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/* SPDX-License-Identifier: GPL-2.0-only / / * Linux WiMAX * Kernel space API for accessing WiMAX devices * * Copyright (C) 2007-2008 Intel Corporation <linux-wimax@intel.com> * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com> * * 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. * * USAGE * * 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). * * DESIGN * * 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`. * * EXPORTING TO USER SPACE THROUGH GENERIC NETLINK * * 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). * * TESTING FOR THE INTERFACE AND VERSIONING * * 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. * * THE OPERATIONS: * * 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. * * THE PIPE INTERFACE: * * 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: * * 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. * * MISCELLANEOUS OPS: * * 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 * WIMAX_RF_OFF). * 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 immediately. * 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 * * CONCURRENCY: * * 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). * * REFERENCE COUNTING: * * 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). * * RFKILL: * * 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, that can be interpreted as the name of * the pipe or recipient; 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__ */

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