address.
static struct i2c_driver foo_driver = {
- .owner = THIS_MODULE,
- .name = "Foo version 2.3 driver",
- .flags = I2C_DF_NOTIFY,
+ .driver = {
+ .name = "foo",
+ },
.attach_adapter = &foo_attach_adapter,
.detach_client = &foo_detach_client,
.command = &foo_command /* may be NULL */
}
-The name can be chosen freely, and may be upto 40 characters long. Please
-use something descriptive here.
-
-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.
-This is almost always what you want.
+The name field must match the driver name, including the case. It must not
+contain spaces, and may be up to 31 characters long.
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
=================
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. */
detection algorithm.
You do not have to use this parameter interface; but don't try to use
-function i2c_probe() (or i2c_detect()) if you don't.
+function i2c_probe() if you don't.
NOTE: If you want to write a `sensors' driver, the interface is slightly
different! See below.
-Probing classes (i2c)
----------------------
+Probing classes
+---------------
All parameters are given as lists of unsigned 16-bit integers. Lists are
terminated by I2C_CLIENT_END.
ignore: insmod parameter.
A list of pairs. The first value is a bus number (-1 for any I2C bus),
the second is the I2C address. These addresses are never probed.
- This parameter overrules 'normal' and 'probe', but not the 'force' lists.
+ This parameter overrules the 'normal_i2c' list only.
force: insmod parameter.
A list of pairs. The first value is a bus number (-1 for any I2C bus),
the second is the I2C address. A device is blindly assumed to be on
the given address, no probing is done.
+Additionally, kind-specific force lists may optionally be defined if
+the driver supports several chip kinds. They are grouped in a
+NULL-terminated list of pointers named forces, those first element if the
+generic force list mentioned above. Each additional list correspond to an
+insmod parameter of the form force_<kind>.
+
Fortunately, as a module writer, you just have to define the `normal_i2c'
parameter. The complete declaration could look like this:
/* Magic definition of all other variables and things */
I2C_CLIENT_INSMOD;
+ /* Or, if your driver supports, say, 2 kind of devices: */
+ I2C_CLIENT_INSMOD_2(foo, bar);
+
+If you use the multi-kind form, an enum will be defined for you:
+ enum chips { any_chip, foo, bar, ... }
+You can then (and certainly should) use it in the driver code.
Note that you *have* to call the defined variable `normal_i2c',
without any prefix!
-Probing classes (sensors)
--------------------------
-
-If you write a `sensors' driver, you use a slightly different interface.
-Also, we use a enum of chip types. Don't forget to include `sensors.h'.
-
-The following lists are used internally. They are all lists of integers.
-
- normal_i2c: filled in by the module writer. Terminated by I2C_CLIENT_END.
- A list of I2C addresses which should normally be examined.
- probe: insmod parameter. Initialize this list with I2C_CLIENT_END values.
- A list of pairs. The first value is a bus number (ANY_I2C_BUS for any
- I2C bus), the second is the address. These addresses are also probed,
- as if they were in the 'normal' list.
- ignore: insmod parameter. Initialize this list with I2C_CLIENT_END values.
- A list of pairs. The first value is a bus number (ANY_I2C_BUS for any
- I2C bus), the second is the I2C address. These addresses are never
- probed. This parameter overrules 'normal' and 'probe', but not the
- 'force' lists.
-
-Also used is a list of pointers to sensors_force_data structures:
- force_data: insmod parameters. A list, ending with an element of which
- the force field is NULL.
- Each element contains the type of chip and a list of pairs.
- The first value is a bus number (ANY_I2C_BUS for any I2C bus), the
- second is the address.
- These are automatically translated to insmod variables of the form
- force_foo.
-
-So we have a generic insmod variabled `force', and chip-specific variables
-`force_CHIPNAME'.
-
-Fortunately, as a module writer, you just have to define the `normal_i2c'
-parameter, and define what chip names are used. The complete declaration
-could look like this:
- /* Scan i2c addresses 0x37, and 0x48 to 0x4f */
- static unsigned short normal_i2c[] = { 0x37, 0x48, 0x49, 0x4a, 0x4b, 0x4c,
- 0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
-
- /* Define chips foo and bar, as well as all module parameters and things */
- SENSORS_INSMOD_2(foo,bar);
-
-If you have one chip, you use macro SENSORS_INSMOD_1(chip), if you have 2
-you use macro SENSORS_INSMOD_2(chip1,chip2), etc. If you do not want to
-bother with chip types, you can use SENSORS_INSMOD_0.
-
-A enum is automatically defined as follows:
- enum chips { any_chip, chip1, chip2, ... }
-
-
Attaching to an adapter
-----------------------
return i2c_probe(adapter,&addr_data,&foo_detect_client);
}
-For `sensors' drivers, use the i2c_detect function instead:
-
- int foo_attach_adapter(struct i2c_adapter *adapter)
- {
- return i2c_detect(adapter,&addr_data,&foo_detect_client);
- }
-
Remember, structure `addr_data' is defined by the macros explained above,
so you do not have to define it yourself.
-The i2c_probe or i2c_detect function will call the foo_detect_client
+The i2c_probe function will call the foo_detect_client
function only for those i2c addresses that actually have a device on
them (unless a `force' parameter was used). In addition, addresses that
are already in use (by some other registered client) are skipped.
The detect client function
--------------------------
-The detect client function is called by i2c_probe or i2c_detect.
-The `kind' parameter contains 0 if this call is due to a `force'
-parameter, and -1 otherwise (for i2c_detect, it contains 0 if
-this call is due to the generic `force' parameter, and the chip type
-number if it is due to a specific `force' parameter).
+The detect client function is called by i2c_probe. The `kind' parameter
+contains -1 for a probed detection, 0 for a forced detection, or a positive
+number for a forced detection with a chip type forced.
Below, some things are only needed if this is a `sensors' driver. Those
parts are between /* SENSORS ONLY START */ and /* SENSORS ONLY END */
markers.
-This function should only return an error (any value != 0) if there is
-some reason why no more detection should be done anymore. If the
-detection just fails for this address, return 0.
+Returning an error different from -ENODEV in a detect function will cause
+the detection to stop: other addresses and adapters won't be scanned.
+This should only be done on fatal or internal errors, such as a memory
+shortage or i2c_attach_client failing.
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;
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;
release_region(address,FOO_EXTENT);
/* SENSORS ONLY END */
ERROR1:
- kfree(new_client);
+ kfree(data);
ERROR0:
return err;
}
release_region(client->addr,LM78_EXTENT);
/* HYBRID SENSORS CHIP ONLY END */
- kfree(client); /* Frees client data too, if allocated at the same time */
+ kfree(i2c_get_clientdata(client));
return 0;
}
by `__init_data'. Hose functions and structures can be removed after
kernel booting (or module loading) is completed.
+
Command function
================
A generic ioctl-like function call back is supported. You will seldom
-need this. You may even set it to NULL.
-
- /* No commands defined */
- int foo_command(struct i2c_client *client, unsigned int cmd, void *arg)
- {
- return 0;
- }
+need this, and its use is deprecated anyway, so newer design should not
+use it. Set it to NULL.
Sending and receiving
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,
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff