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https://github.com/zephyrproject-rtos/zephyr
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7832738ae9
Add a k_timeout_t type, and use it everywhere that kernel API functions were accepting a millisecond timeout argument. Instead of forcing milliseconds everywhere (which are often not integrally representable as system ticks), do the conversion to ticks at the point where the timeout is created. This avoids an extra unit conversion in some application code, and allows us to express the timeout in units other than milliseconds to achieve greater precision. The existing K_MSEC() et. al. macros now return initializers for a k_timeout_t. The K_NO_WAIT and K_FOREVER constants have now become k_timeout_t values, which means they cannot be operated on as integers. Applications which have their own APIs that need to inspect these vs. user-provided timeouts can now use a K_TIMEOUT_EQ() predicate to test for equality. Timer drivers, which receive an integer tick count in ther z_clock_set_timeout() functions, now use the integer-valued K_TICKS_FOREVER constant instead of K_FOREVER. For the initial release, to preserve source compatibility, a CONFIG_LEGACY_TIMEOUT_API kconfig is provided. When true, the k_timeout_t will remain a compatible 32 bit value that will work with any legacy Zephyr application. Some subsystems present timeout (or timeout-like) values to their own users as APIs that would re-use the kernel's own constants and conventions. These will require some minor design work to adapt to the new scheme (in most cases just using k_timeout_t directly in their own API), and they have not been changed in this patch, instead selecting CONFIG_LEGACY_TIMEOUT_API via kconfig. These subsystems include: CAN Bus, the Microbit display driver, I2S, LoRa modem drivers, the UART Async API, Video hardware drivers, the console subsystem, and the network buffer abstraction. k_sleep() now takes a k_timeout_t argument, with a k_msleep() variant provided that works identically to the original API. Most of the changes here are just type/configuration management and documentation, but there are logic changes in mempool, where a loop that used a timeout numerically has been reworked using a new z_timeout_end_calc() predicate. Also in queue.c, a (when POLL was enabled) a similar loop was needlessly used to try to retry the k_poll() call after a spurious failure. But k_poll() does not fail spuriously, so the loop was removed. Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
139 lines
3.4 KiB
C
139 lines
3.4 KiB
C
/*
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* Copyright (c) 2019 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file
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*
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* @brief public sys_sem APIs.
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*/
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#ifndef ZEPHYR_INCLUDE_SYS_SEM_H_
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#define ZEPHYR_INCLUDE_SYS_SEM_H_
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/*
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* sys_sem exists in user memory working as counter semaphore for
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* user mode thread when user mode enabled. When user mode isn't
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* enabled, sys_sem behaves like k_sem.
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*/
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#include <kernel.h>
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#include <sys/atomic.h>
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#include <zephyr/types.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* sys_sem structure
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*/
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struct sys_sem {
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#ifdef CONFIG_USERSPACE
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struct k_futex futex;
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int limit;
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#else
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struct k_sem kernel_sem;
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#endif
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};
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/**
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* @brief Statically define and initialize a sys_sem
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*
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* The semaphore can be accessed outside the module where it is defined using:
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*
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* @code extern struct sys_sem <name>; @endcode
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*
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* Route this to memory domains using K_APP_DMEM().
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*
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* @param _name Name of the semaphore.
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* @param _initial_count Initial semaphore count.
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* @param _count_limit Maximum permitted semaphore count.
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*/
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#ifdef CONFIG_USERSPACE
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#define SYS_SEM_DEFINE(_name, _initial_count, _count_limit) \
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struct sys_sem _name = { \
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.futex = { _initial_count }, \
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.limit = _count_limit \
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}; \
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BUILD_ASSERT(((_count_limit) != 0) && \
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((_initial_count) <= (_count_limit)))
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#else
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/* Stuff this in the section with the rest of the k_sem objects, since they
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* are identical and can be treated as a k_sem in the boot initialization code
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*/
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#define SYS_SEM_DEFINE(_name, _initial_count, _count_limit) \
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Z_STRUCT_SECTION_ITERABLE(sys_sem, _name) = { \
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.kernel_sem = Z_SEM_INITIALIZER(_name.kernel_sem, \
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_initial_count, _count_limit) \
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}; \
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BUILD_ASSERT(((_count_limit) != 0) && \
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((_initial_count) <= (_count_limit)))
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#endif
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/**
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* @brief Initialize a semaphore.
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*
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* This routine initializes a semaphore instance, prior to its first use.
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*
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* @param sem Address of the semaphore.
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* @param initial_count Initial semaphore count.
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* @param limit Maximum permitted semaphore count.
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*
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* @retval 0 Initial success.
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* @retval -EINVAL Bad parameters, the value of limit should be located in
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* (0, INT_MAX] and initial_count shouldn't be greater than limit.
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*/
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int sys_sem_init(struct sys_sem *sem, unsigned int initial_count,
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unsigned int limit);
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/**
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* @brief Give a semaphore.
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*
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* This routine gives @a sem, unless the semaphore is already at its
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* maximum permitted count.
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*
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* @param sem Address of the semaphore.
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*
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* @retval 0 Semaphore given.
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* @retval -EINVAL Parameter address not recognized.
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* @retval -EACCES Caller does not have enough access.
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* @retval -EAGAIN Count reached Maximum permitted count and try again.
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*/
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int sys_sem_give(struct sys_sem *sem);
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/**
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* @brief Take a sys_sem.
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*
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* This routine takes @a sem.
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*
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* @param sem Address of the sys_sem.
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* @param timeout Waiting period to take the sys_sem,
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* or one of the special values K_NO_WAIT and K_FOREVER.
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*
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* @retval 0 sys_sem taken.
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* @retval -EINVAL Parameter address not recognized.
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* @retval -ETIMEDOUT Waiting period timed out.
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* @retval -EACCES Caller does not have enough access.
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*/
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int sys_sem_take(struct sys_sem *sem, k_timeout_t timeout);
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/**
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* @brief Get sys_sem's value
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*
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* This routine returns the current value of @a sem.
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*
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* @param sem Address of the sys_sem.
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*
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* @return Current value of sys_sem.
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*/
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unsigned int sys_sem_count_get(struct sys_sem *sem);
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#ifdef __cplusplus
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}
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#endif
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#endif
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