diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig | 21 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/time.c | 9 | ||||
| -rw-r--r-- | lib/uthread.c | 165 |
4 files changed, 196 insertions, 1 deletions
diff --git a/lib/Kconfig b/lib/Kconfig index ac34ec45bb1..b2aecd8a49e 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -1258,6 +1258,27 @@ config PHANDLE_CHECK_SEQ enable this config option to distinguish them using phandles in fdtdec_get_alias_seq() function. +config UTHREAD + bool "Enable thread support" + depends on HAVE_INITJMP + help + Implement a simple form of cooperative multi-tasking based on + context-switching via initjmp(), setjmp() and longjmp(). The + uthread_ interface enables the main thread of execution to create + one or more secondary threads and schedule them until they all have + returned. At any point a thread may suspend its execution and + schedule another thread, which allows for the efficient multiplexing + of leghthy operations. + +config UTHREAD_STACK_SIZE + int "Default uthread stack size" + depends on UTHREAD + default 32768 + help + The default stack size for uthreads. Each uthread has its own stack. + When the stack_sz argument to uthread_create() is zero then this + value is used. + endmenu source "lib/fwu_updates/Kconfig" diff --git a/lib/Makefile b/lib/Makefile index 7178c5a3e3c..18ae0cd87bf 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -159,6 +159,8 @@ obj-$(CONFIG_LIB_ELF) += elf.o obj-$(CONFIG_$(PHASE_)SEMIHOSTING) += semihosting.o +obj-$(CONFIG_UTHREAD) += uthread.o + # # Build a fast OID lookup registry from include/linux/oid_registry.h # diff --git a/lib/time.c b/lib/time.c index d88edafb196..0e9b079f9cf 100644 --- a/lib/time.c +++ b/lib/time.c @@ -17,6 +17,7 @@ #include <asm/global_data.h> #include <asm/io.h> #include <linux/delay.h> +#include <uthread.h> #ifndef CFG_WD_PERIOD # define CFG_WD_PERIOD (10 * 1000 * 1000) /* 10 seconds default */ @@ -197,7 +198,13 @@ void udelay(unsigned long usec) do { schedule(); kv = usec > CFG_WD_PERIOD ? CFG_WD_PERIOD : usec; - __udelay(kv); + if (CONFIG_IS_ENABLED(UTHREAD)) { + ulong t0 = timer_get_us(); + while (timer_get_us() - t0 < kv) + uthread_schedule(); + } else { + __udelay(kv); + } usec -= kv; } while(usec); } diff --git a/lib/uthread.c b/lib/uthread.c new file mode 100644 index 00000000000..062fca7d209 --- /dev/null +++ b/lib/uthread.c @@ -0,0 +1,165 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2021 Ahmad Fatoum, Pengutronix + * Copyright (C) 2025 Linaro Limited + * + * An implementation of cooperative multi-tasking inspired from barebox threads + * https://github.com/barebox/barebox/blob/master/common/bthread.c + */ + +#include <compiler.h> +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <malloc.h> +#include <setjmp.h> +#include <stdint.h> +#include <uthread.h> + +static struct uthread main_thread = { + .list = LIST_HEAD_INIT(main_thread.list), +}; + +static struct uthread *current = &main_thread; + +/** + * uthread_trampoline() - Call the current thread's entry point then resume the + * main thread. + * + * This is a helper function which is used as the @func argument to the + * initjmp() function, and ultimately invoked via setjmp(). It does not return + * but instead longjmp()'s back to the main thread. + */ +static void __noreturn uthread_trampoline(void) +{ + struct uthread *curr = current; + + curr->fn(curr->arg); + curr->done = true; + current = &main_thread; + longjmp(current->ctx, 1); + /* Not reached */ + while (true) + ; +} + +/** + * uthread_free() - Free memory used by a uthread object. + */ +static void uthread_free(struct uthread *uthread) +{ + if (!uthread) + return; + free(uthread->stack); + free(uthread); +} + +int uthread_create(struct uthread *uthr, void (*fn)(void *), void *arg, + size_t stack_sz, unsigned int grp_id) +{ + bool user_allocated = false; + + if (!stack_sz) + stack_sz = CONFIG_UTHREAD_STACK_SIZE; + + if (uthr) { + user_allocated = true; + } else { + uthr = calloc(1, sizeof(*uthr)); + if (!uthr) + return -1; + } + + uthr->stack = memalign(16, stack_sz); + if (!uthr->stack) + goto err; + + uthr->fn = fn; + uthr->arg = arg; + uthr->grp_id = grp_id; + + list_add_tail(&uthr->list, ¤t->list); + + initjmp(uthr->ctx, uthread_trampoline, uthr->stack, stack_sz); + + return 0; +err: + if (!user_allocated) + free(uthr); + return -1; +} + +/** + * uthread_resume() - switch execution to a given thread + * + * @uthread: the thread object that should be resumed + */ +static void uthread_resume(struct uthread *uthread) +{ + if (!setjmp(current->ctx)) { + current = uthread; + longjmp(uthread->ctx, 1); + } +} + +bool uthread_schedule(void) +{ + struct uthread *next; + struct uthread *tmp; + + list_for_each_entry_safe(next, tmp, ¤t->list, list) { + if (!next->done) { + uthread_resume(next); + return true; + } + /* Found a 'done' thread, free its resources */ + list_del(&next->list); + uthread_free(next); + } + return false; +} + +unsigned int uthread_grp_new_id(void) +{ + static unsigned int id; + + return ++id; +} + +bool uthread_grp_done(unsigned int grp_id) +{ + struct uthread *next; + + list_for_each_entry(next, &main_thread.list, list) { + if (next->grp_id == grp_id && !next->done) + return false; + } + + return true; +} + +int uthread_mutex_lock(struct uthread_mutex *mutex) +{ + while (mutex->state == UTHREAD_MUTEX_LOCKED) + uthread_schedule(); + + mutex->state = UTHREAD_MUTEX_LOCKED; + return 0; +} + +int uthread_mutex_trylock(struct uthread_mutex *mutex) +{ + if (mutex->state == UTHREAD_MUTEX_UNLOCKED) { + mutex->state = UTHREAD_MUTEX_LOCKED; + return 0; + } + + return -EBUSY; +} + +int uthread_mutex_unlock(struct uthread_mutex *mutex) +{ + mutex->state = UTHREAD_MUTEX_UNLOCKED; + + return 0; +} |