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

Browse source 
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 <[email protected]>
This commit is contained in:
Jean Delvare 2008-07-16 19:30:06 +02:00 • committed by Jean Delvare
commit 833bedb813
2 changed files with 51 additions and 69 deletions
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108
drivers/i2c/chips/pcf8574.c
View file

@ -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 0 if detection is successful, -ENODEV otherwise */
static int pcf8574_detect(struct i2c_client *client, int kind,
struct i2c_board_info *info)
{
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)
{
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);