1 // Copyright 2021 Espressif Systems (Shanghai) CO LTD
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 
7 //     http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License
14 
15 #pragma once
16 
17 #include <stddef.h>
18 #include <sys/types.h>
19 
20 #include "esp_err.h"
21 
22 #define EFD_SUPPORT_ISR (1 << 4)
23 
24 #ifdef __cplusplus
25 extern "C" {
26 #endif
27 
28 /**
29  * @brief Eventfd vfs initialization settings
30  */
31 typedef struct {
32     size_t max_fds;     /*!< The maxinum number of eventfds supported */
33 } esp_vfs_eventfd_config_t;
34 
35 #define ESP_VFS_EVENTD_CONFIG_DEFAULT() (esp_vfs_eventfd_config_t) { \
36       .max_fds = 5, \
37 };
38 
39 /**
40  * @brief  Registers the event vfs.
41  *
42  * @return  ESP_OK if successful, ESP_ERR_NO_MEM if too many VFSes are
43  *          registered.
44  */
45 esp_err_t esp_vfs_eventfd_register(const esp_vfs_eventfd_config_t *config);
46 
47 /**
48  * @brief  Unregisters the event vfs.
49  *
50  * @return ESP_OK if successful, ESP_ERR_INVALID_STATE if VFS for given prefix
51  *         hasn't been registered
52  */
53 esp_err_t esp_vfs_eventfd_unregister(void);
54 
55 /*
56  * @brief Creates an event file descirptor.
57  *
58  * The behavior of read, write and select is the same as man(2) eventfd with
59  * EFD_SEMAPHORE **NOT** specified. A new flag EFD_SUPPORT_ISR has been added.
60  * This flag is required to write to event fds in interrupt handlers. Accessing
61  * the control blocks of event fds with EFD_SUPPORT_ISR will cause interrupts to
62  * be temporarily blocked (e.g. during read, write and beginning and ending of
63  * the * select).
64  *
65  * @return The file descriptor if successful, -1 if error happens.
66  */
67 int eventfd(unsigned int initval, int flags);
68 
69 #ifdef __cplusplus
70 }
71 #endif
72