/* * This file is part of the coreboot project. * * Copyright (C) 2013 Google, Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #include <stddef.h> #include <stdint.h> #include <stdlib.h> #include <arch/cpu.h> #include <bootstate.h> #include <console/console.h> #include <thread.h> static void idle_thread_init(void); /* There needs to be at least one thread to run the ramstate state machine. */ #define TOTAL_NUM_THREADS (CONFIG_NUM_THREADS + 1) /* Storage space for the thread structs .*/ static struct thread all_threads[TOTAL_NUM_THREADS]; /* All runnable (but not running) and free threads are kept on their * respective lists. */ static struct thread *runnable_threads; static struct thread *free_threads; static inline struct cpu_info *thread_cpu_info(const struct thread *t) { return (void *)(t->stack_orig); } static inline int thread_can_yield(const struct thread *t) { return (t != NULL && t->can_yield); } /* Assumes current CPU info can switch. */ static inline struct thread *cpu_info_to_thread(const struct cpu_info *ci) { return ci->thread; } static inline struct thread *current_thread(void) { return cpu_info_to_thread(cpu_info()); } static inline int thread_list_empty(struct thread **list) { return *list == NULL; } static inline struct thread *pop_thread(struct thread **list) { struct thread *t; t = *list; *list = t->next; t->next = NULL; return t; } static inline void push_thread(struct thread **list, struct thread *t) { t->next = *list; *list = t; } static inline void push_runnable(struct thread *t) { push_thread(&runnable_threads, t); } static inline struct thread *pop_runnable(void) { return pop_thread(&runnable_threads); } static inline struct thread *get_free_thread(void) { struct thread *t; struct cpu_info *ci; struct cpu_info *new_ci; if (thread_list_empty(&free_threads)) return NULL; t = pop_thread(&free_threads); ci = cpu_info(); /* Initialize the cpu_info structure on the new stack. */ new_ci = thread_cpu_info(t); *new_ci = *ci; new_ci->thread = t; /* Reset the current stack value to the original. */ t->stack_current = t->stack_orig; return t; } static inline void free_thread(struct thread *t) { push_thread(&free_threads, t); } /* The idle thread is ran whenever there isn't anything else that is runnable. * It's sole responsibility is to ensure progress is made by running the timer * callbacks. */ static void idle_thread(void *unused) { /* This thread never voluntarily yields. */ thread_prevent_coop(); while (1) timers_run(); } static void schedule(struct thread *t) { struct thread *current = current_thread(); /* If t is NULL need to find new runnable thread. */ if (t == NULL) { if (thread_list_empty(&runnable_threads)) die("Runnable thread list is empty!\n"); t = pop_runnable(); } else { /* current is still runnable. */ push_runnable(current); } switch_to_thread(t->stack_current, ¤t->stack_current); } static void terminate_thread(struct thread *t) { free_thread(t); schedule(NULL); } static void asmlinkage call_wrapper(void *unused) { struct thread *current = current_thread(); current->entry(current->entry_arg); terminate_thread(current); } /* Block the current state transitions until thread is complete. */ static void asmlinkage call_wrapper_block_current(void *unused) { struct thread *current = current_thread(); boot_state_current_block(); current->entry(current->entry_arg); boot_state_current_unblock(); terminate_thread(current); } struct block_boot_state { boot_state_t state; boot_state_sequence_t seq; }; /* Block the provided state until thread is complete. */ static void asmlinkage call_wrapper_block_state(void *arg) { struct block_boot_state *bbs = arg; struct thread *current = current_thread(); boot_state_block(bbs->state, bbs->seq); current->entry(current->entry_arg); boot_state_unblock(bbs->state, bbs->seq); terminate_thread(current); } /* Prepare a thread so that it starts by executing thread_entry(thread_arg). * Within thread_entry() it will call func(arg). */ static void prepare_thread(struct thread *t, void *func, void *arg, asmlinkage void (*thread_entry)(void *), void *thread_arg) { /* Stash the function and argument to run. */ t->entry = func; t->entry_arg = arg; /* All new threads can yield by default. */ t->can_yield = 1; arch_prepare_thread(t, thread_entry, thread_arg); } static void thread_resume_from_timeout(struct timeout_callback *tocb) { struct thread *to; to = tocb->priv; schedule(to); } static void idle_thread_init(void) { struct thread *t; t = get_free_thread(); if (t == NULL) die("No threads available for idle thread!\n"); /* Queue idle thread to run once all other threads have yielded. */ prepare_thread(t, idle_thread, NULL, call_wrapper, NULL); push_runnable(t); /* Mark the currently executing thread to cooperate. */ thread_cooperate(); } /* Don't inline this function so the timeout_callback won't have its storage * space on the stack cleaned up before the call to schedule(). */ static int __attribute__((noinline)) thread_yield_timed_callback(struct timeout_callback *tocb, unsigned int microsecs) { tocb->priv = current_thread(); tocb->callback = thread_resume_from_timeout; if (timer_sched_callback(tocb, microsecs)) return -1; /* The timer callback will wake up the current thread. */ schedule(NULL); return 0; } static void *thread_alloc_space(struct thread *t, size_t bytes) { /* Allocate the amount of space on the stack keeping the stack * aligned to the pointer size. */ t->stack_current -= ALIGN_UP(bytes, sizeof(uintptr_t)); return (void *)t->stack_current; } void threads_initialize(void) { int i; struct thread *t; u8 *stack_top; struct cpu_info *ci; u8 *thread_stacks; thread_stacks = arch_get_thread_stackbase(); /* Initialize the BSP thread first. The cpu_info structure is assumed * to be just under the top of the stack. */ t = &all_threads[0]; ci = cpu_info(); ci->thread = t; t->stack_orig = (uintptr_t)ci; t->id = 0; stack_top = &thread_stacks[CONFIG_STACK_SIZE] - sizeof(struct cpu_info); for (i = 1; i < TOTAL_NUM_THREADS; i++) { t = &all_threads[i]; t->stack_orig = (uintptr_t)stack_top; t->id = i; stack_top += CONFIG_STACK_SIZE; free_thread(t); } idle_thread_init(); } int thread_run(void (*func)(void *), void *arg) { struct thread *current; struct thread *t; current = current_thread(); if (!thread_can_yield(current)) { printk(BIOS_ERR, "thread_run() called from non-yielding context!\n"); return -1; } t = get_free_thread(); if (t == NULL) { printk(BIOS_ERR, "thread_run() No more threads!\n"); return -1; } prepare_thread(t, func, arg, call_wrapper_block_current, NULL); schedule(t); return 0; } int thread_run_until(void (*func)(void *), void *arg, boot_state_t state, boot_state_sequence_t seq) { struct thread *current; struct thread *t; struct block_boot_state *bbs; current = current_thread(); if (!thread_can_yield(current)) { printk(BIOS_ERR, "thread_run() called from non-yielding context!\n"); return -1; } t = get_free_thread(); if (t == NULL) { printk(BIOS_ERR, "thread_run() No more threads!\n"); return -1; } bbs = thread_alloc_space(t, sizeof(*bbs)); bbs->state = state; bbs->seq = seq; prepare_thread(t, func, arg, call_wrapper_block_state, bbs); schedule(t); return 0; } int thread_yield_microseconds(unsigned int microsecs) { struct thread *current; struct timeout_callback tocb; current = current_thread(); if (!thread_can_yield(current)) return -1; if (thread_yield_timed_callback(&tocb, microsecs)) return -1; return 0; } void thread_cooperate(void) { struct thread *current; current = current_thread(); if (current != NULL) current->can_yield = 1; } void thread_prevent_coop(void) { struct thread *current; current = current_thread(); if (current != NULL) current->can_yield = 0; }