efi_boottime.c

/*
 *  EFI application boot time services
 *
 *  Copyright (c) 2016 Alexander Graf
 *
 *  SPDX-License-Identifier:     GPL-2.0+
 */

#include <common.h>
#include <div64.h>
#include <efi_loader.h>
#include <environment.h>
#include <malloc.h>
#include <asm/global_data.h>
#include <libfdt_env.h>
#include <u-boot/crc.h>
#include <bootm.h>
#include <inttypes.h>
#include <watchdog.h>

DECLARE_GLOBAL_DATA_PTR;

/* Task priority level */
static efi_uintn_t efi_tpl = TPL_APPLICATION;

/* This list contains all the EFI objects our payload has access to */
LIST_HEAD(efi_obj_list);

/*
 * If we're running on nasty systems (32bit ARM booting into non-EFI Linux)
 * we need to do trickery with caches. Since we don't want to break the EFI
 * aware boot path, only apply hacks when loading exiting directly (breaking
 * direct Linux EFI booting along the way - oh well).
 */
static bool efi_is_direct_boot = true;

/*
 * EFI can pass arbitrary additional "tables" containing vendor specific
 * information to the payload. One such table is the FDT table which contains
 * a pointer to a flattened device tree blob.
 *
 * In most cases we want to pass an FDT to the payload, so reserve one slot of
 * config table space for it. The pointer gets populated by do_bootefi_exec().
 */
static struct efi_configuration_table __efi_runtime_data efi_conf_table[2];

#ifdef CONFIG_ARM
/*
 * The "gd" pointer lives in a register on ARM and AArch64 that we declare
 * fixed when compiling U-Boot. However, the payload does not know about that
 * restriction so we need to manually swap its and our view of that register on
 * EFI callback entry/exit.
 */
static volatile void *efi_gd, *app_gd;
#endif

static int entry_count;
static int nesting_level;

/* Called on every callback entry */
int __efi_entry_check(void)
{
	int ret = entry_count++ == 0;
#ifdef CONFIG_ARM
	assert(efi_gd);
	app_gd = gd;
	gd = efi_gd;
#endif
	return ret;
}

/* Called on every callback exit */
int __efi_exit_check(void)
{
	int ret = --entry_count == 0;
#ifdef CONFIG_ARM
	gd = app_gd;
#endif
	return ret;
}

/* Called from do_bootefi_exec() */
void efi_save_gd(void)
{
#ifdef CONFIG_ARM
	efi_gd = gd;
#endif
}

/*
 * Special case handler for error/abort that just forces things back
 * to u-boot world so we can dump out an abort msg, without any care
 * about returning back to UEFI world.
 */
void efi_restore_gd(void)
{
#ifdef CONFIG_ARM
	/* Only restore if we're already in EFI context */
	if (!efi_gd)
		return;
	gd = efi_gd;
#endif
}

/*
 * Two spaces per indent level, maxing out at 10.. which ought to be
 * enough for anyone ;-)
 */
static const char *indent_string(int level)
{
	const char *indent = "                    ";
	const int max = strlen(indent);
	level = min(max, level * 2);
	return &indent[max - level];
}

const char *__efi_nesting(void)
{
	return indent_string(nesting_level);
}

const char *__efi_nesting_inc(void)
{
	return indent_string(nesting_level++);
}

const char *__efi_nesting_dec(void)
{
	return indent_string(--nesting_level);
}

/*
 * Queue an EFI event.
 *
 * This function queues the notification function of the event for future
 * execution.
 *
 * The notification function is called if the task priority level of the
 * event is higher than the current task priority level.
 *
 * For the SignalEvent service see efi_signal_event_ext.
 *
 * @event	event to signal
 */
void efi_signal_event(struct efi_event *event)
{
	if (event->notify_function) {
		event->is_queued = true;
		/* Check TPL */
		if (efi_tpl >= event->notify_tpl)
			return;
		EFI_CALL_VOID(event->notify_function(event,
						     event->notify_context));
	}
	event->is_queued = false;
}

/*
 * Raise the task priority level.
 *
 * This function implements the RaiseTpl service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @new_tpl	new value of the task priority level
 * @return	old value of the task priority level
 */
static unsigned long EFIAPI efi_raise_tpl(efi_uintn_t new_tpl)
{
	efi_uintn_t old_tpl = efi_tpl;

	EFI_ENTRY("0x%zx", new_tpl);

	if (new_tpl < efi_tpl)
		debug("WARNING: new_tpl < current_tpl in %s\n", __func__);
	efi_tpl = new_tpl;
	if (efi_tpl > TPL_HIGH_LEVEL)
		efi_tpl = TPL_HIGH_LEVEL;

	EFI_EXIT(EFI_SUCCESS);
	return old_tpl;
}

/*
 * Lower the task priority level.
 *
 * This function implements the RestoreTpl service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @old_tpl	value of the task priority level to be restored
 */
static void EFIAPI efi_restore_tpl(efi_uintn_t old_tpl)
{
	EFI_ENTRY("0x%zx", old_tpl);

	if (old_tpl > efi_tpl)
		debug("WARNING: old_tpl > current_tpl in %s\n", __func__);
	efi_tpl = old_tpl;
	if (efi_tpl > TPL_HIGH_LEVEL)
		efi_tpl = TPL_HIGH_LEVEL;

	EFI_EXIT(EFI_SUCCESS);
}

/*
 * Allocate memory pages.
 *
 * This function implements the AllocatePages service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @type		type of allocation to be performed
 * @memory_type		usage type of the allocated memory
 * @pages		number of pages to be allocated
 * @memory		allocated memory
 * @return		status code
 */
static efi_status_t EFIAPI efi_allocate_pages_ext(int type, int memory_type,
						  efi_uintn_t pages,
						  uint64_t *memory)
{
	efi_status_t r;

	EFI_ENTRY("%d, %d, 0x%zx, %p", type, memory_type, pages, memory);
	r = efi_allocate_pages(type, memory_type, pages, memory);
	return EFI_EXIT(r);
}

/*
 * Free memory pages.
 *
 * This function implements the FreePages service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @memory	start of the memory area to be freed
 * @pages	number of pages to be freed
 * @return	status code
 */
static efi_status_t EFIAPI efi_free_pages_ext(uint64_t memory,
					      efi_uintn_t pages)
{
	efi_status_t r;

	EFI_ENTRY("%"PRIx64", 0x%zx", memory, pages);
	r = efi_free_pages(memory, pages);
	return EFI_EXIT(r);
}

/*
 * Get map describing memory usage.
 *
 * This function implements the GetMemoryMap service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @memory_map_size	on entry the size, in bytes, of the memory map buffer,
 *			on exit the size of the copied memory map
 * @memory_map		buffer to which the memory map is written
 * @map_key		key for the memory map
 * @descriptor_size	size of an individual memory descriptor
 * @descriptor_version	version number of the memory descriptor structure
 * @return		status code
 */
static efi_status_t EFIAPI efi_get_memory_map_ext(
					efi_uintn_t *memory_map_size,
					struct efi_mem_desc *memory_map,
					efi_uintn_t *map_key,
					efi_uintn_t *descriptor_size,
					uint32_t *descriptor_version)
{
	efi_status_t r;

	EFI_ENTRY("%p, %p, %p, %p, %p", memory_map_size, memory_map,
		  map_key, descriptor_size, descriptor_version);
	r = efi_get_memory_map(memory_map_size, memory_map, map_key,
			       descriptor_size, descriptor_version);
	return EFI_EXIT(r);
}

/*
 * Allocate memory from pool.
 *
 * This function implements the AllocatePool service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @pool_type	type of the pool from which memory is to be allocated
 * @size	number of bytes to be allocated
 * @buffer	allocated memory
 * @return	status code
 */
static efi_status_t EFIAPI efi_allocate_pool_ext(int pool_type,
						 efi_uintn_t size,
						 void **buffer)
{
	efi_status_t r;

	EFI_ENTRY("%d, %zd, %p", pool_type, size, buffer);
	r = efi_allocate_pool(pool_type, size, buffer);
	return EFI_EXIT(r);
}

/*
 * Free memory from pool.
 *
 * This function implements the FreePool service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @buffer	start of memory to be freed
 * @return	status code
 */
static efi_status_t EFIAPI efi_free_pool_ext(void *buffer)
{
	efi_status_t r;

	EFI_ENTRY("%p", buffer);
	r = efi_free_pool(buffer);
	return EFI_EXIT(r);
}

/*
 * Add a new object to the object list.
 *
 * The protocols list is initialized.
 * The object handle is set.
 *
 * @obj	object to be added
 */
void efi_add_handle(struct efi_object *obj)
{
	if (!obj)
		return;
	INIT_LIST_HEAD(&obj->protocols);
	obj->handle = obj;
	list_add_tail(&obj->link, &efi_obj_list);
}

/*
 * Create handle.
 *
 * @handle	new handle
 * @return	status code
 */
efi_status_t efi_create_handle(void **handle)
{
	struct efi_object *obj;
	efi_status_t r;

	r = efi_allocate_pool(EFI_ALLOCATE_ANY_PAGES,
			      sizeof(struct efi_object),
			      (void **)&obj);
	if (r != EFI_SUCCESS)
		return r;
	efi_add_handle(obj);
	*handle = obj->handle;
	return r;
}

/*
 * Our event capabilities are very limited. Only a small limited
 * number of events is allowed to coexist.
 */
static struct efi_event efi_events[16];

/*
 * Create an event.
 *
 * This function is used inside U-Boot code to create an event.
 *
 * For the API function implementing the CreateEvent service see
 * efi_create_event_ext.
 *
 * @type		type of the event to create
 * @notify_tpl		task priority level of the event
 * @notify_function	notification function of the event
 * @notify_context	pointer passed to the notification function
 * @event		created event
 * @return		status code
 */
efi_status_t efi_create_event(uint32_t type, efi_uintn_t notify_tpl,
			      void (EFIAPI *notify_function) (
					struct efi_event *event,
					void *context),
			      void *notify_context, struct efi_event **event)
{
	int i;

	if (event == NULL)
		return EFI_INVALID_PARAMETER;

	if ((type & EVT_NOTIFY_SIGNAL) && (type & EVT_NOTIFY_WAIT))
		return EFI_INVALID_PARAMETER;

	if ((type & (EVT_NOTIFY_SIGNAL|EVT_NOTIFY_WAIT)) &&
	    notify_function == NULL)
		return EFI_INVALID_PARAMETER;

	for (i = 0; i < ARRAY_SIZE(efi_events); ++i) {
		if (efi_events[i].type)
			continue;
		efi_events[i].type = type;
		efi_events[i].notify_tpl = notify_tpl;
		efi_events[i].notify_function = notify_function;
		efi_events[i].notify_context = notify_context;
		/* Disable timers on bootup */
		efi_events[i].trigger_next = -1ULL;
		efi_events[i].is_queued = false;
		efi_events[i].is_signaled = false;
		*event = &efi_events[i];
		return EFI_SUCCESS;
	}
	return EFI_OUT_OF_RESOURCES;
}

/*
 * Create an event.
 *
 * This function implements the CreateEvent service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @type		type of the event to create
 * @notify_tpl		task priority level of the event
 * @notify_function	notification function of the event
 * @notify_context	pointer passed to the notification function
 * @event		created event
 * @return		status code
 */
static efi_status_t EFIAPI efi_create_event_ext(
			uint32_t type, efi_uintn_t notify_tpl,
			void (EFIAPI *notify_function) (
					struct efi_event *event,
					void *context),
			void *notify_context, struct efi_event **event)
{
	EFI_ENTRY("%d, 0x%zx, %p, %p", type, notify_tpl, notify_function,
		  notify_context);
	return EFI_EXIT(efi_create_event(type, notify_tpl, notify_function,
					 notify_context, event));
}


/*
 * Check if a timer event has occurred or a queued notification function should
 * be called.
 *
 * Our timers have to work without interrupts, so we check whenever keyboard
 * input or disk accesses happen if enough time elapsed for them to fire.
 */
void efi_timer_check(void)
{
	int i;
	u64 now = timer_get_us();

	for (i = 0; i < ARRAY_SIZE(efi_events); ++i) {
		if (!efi_events[i].type)
			continue;
		if (efi_events[i].is_queued)
			efi_signal_event(&efi_events[i]);
		if (!(efi_events[i].type & EVT_TIMER) ||
		    now < efi_events[i].trigger_next)
			continue;
		switch (efi_events[i].trigger_type) {
		case EFI_TIMER_RELATIVE:
			efi_events[i].trigger_type = EFI_TIMER_STOP;
			break;
		case EFI_TIMER_PERIODIC:
			efi_events[i].trigger_next +=
				efi_events[i].trigger_time;
			break;
		default:
			continue;
		}
		efi_events[i].is_signaled = true;
		efi_signal_event(&efi_events[i]);
	}
	WATCHDOG_RESET();
}

/*
 * Set the trigger time for a timer event or stop the event.
 *
 * This is the function for internal usage in U-Boot. For the API function
 * implementing the SetTimer service see efi_set_timer_ext.
 *
 * @event		event for which the timer is set
 * @type		type of the timer
 * @trigger_time	trigger period in multiples of 100ns
 * @return		status code
 */
efi_status_t efi_set_timer(struct efi_event *event, enum efi_timer_delay type,
			   uint64_t trigger_time)
{
	int i;

	/*
	 * The parameter defines a multiple of 100ns.
	 * We use multiples of 1000ns. So divide by 10.
	 */
	do_div(trigger_time, 10);

	for (i = 0; i < ARRAY_SIZE(efi_events); ++i) {
		if (event != &efi_events[i])
			continue;

		if (!(event->type & EVT_TIMER))
			break;
		switch (type) {
		case EFI_TIMER_STOP:
			event->trigger_next = -1ULL;
			break;
		case EFI_TIMER_PERIODIC:
		case EFI_TIMER_RELATIVE:
			event->trigger_next =
				timer_get_us() + trigger_time;
			break;
		default:
			return EFI_INVALID_PARAMETER;
		}
		event->trigger_type = type;
		event->trigger_time = trigger_time;
		event->is_signaled = false;
		return EFI_SUCCESS;
	}
	return EFI_INVALID_PARAMETER;
}

/*
 * Set the trigger time for a timer event or stop the event.
 *
 * This function implements the SetTimer service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @event		event for which the timer is set
 * @type		type of the timer
 * @trigger_time	trigger period in multiples of 100ns
 * @return		status code
 */
static efi_status_t EFIAPI efi_set_timer_ext(struct efi_event *event,
					     enum efi_timer_delay type,
					     uint64_t trigger_time)
{
	EFI_ENTRY("%p, %d, %"PRIx64, event, type, trigger_time);
	return EFI_EXIT(efi_set_timer(event, type, trigger_time));
}

/*
 * Wait for events to be signaled.
 *
 * This function implements the WaitForEvent service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @num_events	number of events to be waited for
 * @events	events to be waited for
 * @index	index of the event that was signaled
 * @return	status code
 */
static efi_status_t EFIAPI efi_wait_for_event(efi_uintn_t num_events,
					      struct efi_event **event,
					      efi_uintn_t *index)
{
	int i, j;

	EFI_ENTRY("%zd, %p, %p", num_events, event, index);

	/* Check parameters */
	if (!num_events || !event)
		return EFI_EXIT(EFI_INVALID_PARAMETER);
	/* Check TPL */
	if (efi_tpl != TPL_APPLICATION)
		return EFI_EXIT(EFI_UNSUPPORTED);
	for (i = 0; i < num_events; ++i) {
		for (j = 0; j < ARRAY_SIZE(efi_events); ++j) {
			if (event[i] == &efi_events[j])
				goto known_event;
		}
		return EFI_EXIT(EFI_INVALID_PARAMETER);
known_event:
		if (!event[i]->type || event[i]->type & EVT_NOTIFY_SIGNAL)
			return EFI_EXIT(EFI_INVALID_PARAMETER);
		if (!event[i]->is_signaled)
			efi_signal_event(event[i]);
	}

	/* Wait for signal */
	for (;;) {
		for (i = 0; i < num_events; ++i) {
			if (event[i]->is_signaled)
				goto out;
		}
		/* Allow events to occur. */
		efi_timer_check();
	}

out:
	/*
	 * Reset the signal which is passed to the caller to allow periodic
	 * events to occur.
	 */
	event[i]->is_signaled = false;
	if (index)
		*index = i;

	return EFI_EXIT(EFI_SUCCESS);
}

/*
 * Signal an EFI event.
 *
 * This function implements the SignalEvent service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * This functions sets the signaled state of the event and queues the
 * notification function for execution.
 *
 * @event	event to signal
 * @return	status code
 */
static efi_status_t EFIAPI efi_signal_event_ext(struct efi_event *event)
{
	int i;

	EFI_ENTRY("%p", event);
	for (i = 0; i < ARRAY_SIZE(efi_events); ++i) {
		if (event != &efi_events[i])
			continue;
		if (event->is_signaled)
			break;
		event->is_signaled = true;
		if (event->type & EVT_NOTIFY_SIGNAL)
			efi_signal_event(event);
		break;
	}
	return EFI_EXIT(EFI_SUCCESS);
}

/*
 * Close an EFI event.
 *
 * This function implements the CloseEvent service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @event	event to close
 * @return	status code
 */
static efi_status_t EFIAPI efi_close_event(struct efi_event *event)
{
	int i;

	EFI_ENTRY("%p", event);
	for (i = 0; i < ARRAY_SIZE(efi_events); ++i) {
		if (event == &efi_events[i]) {
			event->type = 0;
			event->trigger_next = -1ULL;
			event->is_queued = false;
			event->is_signaled = false;
			return EFI_EXIT(EFI_SUCCESS);
		}
	}
	return EFI_EXIT(EFI_INVALID_PARAMETER);
}

/*
 * Check if an event is signaled.
 *
 * This function implements the CheckEvent service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * If an event is not signaled yet the notification function is queued.
 *
 * @event	event to check
 * @return	status code
 */
static efi_status_t EFIAPI efi_check_event(struct efi_event *event)
{
	int i;

	EFI_ENTRY("%p", event);
	efi_timer_check();
	for (i = 0; i < ARRAY_SIZE(efi_events); ++i) {
		if (event != &efi_events[i])
			continue;
		if (!event->type || event->type & EVT_NOTIFY_SIGNAL)
			break;
		if (!event->is_signaled)
			efi_signal_event(event);
		if (event->is_signaled)
			return EFI_EXIT(EFI_SUCCESS);
		return EFI_EXIT(EFI_NOT_READY);
	}
	return EFI_EXIT(EFI_INVALID_PARAMETER);
}

/*
 * Find the internal EFI object for a handle.
 *
 * @handle	handle to find
 * @return	EFI object
 */
struct efi_object *efi_search_obj(const void *handle)
{
	struct efi_object *efiobj;

	list_for_each_entry(efiobj, &efi_obj_list, link) {
		if (efiobj->handle == handle)
			return efiobj;
	}

	return NULL;
}

/*
 * Find a protocol on a handle.
 *
 * @handle		handle
 * @protocol_guid	GUID of the protocol
 * @handler		reference to the protocol
 * @return		status code
 */
efi_status_t efi_search_protocol(const void *handle,
				 const efi_guid_t *protocol_guid,
				 struct efi_handler **handler)
{
	struct efi_object *efiobj;
	struct list_head *lhandle;

	if (!handle || !protocol_guid)
		return EFI_INVALID_PARAMETER;
	efiobj = efi_search_obj(handle);
	if (!efiobj)
		return EFI_INVALID_PARAMETER;
	list_for_each(lhandle, &efiobj->protocols) {
		struct efi_handler *protocol;

		protocol = list_entry(lhandle, struct efi_handler, link);
		if (!guidcmp(protocol->guid, protocol_guid)) {
			if (handler)
				*handler = protocol;
			return EFI_SUCCESS;
		}
	}
	return EFI_NOT_FOUND;
}

/*
 * Install new protocol on a handle.
 *
 * @handle			handle on which the protocol shall be installed
 * @protocol			GUID of the protocol to be installed
 * @protocol_interface		interface of the protocol implementation
 * @return			status code
 */
efi_status_t efi_add_protocol(const void *handle, const efi_guid_t *protocol,
			      void *protocol_interface)
{
	struct efi_object *efiobj;
	struct efi_handler *handler;
	efi_status_t ret;

	efiobj = efi_search_obj(handle);
	if (!efiobj)
		return EFI_INVALID_PARAMETER;
	ret = efi_search_protocol(handle, protocol, NULL);
	if (ret != EFI_NOT_FOUND)
		return EFI_INVALID_PARAMETER;
	handler = calloc(1, sizeof(struct efi_handler));
	if (!handler)
		return EFI_OUT_OF_RESOURCES;
	handler->guid = protocol;
	handler->protocol_interface = protocol_interface;
	list_add_tail(&handler->link, &efiobj->protocols);
	return EFI_SUCCESS;
}

/*
 * Delete protocol from a handle.
 *
 * @handle			handle from which the protocol shall be deleted
 * @protocol			GUID of the protocol to be deleted
 * @protocol_interface		interface of the protocol implementation
 * @return			status code
 */
efi_status_t efi_remove_protocol(const void *handle, const efi_guid_t *protocol,
				 void *protocol_interface)
{
	struct efi_handler *handler;
	efi_status_t ret;

	ret = efi_search_protocol(handle, protocol, &handler);
	if (ret != EFI_SUCCESS)
		return ret;
	if (guidcmp(handler->guid, protocol))
		return EFI_INVALID_PARAMETER;
	list_del(&handler->link);
	free(handler);
	return EFI_SUCCESS;
}

/*
 * Delete all protocols from a handle.
 *
 * @handle			handle from which the protocols shall be deleted
 * @return			status code
 */
efi_status_t efi_remove_all_protocols(const void *handle)
{
	struct efi_object *efiobj;
	struct list_head *lhandle;
	struct list_head *pos;

	efiobj = efi_search_obj(handle);
	if (!efiobj)
		return EFI_INVALID_PARAMETER;
	list_for_each_safe(lhandle, pos, &efiobj->protocols) {
		struct efi_handler *protocol;
		efi_status_t ret;

		protocol = list_entry(lhandle, struct efi_handler, link);

		ret = efi_remove_protocol(handle, protocol->guid,
					  protocol->protocol_interface);
		if (ret != EFI_SUCCESS)
			return ret;
	}
	return EFI_SUCCESS;
}

/*
 * Install protocol interface.
 *
 * This function implements the InstallProtocolInterface service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @handle			handle on which the protocol shall be installed
 * @protocol			GUID of the protocol to be installed
 * @protocol_interface_type	type of the interface to be installed,
 *				always EFI_NATIVE_INTERFACE
 * @protocol_interface		interface of the protocol implementation
 * @return			status code
 */
static efi_status_t EFIAPI efi_install_protocol_interface(
			void **handle, const efi_guid_t *protocol,
			int protocol_interface_type, void *protocol_interface)
{
	efi_status_t r;

	EFI_ENTRY("%p, %pUl, %d, %p", handle, protocol, protocol_interface_type,
		  protocol_interface);

	if (!handle || !protocol ||
	    protocol_interface_type != EFI_NATIVE_INTERFACE) {
		r = EFI_INVALID_PARAMETER;
		goto out;
	}

	/* Create new handle if requested. */
	if (!*handle) {
		r = efi_create_handle(handle);
		if (r != EFI_SUCCESS)
			goto out;
		debug("%sEFI: new handle %p\n", indent_string(nesting_level),
		      *handle);
	} else {
		debug("%sEFI: handle %p\n", indent_string(nesting_level),
		      *handle);
	}
	/* Add new protocol */
	r = efi_add_protocol(*handle, protocol, protocol_interface);
out:
	return EFI_EXIT(r);
}

/*
 * Reinstall protocol interface.
 *
 * This function implements the ReinstallProtocolInterface service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @handle			handle on which the protocol shall be
 *				reinstalled
 * @protocol			GUID of the protocol to be installed
 * @old_interface		interface to be removed
 * @new_interface		interface to be installed
 * @return			status code
 */
static efi_status_t EFIAPI efi_reinstall_protocol_interface(void *handle,
			const efi_guid_t *protocol, void *old_interface,
			void *new_interface)
{
	EFI_ENTRY("%p, %pUl, %p, %p", handle, protocol, old_interface,
		  new_interface);
	return EFI_EXIT(EFI_ACCESS_DENIED);
}

/*
 * Uninstall protocol interface.
 *
 * This function implements the UninstallProtocolInterface service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @handle			handle from which the protocol shall be removed
 * @protocol			GUID of the protocol to be removed
 * @protocol_interface		interface to be removed
 * @return			status code
 */
static efi_status_t EFIAPI efi_uninstall_protocol_interface(
				void *handle, const efi_guid_t *protocol,
				void *protocol_interface)
{
	struct efi_handler *handler;
	efi_status_t r;

	EFI_ENTRY("%p, %pUl, %p", handle, protocol, protocol_interface);

	if (!handle || !protocol) {
		r = EFI_INVALID_PARAMETER;
		goto out;
	}

	/* Find the protocol on the handle */
	r = efi_search_protocol(handle, protocol, &handler);
	if (r != EFI_SUCCESS)
		goto out;
	if (handler->protocol_interface) {
		/* TODO disconnect controllers */
		r =  EFI_ACCESS_DENIED;
	} else {
		r = efi_remove_protocol(handle, protocol, protocol_interface);
	}
out:
	return EFI_EXIT(r);
}

/*
 * Register an event for notification when a protocol is installed.
 *
 * This function implements the RegisterProtocolNotify service.
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @protocol		GUID of the protocol whose installation shall be
 *			notified
 * @event		event to be signaled upon installation of the protocol
 * @registration	key for retrieving the registration information
 * @return		status code
 */
static efi_status_t EFIAPI efi_register_protocol_notify(
						const efi_guid_t *protocol,
						struct efi_event *event,
						void **registration)
{
	EFI_ENTRY("%pUl, %p, %p", protocol, event, registration);
	return EFI_EXIT(EFI_OUT_OF_RESOURCES);
}

/*
 * Determine if an EFI handle implements a protocol.
 *
 * See the documentation of the LocateHandle service in the UEFI specification.
 *
 * @search_type		selection criterion
 * @protocol		GUID of the protocol
 * @search_key		registration key
 * @efiobj		handle
 * @return		0 if the handle implements the protocol
 */
static int efi_search(enum efi_locate_search_type search_type,
		      const efi_guid_t *protocol, void *search_key,
		      struct efi_object *efiobj)
{
	efi_status_t ret;

	switch (search_type) {
	case ALL_HANDLES:
		return 0;
	case BY_REGISTER_NOTIFY:
		/* TODO: RegisterProtocolNotify is not implemented yet */
		return -1;
	case BY_PROTOCOL:
		ret = efi_search_protocol(efiobj->handle, protocol, NULL);
		return (ret != EFI_SUCCESS);
	default:
		/* Invalid search type */
		return -1;
	}
}

/*
 * Locate handles implementing a protocol.