diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 21 | ||||
| -rw-r--r-- | Documentation/i2c/busses/i2c-nforce2 | 2 | ||||
| -rw-r--r-- | Documentation/i2c/porting-clients | 18 | ||||
| -rw-r--r-- | Documentation/i2c/summary | 29 | ||||
| -rw-r--r-- | Documentation/i2c/writing-clients | 415 |
5 files changed, 181 insertions, 304 deletions
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 1a9e600a73a8..7d252dbe7d17 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -190,18 +190,10 @@ Who: Jean Delvare <khali@linux-fr.org> --------------------------- -What: i2c_adapter.dev - i2c_adapter.list +What: i2c_adapter.list When: July 2007 -Why: Superfluous, given i2c_adapter.class_dev: - * The "dev" was a stand-in for the physical device node that legacy - drivers would not have; but now it's almost always present. Any - remaining legacy drivers must upgrade (they now trigger warnings). - * The "list" duplicates class device children. - The delay in removing this is so upgraded lm_sensors and libsensors - can get deployed. (Removal causes minor changes in the sysfs layout, - notably the location of the adapter type name and parenting the i2c - client hardware directly from their controller.) +Why: Superfluous, this list duplicates the one maintained by the driver + core. Who: Jean Delvare <khali@linux-fr.org>, David Brownell <dbrownell@users.sourceforge.net> @@ -331,3 +323,10 @@ Who: Cornelia Huck <cornelia.huck@de.ibm.com> --------------------------- +What: i2c-ixp2000, i2c-ixp4xx and scx200_i2c drivers +When: September 2007 +Why: Obsolete. The new i2c-gpio driver replaces all hardware-specific + I2C-over-GPIO drivers. +Who: Jean Delvare <khali@linux-fr.org> + +--------------------------- diff --git a/Documentation/i2c/busses/i2c-nforce2 b/Documentation/i2c/busses/i2c-nforce2 index 7f61fbc03f7f..fae3495bcbaf 100644 --- a/Documentation/i2c/busses/i2c-nforce2 +++ b/Documentation/i2c/busses/i2c-nforce2 @@ -9,6 +9,8 @@ Supported adapters: * nForce4 MCP-04 10de:0034 * nForce4 MCP51 10de:0264 * nForce4 MCP55 10de:0368 + * nForce4 MCP61 10de:03EB + * nForce4 MCP65 10de:0446 Datasheet: not publicly available, but seems to be similar to the AMD-8111 SMBus 2.0 adapter. diff --git a/Documentation/i2c/porting-clients b/Documentation/i2c/porting-clients index ca272b263a92..7bf82c08f6ca 100644 --- a/Documentation/i2c/porting-clients +++ b/Documentation/i2c/porting-clients @@ -1,4 +1,4 @@ -Revision 6, 2005-11-20 +Revision 7, 2007-04-19 Jean Delvare <khali@linux-fr.org> Greg KH <greg@kroah.com> @@ -20,6 +20,10 @@ yours for best results. Technical changes: +* [Driver type] Any driver that was relying on i2c-isa has to be + converted to a proper isa, platform or pci driver. This is not + covered by this guide. + * [Includes] Get rid of "version.h" and <linux/i2c-proc.h>. Includes typically look like that: #include <linux/module.h> @@ -27,12 +31,10 @@ Technical changes: #include <linux/slab.h> #include <linux/jiffies.h> #include <linux/i2c.h> - #include <linux/i2c-isa.h> /* for ISA drivers */ #include <linux/hwmon.h> /* for hardware monitoring drivers */ #include <linux/hwmon-sysfs.h> #include <linux/hwmon-vid.h> /* if you need VRM support */ #include <linux/err.h> /* for class registration */ - #include <asm/io.h> /* if you have I/O operations */ Please respect this inclusion order. Some extra headers may be required for a given driver (e.g. "lm75.h"). @@ -69,20 +71,16 @@ Technical changes: sensors mailing list <lm-sensors@lm-sensors.org> by providing a patch to the Documentation/hwmon/sysfs-interface file. -* [Attach] For I2C drivers, the attach function should make sure - that the adapter's class has I2C_CLASS_HWMON (or whatever class is - suitable for your driver), using the following construct: +* [Attach] The attach function should make sure that the adapter's + class has I2C_CLASS_HWMON (or whatever class is suitable for your + driver), using the following construct: if (!(adapter->class & I2C_CLASS_HWMON)) return 0; - ISA-only drivers of course don't need this. Call i2c_probe() instead of i2c_detect(). * [Detect] As mentioned earlier, the flags parameter is gone. The type_name and client_name strings are replaced by a single name string, which will be filled with a lowercase, short string. - In i2c-only drivers, drop the i2c_is_isa_adapter check, it's - useless. Same for isa-only drivers, as the test would always be - true. Only hybrid drivers (which are quite rare) still need it. The labels used for error paths are reduced to the number needed. It is advised that the labels are given descriptive names such as exit and exit_free. Don't forget to properly set err before diff --git a/Documentation/i2c/summary b/Documentation/i2c/summary index 41dde8776791..aea60bf7e8f0 100644 --- a/Documentation/i2c/summary +++ b/Documentation/i2c/summary @@ -4,17 +4,23 @@ I2C and SMBus ============= I2C (pronounce: I squared C) is a protocol developed by Philips. It is a -slow two-wire protocol (10-400 kHz), but it suffices for many types of -devices. +slow two-wire protocol (variable speed, up to 400 kHz), with a high speed +extension (3.4 MHz). It provides an inexpensive bus for connecting many +types of devices with infrequent or low bandwidth communications needs. +I2C is widely used with embedded systems. Some systems use variants that +don't meet branding requirements, and so are not advertised as being I2C. -SMBus (System Management Bus) is a subset of the I2C protocol. Many -modern mainboards have a System Management Bus. There are a lot of -devices which can be connected to a SMBus; the most notable are modern -memory chips with EEPROM memories and chips for hardware monitoring. +SMBus (System Management Bus) is based on the I2C protocol, and is mostly +a subset of I2C protocols and signaling. Many I2C devices will work on an +SMBus, but some SMBus protocols add semantics beyond what is required to +achieve I2C branding. Modern PC mainboards rely on SMBus. The most common +devices connected through SMBus are RAM modules configured using I2C EEPROMs, +and hardware monitoring chips. -Because the SMBus is just a special case of the generalized I2C bus, we -can simulate the SMBus protocol on plain I2C busses. The reverse is -regretfully impossible. +Because the SMBus is mostly a subset of the generalized I2C bus, we can +use its protocols on many I2C systems. However, there are systems that don't +meet both SMBus and I2C electrical constraints; and others which can't +implement all the common SMBus protocol semantics or messages. Terminology @@ -29,6 +35,7 @@ When we talk about I2C, we use the following terms: An Algorithm driver contains general code that can be used for a whole class of I2C adapters. Each specific adapter driver depends on one algorithm driver. + A Driver driver (yes, this sounds ridiculous, sorry) contains the general code to access some type of device. Each detected device gets its own data in the Client structure. Usually, Driver and Client are more closely @@ -40,6 +47,10 @@ a separate Adapter and Algorithm driver), and drivers for your I2C devices in this package. See the lm_sensors project http://www.lm-sensors.nu for device drivers. +At this time, Linux only operates I2C (or SMBus) in master mode; you can't +use these APIs to make a Linux system behave as a slave/device, either to +speak a custom protocol or to emulate some other device. + Included Bus Drivers ==================== diff --git a/Documentation/i2c/writing-clients b/Documentation/i2c/writing-clients index fbcff96f4ca1..3d8d36b0ad12 100644 --- a/Documentation/i2c/writing-clients +++ b/Documentation/i2c/writing-clients @@ -1,5 +1,5 @@ This is a small guide for those who want to write kernel drivers for I2C -or SMBus devices. +or SMBus devices, using Linux as the protocol host/master (not slave). To set up a driver, you need to do several things. Some are optional, and some things can be done slightly or completely different. Use this as a @@ -29,8 +29,16 @@ static struct i2c_driver foo_driver = { .driver = { .name = "foo", }, + + /* iff driver uses driver model ("new style") binding model: */ + .probe = foo_probe, + .remove = foo_remove, + + /* else, driver uses "legacy" binding model: */ .attach_adapter = foo_attach_adapter, .detach_client = foo_detach_client, + + /* these may be used regardless of the driver binding model */ .shutdown = foo_shutdown, /* optional */ .suspend = foo_suspend, /* optional */ .resume = foo_resume, /* optional */ @@ -40,7 +48,8 @@ static struct i2c_driver foo_driver = { The name field is the driver name, and must not contain spaces. It should match the module name (if the driver can be compiled as a module), although you can use MODULE_ALIAS (passing "foo" in this example) to add -another name for the module. +another name for the module. If the driver name doesn't match the module +name, the module won't be automatically loaded (hotplug/coldplug). All other fields are for call-back functions which will be explained below. @@ -65,16 +74,13 @@ 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. */ 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. */ @@ -95,8 +101,7 @@ some obscure clients). But we need generic reading and writing routines. 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. @@ -119,28 +124,101 @@ 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 ===================== +The Linux I2C stack was originally written to support access to hardware +monitoring chips on PC motherboards, and thus it embeds some assumptions +that are more appropriate to SMBus (and PCs) than to I2C. One of these +assumptions is that most adapters and devices drivers support the SMBUS_QUICK +protocol to probe device presence. Another is that devices and their drivers +can be sufficiently configured using only such probe primitives. + +As Linux and its I2C stack became more widely used in embedded systems +and complex components such as DVB adapters, those assumptions became more +problematic. Drivers for I2C devices that issue interrupts need more (and +different) configuration information, as do drivers handling chip variants +that can't be distinguished by protocol probing, or which need some board +specific information to operate correctly. + +Accordingly, the I2C stack now has two models for associating I2C devices +with their drivers: the original "legacy" model, and a newer one that's +fully compatible with the Linux 2.6 driver model. These models do not mix, +since the "legacy" model requires drivers to create "i2c_client" device +objects after SMBus style probing, while the Linux driver model expects +drivers to be given such device objects in their probe() routines. + + +Standard Driver Model Binding ("New Style") +------------------------------------------- + +System infrastructure, typically board-specific initialization code or +boot firmware, reports what I2C devices exist. For example, there may be +a table, in the kernel or from the boot loader, identifying I2C devices +and linking them to board-specific configuration information about IRQs +and other wiring artifacts, chip type, and so on. That could be used to +create i2c_client objects for each I2C device. + +I2C device drivers using this binding model work just like any other +kind of driver in Linux: they provide a probe() method to bind to +those devices, and a remove() method to unbind. + + static int foo_probe(struct i2c_client *client); + static int foo_remove(struct i2c_client *client); + +Remember that the i2c_driver does not create those client handles. The +handle may be used during foo_probe(). If foo_probe() reports success +(zero not a negative status code) it may save the handle and use it until +foo_remove() returns. That binding model is used by most Linux drivers. + +Drivers match devices when i2c_client.driver_name and the driver name are +the same; this approach is used in several other busses that don't have +device typing support in the hardware. The driver and module name should +match, so hotplug/coldplug mechanisms will modprobe the driver. + + +Device Creation (Standard driver model) +--------------------------------------- + +If you know for a fact that an I2C device is connected to a given I2C bus, +you can instantiate that device by simply filling an i2c_board_info +structure with the device address and driver name, and calling +i2c_new_device(). This will create the device, then the driver core will +take care of finding the right driver and will call its probe() method. +If a driver supports different device types, you can specify the type you +want using the type field. You can also specify an IRQ and platform data +if needed. + +Sometimes you know that a device is connected to a given I2C bus, but you +don't know the exact address it uses. This happens on TV adapters for +example, where the same driver supports dozens of slightly different +models, and I2C device addresses change from one model to the next. In +that case, you can use the i2c_new_probed_device() variant, which is +similar to i2c_new_device(), except that it takes an additional list of +possible I2C addresses to probe. A device is created for the first +responsive address in the list. If you expect more than one device to be +present in the address range, simply call i2c_new_probed_device() that +many times. + +The call to i2c_new_device() or i2c_new_probed_device() typically happens +in the I2C bus driver. You may want to save the returned i2c_client +reference for later use. + + +Device Deletion (Standard driver model) +--------------------------------------- + +Each I2C device which has been created using i2c_new_device() or +i2c_new_probed_device() can be unregistered by calling +i2c_unregister_device(). If you don't call it explicitly, it will be +called automatically before the underlying I2C bus itself is removed, as a +device can't survive its parent in the device driver model. + + +Legacy Driver Binding Model +--------------------------- + Most i2c devices can be present on several i2c addresses; for some this is determined in hardware (by soldering some chip pins to Vcc or Ground), for others this can be changed in software (by writing to specific client @@ -157,13 +235,9 @@ detection algorithm. 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 ---------------- +Probing classes (Legacy model) +------------------------------ All parameters are given as lists of unsigned 16-bit integers. Lists are terminated by I2C_CLIENT_END. @@ -210,8 +284,8 @@ Note that you *have* to call the defined variable `normal_i2c', without any prefix! -Attaching to an adapter ------------------------ +Attaching to an adapter (Legacy model) +-------------------------------------- Whenever a new adapter is inserted, or for all adapters if the driver is being registered, the callback attach_adapter() is called. Now is the @@ -237,17 +311,13 @@ 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 (Legacy model) +----------------------------------------- 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. - 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 @@ -256,64 +326,20 @@ shortage or i2c_attach_client failing. 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 */ @@ -323,13 +349,12 @@ For now, you can ignore the `flags' parameter. It is there for future use. 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. */ @@ -337,19 +362,17 @@ For now, you can ignore the `flags' parameter. It is there for future use. 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) @@ -363,63 +386,31 @@ For now, you can ignore the `flags' parameter. It is there for future use. /* 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: @@ -427,8 +418,8 @@ For now, you can ignore the `flags' parameter. It is there for future use. } -Removing the client -=================== +Removing the client (Legacy model) +================================== The detach_client call back function is called when a client should be removed. It may actually fail, but only when panicking. This code is @@ -436,22 +427,12 @@ much simpler than the attachment code, fortunately! 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; } @@ -464,45 +445,34 @@ When the kernel is booted, or when your foo driver module is inserted, 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) { - if ((res = i2c_del_driver(&foo_driver))) { - printk("foo: Driver registration failed, module not removed.\n"); - return; - } - 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. @@ -632,110 +602,7 @@ General purpose routines 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]); - } - } - } |