thread.h

Go to the documentation of this file.

/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef THREAD_H_
#define THREAD_H_
 
#include <arch/cpu.h>
#include <bootstate.h>
#include <types.h>
 
struct thread_mutex {
        bool locked;
};
 
enum thread_state {
        THREAD_UNINITIALIZED,
        THREAD_STARTED,
        THREAD_DONE,
};
 
struct thread_handle {
        enum thread_state state;
        /* Only valid when state == THREAD_DONE */
        enum cb_err error;
};
 
/* Run func(arg) on a new thread. Return 0 on successful start of thread, < 0
 * when thread could not be started. The thread handle if populated, will
 * reflect the state and return code of the thread.
 */
int thread_run(struct thread_handle *handle, enum cb_err (*func)(void *), void *arg);
 
/* thread_run_until is the same as thread_run() except that it blocks state
 * transitions from occurring in the (state, seq) pair of the boot state
 * machine. */
int thread_run_until(struct thread_handle *handle, enum cb_err (*func)(void *), void *arg,
                     boot_state_t state, boot_state_sequence_t seq);
 
/* Waits until the thread has terminated and returns the error code */
enum cb_err thread_join(struct thread_handle *handle);
 
#if ENV_STAGE_SUPPORTS_COOP
 
struct thread {
        int id;
        uintptr_t stack_current;
        uintptr_t stack_orig;
        struct thread *next;
        enum cb_err (*entry)(void *);
        void *entry_arg;
        int can_yield;
        struct thread_handle *handle;
};
 
/* Return 0 on successful yield, < 0 when thread did not yield. */
int thread_yield(void);
 
/* Return 0 on successful yield for the given amount of time, < 0 when thread
 * did not yield. */
int thread_yield_microseconds(unsigned int microsecs);
 
/* Allow and prevent thread cooperation on current running thread. By default
 * all threads are marked to be cooperative. That means a thread can yield
 * to another thread at a pre-determined switch point. i.e., udelay,
 * thread_yield, or thread_yield_microseconds.
 *
 * These methods should be used to guard critical sections so a dead lock does
 * not occur. The critical sections can be nested. Just make sure the methods
 * are used in pairs.
 */
void thread_coop_enable(void);
void thread_coop_disable(void);
 
void thread_mutex_lock(struct thread_mutex *mutex);
void thread_mutex_unlock(struct thread_mutex *mutex);
 
/* Architecture specific thread functions. */
asmlinkage void switch_to_thread(uintptr_t new_stack, uintptr_t *saved_stack);
/* Set up the stack frame for a new thread so that a switch_to_thread() call
 * will enter the thread_entry() function with arg as a parameter. The
 * saved_stack field in the struct thread needs to be updated accordingly. */
void arch_prepare_thread(struct thread *t,
                         asmlinkage void (*thread_entry)(void *), void *arg);
#else
static inline int thread_yield(void)
{
        return -1;
}
static inline int thread_yield_microseconds(unsigned int microsecs)
{
        return -1;
}
static inline void thread_coop_enable(void) {}
static inline void thread_coop_disable(void) {}
 
static inline void thread_mutex_lock(struct thread_mutex *mutex) {}
 
static inline void thread_mutex_unlock(struct thread_mutex *mutex) {}
#endif
 
#endif /* THREAD_H_ */