281 lines
8.9 KiB
C
281 lines
8.9 KiB
C
#ifndef DEV_H
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#define DEV_H
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#include "stdint.h"
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#include "string.h"
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#include <gpxe/buffer.h>
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#include "dhcp.h" /* for dhcp_dev_id */
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#include <gpxe/tables.h>
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#include <assert.h>
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/*
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* Forward declarations
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*
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*/
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struct type_dev;
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struct type_driver;
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struct bus_driver;
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struct bus_dev;
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struct device_driver;
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/*
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* When looking at the following data structures, mentally substitute
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* "<bus>_" in place of "bus_" and everything will become clear.
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* "struct bus_location" becomes "struct <bus>_location", which means
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* "the location of a device on a <bus> bus", where <bus> is a
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* particular type of bus such as "pci" or "isapnp".
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*
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*/
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/*
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* A physical device location on a bus.
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*
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*/
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#define BUS_LOC_SIZE 8
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struct bus_loc {
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char bytes[BUS_LOC_SIZE];
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};
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/*
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* A structure fully describing a physical device on a bus.
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*
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*/
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#define BUS_DEV_SIZE 32
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struct bus_dev {
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char bytes[BUS_DEV_SIZE];
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};
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/*
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* Individual buses will have different sizes for their <bus>_location
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* and <bus>_device structures. We need to be able to allocate static
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* storage that's large enough to contain these structures for any
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* bus type that's being used in the current binary.
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*
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* We can't just create a union of all the various types, because some
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* may be architecture-dependent (and some are even embedded in
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* specific drivers, e.g. 3c509), so this would quickly get messy.
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*
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* We could use the magic of common symbols. Each bus could declare a
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* common symbol with the name "_bus_dev" of the correct size; this
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* is easily done using code like
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* struct pci_device _bus_dev;
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* The linker would then use the largest size of the "_bus_dev" symbol
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* in any included object, thus giving us a single _bus_dev symbol of
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* *exactly* the required size. However, there's no way to extract
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* the size of this symbol, either directly as a linker symbol
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* ("_bus_dev_size = SIZEOF(_bus_dev)"; the linker language just
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* doesn't provide this construct) or via any linker trickery I can
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* think of (such as creating a special common symbol section just for
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* this symbol then using SIZE(section) to read the size of the
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* section; ld recognises only a single common symbol section called
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* "COMMON").
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*
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* Since there's no way to get the size of the symbol, this
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* effectively limits us to just one instance of the symbol. This is
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* all very well for the simple case of "just boot from any single
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* device you can", but becomes limiting when you want to do things
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* like introducing PCMCIA buses (which must instantiate other devices
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* such as PCMCIA controllers).
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*
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* So, we declare the maximum sizes of these constructions to be
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* compile-time constants. Each individual bus driver should define
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* its own struct <bus>_location and struct <bus>_device however it
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* likes, and can freely cast pointers from struct bus_loc to
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* struct <bus>_location (and similarly for bus_dev). To guard
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* against bounding errors, each bus driver *MUST* use the macros
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* BUS_LOC_CHECK() and BUS_DEV_CHECK(), as in:
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*
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* BUS_LOC_CHECK ( struct pci_location );
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* BUS_DEV_CHECK ( struct pci_device );
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*
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* These macros will generate a link-time error if the size of the
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* <bus> structure exceeds the declared maximum size.
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*
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* The macros will generate no binary object code, but must be placed
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* inside a function (in order to generate syntactically valid C).
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* The easiest wy to do this is to place them in the
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* <bus>_next_location() function.
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*
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* If anyone can think of a better way of doing this that avoids *ALL*
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* of the problems described above, please implement it!
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*
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*/
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#define BUS_LOC_CHECK(datatype) \
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linker_assert( ( sizeof (datatype) <= sizeof (struct bus_loc) ), \
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__BUS_LOC_SIZE_is_too_small__see_dev_h )
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#define BUS_DEV_CHECK(datatype) \
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linker_assert( ( sizeof (datatype) <= sizeof (struct bus_dev) ), \
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__BUS_DEV_SIZE_is_too_small__see_dev_h )
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/*
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* Bus-level operations.
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*
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* int next_location ( struct bus_loc * bus_loc )
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*
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* Increment bus_loc to point to the next possible device on
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* the bus (e.g. the next PCI busdevfn, or the next ISAPnP CSN).
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* If there are no more valid locations, return 0 and leave
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* struct bus_loc zeroed, otherwise return true.
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*
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* int fill_device ( struct bus_dev *bus_dev,
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* struct bus_loc *bus_loc )
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*
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* Fill out a bus_dev structure with the parameters for the
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* device at bus_loc. (For example, fill in the PCI vendor
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* and device IDs). Return true if there is a device physically
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* present at this location, otherwise 0.
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*
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* int check_driver ( struct bus_dev *bus_dev,
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* struct device_driver *device_driver )
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*
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* Test whether or not the specified driver is capable of driving
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* the specified device by, for example, comparing the device's
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* PCI IDs against the list of PCI IDs claimed by the driver.
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*
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* char * describe ( struct bus_dev *bus_dev )
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*
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* Return a text string describing the bus device bus_dev
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* (e.g. "PCI 00:01.2")
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*
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* char * name ( struct bus_dev *bus_dev )
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*
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* Return a text string describing the bus device bus_dev
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* (e.g. "dfe538")
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*
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*/
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struct bus_driver {
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const char *name;
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int ( *next_location ) ( struct bus_loc *bus_loc );
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int ( *fill_device ) ( struct bus_dev *bus_dev,
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struct bus_loc *bus_loc );
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int ( *check_driver ) ( struct bus_dev *bus_dev,
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struct device_driver *device_driver );
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char * ( *describe_device ) ( struct bus_dev *bus_dev );
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const char * ( *name_device ) ( struct bus_dev *bus_dev );
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};
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#define __bus_driver __table ( struct bus_driver, bus_driver, 01 )
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/*
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* A structure fully describing the bus-independent parts of a
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* particular type (e.g. nic or disk) of device.
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*
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* Unlike struct bus_dev, e can limit ourselves to having no more than
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* one instance of this data structure. We therefore place an
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* instance in each type driver file (e.g. nic.c), and simply use a
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* pointer to the struct type_dev in the struct dev.
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*
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*/
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struct type_dev;
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/*
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* A type driver (e.g. nic, disk)
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*
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*/
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struct type_driver {
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char *name;
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struct type_dev *type_dev; /* single instance */
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char * ( * describe_device ) ( struct type_dev *type_dev );
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int ( * configure ) ( struct type_dev *type_dev );
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int ( * load ) ( struct type_dev *type_dev, struct buffer *buffer );
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};
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#define __type_driver __table ( struct type_driver, type_driver, 01 )
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/*
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* A driver for a device.
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*
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*/
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struct device_driver {
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const char *name;
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struct type_driver *type_driver;
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struct bus_driver *bus_driver;
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struct bus_driver_info *bus_driver_info;
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int ( * probe ) ( struct type_dev *type_dev,
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struct bus_dev *bus_dev );
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void ( * disable ) ( struct type_dev *type_dev,
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struct bus_dev *bus_dev );
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};
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#define __device_driver __table ( struct device_driver, device_driver, 01 )
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#if 0
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#define DRIVER(_name,_type_driver,_bus_driver,_bus_info, \
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_probe,_disable) \
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struct device_driver device_ ## _bus_info __device_driver = { \
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.name = _name, \
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.type_driver = &_type_driver, \
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.bus_driver = &_bus_driver, \
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.bus_driver_info = ( struct bus_driver_info * ) &_bus_info, \
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.probe = ( int (*) () ) _probe, \
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.disable = ( void (*) () ) _disable, \
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};
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#endif
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#define DRIVER(a,b,c,d,e,f)
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/*
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* A bootable device, comprising a physical device on a bus, a driver
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* for that device, and a type device
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*
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*/
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struct dev {
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struct bus_driver *bus_driver;
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struct bus_loc bus_loc;
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struct bus_dev bus_dev;
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struct device_driver *device_driver;
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struct type_driver *type_driver;
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struct type_dev *type_dev;
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};
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/* The current boot device */
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extern struct dev dev;
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/*
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* Functions in dev.c
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*
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*/
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extern void print_drivers ( void );
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extern int find_any ( struct bus_driver **bus_driver, struct bus_loc *bus_loc,
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struct bus_dev *bus_dev, signed int skip );
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extern int find_by_device ( struct device_driver **device_driver,
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struct bus_driver *bus_driver,
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struct bus_dev *bus_dev,
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signed int skip );
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extern int find_by_driver ( struct bus_loc *bus_loc, struct bus_dev *bus_dev,
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struct device_driver *device_driver,
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signed int skip );
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extern int find_any_with_driver ( struct dev *dev, signed int skip );
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/*
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* Functions inlined to save space
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*
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*/
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/* Probe a device */
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static inline int probe ( struct dev *dev ) {
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return dev->device_driver->probe ( dev->type_dev, &dev->bus_dev );
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}
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/* Disable a device */
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static inline void disable ( struct dev *dev ) {
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dev->device_driver->disable ( dev->type_dev, &dev->bus_dev );
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}
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/* Set the default boot device */
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static inline void select_device ( struct dev *dev,
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struct bus_driver *bus_driver,
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struct bus_loc *bus_loc ) {
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dev->bus_driver = bus_driver;
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memcpy ( &dev->bus_loc, bus_loc, sizeof ( dev->bus_loc ) );
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}
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/* Configure a device */
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static inline int configure ( struct dev *dev ) {
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return dev->type_driver->configure ( dev->type_dev );
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}
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/* Boot from a device */
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static inline int load ( struct dev *dev, struct buffer *buffer ) {
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return dev->type_driver->load ( dev->type_dev, buffer );
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}
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#endif /* DEV_H */
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