diff options
Diffstat (limited to 'Documentation/i2c/writing-clients')
| -rw-r--r-- | Documentation/i2c/writing-clients | 28 |
1 files changed, 10 insertions, 18 deletions
diff --git a/Documentation/i2c/writing-clients b/Documentation/i2c/writing-clients index 077275722a7..cff7b652588 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, |