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. */
enum chips type; /* To keep the chips type for `sensors' drivers. */
/* Because the i2c bus is slow, it is often useful to cache the read
information of a chip for some time (for example, 1 or 2 seconds).
It depends of course on the device whether this is really worthwhile
or even sensible. */
- struct semaphore update_lock; /* When we are reading lots of information,
+ struct mutex update_lock; /* When we are reading lots of information,
another process should not update the
below information */
char valid; /* != 0 if the following fields are valid. */
I have found it useful to define foo_read and foo_write function for this.
For some cases, it will be easier to call the i2c functions directly,
but many chips have some kind of register-value idea that can easily
-be encapsulated. Also, some chips have both ISA and I2C interfaces, and
-it useful to abstract from this (only for `sensors' drivers).
+be encapsulated.
The below functions are simple examples, and should not be copied
literally.
return i2c_smbus_write_word_data(client,reg,value);
}
-For sensors code, you may have to cope with ISA registers too. Something
-like the below often works. Note the locking!
-
- int foo_read_value(struct i2c_client *client, u8 reg)
- {
- int res;
- if (i2c_is_isa_client(client)) {
- down(&(((struct foo_data *) (client->data)) -> lock));
- outb_p(reg,client->addr + FOO_ADDR_REG_OFFSET);
- res = inb_p(client->addr + FOO_DATA_REG_OFFSET);
- up(&(((struct foo_data *) (client->data)) -> lock));
- return res;
- } else
- return i2c_smbus_read_byte_data(client,reg);
- }
-
-Writing is done the same way.
-
Probing and attaching
=====================
You do not have to use this parameter interface; but don't try to use
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 (Legacy model)
------------------------------
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.
-
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
For now, you can ignore the `flags' parameter. It is there for future use.
int foo_detect_client(struct i2c_adapter *adapter, int address,
- unsigned short flags, int kind)
+ int kind)
{
int err = 0;
int i;
- struct i2c_client *new_client;
+ struct i2c_client *client;
struct foo_data *data;
- const char *client_name = ""; /* For non-`sensors' drivers, put the real
- name here! */
+ const char *name = "";
/* Let's see whether this adapter can support what we need.
- Please substitute the things you need here!
- For `sensors' drivers, add `! is_isa &&' to the if statement */
+ Please substitute the things you need here! */
if (!i2c_check_functionality(adapter,I2C_FUNC_SMBUS_WORD_DATA |
I2C_FUNC_SMBUS_WRITE_BYTE))
goto ERROR0;
- /* SENSORS ONLY START */
- const char *type_name = "";
- int is_isa = i2c_is_isa_adapter(adapter);
-
- /* Do this only if the chip can additionally be found on the ISA bus
- (hybrid chip). */
-
- 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;
-
- /* Probe whether there is anything on this address.
- Some example code is below, but you will have to adapt this
- for your own driver */
-
- if (kind < 0) /* Only if no force parameter was used */ {
- /* We may need long timeouts at least for some chips. */
- #define REALLY_SLOW_IO
- i = inb_p(address + 1);
- if (inb_p(address + 2) != i)
- goto ERROR0;
- if (inb_p(address + 3) != i)
- goto ERROR0;
- if (inb_p(address + 7) != i)
- goto ERROR0;
- #undef REALLY_SLOW_IO
-
- /* Let's just hope nothing breaks here */
- i = inb_p(address + 5) & 0x7f;
- outb_p(~i & 0x7f,address+5);
- if ((inb_p(address + 5) & 0x7f) != (~i & 0x7f)) {
- outb_p(i,address+5);
- return 0;
- }
- }
- }
-
- /* SENSORS ONLY END */
-
/* OK. For now, we presume we have a valid client. We now create the
client structure, even though we cannot fill it completely yet.
But it allows us to access several i2c functions safely */
goto ERROR0;
}
- new_client = &data->client;
- i2c_set_clientdata(new_client, data);
+ client = &data->client;
+ i2c_set_clientdata(client, data);
- new_client->addr = address;
- new_client->adapter = adapter;
- new_client->driver = &foo_driver;
- new_client->flags = 0;
+ client->addr = address;
+ client->adapter = adapter;
+ client->driver = &foo_driver;
/* Now, we do the remaining detection. If no `force' parameter is used. */
parameter was used. */
if (kind < 0) {
/* The below is of course bogus */
- if (foo_read(new_client,FOO_REG_GENERIC) != FOO_GENERIC_VALUE)
+ if (foo_read(client, FOO_REG_GENERIC) != FOO_GENERIC_VALUE)
goto ERROR1;
}
- /* SENSORS ONLY START */
-
/* Next, specific detection. This is especially important for `sensors'
devices. */
/* Determine the chip type. Not needed if a `force_CHIPTYPE' parameter
was used. */
if (kind <= 0) {
- i = foo_read(new_client,FOO_REG_CHIPTYPE);
+ i = foo_read(client, FOO_REG_CHIPTYPE);
if (i == FOO_TYPE_1)
kind = chip1; /* As defined in the enum */
else if (i == FOO_TYPE_2)
/* Now set the type and chip names */
if (kind == chip1) {
- type_name = "chip1"; /* For /proc entry */
- client_name = "CHIP 1";
+ name = "chip1";
} else if (kind == chip2) {
- type_name = "chip2"; /* For /proc entry */
- client_name = "CHIP 2";
+ name = "chip2";
}
- /* Reserve the ISA region */
- if (is_isa)
- request_region(address,FOO_EXTENT,type_name);
-
- /* SENSORS ONLY END */
-
/* Fill in the remaining client fields. */
- strcpy(new_client->name,client_name);
-
- /* SENSORS ONLY BEGIN */
+ strlcpy(client->name, name, I2C_NAME_SIZE);
data->type = kind;
- /* SENSORS ONLY END */
-
- data->valid = 0; /* Only if you use this field */
- init_MUTEX(&data->update_lock); /* Only if you use this field */
+ mutex_init(&data->update_lock); /* Only if you use this field */
/* Any other initializations in data must be done here too. */
- /* Tell the i2c layer a new client has arrived */
- if ((err = i2c_attach_client(new_client)))
- goto ERROR3;
-
- /* SENSORS ONLY BEGIN */
- /* Register a new directory entry with module sensors. See below for
- the `template' structure. */
- if ((i = i2c_register_entry(new_client, type_name,
- foo_dir_table_template,THIS_MODULE)) < 0) {
- err = i;
- goto ERROR4;
- }
- data->sysctl_id = i;
-
- /* SENSORS ONLY END */
-
/* This function can write default values to the client registers, if
needed. */
- foo_init_client(new_client);
+ foo_init_client(client);
+
+ /* Tell the i2c layer a new client has arrived */
+ if ((err = i2c_attach_client(client)))
+ goto ERROR1;
+
return 0;
/* OK, this is not exactly good programming practice, usually. But it is
very code-efficient in this case. */
- ERROR4:
- i2c_detach_client(new_client);
- ERROR3:
- ERROR2:
- /* SENSORS ONLY START */
- if (is_isa)
- release_region(address,FOO_EXTENT);
- /* SENSORS ONLY END */
ERROR1:
kfree(data);
ERROR0:
int foo_detach_client(struct i2c_client *client)
{
- int err,i;
-
- /* SENSORS ONLY START */
- /* Deregister with the `i2c-proc' module. */
- i2c_deregister_entry(((struct lm78_data *)(client->data))->sysctl_id);
- /* SENSORS ONLY END */
+ int err;
/* Try to detach the client from i2c space */
if ((err = i2c_detach_client(client)))
return err;
- /* HYBRID SENSORS CHIP ONLY START */
- if i2c_is_isa_client(client)
- release_region(client->addr,LM78_EXTENT);
- /* HYBRID SENSORS CHIP ONLY END */
-
kfree(i2c_get_clientdata(client));
return 0;
}
you have to do some initializing. Fortunately, just attaching (registering)
the driver module is usually enough.
- /* Keep track of how far we got in the initialization process. If several
- things have to initialized, and we fail halfway, only those things
- have to be cleaned up! */
- static int __initdata foo_initialized = 0;
-
static int __init foo_init(void)
{
int res;
- printk("foo version %s (%s)\n",FOO_VERSION,FOO_DATE);
if ((res = i2c_add_driver(&foo_driver))) {
printk("foo: Driver registration failed, module not inserted.\n");
- foo_cleanup();
return res;
}
- foo_initialized ++;
return 0;
}
- void foo_cleanup(void)
+ static void __exit foo_cleanup(void)
{
- if (foo_initialized == 1) {
- i2c_del_driver(&foo_driver);
- foo_initialized --;
- }
+ i2c_del_driver(&foo_driver);
}
/* Substitute your own name and email address */
MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>"
MODULE_DESCRIPTION("Driver for Barf Inc. Foo I2C devices");
+ /* a few non-GPL license types are also allowed */
+ MODULE_LICENSE("GPL");
+
module_init(foo_init);
module_exit(foo_cleanup);
Note that some functions are marked by `__init', and some data structures
-by `__init_data'. Hose functions and structures can be removed after
+by `__initdata'. These functions and structures can be removed after
kernel booting (or module loading) is completed.
Below all general purpose routines are listed, that were not mentioned
before.
- /* This call returns a unique low identifier for each registered adapter,
- * or -1 if the adapter was not registered.
+ /* This call returns a unique low identifier for each registered adapter.
*/
extern int i2c_adapter_id(struct i2c_adapter *adap);
-
-The sensors sysctl/proc interface
-=================================
-
-This section only applies if you write `sensors' drivers.
-
-Each sensors driver creates a directory in /proc/sys/dev/sensors for each
-registered client. The directory is called something like foo-i2c-4-65.
-The sensors module helps you to do this as easily as possible.
-
-The template
-------------
-
-You will need to define a ctl_table template. This template will automatically
-be copied to a newly allocated structure and filled in where necessary when
-you call sensors_register_entry.
-
-First, I will give an example definition.
- static ctl_table foo_dir_table_template[] = {
- { FOO_SYSCTL_FUNC1, "func1", NULL, 0, 0644, NULL, &i2c_proc_real,
- &i2c_sysctl_real,NULL,&foo_func },
- { FOO_SYSCTL_FUNC2, "func2", NULL, 0, 0644, NULL, &i2c_proc_real,
- &i2c_sysctl_real,NULL,&foo_func },
- { FOO_SYSCTL_DATA, "data", NULL, 0, 0644, NULL, &i2c_proc_real,
- &i2c_sysctl_real,NULL,&foo_data },
- { 0 }
- };
-
-In the above example, three entries are defined. They can either be
-accessed through the /proc interface, in the /proc/sys/dev/sensors/*
-directories, as files named func1, func2 and data, or alternatively
-through the sysctl interface, in the appropriate table, with identifiers
-FOO_SYSCTL_FUNC1, FOO_SYSCTL_FUNC2 and FOO_SYSCTL_DATA.
-
-The third, sixth and ninth parameters should always be NULL, and the
-fourth should always be 0. The fifth is the mode of the /proc file;
-0644 is safe, as the file will be owned by root:root.
-
-The seventh and eighth parameters should be &i2c_proc_real and
-&i2c_sysctl_real if you want to export lists of reals (scaled
-integers). You can also use your own function for them, as usual.
-Finally, the last parameter is the call-back to gather the data
-(see below) if you use the *_proc_real functions.
-
-
-Gathering the data
-------------------
-
-The call back functions (foo_func and foo_data in the above example)
-can be called in several ways; the operation parameter determines
-what should be done:
-
- * If operation == SENSORS_PROC_REAL_INFO, you must return the
- magnitude (scaling) in nrels_mag;
- * If operation == SENSORS_PROC_REAL_READ, you must read information
- from the chip and return it in results. The number of integers
- to display should be put in nrels_mag;
- * If operation == SENSORS_PROC_REAL_WRITE, you must write the
- supplied information to the chip. nrels_mag will contain the number
- of integers, results the integers themselves.
-
-The *_proc_real functions will display the elements as reals for the
-/proc interface. If you set the magnitude to 2, and supply 345 for
-SENSORS_PROC_REAL_READ, it would display 3.45; and if the user would
-write 45.6 to the /proc file, it would be returned as 4560 for
-SENSORS_PROC_REAL_WRITE. A magnitude may even be negative!
-
-An example function:
-
- /* FOO_FROM_REG and FOO_TO_REG translate between scaled values and
- register values. Note the use of the read cache. */
- void foo_in(struct i2c_client *client, int operation, int ctl_name,
- int *nrels_mag, long *results)
- {
- struct foo_data *data = client->data;
- int nr = ctl_name - FOO_SYSCTL_FUNC1; /* reduce to 0 upwards */
-
- if (operation == SENSORS_PROC_REAL_INFO)
- *nrels_mag = 2;
- else if (operation == SENSORS_PROC_REAL_READ) {
- /* Update the readings cache (if necessary) */
- foo_update_client(client);
- /* Get the readings from the cache */
- results[0] = FOO_FROM_REG(data->foo_func_base[nr]);
- results[1] = FOO_FROM_REG(data->foo_func_more[nr]);
- results[2] = FOO_FROM_REG(data->foo_func_readonly[nr]);
- *nrels_mag = 2;
- } else if (operation == SENSORS_PROC_REAL_WRITE) {
- if (*nrels_mag >= 1) {
- /* Update the cache */
- data->foo_base[nr] = FOO_TO_REG(results[0]);
- /* Update the chip */
- foo_write_value(client,FOO_REG_FUNC_BASE(nr),data->foo_base[nr]);
- }
- if (*nrels_mag >= 2) {
- /* Update the cache */
- data->foo_more[nr] = FOO_TO_REG(results[1]);
- /* Update the chip */
- foo_write_value(client,FOO_REG_FUNC_MORE(nr),data->foo_more[nr]);
- }
- }
- }
projects / cascardo / linux.git / blobdiff