1 files changed, 229 insertions, 0 deletions

diff --git a/drivers/i2c/chips/pcf8574.c b/drivers/i2c/chips/pcf8574.c
new file mode 100644
index 000000000000..48b4e22eaffe
--- /dev/null
+++ b/drivers/i2c/chips/pcf8574.c
@@ -0,0 +1,229 @@
+/*
+    pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware
+             monitoring
+    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>
+#include <linux/i2c-sensor.h>
+
+/* Addresses to scan */
+static unsigned short normal_i2c[] = { 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+                                        0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
+                                        I2C_CLIENT_END };
+static unsigned int normal_isa[] = { 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 i2c_client client;
+
+        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);
+
+/* 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,
+};
+
+/* following are the sysfs callback functions */
+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);
+        data->read = i2c_smbus_read_byte(client); 
+        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);
+        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);
+
+/*
+ * 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 (!(data = kmalloc(sizeof(struct pcf8574_data), GFP_KERNEL))) {
+                err = -ENOMEM;
+                goto exit;
+        }
+        memset(data, 0, sizeof(struct pcf8574_data));
+
+        new_client = &data->client;
+        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);
+
+        /* 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(data);
+      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(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 = PCF8574_INIT;
+        i2c_smbus_write_byte(client, data->write);
+}
+
+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);