iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

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 <khali@linux-fr.org>
This commit is contained in:
Jean Delvare 2008-07-16 19:30:06 +02:00 committed by Jean Delvare
parent 8b77e6ac49
commit 833bedb813
2 changed files with 51 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
Documentation/i2c/chips/pcf8574
View File

@ -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):

106
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;
@ -163,13 +126,24 @@ 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;
}
/* Tell the I2C layer a new client has arrived */
if ((err = i2c_attach_client(client)))
goto exit_free;
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);
/* Initialize the PCF8574 chip */
pcf8574_init_client(client);
@ -177,26 +151,18 @@ static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind)
/* 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);