;
+ i2c_smbus_write_byte(client, data->write);
+}
+
+static struct pcf8574_data *pcf8574_update_client(struct device *dev)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct pcf8574_data *data = i2c_get_clientdata(client);
+
+ down(&data->update_lock);
+ dev_dbg(&client->dev, "Starting pcf8574 update\n");
+ data->read = i2c_smbus_read_byte(client);
+ up(&data->update_lock);
+
+ return 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 at dds.nl>, "
+ "Philip Edelbrock <phil at netroedge.com>, "
+ "Dan Eaton <dan.eaton at rocketlogix.com> "
+ "and Aurelien Jarno <aurelien at aurel32.net>");
+MODULE_DESCRIPTION("PCF8574 driver");
+MODULE_LICENSE("GPL");
+
+module_init(pcf8574_init);
+module_exit(pcf8574_exit);
