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Diffstat (limited to 'core/nds32/task.c')
-rw-r--r-- | core/nds32/task.c | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/core/nds32/task.c b/core/nds32/task.c new file mode 100644 index 0000000000..9fe371e716 --- /dev/null +++ b/core/nds32/task.c @@ -0,0 +1,515 @@ +/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved. + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +/* Task scheduling / events module for Chrome EC operating system */ + +#include "atomic.h" +#include "common.h" +#include "console.h" +#include "cpu.h" +#include "irq_chip.h" +#include "link_defs.h" +#include "task.h" +#include "timer.h" +#include "uart.h" +#include "util.h" + +typedef union { + struct { + /* + * Note that sp must be the first element in the task struct + * for __switchto() to work. + */ + uint32_t sp; /* Saved stack pointer for context switch */ + uint32_t events; /* Bitmaps of received events */ + uint64_t runtime; /* Time spent in task */ + uint32_t *stack; /* Start of stack */ + }; +} task_; + +/* Value to store in unused stack */ +#define STACK_UNUSED_VALUE 0xdeadd00d + +/* declare task routine prototypes */ +#define TASK(n, r, d, s) int r(void *); +void __idle(void); +CONFIG_TASK_LIST +CONFIG_TEST_TASK_LIST +#undef TASK + +/* Task names for easier debugging */ +#define TASK(n, r, d, s) #n, +static const char * const task_names[] = { + "<< idle >>", + CONFIG_TASK_LIST + CONFIG_TEST_TASK_LIST +}; +#undef TASK + +extern int __task_start(void); + +#ifndef CONFIG_LOW_POWER_IDLE +/* Idle task. Executed when no tasks are ready to be scheduled. */ +void __idle(void) +{ + /* + * Print when the idle task starts. This is the lowest priority task, + * so this only starts once all other tasks have gotten a chance to do + * their task inits and have gone to sleep. + */ + cprintf(CC_TASK, "[%T idle task started]\n"); + + while (1) { + /* + * Wait for the next irq event. This stops the CPU clock + * (sleep / deep sleep, depending on chip config). + */ + asm("standby no_wake_grant"); + } +} +#endif /* !CONFIG_LOW_POWER_IDLE */ + +static void task_exit_trap(void) +{ + int i = task_get_current(); + cprintf(CC_TASK, "[%T Task %d (%s) exited!]\n", i, task_names[i]); + /* Exited tasks simply sleep forever */ + while (1) + task_wait_event(-1); +} + +/* Startup parameters for all tasks. */ +#define TASK(n, r, d, s) { \ + .r0 = (uint32_t)d, \ + .pc = (uint32_t)r, \ + .stack_size = s, \ +}, +static const struct { + uint32_t r0; + uint32_t pc; + uint16_t stack_size; +} const tasks_init[] = { + TASK(IDLE, __idle, 0, IDLE_TASK_STACK_SIZE) + CONFIG_TASK_LIST + CONFIG_TEST_TASK_LIST +}; +#undef TASK + +/* Contexts for all tasks */ +static task_ tasks[TASK_ID_COUNT]; +/* Sanity checks about static task invariants */ +BUILD_ASSERT(TASK_ID_COUNT <= sizeof(unsigned) * 8); +BUILD_ASSERT(TASK_ID_COUNT < (1 << (sizeof(task_id_t) * 8))); + + +/* Stacks for all tasks */ +#define TASK(n, r, d, s) + s +uint8_t task_stacks[0 + TASK(IDLE, __idle, 0, IDLE_TASK_STACK_SIZE) + CONFIG_TASK_LIST + CONFIG_TEST_TASK_LIST +] __aligned(8); + +#undef TASK + +/* Reserve space to discard context on first context switch. */ +#ifdef CONFIG_FPU +uint32_t scratchpad[17+18]; +#else +uint32_t scratchpad[17]; +#endif + +task_ *current_task = (task_ *)scratchpad; + +/* + * Should IRQs chain to svc_handler()? This should be set if either of the + * following is true: + * + * 1) Task scheduling has started, and task profiling is enabled. Task + * profiling does its tracking in svc_handler(). + * + * 2) An event was set by an interrupt; this could result in a higher-priority + * task unblocking. After checking for a task switch, svc_handler() will clear + * the flag (unless profiling is also enabled; then the flag remains set). + */ +int need_resched; + +/* + * Bitmap of all tasks ready to be run. + * + * Currently all tasks are enabled at startup. + */ +static uint32_t tasks_ready = (1<<TASK_ID_COUNT) - 1; + +static int start_called; /* Has task swapping started */ + +static inline task_ *__task_id_to_ptr(task_id_t id) +{ + return tasks + id; +} + +void interrupt_disable(void) +{ + /* clear GIE (Global Interrupt Enable) bit */ + asm volatile ("setgie.d"); + asm volatile ("dsb"); +} + +void interrupt_enable(void) +{ + /* set GIE (Global Interrupt Enable) bit */ + asm volatile ("setgie.e"); +} + +inline int in_interrupt_context(void) +{ + /* check INTL (Interrupt Stack Level) bits */ + return get_psw() & PSW_INTL_MASK; +} + +task_id_t task_get_current(void) +{ + return current_task - tasks; +} + +uint32_t *task_get_event_bitmap(task_id_t tskid) +{ + task_ *tsk = __task_id_to_ptr(tskid); + return &tsk->events; +} + +int task_start_called(void) +{ + return start_called; +} + +/** + * Scheduling system call + * + * Also includes emulation of software triggering interrupt vector + */ +void syscall_handler(int desched, task_id_t resched, int swirq) +{ + /* are we emulating an interrupt ? */ + if (swirq) { + void (*handler)(void) = __irqhandler[swirq + 1]; + /* adjust IPC to return *after* the syscall instruction */ + set_ipc(get_ipc() + 4); + /* call the regular IRQ handler */ + handler(); + return; + } + + if (desched && !current_task->events) { + /* + * Remove our own ready bit (current - tasks is same as + * task_get_current()) + */ + tasks_ready &= ~(1 << (current_task - tasks)); + } + tasks_ready |= 1 << resched; + + /* trigger a re-scheduling on exit */ + need_resched = 1; + + /* adjust IPC to return *after* the syscall instruction */ + set_ipc(get_ipc() + 4); +} + +task_ *next_sched_task(void) +{ + return __task_id_to_ptr(31 - __builtin_clz(tasks_ready)); +} + +static inline void __schedule(int desched, int resched, int swirq) +{ + register int p0 asm("$r0") = desched; + register int p1 asm("$r1") = resched; + register int p2 asm("$r2") = swirq; + + asm("syscall 0" : : "r"(p0), "r"(p1), "r"(p2)); +} + +static uint32_t __wait_evt(int timeout_us, task_id_t resched) +{ + task_ *tsk = current_task; + task_id_t me = tsk - tasks; + uint32_t evt; + int ret; + + ASSERT(!in_interrupt_context()); + + if (timeout_us > 0) { + timestamp_t deadline = get_time(); + deadline.val += timeout_us; + ret = timer_arm(deadline, me); + ASSERT(ret == EC_SUCCESS); + } + while (!(evt = atomic_read_clear(&tsk->events))) { + /* Remove ourself and get the next task in the scheduler */ + __schedule(1, resched, 0); + resched = TASK_ID_IDLE; + } + if (timeout_us > 0) + timer_cancel(me); + return evt; +} + +uint32_t task_set_event(task_id_t tskid, uint32_t event, int wait) +{ + task_ *receiver = __task_id_to_ptr(tskid); + ASSERT(receiver); + + /* Set the event bit in the receiver message bitmap */ + atomic_or(&receiver->events, event); + + /* Re-schedule if priorities have changed */ + if (in_interrupt_context()) { + /* The receiver might run again */ + atomic_or(&tasks_ready, 1 << tskid); + need_resched = 1; + } else { + if (wait) + return __wait_evt(-1, tskid); + else + __schedule(0, tskid, 0); + } + + return 0; +} + +uint32_t task_wait_event(int timeout_us) +{ + return __wait_evt(timeout_us, TASK_ID_IDLE); +} + +static uint32_t get_int_mask(void) +{ + uint32_t ret; + asm volatile ("mfsr %0, $INT_MASK" : "=r"(ret)); + return ret; +} + +static void set_int_mask(uint32_t val) +{ + asm volatile ("mtsr %0, $INT_MASK" : : "r"(val)); +} + +static void set_int_priority(uint32_t val) +{ + asm volatile ("mtsr %0, $INT_PRI" : : "r"(val)); +} + +void task_enable_irq(int irq) +{ + int cpu_int = chip_enable_irq(irq); + if (cpu_int >= 0) + set_int_mask(get_int_mask() | (1 << cpu_int)); +} + +void task_disable_irq(int irq) +{ + int cpu_int = chip_disable_irq(irq); + if (cpu_int >= 0) + set_int_mask(get_int_mask() & ~(1 << cpu_int)); +} + +void task_clear_pending_irq(int irq) +{ + chip_clear_pending_irq(irq); +} + +void task_trigger_irq(int irq) +{ + int cpu_int = chip_trigger_irq(irq); + if (cpu_int > 0) + __schedule(0, 0, cpu_int); +} + +/* + * Initialize IRQs in the IVIC and set their priorities as defined by the + * DECLARE_IRQ statements. + */ +static void ivic_init_irqs(void) +{ + /* Get the IRQ priorities section from the linker */ + int exc_calls = __irqprio_end - __irqprio; + int i; + uint32_t all_priorities = 0; + + /* chip-specific interrupt controller initialization */ + chip_init_irqs(); + + /* Mask all interrupts, only keep division by zero exception */ + set_int_mask(1 << 30 /* IDIVZ */); + + /* + * Re-enable global interrupts in case they're disabled. On a reboot, + * they're already enabled; if we've jumped here from another image, + * they're not. + */ + interrupt_enable(); + + /* Set priorities */ + for (i = 0; i < exc_calls; i++) { + uint8_t irq = __irqprio[i].irq; + uint8_t prio = __irqprio[i].priority; + all_priorities |= (prio & 0x3) << (irq * 2); + } + set_int_priority(all_priorities); +} + +void mutex_lock(struct mutex *mtx) +{ + uint32_t id = 1 << task_get_current(); + + ASSERT(id != TASK_ID_INVALID); + + /* critical section with interrupts off */ + asm volatile ("setgie.d ; dsb"); + mtx->waiters |= id; + while (1) { + if (!mtx->lock) { /* we got it ! */ + mtx->lock = 2; + mtx->waiters &= ~id; + /* end of critical section : re-enable interrupts */ + asm volatile ("setgie.e"); + return; + } else { /* Contention on the mutex */ + /* end of critical section : re-enable interrupts */ + asm volatile ("setgie.e"); + /* Sleep waiting for our turn */ + task_wait_event(0); + /* re-enter critical section */ + asm volatile ("setgie.d ; dsb"); + } + } +} + +void mutex_unlock(struct mutex *mtx) +{ + uint32_t waiters; + task_ *tsk = current_task; + + waiters = mtx->waiters; + /* give back the lock */ + mtx->lock = 0; + + while (waiters) { + task_id_t id = 31 - __builtin_clz(waiters); + + /* Somebody is waiting on the mutex */ + task_set_event(id, TASK_EVENT_MUTEX, 0); + waiters &= ~(1 << id); + } + + /* Ensure no event is remaining from mutex wake-up */ + atomic_clear(&tsk->events, TASK_EVENT_MUTEX); +} + +void task_print_list(void) +{ + int i; + + ccputs("Task Ready Name Events Time (s) StkUsed\n"); + + for (i = 0; i < TASK_ID_COUNT; i++) { + char is_ready = (tasks_ready & (1<<i)) ? 'R' : ' '; + uint32_t *sp; + + int stackused = tasks_init[i].stack_size; + + for (sp = tasks[i].stack; + sp < (uint32_t *)tasks[i].sp && *sp == STACK_UNUSED_VALUE; + sp++) + stackused -= sizeof(uint32_t); + + ccprintf("%4d %c %-16s %08x %11.6ld %3d/%3d\n", i, is_ready, + task_names[i], tasks[i].events, tasks[i].runtime, + stackused, tasks_init[i].stack_size); + cflush(); + } +} + +int command_task_info(int argc, char **argv) +{ + task_print_list(); + + return EC_SUCCESS; +} +DECLARE_CONSOLE_COMMAND(taskinfo, command_task_info, + NULL, + "Print task info", + NULL); + +static int command_task_ready(int argc, char **argv) +{ + if (argc < 2) { + ccprintf("tasks_ready: 0x%08x\n", tasks_ready); + } else { + tasks_ready = strtoi(argv[1], NULL, 16); + ccprintf("Setting tasks_ready to 0x%08x\n", tasks_ready); + __schedule(0, 0, 0); + } + + return EC_SUCCESS; +} +DECLARE_CONSOLE_COMMAND(taskready, command_task_ready, + "[setmask]", + "Print/set ready tasks", + NULL); + +void task_pre_init(void) +{ + uint32_t *stack_next = (uint32_t *)task_stacks; + int i; + + /* Fill the task memory with initial values */ + for (i = 0; i < TASK_ID_COUNT; i++) { + uint32_t *sp; + /* Stack size in words */ + uint32_t ssize = tasks_init[i].stack_size / 4; + + tasks[i].stack = stack_next; + + /* + * Update stack used by first frame: 15 regs + PC + PSW + */ + sp = stack_next + ssize - 17; + tasks[i].sp = (uint32_t)sp; + + /* Initial context on stack (see __switchto()) */ + sp[7] = tasks_init[i].r0; /* r0 */ + sp[15] = (uint32_t)task_exit_trap; /* lr */ + sp[1] = tasks_init[i].pc; /* pc */ + sp[0] = 0x70009; /* psw */ + sp[16] = (uint32_t)(sp + 17); /* sp */ + + /* Fill unused stack; also used to detect stack overflow. */ + for (sp = stack_next; sp < (uint32_t *)tasks[i].sp; sp++) + *sp = STACK_UNUSED_VALUE; + + stack_next += ssize; + } + + /* + * Fill in guard value in scratchpad to prevent stack overflow + * detection failure on the first context switch. This works because + * the first word in the scratchpad is where the switcher will store + * sp, so it's ok to blow away. + */ + ((task_ *)scratchpad)->stack = (uint32_t *)scratchpad; + *(uint32_t *)scratchpad = STACK_UNUSED_VALUE; + + /* Initialize IRQs */ + ivic_init_irqs(); +} + +int task_start(void) +{ + start_called = 1; + + return __task_start(); +} |