timerfd

include/zephyr/posix/sys/timerfd.h

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2025 Atym, Inc
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_POSIX_SYS_TIMERFD_H_
+#define ZEPHYR_INCLUDE_POSIX_SYS_TIMERFD_H_
+
+#include <zephyr/zvfs/timerfd.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define TFD_NONBLOCK  ZVFS_TFD_NONBLOCK
+
+#define TFD_IOC_SET_TICKS ZVFS_TFD_IOC_SET_TICKS
+
+#define TFD_TIMER_ABSTIME 1
+
+typedef zvfs_timerfd_t timerfd_t;
+
+/**
+ * @brief Create a file descriptor for ZVFS timer notification
+ *
+ * The returned file descriptor can be used with POSIX read calls or
+ * with the @ref zvfs_timerfd_settime or @ref zvfs_timerfd_gettime functions.
+ *
+ * It also supports polling and by including an timerfd in a call to poll,
+ * it is possible to signal and wake the polling thread by simply writing to
+ * the timerfd.
+ *
+ * When using read() on a ZVFS timerfd, the size must always be at
+ * least 8 bytes or the operation will fail with EINVAL.
+ *
+ * @return New ZVFS timerfd file descriptor on success, -1 on error
+ */
+int timerfd_create(int clockid, int flags);
+
+/**
+ * @brief Get the itimespec configuration ZVFS timerfd
+ *
+ * @param fd File descriptor
+ * @param curr_value Pointer to struct itimerspec to store current value
+ *
+ * @return 0 on success, -1 on error
+ */
+int timerfd_gettime(int fd, struct itimerspec *curr_value);
+
+/**
+ * @brief Set the itimespec configuration ZVFS timerfd
+ *
+ * The current value is stored in old_value if it is not NULL.
+ *
+ * @param fd File descriptor
+ * @param new_value Pointer to struct itimerspec to set new value
+ * @param old_value Pointer to struct itimerspec to store old value
+ *
+ * @return 0 on success, -1 on error
+ */
+int timerfd_settime(int fd, int flags, const struct itimerspec *new_value,
+    struct itimerspec *old_value);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_POSIX_SYS_TIMERFD_H_ */

include/zephyr/zvfs/timerfd.h

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2025 Atym, Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_ZEPHYR_ZVFS_TIMERFD_H_
+#define ZEPHYR_INCLUDE_ZEPHYR_ZVFS_TIMERFD_H_
+
+#include <stdint.h>
+
+#include <zephyr/kernel.h>
+#include <zephyr/sys/timeutil.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define ZVFS_TFD_NONBLOCK 0x4000
+
+#define ZVFS_TFD_IOC_SET_TICKS 1
+
+typedef uint64_t zvfs_timerfd_t;
+
+/**
+ * @brief Create a file descriptor for ZVFS timer
+ *
+ * The returned file descriptor can be used with POSIX read calls or with
+ * the @ref zvfs_timerfd_* functions.
+ *
+ * It also supports polling and by including an timerfd in a call to poll,
+ * it is possible to signal and wake the polling thread when the timer
+ * expires.
+ *
+ * When using read() on a ZVFS timerfd, the size must always be at least
+ * 8 bytes or the operation will fail with EINVAL.
+ *
+ * @return New ZVFS timerfd file descriptor on success, -1 on error
+ */
+int zvfs_timerfd(unsigned int clockid, int flags);
+
+/**
+ * @brief Read from a ZVFS timerfd
+ *
+ * If call is successful, the value parameter will have the number of
+ * times the timer has expired since the last read.
+ *
+ * @param fd File descriptor
+ * @param value Pointer for storing the expired times value
+ *
+ * @return 0 on success, -1 on error
+ */
+int zvfs_timerfd_read(int fd, zvfs_timerfd_t *value);
+
+/**
+ * @brief Get the current value and period of a ZVFS timerfd.
+ *
+ * @param fd File descriptor
+ * @param remaining Pointer for storing the remaining milliseconds
+ * @param period Pointer for storing the period milliseconds
+ *
+ * @return 0 on success, -1 on error
+ */
+int zvfs_timerfd_gettime(int fd, uint32_t *remaining, uint32_t *period);
+
+/**
+ * @brief Set the value and period of a ZVFS timerfd.
+ *
+ * @param fd File descriptor
+ * @param duration Duration to write
+ * @param period Period to write
+ *
+ * @return 0 on success, -1 on error
+ */
+int zvfs_timerfd_settime(int fd, k_timeout_t duration, k_timeout_t period);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_ZEPHYR_ZVFS_TIMERFD_H_ */

lib/os/zvfs/CMakeLists.txt

@@ -2,5 +2,6 @@
 
 zephyr_library()
 zephyr_library_sources_ifdef(CONFIG_ZVFS_EVENTFD zvfs_eventfd.c)
+zephyr_library_sources_ifdef(CONFIG_ZVFS_TIMERFD zvfs_timerfd.c)
 zephyr_library_sources_ifdef(CONFIG_ZVFS_POLL zvfs_poll.c)
 zephyr_library_sources_ifdef(CONFIG_ZVFS_SELECT zvfs_select.c)

lib/os/zvfs/Kconfig

@@ -34,6 +34,25 @@ config ZVFS_EVENTFD_MAX
 
 endif # ZVFS_EVENTFD
 
+config ZVFS_TIMERFD
+	bool "ZVFS timer file descriptor support"
+	imply ZVFS_POLL
+	help
+	  Enable support for ZVFS timer file descriptors. An timerfd can
+	  be used as an event wait/notify mechanism together with POSIX calls
+	  like read, write and poll.
+
+if ZVFS_TIMERFD
+
+config ZVFS_TIMERFD_MAX
+	int "Maximum number of ZVFS timerfd's"
+	default 1
+	range 1 4096
+	help
+	  The maximum number of supported timer file descriptors.
+
+endif # ZVFS_TIMERFD
+
 config ZVFS_POLL
 	bool "ZVFS poll"
 	select POLL