Hi all,
Please find attached a patch to support the PCF8574 chip to the 2.6
kernel series.
This driver doesn't follow the sysfs-interface document as it creates
only two files: "read" and "write". However, as the aim of this driver
is to be used directly from the /sys interface and not through the
libsensors interface, I think it is not really a problem.
Aurelien
--
.''`. Aurelien Jarno GPG: 1024D/F1BCDB73
: :' : Debian GNU/Linux developer | Electrical Engineering Student
`. `' aurel32 at debian.org | aurelien at aurel32.net
`- people.debian.org/~aurel32 | www.aurel32.net
-------------- next part --------------
diff -urN linux-2.6.3.orig/drivers/i2c/chips/Kconfig linux-2.6.3/drivers/i2c/chips/Kconfig
--- linux-2.6.3.orig/drivers/i2c/chips/Kconfig 2004-02-18 04:58:10.000000000 +0100
+++ linux-2.6.3/drivers/i2c/chips/Kconfig 2004-03-06 14:20:09.000000000 +0100
@@ -135,6 +135,17 @@
This driver can also be built as a module. If so, the module
will be called lm90.
+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.
+
config SENSORS_VIA686A
tristate "VIA686A"
depends on I2C && EXPERIMENTAL
diff -urN linux-2.6.3.orig/drivers/i2c/chips/Makefile linux-2.6.3/drivers/i2c/chips/Makefile
--- linux-2.6.3.orig/drivers/i2c/chips/Makefile 2004-02-18 05:00:01.000000000 +0100
+++ linux-2.6.3/drivers/i2c/chips/Makefile 2004-03-06 14:20:09.000000000 +0100
@@ -16,5 +16,6 @@
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-2.6.3.orig/drivers/i2c/chips/pcf8574.c linux-2.6.3/drivers/i2c/chips/pcf8574.c
--- linux-2.6.3.orig/drivers/i2c/chips/pcf8574.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.3/drivers/i2c/chips/pcf8574.c 2004-03-06 14:20:09.000000000 +0100
@@ -0,0 +1,283 @@
+/*
+ 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>
+
+ 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.
+
+* Because of the general purpose nature of this device, it will most
+ likely be necessary to customize the /proc interface to suit the
+ specific application.
+
+ --Dan
+
+*/
+
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/i2c-sensor.h>
+#include <linux/init.h>
+
+MODULE_LICENSE("GPL");
+
+/* 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);
+
+/* The PCF8574 registers */
+
+/* (No registers. [Wow! This thing is SIMPLE!] ) */
+
+/* Initial values */
+#define PCF8574_INIT 255 /* All outputs on (input mode) */
+
+/* Each client has this additional data */
+struct pcf8574_data {
+ struct semaphore update_lock;
+ char valid; /* !=0 if following fields are valid */
+ unsigned long last_updated; /* In jiffies */
+
+ 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 void pcf8574_update_client(struct i2c_client *client);
+
+/* 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,
+};
+
+/* I choose here for semi-static PCF8574 allocation. Complete dynamic
+ allocation could also be used; the code needed for this would probably
+ take more memory than the datastructure takes now. */
+static int pcf8574_id = 0;
+
+
+static ssize_t show_read(struct device *dev, char *buf)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct pcf8574_data *data = i2c_get_clientdata(client);
+ pcf8574_update_client(client);
+ return sprintf(buf, "%d\n", data->read);
+}
+
+static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);
+
+static ssize_t show_write(struct device *dev, char *buf)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct pcf8574_data *data = i2c_get_clientdata(client);
+ return sprintf(buf, "%d\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);
+
+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 = "";
+
+ /* Make sure we aren't probing the ISA bus!! This is just a safety check
+ at this moment; i2c_detect really won't call us. */
+ if (i2c_is_isa_adapter(adapter)) {
+ dev_dbg(&adapter->dev,
+ "pcf8574.o: pcf8574_detect called for an ISA bus adapter?!?\n");
+ return 0;
+ }
+
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
+ goto ERROR0;
+
+ /* OK. For now, we presume we have a valid client. We now create the
+ client structure, even though we cannot fill it completely yet.
+ But it allows us to access pcf8574_{read,write}_value. */
+ if (!(new_client = kmalloc(sizeof(struct i2c_client) +
+ sizeof(struct pcf8574_data),
+ GFP_KERNEL))) {
+ err = -ENOMEM;
+ goto ERROR1;
+ }
+
+ 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 >= 0x20 && address <= 0x27)
+ kind = pcf8574;
+ else if (address >= 0x38 && address <= 0x3f)
+ kind = pcf8574a;
+ else goto ERROR2;
+ }
+
+ if (kind == pcf8574) {
+ client_name = "pcf8574";
+ } else
+ if (kind == pcf8574a) {
+ client_name = "pcf8574a";
+ } else {
+ dev_dbg(&adapter->dev,
+ "pcf8574.o: Internal error: unknown kind (%d)?!?",
+ kind);
+ goto ERROR2;
+ }
+
+ /* 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++;
+ data->valid = 0;
+ init_MUTEX(&data->update_lock);
+
+ /* Tell the I2C layer a new client has arrived */
+ if ((err = i2c_attach_client(new_client)))
+ goto ERROR2;
+
+ /* 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. */
+
+ ERROR2:
+ kfree(new_client);
+ ERROR1:
+ ERROR0:
+ return err;
+}
+
+
+static int pcf8574_detach_client(struct i2c_client *client)
+{
+ int err;
+
+ if ((err = i2c_detach_client(client))) {
+ dev_err(&client->dev,
+ "pcf8574.o: 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 void pcf8574_update_client(struct i2c_client *client)
+{
+ struct pcf8574_data *data = i2c_get_clientdata(client);
+
+ down(&data->update_lock);
+
+ if ((jiffies - data->last_updated > 5*HZ) ||
+ (jiffies < data->last_updated) || !data->valid) {
+
+ dev_dbg(&client->dev, "Starting pcf8574 update\n");
+ data->read = i2c_smbus_read_byte(client);
+ data->last_updated = jiffies;
+ data->valid = 1;
+ }
+
+ up(&data->update_lock);
+}
+
+
+static int __init sm_pcf8574_init(void)
+{
+ return i2c_add_driver(&pcf8574_driver);
+}
+
+static void __exit sm_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_init(sm_pcf8574_init);
+module_exit(sm_pcf8574_exit);
