diff options
| author | Randall Spangler <rspangler@chromium.org> | 2012-04-06 09:33:41 -0700 |
|---|---|---|
| committer | Randall Spangler <rspangler@chromium.org> | 2012-04-09 10:33:35 -0700 |
| commit | e9328ac4f63351b4282916034270aa86b7e74922 (patch) | |
| tree | d0fde5840594c33709927a5a4d1fabfe0f858c26 /core/cortex-m/task.c | |
| parent | 1a9a415cf68c6e8e3b31972c072c81ed886290ab (diff) | |
| download | chrome-ec-e9328ac4f63351b4282916034270aa86b7e74922.tar.gz | |
Support dynamically changing the system clock
Add nopll command to turn off the PLL, reducing the system clock to 16Mhz.
Signed-off-by: Randall Spangler <rspangler@chromium.org>
BUG=chrome-os-partner:8798
TEST=manual
boot system
press power button to boot x86
temps // should print all temperatures
timerinfo
timerinfo
timerinfo // convince yourself this is counting up at about 1MHz
nopll // this drops the system clock to 16MHz
temps // should still print all temperatures
timerinfo
timerinfo
timerinfo // should still be counting up at about 1MHz
Change-Id: Ie29ceb17af348148bffadf63d60c1b731f4c3f6d
Diffstat (limited to 'core/cortex-m/task.c')
| -rw-r--r-- | core/cortex-m/task.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/core/cortex-m/task.c b/core/cortex-m/task.c index 1f15bf5df6..34c12d674c 100644 --- a/core/cortex-m/task.c +++ b/core/cortex-m/task.c @@ -35,7 +35,7 @@ typedef union { /* declare task routine prototypes */ #define TASK(n, r, d) int r(void *); #include TASK_LIST -void __idle(void); +static void __idle(void); CONFIG_TASK_LIST #undef TASK @@ -51,6 +51,17 @@ static const char * const task_names[] = { extern void __switchto(task_ *from, task_ *to); +/* Idle task. Executed when no tasks are ready to be scheduled. */ +void __idle(void) +{ + while (1) { + /* Wait for the irq event */ + asm("wfi"); + /* TODO: more power management here */ + } +} + + static void task_exit_trap(void) { int i = task_get_current(); |