address.
static struct i2c_driver foo_driver = {
- .owner = THIS_MODULE,
- .name = "Foo version 2.3 driver",
- .id = I2C_DRIVERID_FOO, /* from i2c-id.h, optional */
- .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.
-
-If used, the id should be a unique ID. The range 0xf000 to 0xffff is
-reserved for local use, and you can use one of those until you start
-distributing the driver, at which time you should contact the i2c authors
-to get your own ID(s). Note that most of the time you don't need an ID
-at all so you can just omit it.
-
-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.
normal_i2c: filled in by the module writer.
A list of I2C addresses which should normally be examined.
- normal_i2c_range: filled in by the module writer.
- A list of pairs of I2C addresses, each pair being an inclusive range of
- addresses which should normally be examined.
probe: insmod parameter.
A list of pairs. The first value is a bus number (-1 for any I2C bus),
the second is the address. These addresses are also probed, as if they
were in the 'normal' list.
- probe_range: insmod parameter.
- A list of triples. The first value is a bus number (-1 for any I2C bus),
- the second and third are addresses. These form an inclusive range of
- addresses that are also probed, as if they were in the 'normal' list.
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.
- ignore_range: insmod parameter.
- A list of triples. The first value is a bus number (-1 for any I2C bus),
- the second and third are addresses. These form an inclusive range of
- I2C addresses that 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.
-Fortunately, as a module writer, you just have to define the `normal'
-and/or `normal_range' parameters. The complete declaration could look
-like this:
+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:
- /* Scan 0x20 to 0x2f, 0x37, and 0x40 to 0x4f */
- static unsigned short normal_i2c[] = { 0x37,I2C_CLIENT_END };
- static unsigned short normal_i2c_range[] = { 0x20, 0x2f, 0x40, 0x4f,
- I2C_CLIENT_END };
+ /* Scan 0x37, and 0x48 to 0x4f */
+ static unsigned short normal_i2c[] = { 0x37, 0x48, 0x49, 0x4a, 0x4b, 0x4c,
+ 0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
/* 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);
-Note that you *have* to call the two defined variables `normal_i2c' and
-`normal_i2c_range', without any prefix!
-
-
-Probing classes (sensors)
--------------------------
-
-If you write a `sensors' driver, you use a slightly different interface.
-As well as I2C addresses, we have to cope with ISA addresses. Also, we
-use a enum of chip types. Don't forget to include `sensors.h'.
+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.
-The following lists are used internally. They are all lists of integers.
-
- normal_i2c: filled in by the module writer. Terminated by SENSORS_I2C_END.
- A list of I2C addresses which should normally be examined.
- normal_i2c_range: filled in by the module writer. Terminated by
- SENSORS_I2C_END
- A list of pairs of I2C addresses, each pair being an inclusive range of
- addresses which should normally be examined.
- normal_isa: filled in by the module writer. Terminated by SENSORS_ISA_END.
- A list of ISA addresses which should normally be examined.
- normal_isa_range: filled in by the module writer. Terminated by
- SENSORS_ISA_END
- A list of triples. The first two elements are ISA addresses, being an
- range of addresses which should normally be examined. The third is the
- modulo parameter: only addresses which are 0 module this value relative
- to the first address of the range are actually considered.
- probe: insmod parameter. Initialize this list with SENSORS_I2C_END values.
- A list of pairs. The first value is a bus number (SENSORS_ISA_BUS for
- the ISA bus, -1 for any I2C bus), the second is the address. These
- addresses are also probed, as if they were in the 'normal' list.
- probe_range: insmod parameter. Initialize this list with SENSORS_I2C_END
- values.
- A list of triples. The first value is a bus number (SENSORS_ISA_BUS for
- the ISA bus, -1 for any I2C bus), the second and third are addresses.
- These form an inclusive range of addresses that are also probed, as
- if they were in the 'normal' list.
- ignore: insmod parameter. Initialize this list with SENSORS_I2C_END values.
- A list of pairs. The first value is a bus number (SENSORS_ISA_BUS for
- the ISA bus, -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.
- ignore_range: insmod parameter. Initialize this list with SENSORS_I2C_END
- values.
- A list of triples. The first value is a bus number (SENSORS_ISA_BUS for
- the ISA bus, -1 for any I2C bus), the second and third are addresses.
- These form an inclusive range of I2C addresses that 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 (SENSORS_ISA_BUS for the ISA bus,
- -1 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'
-and/or `normal_range' parameters, and define what chip names are used.
-The complete declaration could look like this:
- /* Scan i2c addresses 0x20 to 0x2f, 0x37, and 0x40 to 0x4f
- static unsigned short normal_i2c[] = {0x37,SENSORS_I2C_END};
- static unsigned short normal_i2c_range[] = {0x20,0x2f,0x40,0x4f,
- SENSORS_I2C_END};
- /* Scan ISA address 0x290 */
- static unsigned int normal_isa[] = {0x0290,SENSORS_ISA_END};
- static unsigned int normal_isa_range[] = {SENSORS_ISA_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, ... }
+Note that you *have* to call the defined variable `normal_i2c',
+without any prefix!
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.
const char *type_name = "";
int is_isa = i2c_is_isa_adapter(adapter);
- if (is_isa) {
+ /* Do this only if the chip can additionally be found on the ISA bus
+ (hybrid chip). */
- /* If this client can't be on the ISA bus at all, we can stop now
- (call `goto ERROR0'). But for kicks, we will assume it is all
- right. */
+ 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;
}
/* SENSORS ONLY END */
/* Try to detach the client from i2c space */
- if ((err = i2c_detach_client(client))) {
- printk("foo.o: Client deregistration failed, client not detached.\n");
+ if ((err = i2c_detach_client(client)))
return err;
- }
- /* SENSORS ONLY START */
+ /* HYBRID SENSORS CHIP ONLY START */
if i2c_is_isa_client(client)
release_region(client->addr,LM78_EXTENT);
- /* SENSORS ONLY END */
+ /* 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://git.onelab.eu / linux-2.6.git / blobdiff