i2c: Convert the pcf8574 driver to a new-style i2c driver

The new-style pcf8574 driver implements the optional detect() callback
to cover the use cases of the legacy driver.

Warning: users will now have to use the force module parameter to get
the driver to attach to their device. That's not a bad thing as these
devices can't be detected anyway.

Note that this doesn't change the fact that this driver is deprecated
in favor of gpio/pcf857x.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

diff --git a/Documentation/i2c/chips/pcf8574 b/Documentation/i2c/chips/pcf8574
index 5c1ad13..235815c 100644 (file)
--- a/Documentation/i2c/chips/pcf8574
+++ b/Documentation/i2c/chips/pcf8574
@@ -4,13 +4,13 @@ Kernel driver pcf8574
 Supported chips:
   * Philips PCF8574
     Prefix: 'pcf8574'
-    Addresses scanned: I2C 0x20 - 0x27
+    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: I2C 0x38 - 0x3f
+    Addresses scanned: none
     Datasheet: Publicly available at the Philips Semiconductors website
                http://www.semiconductors.philips.com/pip/PCF8574P.html
 
@@ -38,12 +38,10 @@ For more informations see the datasheet.
 Accessing PCF8574(A) via /sys interface
 -------------------------------------
 
-! Be careful !
 The PCF8574(A) is plainly impossible to detect ! Stupid chip.
-So every chip with address in the interval [20..27] and [38..3f] are
-detected as PCF8574(A). If you have other chips in this address
-range, the workaround is to load this module after the one
-for your others chips.
+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):

diff --git a/drivers/i2c/chips/pcf8574.c b/drivers/i2c/chips/pcf8574.c
index 1b3db2b..6ec3098 100644 (file)
--- a/drivers/i2c/chips/pcf8574.c
+++ b/drivers/i2c/chips/pcf8574.c
@@ -38,37 +38,19 @@
 #include <linux/slab.h>
 #include <linux/i2c.h>
 
-/* Addresses to scan */
-static const unsigned short normal_i2c[] = {
-       0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
-       0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
-       I2C_CLIENT_END
-};
+/* 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 {
-       struct i2c_client client;
-
        int write;                      /* Remember last written value */
 };
 
-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 = {
-       .driver = {
-               .name   = "pcf8574",
-       },
-       .attach_adapter = pcf8574_attach_adapter,
-       .detach_client  = pcf8574_detach_client,
-};
-
 /* following are the sysfs callback functions */
 static ssize_t show_read(struct device *dev, struct device_attribute *attr, char *buf)
 {
@@ -119,41 +101,22 @@ static const struct attribute_group pcf8574_attr_group = {
  * Real code
  */
 
-static int pcf8574_attach_adapter(struct i2c_adapter *adapter)
-{
-       return i2c_probe(adapter, &addr_data, pcf8574_detect);
-}
-
-/* This function is called by i2c_probe */
-static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind)
+/* 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_client *client;
-       struct pcf8574_data *data;
-       int err = 0;
-       const char *client_name = "";
+       struct i2c_adapter *adapter = client->adapter;
+       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 = kzalloc(sizeof(struct pcf8574_data), GFP_KERNEL))) {
-               err = -ENOMEM;
-               goto exit;
-       }
-
-       client = &data->client;
-       i2c_set_clientdata(client, data);
-       client->addr = address;
-       client->adapter = adapter;
-       client->driver = &pcf8574_driver;
+               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 (address >= 0x38 && address <= 0x3f)
+               if (client->addr >= 0x38 && client->addr <= 0x3f)
                        kind = pcf8574a;
                else
                        kind = pcf8574;
@@ -163,40 +126,43 @@ static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind)
                client_name = "pcf8574a";
        else
                client_name = "pcf8574";
+       strlcpy(info->type, client_name, I2C_NAME_SIZE);
 
-       /* Fill in the remaining client fields and put it into the global list */
-       strlcpy(client->name, 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);
 
-       /* Tell the I2C layer a new client has arrived */
-       if ((err = i2c_attach_client(client)))
-               goto exit_free;
-       
        /* 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_detach;
+               goto exit_free;
        return 0;
 
-      exit_detach:
-       i2c_detach_client(client);
       exit_free:
        kfree(data);
       exit:
        return err;
 }
 
-static int pcf8574_detach_client(struct i2c_client *client)
+static int pcf8574_remove(struct i2c_client *client)
 {
-       int err;
-
        sysfs_remove_group(&client->dev.kobj, &pcf8574_attr_group);
-
-       if ((err = i2c_detach_client(client)))
-               return err;
-
        kfree(i2c_get_clientdata(client));
        return 0;
 }
@@ -208,6 +174,24 @@ static void pcf8574_init_client(struct i2c_client *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);