2 # Copyright (c) 1998-2004 Doug Rabson
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32 * @defgroup DEVICE device - KObj methods for all device drivers
33 * @brief A basic set of methods required for all device drivers.
35 * The device interface is used to match devices to drivers during
36 * autoconfiguration and provides methods to allow drivers to handle
37 * system-wide events such as suspend, resume or shutdown.
43 # Default implementations of some methods.
46 static int null_shutdown(device_t dev)
51 static int null_suspend(device_t dev)
56 static int null_resume(device_t dev)
61 static int null_quiesce(device_t dev)
66 static void * null_register(device_t dev)
73 * @brief Probe to see if a device matches a driver.
75 * Users should not call this method directly. Normally, this
76 * is called via device_probe_and_attach() to select a driver
77 * calling the DEVICE_PROBE() of all candidate drivers and attach
78 * the winning driver (if any) to the device.
80 * This function is used to match devices to device drivers.
81 * Typically, the driver will examine the device to see if
82 * it is suitable for this driver. This might include checking
83 * the values of various device instance variables or reading
86 * In some cases, there may be more than one driver available
87 * which can be used for a device (for instance there might
88 * be a generic driver which works for a set of many types of
89 * device and a more specific driver which works for a subset
90 * of devices). Because of this, a driver should not assume
91 * that it will be the driver that attaches to the device even
92 * if it returns a success status from DEVICE_PROBE(). In particular,
93 * a driver must free any resources which it allocated during
94 * the probe before returning. The return value of DEVICE_PROBE()
95 * is used to elect which driver is used - the driver which returns
96 * the largest non-error value wins the election and attaches to
97 * the device. Common non-error values are described in the
98 * DEVICE_PROBE(9) manual page.
100 * If a driver matches the hardware, it should set the device
101 * description string using device_set_desc() or
102 * device_set_desc_copy(). This string is used to generate an
103 * informative message when DEVICE_ATTACH() is called.
105 * As a special case, if a driver returns zero, the driver election
106 * is cut short and that driver will attach to the device
107 * immediately. This should rarely be used.
109 * For example, a probe method for a PCI device driver might look
114 * foo_probe(device_t dev)
116 * if (pci_get_vendor(dev) == FOOVENDOR &&
117 * pci_get_device(dev) == FOODEVICE) {
118 * device_set_desc(dev, "Foo device");
119 * return (BUS_PROBE_DEFAULT);
125 * To include this method in a device driver, use a line like this
126 * in the driver's method list:
129 * KOBJMETHOD(device_probe, foo_probe)
132 * @param dev the device to probe
134 * @retval 0 if this is the only possible driver for this
136 * @retval negative if the driver can match this device - the
137 * least negative value is used to select the
139 * @retval ENXIO if the driver does not match the device
140 * @retval positive if some kind of error was detected during
141 * the probe, a regular unix error code should
142 * be returned to indicate the type of error
143 * @see DEVICE_ATTACH(), pci_get_vendor(), pci_get_device()
150 * @brief Allow a device driver to detect devices not otherwise enumerated.
152 * The DEVICE_IDENTIFY() method is used by some drivers (e.g. the ISA
153 * bus driver) to help populate the bus device with a useful set of
154 * child devices, normally by calling the BUS_ADD_CHILD() method of
155 * the parent device. For instance, the ISA bus driver uses several
156 * special drivers, including the isahint driver and the pnp driver to
157 * create child devices based on configuration hints and PnP bus
158 * probes respectively.
160 * Many bus drivers which support true plug-and-play do not need to
161 * use this method at all since child devices can be discovered
162 * automatically without help from child drivers.
164 * To include this method in a device driver, use a line like this
165 * in the driver's method list:
168 * KOBJMETHOD(device_identify, foo_identify)
171 * @param driver the driver whose identify method is being called
172 * @param parent the parent device to use when adding new children
174 STATICMETHOD void identify {
180 * @brief Attach a device to a device driver
182 * Normally only called via device_probe_and_attach(), this is called
183 * when a driver has succeeded in probing against a device.
184 * This method should initialise the hardware and allocate other
185 * system resources (e.g. devfs entries) as required.
187 * To include this method in a device driver, use a line like this
188 * in the driver's method list:
191 * KOBJMETHOD(device_attach, foo_attach)
194 * @param dev the device to probe
197 * @retval non-zero if some kind of error was detected during
198 * the attach, a regular unix error code should
199 * be returned to indicate the type of error
200 * @see DEVICE_PROBE()
207 * @brief Detach a driver from a device.
209 * This can be called if the user is replacing the
210 * driver software or if a device is about to be physically removed
211 * from the system (e.g. for removable hardware such as USB or PCCARD).
213 * To include this method in a device driver, use a line like this
214 * in the driver's method list:
217 * KOBJMETHOD(device_detach, foo_detach)
220 * @param dev the device to detach
223 * @retval non-zero the detach could not be performed, e.g. if the
224 * driver does not support detaching.
226 * @see DEVICE_ATTACH()
233 * @brief Called during system shutdown.
235 * This method allows drivers to detect when the system is being shut down.
236 * Some drivers need to use this to place their hardware in a consistent
237 * state before rebooting the computer.
239 * To include this method in a device driver, use a line like this
240 * in the driver's method list:
243 * KOBJMETHOD(device_shutdown, foo_shutdown)
246 METHOD int shutdown {
248 } DEFAULT null_shutdown;
251 * @brief This is called by the power-management subsystem when a
252 * suspend has been requested by the user or by some automatic
255 * This gives drivers a chance to veto the suspend or save their
256 * configuration before power is removed.
258 * To include this method in a device driver, use a line like this in
259 * the driver's method list:
262 * KOBJMETHOD(device_suspend, foo_suspend)
265 * @param dev the device being suspended
268 * @retval non-zero an error occurred while attempting to prepare the
269 * device for suspension
271 * @see DEVICE_RESUME()
275 } DEFAULT null_suspend;
278 * @brief This is called when the system resumes after a suspend.
280 * To include this method in a device driver, use a line like this
281 * in the driver's method list:
284 * KOBJMETHOD(device_resume, foo_resume)
287 * @param dev the device being resumed
290 * @retval non-zero an error occurred while attempting to restore the
291 * device from suspension
293 * @see DEVICE_SUSPEND()
297 } DEFAULT null_resume;
300 * @brief This is called when the driver is asked to quiesce itself.
302 * The driver should arrange for the orderly shutdown of this device.
303 * All further access to the device should be curtailed. Soon there
304 * will be a request to detach, but there won't necessarily be one.
306 * To include this method in a device driver, use a line like this
307 * in the driver's method list:
310 * KOBJMETHOD(device_quiesce, foo_quiesce)
313 * @param dev the device being quiesced
316 * @retval non-zero an error occurred while attempting to quiesce the
319 * @see DEVICE_DETACH()
323 } DEFAULT null_quiesce;
326 * @brief This is called when the driver is asked to register handlers.
329 * To include this method in a device driver, use a line like this
330 * in the driver's method list:
333 * KOBJMETHOD(device_register, foo_register)
336 * @param dev the device for which handlers are being registered
338 * @retval NULL method not implemented
339 * @retval non-NULL a pointer to implementation specific static driver state
342 METHOD void * register {
344 } DEFAULT null_register;