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authorJean Delvare <khali@linux-fr.org>2008-07-16 19:30:06 +0200
committerJean Delvare <khali@mahadeva.delvare>2008-07-16 19:30:06 +0200
commit833bedb813689807385ae73175389c73a3f855c1 (patch)
treef9b33add52ca947fd9f8ae89753eb8d534efc70e
parent8b77e6ac4911a79993e583ece719736a9e035b1d (diff)
downloadtalos-op-linux-833bedb813689807385ae73175389c73a3f855c1.tar.gz
talos-op-linux-833bedb813689807385ae73175389c73a3f855c1.zip
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>
-rw-r--r--Documentation/i2c/chips/pcf857412
-rw-r--r--drivers/i2c/chips/pcf8574.c108
2 files changed, 51 insertions, 69 deletions
diff --git a/Documentation/i2c/chips/pcf8574 b/Documentation/i2c/chips/pcf8574
index 5c1ad1376b62..235815c075ff 100644
--- 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 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);
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