i2c: Convert the pcf8575 driver to a new-style i2c driver

The new-style pcf8575 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>

2 files changed, 43 insertions, 62 deletions

diff --git a/Documentation/i2c/chips/pcf8575 b/Documentation/i2c/chips/pcf8575
index 25f5698a61cf..40b268eb276f 100644
--- a/Documentation/i2c/chips/pcf8575
+++ b/Documentation/i2c/chips/pcf8575
@@ -40,12 +40,9 @@ Detection
 ---------
 
 There is no method known to detect whether a chip on a given I2C address is
-a PCF8575 or whether it is any other I2C device. So there are two alternatives
-to let the driver find the installed PCF8575 devices:
-- Load this driver after any other I2C driver for I2C devices with addresses
-  in the range 0x20 .. 0x27.
-- Pass the I2C bus and address of the installed PCF8575 devices explicitly to
-  the driver at load time via the probe=... or force=... parameters.
+a PCF8575 or whether it is any other I2C device, so you have to pass the I2C
+bus and address of the installed PCF8575 devices explicitly to the driver at
+load time via the force=... parameter.
 
 /sys interface
 --------------
diff --git a/drivers/i2c/chips/pcf8575.c b/drivers/i2c/chips/pcf8575.c
index 3ea08ac0bfa3..07fd7cb3c57d 100644
--- a/drivers/i2c/chips/pcf8575.c
+++ b/drivers/i2c/chips/pcf8575.c
@@ -32,11 +32,8 @@
 #include <linux/slab.h>  /* kzalloc() */
 #include <linux/sysfs.h> /* sysfs_create_group() */
 
-/* Addresses to scan */
-static const unsigned short normal_i2c[] = {
-        0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
-        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;
@@ -44,24 +41,9 @@ I2C_CLIENT_INSMOD;
 
 /* Each client has this additional data */
 struct pcf8575_data {
-        struct i2c_client client;
         int write;              /* last written value, or error code */
 };
 
-static int pcf8575_attach_adapter(struct i2c_adapter *adapter);
-static int pcf8575_detect(struct i2c_adapter *adapter, int address, int kind);
-static int pcf8575_detach_client(struct i2c_client *client);
-
-/* This is the driver that will be inserted */
-static struct i2c_driver pcf8575_driver = {
-        .driver = {
-                .owner  = THIS_MODULE,
-                .name   = "pcf8575",
-        },
-        .attach_adapter = pcf8575_attach_adapter,
-        .detach_client  = pcf8575_detach_client,
-};
-
 /* following are the sysfs callback functions */
 static ssize_t show_read(struct device *dev, struct device_attribute *attr,
                          char *buf)
@@ -126,75 +108,77 @@ static const struct attribute_group pcf8575_attr_group = {
  * Real code
  */
 
-static int pcf8575_attach_adapter(struct i2c_adapter *adapter)
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int pcf8575_detect(struct i2c_client *client, int kind,
+                          struct i2c_board_info *info)
 {
-        return i2c_probe(adapter, &addr_data, pcf8575_detect);
+        struct i2c_adapter *adapter = client->adapter;
+
+        if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
+                return -ENODEV;
+
+        /* This is the place to detect whether the chip at the specified
+           address really is a PCF8575 chip. However, there is no method known
+           to detect whether an I2C chip is a PCF8575 or any other I2C chip. */
+
+        strlcpy(info->type, "pcf8575", I2C_NAME_SIZE);
+
+        return 0;
 }
 
-/* This function is called by i2c_probe */
-static int pcf8575_detect(struct i2c_adapter *adapter, int address, int kind)
+static int pcf8575_probe(struct i2c_client *client,
+                         const struct i2c_device_id *id)
 {
-        struct i2c_client *client;
         struct pcf8575_data *data;
-        int err = 0;
-
-        if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
-                goto exit;
+        int err;
 
-        /* OK. For now, we presume we have a valid client. We now create the
-           client structure, even though we cannot fill it completely yet. */
         data = kzalloc(sizeof(struct pcf8575_data), GFP_KERNEL);
         if (!data) {
                 err = -ENOMEM;
                 goto exit;
         }
 
-        client = &data->client;
         i2c_set_clientdata(client, data);
-        client->addr = address;
-        client->adapter = adapter;
-        client->driver = &pcf8575_driver;
-        strlcpy(client->name, "pcf8575", I2C_NAME_SIZE);
         data->write = -EAGAIN;
 
-        /* This is the place to detect whether the chip at the specified
-           address really is a PCF8575 chip. However, there is no method known
-           to detect whether an I2C chip is a PCF8575 or any other I2C chip. */
-
-        /* Tell the I2C layer a new client has arrived */
-        err = i2c_attach_client(client);
-        if (err)
-                goto exit_free;
-
         /* Register sysfs hooks */
         err = sysfs_create_group(&client->dev.kobj, &pcf8575_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 pcf8575_detach_client(struct i2c_client *client)
+static int pcf8575_remove(struct i2c_client *client)
 {
-        int err;
-
         sysfs_remove_group(&client->dev.kobj, &pcf8575_attr_group);
-
-        err = i2c_detach_client(client);
-        if (err)
-                return err;
-
         kfree(i2c_get_clientdata(client));
         return 0;
 }
 
+static const struct i2c_device_id pcf8575_id[] = {
+        { "pcf8575", 0 },
+        { }
+};
+
+static struct i2c_driver pcf8575_driver = {
+        .driver = {
+                .owner  = THIS_MODULE,
+                .name   = "pcf8575",
+        },
+        .probe          = pcf8575_probe,
+        .remove         = pcf8575_remove,
+        .id_table       = pcf8575_id,
+
+        .detect         = pcf8575_detect,
+        .address_data   = &addr_data,
+};
+
 static int __init pcf8575_init(void)
 {
         return i2c_add_driver(&pcf8575_driver);