1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (c) 2015-2021, Linaro Limited
  4 */
  5
  6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  7
  8#include <linux/arm-smccc.h>
  9#include <linux/errno.h>
 10#include <linux/slab.h>
 11#include <linux/spinlock.h>
 12#include <linux/tee_drv.h>
 13#include "optee_private.h"
 14
 15struct notif_entry {
 16	struct list_head link;
 17	struct completion c;
 18	u_int key;
 19};
 20
 21static bool have_key(struct optee *optee, u_int key)
 22{
 23	struct notif_entry *entry;
 24
 25	list_for_each_entry(entry, &optee->notif.db, link)
 26		if (entry->key == key)
 27			return true;
 28
 29	return false;
 30}
 31
 32int optee_notif_wait(struct optee *optee, u_int key)
 33{
 34	unsigned long flags;
 35	struct notif_entry *entry;
 36	int rc = 0;
 37
 38	if (key > optee->notif.max_key)
 39		return -EINVAL;
 40
 41	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
 42	if (!entry)
 43		return -ENOMEM;
 44	init_completion(&entry->c);
 45	entry->key = key;
 46
 47	spin_lock_irqsave(&optee->notif.lock, flags);
 48
 49	/*
 50	 * If the bit is already set it means that the key has already
 51	 * been posted and we must not wait.
 52	 */
 53	if (test_bit(key, optee->notif.bitmap)) {
 54		clear_bit(key, optee->notif.bitmap);
 55		goto out;
 56	}
 57
 58	/*
 59	 * Check if someone is already waiting for this key. If there is
 60	 * it's a programming error.
 61	 */
 62	if (have_key(optee, key)) {
 63		rc = -EBUSY;
 64		goto out;
 65	}
 66
 67	list_add_tail(&entry->link, &optee->notif.db);
 68
 69	/*
 70	 * Unlock temporarily and wait for completion.
 71	 */
 72	spin_unlock_irqrestore(&optee->notif.lock, flags);
 73	wait_for_completion(&entry->c);
 74	spin_lock_irqsave(&optee->notif.lock, flags);
 75
 76	list_del(&entry->link);
 77out:
 78	spin_unlock_irqrestore(&optee->notif.lock, flags);
 79
 80	kfree(entry);
 81
 82	return rc;
 83}
 84
 85int optee_notif_send(struct optee *optee, u_int key)
 86{
 87	unsigned long flags;
 88	struct notif_entry *entry;
 89
 90	if (key > optee->notif.max_key)
 91		return -EINVAL;
 92
 93	spin_lock_irqsave(&optee->notif.lock, flags);
 94
 95	list_for_each_entry(entry, &optee->notif.db, link)
 96		if (entry->key == key) {
 97			complete(&entry->c);
 98			goto out;
 99		}
100
101	/* Only set the bit in case there where nobody waiting */
102	set_bit(key, optee->notif.bitmap);
103out:
104	spin_unlock_irqrestore(&optee->notif.lock, flags);
105
106	return 0;
107}
108
109int optee_notif_init(struct optee *optee, u_int max_key)
110{
111	spin_lock_init(&optee->notif.lock);
112	INIT_LIST_HEAD(&optee->notif.db);
113	optee->notif.bitmap = bitmap_zalloc(max_key, GFP_KERNEL);
114	if (!optee->notif.bitmap)
115		return -ENOMEM;
116
117	optee->notif.max_key = max_key;
118
119	return 0;
120}
121
122void optee_notif_uninit(struct optee *optee)
123{
124	bitmap_free(optee->notif.bitmap);
125}