FreeBSD-5.3/sys/kern/device_if.m
#
# Copyright (c) 1998-2004 Doug Rabson
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# $FreeBSD: src/sys/kern/device_if.m,v 1.10 2004/08/12 17:26:22 imp Exp $
#
#include <sys/bus.h>
/**
* @defgroup DEVICE device - KObj methods for all device drivers
* @brief A basic set of methods required for all device drivers.
*
* The device interface is used to match devices to drivers during
* autoconfiguration and provides methods to allow drivers to handle
* system-wide events such as suspend, resume or shutdown.
* @{
*/
INTERFACE device;
#
# Default implementations of some methods.
#
CODE {
static int null_shutdown(device_t dev)
{
return 0;
}
static int null_suspend(device_t dev)
{
return 0;
}
static int null_resume(device_t dev)
{
return 0;
}
};
/**
* @brief Probe to see if a device matches a driver.
*
* Users should not call this method directly. Normally, this
* is called via device_probe_and_attach() to select a driver
* calling the DEVICE_PROBE() of all candidate drivers and attach
* the winning driver (if any) to the device.
*
* This function is used to match devices to device drivers.
* Typically, the driver will examine the device to see if
* it is suitable for this driver. This might include checking
* the values of various device instance variables or reading
* hardware registers.
*
* In some cases, there may be more than one driver available
* which can be used for a device (for instance there might
* be a generic driver which works for a set of many types of
* device and a more specific driver which works for a subset
* of devices). Because of this, a driver should not assume
* that it will be the driver that attaches to the device even
* if it returns a success status from DEVICE_PROBE(). In particular,
* a driver must free any resources which it allocated during
* the probe before returning. The return value of DEVICE_PROBE()
* is used to elect which driver is used - the driver which returns
* the largest non-error value wins the election and attaches to
* the device.
*
* If a driver matches the hardware, it should set the device
* description string using device_set_desc() or
* device_set_desc_copy(). This string is
* used to generate an informative message when DEVICE_ATTACH()
* is called.
*
* As a special case, if a driver returns zero, the driver election
* is cut short and that driver will attach to the device
* immediately.
*
* For example, a probe method for a pci device driver might look
* like this:
*
* @code
* int foo_probe(device_t dev)
* {
* if (pci_get_vendor(dev) == FOOVENDOR &&
* pci_get_device(dev) == FOODEVICE) {
* device_set_desc(dev, "Foo device");
* return (0);
* }
* return (ENXIO);
* }
* @endcode
*
* To include this method in a device driver, use a line like this
* in the driver's method list:
*
* @code
* KOBJMETHOD(device_probe, foo_probe)
* @endcode
*
* @param dev the device to probe
*
* @retval 0 if the driver strongly matches this device
* @retval negative if the driver can match this device - the
* least negative value is used to select the
* driver
* @retval ENXIO if the driver does not match the device
* @retval positive if some kind of error was detected during
* the probe, a regular unix error code should
* be returned to indicate the type of error
* @see DEVICE_ATTACH(), pci_get_vendor(), pci_get_device()
*/
METHOD int probe {
device_t dev;
};
/**
* @brief Allow a device driver to detect devices not otherwise enumerated.
*
* The DEVICE_IDENTIFY() method is used by some drivers (e.g. the ISA
* bus driver) to help populate the bus device with a useful set of
* child devices, normally by calling the BUS_ADD_CHILD() method of
* the parent device. For instance, the ISA bus driver uses several
* special drivers, including the isahint driver and the pnp driver to
* create child devices based on configuration hints and PnP bus
* probes respectively.
*
* Many bus drivers which support true plug-and-play do not need to
* use this method at all since child devices can be discovered
* automatically without help from child drivers.
*
* To include this method in a device driver, use a line like this
* in the driver's method list:
*
* @code
* KOBJMETHOD(device_identify, foo_identify)
* @endcode
*
* @param driver the driver whose identify method is being called
* @param parent the parent device to use when adding new children
*/
STATICMETHOD void identify {
driver_t *driver;
device_t parent;
};
/**
* @brief Attach a device to a device driver
*
* Normally only called via device_probe_and_attach(), this is called
* when a driver has succeeded in probing against a device.
* This method should initialise the hardware and allocate other
* system resources (e.g. devfs entries) as required.
*
* To include this method in a device driver, use a line like this
* in the driver's method list:
*
* @code
* KOBJMETHOD(device_attach, foo_attach)
* @endcode
*
* @param dev the device to probe
*
* @retval 0 success
* @retval non-zero if some kind of error was detected during
* the attach, a regular unix error code should
* be returned to indicate the type of error
* @see DEVICE_PROBE()
*/
METHOD int attach {
device_t dev;
};
/**
* @brief Detach a driver from a device.
*
* This can be called if the user is replacing the
* driver software or if a device is about to be physically removed
* from the system (e.g. for removable hardware such as USB or PCCARD).
*
* To include this method in a device driver, use a line like this
* in the driver's method list:
*
* @code
* KOBJMETHOD(device_detach, foo_detach)
* @endcode
*
* @param dev the device to detach
*
* @retval 0 success
* @retval non-zero the detach could not be performed, e.g. if the
* driver does not support detaching.
*
* @see DEVICE_ATTACH()
*/
METHOD int detach {
device_t dev;
};
/**
* @brief Called during system shutdown.
*
* This method allows drivers to detect when the system is being shut down.
* Some drivers need to use this to place their hardware in a consistent
* state before rebooting the computer.
*
* To include this method in a device driver, use a line like this
* in the driver's method list:
*
* @code
* KOBJMETHOD(device_shutdown, foo_shutdown)
* @endcode
*/
METHOD int shutdown {
device_t dev;
} DEFAULT null_shutdown;
/**
* @brief This is called by the power-management subsystem when a
* suspend has been requested by the user or by some automatic
* mechanism.
*
* This gives drivers a chance to veto the suspend or save their
* configuration before power is removed.
*
* To include this method in a device driver, use a line like this in
* the driver's method list:
*
* @code
* KOBJMETHOD(device_suspend, foo_suspend)
* @endcode
*
* @param dev the device being suspended
*
* @retval 0 success
* @retval non-zero an error occurred while attempting to prepare the
* device for suspension
*
* @see DEVICE_RESUME()
*/
METHOD int suspend {
device_t dev;
} DEFAULT null_suspend;
/**
* @brief This is called when the system resumes after a suspend.
*
* To include this method in a device driver, use a line like this
* in the driver's method list:
*
* @code
* KOBJMETHOD(device_resume, foo_resume)
* @endcode
*
* @param dev the device being resumed
*
* @retval 0 success
* @retval non-zero an error occurred while attempting to restore the
* device from suspension
*
* @see DEVICE_SUSPEND()
*/
METHOD int resume {
device_t dev;
} DEFAULT null_resume;