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Few changes...

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- add a lot of comments
- only lookup symbols as needed to keep the paths thru the function
  as small as possible
- add comments about the problems we have and give some idea about what
  needs fixing and what then needs removal from this file
- show the hooks pointer being passed to detect NULL pointers more
  quickly


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@272 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
David Reid 2002-07-17 12:10:38 +00:00
parent fa10e022b1
commit d2c1ff9a7d
1 changed files with 62 additions and 17 deletions
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79
src/kernel/drivers/dev.c
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@ -71,7 +71,7 @@ image_id dev_load_dev_module(const char *name, const char *dirpath)
{
image_id id;
char path[SYS_MAX_PATH_LEN];
// uint32 * api_version;
uint32 *api_version;
status_t (*init_hardware)(void);
status_t (*init_driver)(void);
status_t (*uninit_driver)(void);
@ -82,15 +82,23 @@ image_id dev_load_dev_module(const char *name, const char *dirpath)
sprintf(path, "%s/%s", dirpath, name);
/* Load the module, return error if unable */
id = elf_load_kspace(path, "");
if(id < 0)
return id;
// get device driver API symbols
// api_version = (uint32 *) elf_lookup_symbol(id, "api_version");
init_hardware = (void *) elf_lookup_symbol(id, "init_hardware");
init_driver = (void *) elf_lookup_symbol(id, "init_driver");
uninit_driver = (void *) elf_lookup_symbol(id, "uninit_driver");
/* Don't get all the symbols we will require initially. Just get the
* ones we need to check we have a valid module.
* elf_find_symbol is an extra call and so we don't make it more often
* than we have to.
*/
/* For a valid device driver we MUST have the publish_devices and
* find_device functions available
*/
/* XXX - very few drivers have the api_version symbol defined yet.
* Add api_version to the rest of the drivers!
*/
api_version = (uint32 *) elf_lookup_symbol(id, "api_version");
publish_devices = (void *) elf_lookup_symbol(id, "publish_devices");
find_device = (void *) elf_lookup_symbol(id, "find_device");
@ -100,44 +108,81 @@ image_id dev_load_dev_module(const char *name, const char *dirpath)
goto error;
}
/* Next, do we have an init_hardware function? If we do run it and
* if it fails simply fall through to the exit...
*/
init_hardware = (void *) elf_lookup_symbol(id, "init_hardware");
if (init_hardware && init_hardware() != 0) {
dprintf("DEV: %s: init_hardware failed :(\n", name);
id = ENXIO;
goto error;
}
/* OK, so we now have what appears to be a valid module that has
* completed init_hardware and thus thinks it should be used.
* XXX - this is bogus!
* XXX - the driver init routines should be called by devfs and
* only when the driver is first needed. However, that level
* level of support is not yet in devfs, so we have a hack
* here that calls the init_driver function at this point.
* As a result we will check to see if we actually manage to
* publish the device, and if we do we will keep the module
* loaded.
* XXX - remove this when devfs is fixed!
*/
init_driver = (void *) elf_lookup_symbol(id, "init_driver");
if (init_driver && init_driver() != 0) {
dprintf("DEV: %s: init_driver failed :(\n", name);
id = ENXIO;
goto error;
}
// dprintf("DEV: Well alright - %s init'd OK!\n", name);
}
/* Should really cycle through these... */
devfs_paths = publish_devices();
/* Start of with the keep_loaded as false. If we have a successful
* call to devfs_publish_device we will set this to true.
*/
keep_loaded = false;
devfs_paths = publish_devices();
for (; *devfs_paths; devfs_paths++) {
device_hooks * hooks;
hooks = find_device(*devfs_paths);
dprintf("DEV: %s: publishing %s\n", name, *devfs_paths);
device_hooks *hooks = find_device(*devfs_paths);
if (hooks) {
dprintf("DEV: %s: publishing %s with hooks %p\n",
name, *devfs_paths, hooks);
if (devfs_publish_device(*devfs_paths, NULL, hooks) == 0)
keep_loaded = true;
}
}
/* If we've managed to publish at least one of the device entry
* points that the driver wished us to then we MUST keep the driver in
* memory or the pointer that devfs has will become invalid.
* XXX - This is bogus, see above
*/
if (keep_loaded)
// okay, keep this driver image in memory, as he publish *something*
return id;
// no need to keep this driver image loaded...
/* If the fucntion gets here then the following has happenned...
* - the driver has been loaded
* - it has appeared valid
* - init_hardware has returned saying it should be used
* - init_driver has been run OK
* - devfs_publish_devices has for some reason failed.
* The error value we're about to return is 0, which probably
* means we're loosing error information here :(
* XXX - what error code should we be returning
*
* However, before we unload ourselves we will try to find and run
* the uninit routine.
*/
uninit_driver = (void *) elf_lookup_symbol(id, "uninit_driver");
if (uninit_driver)
uninit_driver();
id = 0;
error:
/* If we've gotten here then the driver will be unloaded and an
* error code returned.
*/
elf_unload_kspace(path);
return id;
}