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* Linux WiMAX
* Kernel space API for accessing WiMAX devices
* Copyright (C) 2007-2008 Intel Corporation <>
* Inaky Perez-Gonzalez <>
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
* The WiMAX stack provides an API for controlling and managing the
* system's WiMAX devices. This API affects the control plane; the
* data plane is accessed via the network stack (netdev).
* Parts of the WiMAX stack API and notifications are exported to
* user space via Generic Netlink. In user space, libwimax (part of
* the wimax-tools package) provides a shim layer for accessing those
* calls.
* The API is standarized for all WiMAX devices and different drivers
* implement the backend support for it. However, device-specific
* messaging pipes are provided that can be used to issue commands and
* receive notifications in free form.
* Currently the messaging pipes are the only means of control as it
* is not known (due to the lack of more devices in the market) what
* will be a good abstraction layer. Expect this to change as more
* devices show in the market. This API is designed to be growable in
* order to address this problem.
* Embed a `struct wimax_dev` at the beginning of the the device's
* private structure, initialize and register it. For details, see
* `struct wimax_dev`s documentation.
* Once this is done, wimax-tools's libwimaxll can be used to
* communicate with the driver from user space. You user space
* application does not have to forcibily use libwimaxll and can talk
* the generic netlink protocol directly if desired.
* Remember this is a very low level API that will to provide all of
* WiMAX features. Other daemons and services running in user space
* are the expected clients of it. They offer a higher level API that
* applications should use (an example of this is the Intel's WiMAX
* Network Service for the i2400m).
* Although not set on final stone, this very basic interface is
* mostly completed. Remember this is meant to grow as new common
* operations are decided upon. New operations will be added to the
* interface, intent being on keeping backwards compatibility as much
* as possible.
* This layer implements a set of calls to control a WiMAX device,
* exposing a frontend to the rest of the kernel and user space (via
* generic netlink) and a backend implementation in the driver through
* function pointers.
* WiMAX devices have a state, and a kernel-only API allows the
* drivers to manipulate that state. State transitions are atomic, and
* only some of them are allowed (see `enum wimax_st`).
* Most API calls will set the state automatically; in most cases
* drivers have to only report state changes due to external
* conditions.
* All API operations are 'atomic', serialized through a mutex in the
* `struct wimax_dev`.
* The API is exported to user space using generic netlink (other
* methods can be added as needed).
* There is a Generic Netlink Family named "WiMAX", where interfaces
* supporting the WiMAX interface receive commands and broadcast their
* signals over a multicast group named "msg".
* Mapping to the source/destination interface is done by an interface
* index attribute.
* For user-to-kernel traffic (commands) we use a function call
* marshalling mechanism, where a message X with attributes A, B, C
* sent from user space to kernel space means executing the WiMAX API
* call wimax_X(A, B, C), sending the results back as a message.
* Kernel-to-user (notifications or signals) communication is sent
* over multicast groups. This allows to have multiple applications
* monitoring them.
* Each command/signal gets assigned it's own attribute policy. This
* way the validator will verify that all the attributes in there are
* only the ones that should be for each command/signal. Thing of an
* attribute mapping to a type+argumentname for each command/signal.
* If we had a single policy for *all* commands/signals, after running
* the validator we'd have to check "does this attribute belong in
* here"? for each one. It can be done manually, but it's just easier
* to have the validator do that job with multiple policies. As well,
* it makes it easier to later expand each command/signal signature
* without affecting others and keeping the namespace more or less
* sane. Not that it is too complicated, but it makes it even easier.
* No state information is maintained in the kernel for each user
* space connection (the connection is stateless).
* If network interface X is a WiMAX device, there will be a Generic
* Netlink family named "WiMAX X" and the device will present a
* "wimax" directory in it's network sysfs directory
* (/sys/class/net/DEVICE/wimax) [used by HAL].
* The inexistence of any of these means the device does not support
* this WiMAX API.
* By querying the generic netlink controller, versioning information
* and the multicast groups available can be found. Applications using
* the interface can either rely on that or use the generic netlink
* controller to figure out which generic netlink commands/signals are
* supported.
* NOTE: this versioning is a last resort to avoid hard
* incompatibilities. It is the intention of the design of this
* stack not to introduce backward incompatible changes.
* The version code has to fit in one byte (restrictions imposed by
* generic netlink); we use `version / 10` for the major version and
* `version % 10` for the minor. This gives 9 minors for each major
* and 25 majors.
* The version change protocol is as follow:
* - Major versions: needs to be increased if an existing message/API
* call is changed or removed. Doesn't need to be changed if a new
* message is added.
* - Minor version: needs to be increased if new messages/API calls are
* being added or some other consideration that doesn't impact the
* user-kernel interface too much (like some kind of bug fix) and
* that is kind of left up in the air to common sense.
* User space code should not try to work if the major version it was
* compiled for differs from what the kernel offers. As well, if the
* minor version of the kernel interface is lower than the one user
* space is expecting (the one it was compiled for), the kernel
* might be missing API calls; user space shall be ready to handle
* said condition. Use the generic netlink controller operations to
* find which ones are supported and which not.
* libwimaxll:wimaxll_open() takes care of checking versions.
* Each operation is defined in its on file (drivers/net/wimax/op-*.c)
* for clarity. The parts needed for an operation are:
* - a function pointer in `struct wimax_dev`: optional, as the
* operation might be implemented by the stack and not by the
* driver.
* All function pointers are named wimax_dev->op_*(), and drivers
* must implement them except where noted otherwise.
* - When exported to user space, a `struct nla_policy` to define the
* attributes of the generic netlink command and a `struct genl_ops`
* to define the operation.
* All the declarations for the operation codes (WIMAX_GNL_OP_<NAME>)
* and generic netlink attributes (WIMAX_GNL_<NAME>_*) are declared in
* include/linux/wimax.h; this file is intended to be cloned by user
* space to gain access to those declarations.
* A few caveats to remember:
* - Need to define attribute numbers starting in 1; otherwise it
* fails.
* - the `struct genl_family` requires a maximum attribute id; when
* defining the `struct nla_policy` for each message, it has to have
* an array size of WIMAX_GNL_ATTR_MAX+1.
* The op_*() function pointers will not be called if the wimax_dev is
* in a state <= %WIMAX_ST_UNINITIALIZED. The exception is:
* - op_reset: can be called at any time after wimax_dev_add() has
* been called.
* This interface is kept intentionally simple. The driver can send
* and receive free-form messages to/from user space through a
* pipe. See drivers/net/wimax/op-msg.c for details.
* The kernel-to-user messages are sent with
* wimax_msg(). user-to-kernel messages are delivered via
* wimax_dev->op_msg_from_user().
* RFKILL support is built into the wimax_dev layer; the driver just
* needs to call wimax_report_rfkill_{hw,sw}() to inform of changes in
* the hardware or software RF kill switches. When the stack wants to
* turn the radio off, it will call wimax_dev->op_rfkill_sw_toggle(),
* which the driver implements.
* User space can set the software RF Kill switch by calling
* wimax_rfkill().
* The code for now only supports devices that don't require polling;
* If the device needs to be polled, create a self-rearming delayed
* work struct for polling or look into adding polled support to the
* WiMAX stack.
* When initializing the hardware (_probe), after calling
* wimax_dev_add(), query the device for it's RF Kill switches status
* and feed it back to the WiMAX stack using
* wimax_report_rfkill_{hw,sw}(). If any switch is missing, always
* report it as ON.
* NOTE: the wimax stack uses an inverted terminology to that of the
* RFKILL subsystem:
* - ON: radio is ON, RFKILL is DISABLED or OFF.
* - OFF: radio is OFF, RFKILL is ENABLED or ON.
* wimax_reset() can be used to reset the device to power on state; by
* default it issues a warm reset that maintains the same device
* node. If that is not possible, it falls back to a cold reset
* (device reconnect). The driver implements the backend to this
* through wimax_dev->op_reset().
#ifndef __NET__WIMAX_H__
#define __NET__WIMAX_H__
#include <linux/wimax.h>
#include <net/genetlink.h>
#include <linux/netdevice.h>
struct net_device;
struct genl_info;
struct wimax_dev;
* struct wimax_dev - Generic WiMAX device
* @net_dev: [fill] Pointer to the &struct net_device this WiMAX
* device implements.
* @op_msg_from_user: [fill] Driver-specific operation to
* handle a raw message from user space to the driver. The
* driver can send messages to user space using with
* wimax_msg_to_user().
* @op_rfkill_sw_toggle: [fill] Driver-specific operation to act on
* userspace (or any other agent) requesting the WiMAX device to
* change the RF Kill software switch (WIMAX_RF_ON or
* If such hardware support is not present, it is assumed the
* radio cannot be switched off and it is always on (and the stack
* will error out when trying to switch it off). In such case,
* this function pointer can be left as NULL.
* @op_reset: [fill] Driver specific operation to reset the
* device.
* This operation should always attempt first a warm reset that
* does not disconnect the device from the bus and return 0.
* If that fails, it should resort to some sort of cold or bus
* reset (even if it implies a bus disconnection and device
* disappearance). In that case, -ENODEV should be returned to
* indicate the device is gone.
* This operation has to be synchronous, and return only when the
* reset is complete. In case of having had to resort to bus/cold
* reset implying a device disconnection, the call is allowed to
* return inmediately.
* NOTE: wimax_dev->mutex is NOT locked when this op is being
* called; however, wimax_dev->mutex_reset IS locked to ensure
* serialization of calls to wimax_reset().
* See wimax_reset()'s documentation.
* @name: [fill] A way to identify this device. We need to register a
* name with many subsystems (rfkill, workqueue creation, etc).
* We can't use the network device name as that
* might change and in some instances we don't know it yet (until
* we don't call register_netdev()). So we generate an unique one
* using the driver name and device bus id, place it here and use
* it across the board. Recommended naming:
* DRIVERNAME-BUSNAME:BUSID (dev->bus->name, dev->bus_id).
* @id_table_node: [private] link to the list of wimax devices kept by
* id-table.c. Protected by it's own spinlock.
* @mutex: [private] Serializes all concurrent access and execution of
* operations.
* @mutex_reset: [private] Serializes reset operations. Needs to be a
* different mutex because as part of the reset operation, the
* driver has to call back into the stack to do things such as
* state change, that require wimax_dev->mutex.
* @state: [private] Current state of the WiMAX device.
* @rfkill: [private] integration into the RF-Kill infrastructure.
* @rf_sw: [private] State of the software radio switch (OFF/ON)
* @rf_hw: [private] State of the hardware radio switch (OFF/ON)
* @debugfs_dentry: [private] Used to hook up a debugfs entry. This
* shows up in the debugfs root as wimax\:DEVICENAME.
* Description:
* This structure defines a common interface to access all WiMAX
* devices from different vendors and provides a common API as well as
* a free-form device-specific messaging channel.
* Usage:
* 1. Embed a &struct wimax_dev at *the beginning* the network
* device structure so that netdev_priv() points to it.
* 2. memset() it to zero
* 3. Initialize with wimax_dev_init(). This will leave the WiMAX
* device in the %__WIMAX_ST_NULL state.
* 4. Fill all the fields marked with [fill]; once called
* wimax_dev_add(), those fields CANNOT be modified.
* 5. Call wimax_dev_add() *after* registering the network
* device. This will leave the WiMAX device in the %WIMAX_ST_DOWN
* state.
* Protect the driver's net_device->open() against succeeding if
* the wimax device state is lower than %WIMAX_ST_DOWN.
* 6. Select when the device is going to be turned on/initialized;
* for example, it could be initialized on 'ifconfig up' (when the
* netdev op 'open()' is called on the driver).
* When the device is initialized (at `ifconfig up` time, or right
* after calling wimax_dev_add() from _probe(), make sure the
* following steps are taken
* a. Move the device to %WIMAX_ST_UNINITIALIZED. This is needed so
* some API calls that shouldn't work until the device is ready
* can be blocked.
* b. Initialize the device. Make sure to turn the SW radio switch
* off and move the device to state %WIMAX_ST_RADIO_OFF when
* done. When just initialized, a device should be left in RADIO
* OFF state until user space devices to turn it on.
* c. Query the device for the state of the hardware rfkill switch
* and call wimax_rfkill_report_hw() and wimax_rfkill_report_sw()
* as needed. See below.
* wimax_dev_rm() undoes before unregistering the network device. Once
* wimax_dev_add() is called, the driver can get called on the
* wimax_dev->op_* function pointers
* The stack provides a mutex for each device that will disallow API
* calls happening concurrently; thus, op calls into the driver
* through the wimax_dev->op*() function pointers will always be
* serialized and *never* concurrent.
* For locking, take wimax_dev->mutex is taken; (most) operations in
* the API have to check for wimax_dev_is_ready() to return 0 before
* continuing (this is done internally).
* The WiMAX device is reference counted by the associated network
* device. The only operation that can be used to reference the device
* is wimax_dev_get_by_genl_info(), and the reference it acquires has
* to be released with dev_put(wimax_dev->net_dev).
* At startup, both HW and SW radio switchess are assumed to be off.
* At initialization time [after calling wimax_dev_add()], have the
* driver query the device for the status of the software and hardware
* RF kill switches and call wimax_report_rfkill_hw() and
* wimax_rfkill_report_sw() to indicate their state. If any is
* missing, just call it to indicate it is ON (radio always on).
* Whenever the driver detects a change in the state of the RF kill
* switches, it should call wimax_report_rfkill_hw() or
* wimax_report_rfkill_sw() to report it to the stack.
struct wimax_dev {
struct net_device *net_dev;
struct list_head id_table_node;
struct mutex mutex; /* Protects all members and API calls */
struct mutex mutex_reset;
enum wimax_st state;
int (*op_msg_from_user)(struct wimax_dev *wimax_dev,
const char *,
const void *, size_t,
const struct genl_info *info);
int (*op_rfkill_sw_toggle)(struct wimax_dev *wimax_dev,
enum wimax_rf_state);
int (*op_reset)(struct wimax_dev *wimax_dev);
struct rfkill *rfkill;
unsigned int rf_hw;
unsigned int rf_sw;
char name[32];
struct dentry *debugfs_dentry;
* WiMAX stack public API for device drivers
* -----------------------------------------
* These functions are not exported to user space.
void wimax_dev_init(struct wimax_dev *);
int wimax_dev_add(struct wimax_dev *, struct net_device *);
void wimax_dev_rm(struct wimax_dev *);
static inline
struct wimax_dev *net_dev_to_wimax(struct net_device *net_dev)
return netdev_priv(net_dev);
static inline
struct device *wimax_dev_to_dev(struct wimax_dev *wimax_dev)
return wimax_dev->net_dev->dev.parent;
void wimax_state_change(struct wimax_dev *, enum wimax_st);
enum wimax_st wimax_state_get(struct wimax_dev *);
* Radio Switch state reporting.
* enum wimax_rf_state is declared in linux/wimax.h so the exports
* to user space can use it.
void wimax_report_rfkill_hw(struct wimax_dev *, enum wimax_rf_state);
void wimax_report_rfkill_sw(struct wimax_dev *, enum wimax_rf_state);
* Free-form messaging to/from user space
* Sending a message:
* wimax_msg(wimax_dev, pipe_name, buf, buf_size, GFP_KERNEL);
* Broken up:
* skb = wimax_msg_alloc(wimax_dev, pipe_name, buf_size, GFP_KERNEL);
* ...fill up skb...
* wimax_msg_send(wimax_dev, pipe_name, skb);
* Be sure not to modify skb->data in the middle (ie: don't use
* skb_push()/skb_pull()/skb_reserve() on the skb).
* "pipe_name" is any string, than can be interpreted as the name of
* the pipe or destinatary; the interpretation of it is driver
* specific, so the recipient can multiplex it as wished. It can be
* NULL, it won't be used - an example is using a "diagnostics" tag to
* send diagnostics information that a device-specific diagnostics
* tool would be interested in.
struct sk_buff *wimax_msg_alloc(struct wimax_dev *, const char *, const void *,
size_t, gfp_t);
int wimax_msg_send(struct wimax_dev *, struct sk_buff *);
int wimax_msg(struct wimax_dev *, const char *, const void *, size_t, gfp_t);
const void *wimax_msg_data_len(struct sk_buff *, size_t *);
const void *wimax_msg_data(struct sk_buff *);
ssize_t wimax_msg_len(struct sk_buff *);
* WiMAX stack user space API
* --------------------------
* This API is what gets exported to user space for general
* operations. As well, they can be called from within the kernel,
* (with a properly referenced `struct wimax_dev`).
* Properly referenced means: the 'struct net_device' that embeds the
* device's control structure and (as such) the 'struct wimax_dev' is
* referenced by the caller.
int wimax_rfkill(struct wimax_dev *, enum wimax_rf_state);
int wimax_reset(struct wimax_dev *);
#endif /* #ifndef __NET__WIMAX_H__ */