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Diffstat (limited to 'include/net/wimax.h')
| -rw-r--r-- | include/net/wimax.h | 503 |
1 files changed, 503 insertions, 0 deletions
diff --git a/include/net/wimax.h b/include/net/wimax.h new file mode 100644 index 000000000..f6e31d2f4 --- /dev/null +++ b/include/net/wimax.h @@ -0,0 +1,503 @@ +/* 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 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__ */ |