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>

1 files changed, 46 insertions, 62 deletions

diff --git a/drivers/i2c/chips/pcf8574.c b/drivers/i2c/chips/pcf8574.c
index 1b3db2b3ada9..6ec309894c88 100644
--- 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);