src/lib/thread.c - chromiumos/third_party/coreboot - Git at Google

 /*
  * 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.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  */
 #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, &current->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,
                            void asmlinkage (*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 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 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;
 }
	/*
	* 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.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	*/
	#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, &current->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,
	void asmlinkage (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 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 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;
	}