libsel4utils/src/irq_server/irq_server.c - 3p/sel4/sel4_libs - Git at Google

 /*
  * Copyright 2019, Data61
  * Commonwealth Scientific and Industrial Research Organisation (CSIRO)
  * ABN 41 687 119 230.
  *
  * This software may be distributed and modified according to the terms of
  * the BSD 2-Clause license. Note that NO WARRANTY is provided.
  * See "LICENSE_BSD2.txt" for details.
  *
  * @TAG(DATA61_BSD)
  */

 #include <sel4utils/irq_server.h>

 #include <errno.h>
 #include <simple/simple.h>
 #include <sel4utils/thread.h>
 #include <vka/capops.h>
 #include <stdlib.h>
 #include <string.h>
 #include <platsupport/irq.h>
 #include <sel4platsupport/irq.h>

 #include <utils/util.h>

 #define IRQ_SERVER_MESSAGE_LENGTH 2

 typedef struct irq_server_node {
     seL4_CPtr ntfn;
     size_t max_irqs_bound;
     size_t num_irqs_bound;
 } irq_server_node_t;

 typedef struct irq_server_thread irq_server_thread_t;

 /* This is also forwarded declared as we have a pointer to a struct of the same type */
 struct irq_server_thread {
     thread_id_t thread_id;
     irq_server_node_t *node;
     seL4_CPtr delivery_ep;
     seL4_Word label;
     sel4utils_thread_t thread;
     /* Linked list chain of threads */
     irq_server_thread_t *next;
 };

 /* This is forward-declared in the header file, hence no typedef */
 struct irq_server {
     seL4_CPtr delivery_ep;
     seL4_Word label;
     vka_object_t reply;
     irq_server_thread_t *server_threads;
     size_t num_irqs;
     size_t max_irqs;

     /* New thread parameters */
     seL4_Word priority;
     seL4_CPtr cspace;

     /* Allocation interfaces */
     vka_t *vka;
     vspace_t *vspace;
     simple_t *simple;
     ps_irq_ops_t irq_ops;
     ps_malloc_ops_t *malloc_ops;
 };

 /* Executes the registered callback for incoming IRQs */
 static void irq_server_node_handle_irq(irq_server_thread_t *thread_info,
                                        ps_irq_ops_t *irq_ops, seL4_Word badge)
 {
     ntfn_id_t target_ntfn = thread_info->thread_id;
     int error = sel4platsupport_irq_handle(irq_ops, target_ntfn, badge);
     if (error) {
         if (error == -EINVAL) {
             ZF_LOGE("Passed in a wrong ntfn_id to the IRQ interface! Something is very wrong with the IRQ server");
         } else {
             ZF_LOGW("Failed to handle an IRQ");
         }
     }
 }

 /* Registers an IRQ callback and enables the IRQ */
 static irq_id_t irq_server_node_register_irq(irq_server_node_t *node, ps_irq_t irq, irq_callback_fn_t callback,
                                              void *callback_data, ntfn_id_t ntfn_id, irq_server_t *irq_server)
 {
     int error;

     irq_id_t irq_id = ps_irq_register(&(irq_server->irq_ops), irq, callback, callback_data);
     if (irq_id < 0) {
         ZF_LOGE("Failed to register an IRQ");
         /* The ID also serves as an error code */
         return irq_id;
     }

     error = sel4platsupport_irq_set_ntfn(&(irq_server->irq_ops), ntfn_id, irq_id, NULL);
     if (error) {
         ZF_LOGE("Failed to pair an IRQ with a notification");
         ps_irq_unregister(&(irq_server->irq_ops), irq_id);
         return error;
     }

     node->num_irqs_bound++;

     /* Success, return the ID that was assigned to the IRQ */
     return irq_id;
 }

 /* Creates a new IRQ server node */
 static irq_server_node_t *irq_server_node_new(seL4_CPtr ntfn, size_t max_irqs_bound,
                                               ps_malloc_ops_t *malloc_ops)
 {
     irq_server_node_t *new_node = NULL;
     ps_calloc(malloc_ops, 1, sizeof(irq_server_node_t), (void **) &new_node);
     if (new_node) {
         new_node->ntfn = ntfn;
         new_node->max_irqs_bound = max_irqs_bound;
     }
     return new_node;
 }

 /* IRQ handler thread. Wait on a notification object for IRQs. When one arrives, send a
  * synchronous message to the registered endpoint. If no synchronous endpoint was
  * registered, call the appropriate handler function directly (must be thread safe) */
 static void _irq_thread_entry(irq_server_thread_t *my_thread_info, ps_irq_ops_t *irq_ops)
 {
     seL4_CPtr ep;
     seL4_CPtr ntfn;
     uintptr_t thread_info_ptr;
     seL4_Word label;

     ep = my_thread_info->delivery_ep;
     ntfn = my_thread_info->node->ntfn;
     thread_info_ptr = (uintptr_t)my_thread_info;
     label = my_thread_info->label;
     ZF_LOGD("thread started. Waiting on endpoint %lu\n", ntfn);

     while (1) {
         seL4_Word badge = 0;
         seL4_Wait(ntfn, &badge);
         if (ep != seL4_CapNull) {
             /* Synchronous endpoint registered. Send IPC */
             seL4_MessageInfo_t info = seL4_MessageInfo_new(label, 0, 0, IRQ_SERVER_MESSAGE_LENGTH);
             seL4_SetMR(0, badge);
             seL4_SetMR(1, thread_info_ptr);
             seL4_Send(ep, info);
         } else {
             /* No synchronous endpoint. Get the IRQ interface to invoke callbacks */
             irq_server_node_handle_irq(my_thread_info, irq_ops, badge);
         }
     }
 }

 thread_id_t irq_server_thread_new(irq_server_t *irq_server, seL4_CPtr provided_ntfn,
                                   seL4_Word usable_mask, thread_id_t id_hint)
 {
     int error;

     irq_server_thread_t *new_thread = NULL;

     irq_server_node_t *new_node = NULL;

     /* Check if the user provided a notification, if not, then allocate one */
     seL4_CPtr ntfn_to_use = seL4_CapNull;
     seL4_Word mask_to_use = 0;
     vka_object_t ntfn_obj = {0};
     if (provided_ntfn != seL4_CapNull) {
         ntfn_to_use = provided_ntfn;
         if (usable_mask == 0) {
             ZF_LOGE("Can't pair any interrupts on this notification");
             return -EINVAL;
         }
         mask_to_use = usable_mask;
     } else {
         error = vka_alloc_notification(irq_server->vka, &ntfn_obj);
         if (error) {
             ZF_LOGE("Failed to allocate a notification");
             return -ENOMEM;
         }
         ntfn_to_use = ntfn_obj.cptr;
         mask_to_use = MASK(seL4_BadgeBits);
     }

     thread_id_t thread_id_to_use = -1;
     /* Register this notification with the IRQ interface */
     if (id_hint >= 0) {
         error = sel4platsupport_irq_provide_ntfn_with_id(&(irq_server->irq_ops), ntfn_to_use,
                                                          mask_to_use, id_hint);
         if (error) {
             goto fail;
         }
         thread_id_to_use = id_hint;
     } else {
         ntfn_id_t ntfn_id = sel4platsupport_irq_provide_ntfn(&(irq_server->irq_ops), ntfn_to_use, mask_to_use);
         if (ntfn_id < 0) {
             /* 'sel4platsupport_irq_provide_ntfn' returns an error code on failure */
             error = ntfn_id;
             goto fail;
         }
         thread_id_to_use = ntfn_id;
     }

     error = ps_calloc(irq_server->malloc_ops, 1, sizeof(irq_server_thread_t), (void **) &new_thread);
     if (new_thread == NULL) {
         ZF_LOGE("Failed to allocate memory for bookkeeping structure");
         /* ps_calloc returns errnos but these are greater than 0 */
         error *= -1;
         goto fail;
     }

     /* Find the amount of IRQs that can be bound to this node */
     size_t max_irqs_bound = POPCOUNTL(mask_to_use);
     /* Allocate memory for the node */
     new_node = irq_server_node_new(ntfn_to_use, max_irqs_bound, irq_server->malloc_ops);
     if (new_node == NULL) {
         error = -ENOMEM;
         goto fail;
     }

     /* Initialise structure */
     new_thread->delivery_ep = irq_server->delivery_ep;
     new_thread->label = irq_server->label;
     new_thread->node = new_node;
     new_thread->thread_id = thread_id_to_use;

     /* Create the IRQ thread */
     sel4utils_thread_config_t config = thread_config_default(irq_server->simple, irq_server->cspace,
                                                              seL4_NilData, 0, irq_server->priority);
     error = sel4utils_configure_thread_config(irq_server->vka, irq_server->vspace,
                                               irq_server->vspace, config, &(new_thread->thread));
     if (error) {
         ZF_LOGE("Failed to configure IRQ server thread");
         goto fail;
     }

     bool thread_created = true;

     /* Start the thread */
     error = sel4utils_start_thread(&new_thread->thread, (void *)_irq_thread_entry,
                                    new_thread, &(irq_server->irq_ops), 1);
     if (error) {
         ZF_LOGE("Failed to start IRQ server thread");
         goto fail;
     }

     /* Append this thread structure to the head of the list */
     new_thread->next = irq_server->server_threads;
     irq_server->server_threads = new_thread;

     return thread_id_to_use;

 fail:

     /* Check if we've registered a notification with the IRQ interface */
     if (thread_id_to_use) {
         ZF_LOGF_IF(sel4platsupport_irq_return_ntfn(&(irq_server->irq_ops), thread_id_to_use, NULL),
                    "Failed to clean-up a failure situation");
     }

     if (ntfn_obj.cptr) {
         vka_free_object(irq_server->vka, &ntfn_obj);
     }

     if (new_node) {
         ps_free(irq_server->malloc_ops, sizeof(irq_server_node_t), new_node);
     }

     if (thread_created) {
         sel4utils_clean_up_thread(irq_server->vka, irq_server->vspace, &(new_thread->thread));
     }

     if (new_thread) {
         ps_free(irq_server->malloc_ops, sizeof(irq_server_thread_t), new_node);
     }

     return error;
 }

 void irq_server_handle_irq_ipc(irq_server_t *irq_server, seL4_MessageInfo_t msginfo)
 {
     seL4_Word badge = 0;
     uintptr_t thread_info_ptr = 0;

     seL4_Word label = seL4_MessageInfo_get_label(msginfo);
     seL4_Word length = seL4_MessageInfo_get_length(msginfo);

     if (label == irq_server->label && length == IRQ_SERVER_MESSAGE_LENGTH) {
         badge = seL4_GetMR(0);
         thread_info_ptr = seL4_GetMR(1);
         if (thread_info_ptr == 0) {
             ZF_LOGE("Invalid data in IRQ server IPC\n");
         } else {
             irq_server_node_handle_irq((irq_server_thread_t *) thread_info_ptr, &(irq_server->irq_ops), badge);
         }
     }
 }

 /* Register for a function to be called when an IRQ arrives */
 irq_id_t irq_server_register_irq(irq_server_t *irq_server, ps_irq_t irq,
                                  irq_callback_fn_t callback, void *callback_data)
 {
     if (irq_server == NULL) {
         ZF_LOGE("irq_server is NULL");
         return -EINVAL;
     }

     irq_server_thread_t *st = NULL;
     irq_id_t ret_id = 0;

     /* Try to assign the IRQ to an existing node/thread */
     for (st = irq_server->server_threads; st != NULL; st = st->next) {
         if (st->node->num_irqs_bound < st->node->max_irqs_bound) {
             /* thread_id is synonymous with a ntfn_id */
             ret_id = irq_server_node_register_irq(st->node, irq, callback, callback_data,
                                                   (ntfn_id_t) st->thread_id, irq_server);
             if (ret_id >= 0) {
                 return ret_id;
             }
         }
     }

     /* No threads are available to take this IRQ, alert the user */
     ZF_LOGE("No threads are available to take this interrupt, consider making more");
     return -ENOENT;
 }

 irq_server_t *irq_server_new(vspace_t *vspace, vka_t *vka, seL4_Word priority,
                              simple_t *simple, seL4_CPtr cspace, seL4_CPtr delivery_ep, seL4_Word label,
                              size_t num_irqs, ps_malloc_ops_t *malloc_ops)
 {
     if (num_irqs < 0) {
         ZF_LOGE("num_irqs is less than 0");
         return NULL;
     }

     if (!vspace || !vka || !simple || !malloc_ops) {
         ZF_LOGE("ret_irq_server is NULL");
         return NULL;
     }

     int error;

     irq_server_t *new = NULL;

     error = ps_calloc(malloc_ops, 1, sizeof(irq_server_t), (void **) &new);

     if (config_set(CONFIG_KERNEL_MCS) && vka_alloc_reply(vka, &(new->reply)) != 0) {
         ZF_LOGE("Failed to allocate reply object");
         return NULL;
     }

     /* Set max_ntfn_ids to equal the number of IRQs. We can calculate the ntfn IDs we need,
      * but this is really complex, and leads to code that is hard to maintain. */
     irq_interface_config_t irq_config = { .max_irq_ids = num_irqs, .max_ntfn_ids = num_irqs } ;
     error = sel4platsupport_new_irq_ops(&(new->irq_ops), vka, simple, irq_config, malloc_ops);
     if (error) {
         ZF_LOGE("Failed to initialise supporting backend for IRQ server");
         return NULL;
     }

     new->delivery_ep = delivery_ep;
     new->label = label;
     new->max_irqs = num_irqs;
     new->priority = priority;

     new->vka = vka;
     new->vspace = vspace;
     new->simple = simple;
     new->cspace = cspace;
     new->malloc_ops = malloc_ops;

     return new;
 }

 seL4_MessageInfo_t irq_server_wait_for_irq(irq_server_t *irq_server, seL4_Word *ret_badge)
 {
     seL4_MessageInfo_t msginfo = {0};
     seL4_Word badge = 0;

     if (irq_server->delivery_ep == seL4_CapNull) {
         ZF_LOGE("No endpoint was registered with the IRQ server");
         return msginfo;
     }

     /* Wait for an event, api_recv instead of seL4_Recv b/c of MCS */
     msginfo = api_recv(irq_server->delivery_ep, &badge, irq_server->reply.cptr);
     if (ret_badge) {
         *ret_badge = badge;
     }

     /* Forward to IRQ handlers */
     irq_server_handle_irq_ipc(irq_server, msginfo);

     return msginfo;
 }
	/*
	* Copyright 2019, Data61
	* Commonwealth Scientific and Industrial Research Organisation (CSIRO)
	* ABN 41 687 119 230.
	*
	* This software may be distributed and modified according to the terms of
	* the BSD 2-Clause license. Note that NO WARRANTY is provided.
	* See "LICENSE_BSD2.txt" for details.
	*
	* @TAG(DATA61_BSD)
	*/

	#include <sel4utils/irq_server.h>

	#include <errno.h>
	#include <simple/simple.h>
	#include <sel4utils/thread.h>
	#include <vka/capops.h>
	#include <stdlib.h>
	#include <string.h>
	#include <platsupport/irq.h>
	#include <sel4platsupport/irq.h>

	#include <utils/util.h>

	#define IRQ_SERVER_MESSAGE_LENGTH 2

	typedef struct irq_server_node {
	seL4_CPtr ntfn;
	size_t max_irqs_bound;
	size_t num_irqs_bound;
	} irq_server_node_t;

	typedef struct irq_server_thread irq_server_thread_t;

	/* This is also forwarded declared as we have a pointer to a struct of the same type */
	struct irq_server_thread {
	thread_id_t thread_id;
	irq_server_node_t *node;
	seL4_CPtr delivery_ep;
	seL4_Word label;
	sel4utils_thread_t thread;
	/* Linked list chain of threads */
	irq_server_thread_t *next;
	};

	/* This is forward-declared in the header file, hence no typedef */
	struct irq_server {
	seL4_CPtr delivery_ep;
	seL4_Word label;
	vka_object_t reply;
	irq_server_thread_t *server_threads;
	size_t num_irqs;
	size_t max_irqs;

	/* New thread parameters */
	seL4_Word priority;
	seL4_CPtr cspace;

	/* Allocation interfaces */
	vka_t *vka;
	vspace_t *vspace;
	simple_t *simple;
	ps_irq_ops_t irq_ops;
	ps_malloc_ops_t *malloc_ops;
	};

	/* Executes the registered callback for incoming IRQs */
	static void irq_server_node_handle_irq(irq_server_thread_t *thread_info,
	ps_irq_ops_t *irq_ops, seL4_Word badge)
	{
	ntfn_id_t target_ntfn = thread_info->thread_id;
	int error = sel4platsupport_irq_handle(irq_ops, target_ntfn, badge);
	if (error) {
	if (error == -EINVAL) {
	ZF_LOGE("Passed in a wrong ntfn_id to the IRQ interface! Something is very wrong with the IRQ server");
	} else {
	ZF_LOGW("Failed to handle an IRQ");
	}
	}
	}

	/* Registers an IRQ callback and enables the IRQ */
	static irq_id_t irq_server_node_register_irq(irq_server_node_t *node, ps_irq_t irq, irq_callback_fn_t callback,
	void callback_data, ntfn_id_t ntfn_id, irq_server_t irq_server)
	{
	int error;

	irq_id_t irq_id = ps_irq_register(&(irq_server->irq_ops), irq, callback, callback_data);
	if (irq_id < 0) {
	ZF_LOGE("Failed to register an IRQ");
	/* The ID also serves as an error code */
	return irq_id;
	}

	error = sel4platsupport_irq_set_ntfn(&(irq_server->irq_ops), ntfn_id, irq_id, NULL);
	if (error) {
	ZF_LOGE("Failed to pair an IRQ with a notification");
	ps_irq_unregister(&(irq_server->irq_ops), irq_id);
	return error;
	}

	node->num_irqs_bound++;

	/* Success, return the ID that was assigned to the IRQ */
	return irq_id;
	}

	/* Creates a new IRQ server node */
	static irq_server_node_t *irq_server_node_new(seL4_CPtr ntfn, size_t max_irqs_bound,
	ps_malloc_ops_t *malloc_ops)
	{
	irq_server_node_t *new_node = NULL;
	ps_calloc(malloc_ops, 1, sizeof(irq_server_node_t), (void **) &new_node);
	if (new_node) {
	new_node->ntfn = ntfn;
	new_node->max_irqs_bound = max_irqs_bound;
	}
	return new_node;
	}

	/* IRQ handler thread. Wait on a notification object for IRQs. When one arrives, send a
	* synchronous message to the registered endpoint. If no synchronous endpoint was
	* registered, call the appropriate handler function directly (must be thread safe) */
	static void _irq_thread_entry(irq_server_thread_t my_thread_info, ps_irq_ops_t irq_ops)
	{
	seL4_CPtr ep;
	seL4_CPtr ntfn;
	uintptr_t thread_info_ptr;
	seL4_Word label;

	ep = my_thread_info->delivery_ep;
	ntfn = my_thread_info->node->ntfn;
	thread_info_ptr = (uintptr_t)my_thread_info;
	label = my_thread_info->label;
	ZF_LOGD("thread started. Waiting on endpoint %lu\n", ntfn);

	while (1) {
	seL4_Word badge = 0;
	seL4_Wait(ntfn, &badge);
	if (ep != seL4_CapNull) {
	/* Synchronous endpoint registered. Send IPC */
	seL4_MessageInfo_t info = seL4_MessageInfo_new(label, 0, 0, IRQ_SERVER_MESSAGE_LENGTH);
	seL4_SetMR(0, badge);
	seL4_SetMR(1, thread_info_ptr);
	seL4_Send(ep, info);
	} else {
	/* No synchronous endpoint. Get the IRQ interface to invoke callbacks */
	irq_server_node_handle_irq(my_thread_info, irq_ops, badge);
	}
	}
	}

	thread_id_t irq_server_thread_new(irq_server_t *irq_server, seL4_CPtr provided_ntfn,
	seL4_Word usable_mask, thread_id_t id_hint)
	{
	int error;

	irq_server_thread_t *new_thread = NULL;

	irq_server_node_t *new_node = NULL;

	/* Check if the user provided a notification, if not, then allocate one */
	seL4_CPtr ntfn_to_use = seL4_CapNull;
	seL4_Word mask_to_use = 0;
	vka_object_t ntfn_obj = {0};
	if (provided_ntfn != seL4_CapNull) {
	ntfn_to_use = provided_ntfn;
	if (usable_mask == 0) {
	ZF_LOGE("Can't pair any interrupts on this notification");
	return -EINVAL;
	}
	mask_to_use = usable_mask;
	} else {
	error = vka_alloc_notification(irq_server->vka, &ntfn_obj);
	if (error) {
	ZF_LOGE("Failed to allocate a notification");
	return -ENOMEM;
	}
	ntfn_to_use = ntfn_obj.cptr;
	mask_to_use = MASK(seL4_BadgeBits);
	}

	thread_id_t thread_id_to_use = -1;
	/* Register this notification with the IRQ interface */
	if (id_hint >= 0) {
	error = sel4platsupport_irq_provide_ntfn_with_id(&(irq_server->irq_ops), ntfn_to_use,
	mask_to_use, id_hint);
	if (error) {
	goto fail;
	}
	thread_id_to_use = id_hint;
	} else {
	ntfn_id_t ntfn_id = sel4platsupport_irq_provide_ntfn(&(irq_server->irq_ops), ntfn_to_use, mask_to_use);
	if (ntfn_id < 0) {
	/* 'sel4platsupport_irq_provide_ntfn' returns an error code on failure */
	error = ntfn_id;
	goto fail;
	}
	thread_id_to_use = ntfn_id;
	}

	error = ps_calloc(irq_server->malloc_ops, 1, sizeof(irq_server_thread_t), (void **) &new_thread);
	if (new_thread == NULL) {
	ZF_LOGE("Failed to allocate memory for bookkeeping structure");
	/* ps_calloc returns errnos but these are greater than 0 */
	error *= -1;
	goto fail;
	}

	/* Find the amount of IRQs that can be bound to this node */
	size_t max_irqs_bound = POPCOUNTL(mask_to_use);
	/* Allocate memory for the node */
	new_node = irq_server_node_new(ntfn_to_use, max_irqs_bound, irq_server->malloc_ops);
	if (new_node == NULL) {
	error = -ENOMEM;
	goto fail;
	}

	/* Initialise structure */
	new_thread->delivery_ep = irq_server->delivery_ep;
	new_thread->label = irq_server->label;
	new_thread->node = new_node;
	new_thread->thread_id = thread_id_to_use;

	/* Create the IRQ thread */
	sel4utils_thread_config_t config = thread_config_default(irq_server->simple, irq_server->cspace,
	seL4_NilData, 0, irq_server->priority);
	error = sel4utils_configure_thread_config(irq_server->vka, irq_server->vspace,
	irq_server->vspace, config, &(new_thread->thread));
	if (error) {
	ZF_LOGE("Failed to configure IRQ server thread");
	goto fail;
	}

	bool thread_created = true;

	/* Start the thread */
	error = sel4utils_start_thread(&new_thread->thread, (void *)_irq_thread_entry,
	new_thread, &(irq_server->irq_ops), 1);
	if (error) {
	ZF_LOGE("Failed to start IRQ server thread");
	goto fail;
	}

	/* Append this thread structure to the head of the list */
	new_thread->next = irq_server->server_threads;
	irq_server->server_threads = new_thread;

	return thread_id_to_use;

	fail:

	/* Check if we've registered a notification with the IRQ interface */
	if (thread_id_to_use) {
	ZF_LOGF_IF(sel4platsupport_irq_return_ntfn(&(irq_server->irq_ops), thread_id_to_use, NULL),
	"Failed to clean-up a failure situation");
	}

	if (ntfn_obj.cptr) {
	vka_free_object(irq_server->vka, &ntfn_obj);
	}

	if (new_node) {
	ps_free(irq_server->malloc_ops, sizeof(irq_server_node_t), new_node);
	}

	if (thread_created) {
	sel4utils_clean_up_thread(irq_server->vka, irq_server->vspace, &(new_thread->thread));
	}

	if (new_thread) {
	ps_free(irq_server->malloc_ops, sizeof(irq_server_thread_t), new_node);
	}

	return error;
	}

	void irq_server_handle_irq_ipc(irq_server_t *irq_server, seL4_MessageInfo_t msginfo)
	{
	seL4_Word badge = 0;
	uintptr_t thread_info_ptr = 0;

	seL4_Word label = seL4_MessageInfo_get_label(msginfo);
	seL4_Word length = seL4_MessageInfo_get_length(msginfo);

	if (label == irq_server->label && length == IRQ_SERVER_MESSAGE_LENGTH) {
	badge = seL4_GetMR(0);
	thread_info_ptr = seL4_GetMR(1);
	if (thread_info_ptr == 0) {
	ZF_LOGE("Invalid data in IRQ server IPC\n");
	} else {
	irq_server_node_handle_irq((irq_server_thread_t *) thread_info_ptr, &(irq_server->irq_ops), badge);
	}
	}
	}

	/* Register for a function to be called when an IRQ arrives */
	irq_id_t irq_server_register_irq(irq_server_t *irq_server, ps_irq_t irq,
	irq_callback_fn_t callback, void *callback_data)
	{
	if (irq_server == NULL) {
	ZF_LOGE("irq_server is NULL");
	return -EINVAL;
	}

	irq_server_thread_t *st = NULL;
	irq_id_t ret_id = 0;

	/* Try to assign the IRQ to an existing node/thread */
	for (st = irq_server->server_threads; st != NULL; st = st->next) {
	if (st->node->num_irqs_bound < st->node->max_irqs_bound) {
	/* thread_id is synonymous with a ntfn_id */
	ret_id = irq_server_node_register_irq(st->node, irq, callback, callback_data,
	(ntfn_id_t) st->thread_id, irq_server);
	if (ret_id >= 0) {
	return ret_id;
	}
	}
	}

	/* No threads are available to take this IRQ, alert the user */
	ZF_LOGE("No threads are available to take this interrupt, consider making more");
	return -ENOENT;
	}

	irq_server_t irq_server_new(vspace_t vspace, vka_t *vka, seL4_Word priority,
	simple_t *simple, seL4_CPtr cspace, seL4_CPtr delivery_ep, seL4_Word label,
	size_t num_irqs, ps_malloc_ops_t *malloc_ops)
	{
	if (num_irqs < 0) {
	ZF_LOGE("num_irqs is less than 0");
	return NULL;
	}

	if (!vspace \|\| !vka \|\| !simple \|\| !malloc_ops) {
	ZF_LOGE("ret_irq_server is NULL");
	return NULL;
	}

	int error;

	irq_server_t *new = NULL;

	error = ps_calloc(malloc_ops, 1, sizeof(irq_server_t), (void **) &new);

	if (config_set(CONFIG_KERNEL_MCS) && vka_alloc_reply(vka, &(new->reply)) != 0) {
	ZF_LOGE("Failed to allocate reply object");
	return NULL;
	}

	/* Set max_ntfn_ids to equal the number of IRQs. We can calculate the ntfn IDs we need,
	* but this is really complex, and leads to code that is hard to maintain. */
	irq_interface_config_t irq_config = { .max_irq_ids = num_irqs, .max_ntfn_ids = num_irqs } ;
	error = sel4platsupport_new_irq_ops(&(new->irq_ops), vka, simple, irq_config, malloc_ops);
	if (error) {
	ZF_LOGE("Failed to initialise supporting backend for IRQ server");
	return NULL;
	}

	new->delivery_ep = delivery_ep;
	new->label = label;
	new->max_irqs = num_irqs;
	new->priority = priority;

	new->vka = vka;
	new->vspace = vspace;
	new->simple = simple;
	new->cspace = cspace;
	new->malloc_ops = malloc_ops;

	return new;
	}

	seL4_MessageInfo_t irq_server_wait_for_irq(irq_server_t irq_server, seL4_Word ret_badge)
	{
	seL4_MessageInfo_t msginfo = {0};
	seL4_Word badge = 0;

	if (irq_server->delivery_ep == seL4_CapNull) {
	ZF_LOGE("No endpoint was registered with the IRQ server");
	return msginfo;
	}

	/* Wait for an event, api_recv instead of seL4_Recv b/c of MCS */
	msginfo = api_recv(irq_server->delivery_ep, &badge, irq_server->reply.cptr);
	if (ret_badge) {
	*ret_badge = badge;
	}

	/* Forward to IRQ handlers */
	irq_server_handle_irq_ipc(irq_server, msginfo);

	return msginfo;
	}