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-rw-r--r--Documentation/i2c/writing-clients28
1 files changed, 10 insertions, 18 deletions
diff --git a/Documentation/i2c/writing-clients b/Documentation/i2c/writing-clients
index 077275722a7c..cff7b652588a 100644
--- a/Documentation/i2c/writing-clients
+++ b/Documentation/i2c/writing-clients
@@ -33,8 +33,8 @@ static struct i2c_driver foo_driver = {
.command = &foo_command /* may be NULL */
}
-The name can be chosen freely, and may be upto 40 characters long. Please
-use something descriptive here.
+The name field must match the driver name, including the case. It must not
+contain spaces, and may be up to 31 characters long.
Don't worry about the flags field; just put I2C_DF_NOTIFY into it. This
means that your driver will be notified when new adapters are found.
@@ -43,9 +43,6 @@ This is almost always what you want.
All other fields are for call-back functions which will be explained
below.
-There use to be two additional fields in this structure, inc_use et dec_use,
-for module usage count, but these fields were obsoleted and removed.
-
Extra client data
=================
@@ -58,6 +55,7 @@ be very useful.
An example structure is below.
struct foo_data {
+ struct i2c_client client;
struct semaphore lock; /* For ISA access in `sensors' drivers. */
int sysctl_id; /* To keep the /proc directory entry for
`sensors' drivers. */
@@ -275,6 +273,7 @@ For now, you can ignore the `flags' parameter. It is there for future use.
if (is_isa) {
/* Discard immediately if this ISA range is already used */
+ /* FIXME: never use check_region(), only request_region() */
if (check_region(address,FOO_EXTENT))
goto ERROR0;
@@ -310,22 +309,15 @@ For now, you can ignore the `flags' parameter. It is there for future use.
client structure, even though we cannot fill it completely yet.
But it allows us to access several i2c functions safely */
- /* Note that we reserve some space for foo_data too. If you don't
- need it, remove it. We do it here to help to lessen memory
- fragmentation. */
- if (! (new_client = kmalloc(sizeof(struct i2c_client) +
- sizeof(struct foo_data),
- GFP_KERNEL))) {
+ if (!(data = kzalloc(sizeof(struct foo_data), GFP_KERNEL))) {
err = -ENOMEM;
goto ERROR0;
}
- /* This is tricky, but it will set the data to the right value. */
- client->data = new_client + 1;
- data = (struct foo_data *) (client->data);
+ new_client = &data->client;
+ i2c_set_clientdata(new_client, data);
new_client->addr = address;
- new_client->data = data;
new_client->adapter = adapter;
new_client->driver = &foo_driver;
new_client->flags = 0;
@@ -451,7 +443,7 @@ much simpler than the attachment code, fortunately!
release_region(client->addr,LM78_EXTENT);
/* HYBRID SENSORS CHIP ONLY END */
- kfree(client); /* Frees client data too, if allocated at the same time */
+ kfree(data);
return 0;
}
@@ -576,12 +568,12 @@ SMBus communication
extern s32 i2c_smbus_write_block_data(struct i2c_client * client,
u8 command, u8 length,
u8 *values);
+ extern s32 i2c_smbus_read_i2c_block_data(struct i2c_client * client,
+ u8 command, u8 *values);
These ones were removed in Linux 2.6.10 because they had no users, but could
be added back later if needed:
- extern s32 i2c_smbus_read_i2c_block_data(struct i2c_client * client,
- u8 command, u8 *values);
extern s32 i2c_smbus_read_block_data(struct i2c_client * client,
u8 command, u8 *values);
extern s32 i2c_smbus_write_i2c_block_data(struct i2c_client * client,
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