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