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ARM: rebase available priority levels to 0

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We have a new policy: users should not be able to configure
an interrupt with "forbidden" priority levels, and any priority
levels with special semantics will be activated by flags.

Change-Id: I757c19cfedcb1d0938eaf4da348ddafb71b3e001
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2016-02-04 13:55:57 -08:00 • committed by Anas Nashif
commit 4455ee6d87
3 changed files with 49 additions and 15 deletions
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44
arch/arm/core/irq_manage.c
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@ -70,20 +70,42 @@ void irq_disable(unsigned int irq)
*
* @brief Set an interrupt's priority
*
* Valid values are from 1 to 255. Interrupts of priority 1 are not masked when
* interrupts are locked system-wide, so care must be taken when using them. ISR
* installed with priority 1 interrupts cannot make kernel calls.
*
* Priority 0 is reserved for kernel usage and cannot be used.
*
* The priority is verified if ASSERT_ON is enabled.
* The priority is verified if ASSERT_ON is enabled. The maximum number
* of priority levels is a little complex, as there are some hardware
* priority levels which are reserved: three for various types of exceptions,
* and possibly one additional to support zero latency interrupts.
*
* @return N/A
*/
void _irq_priority_set(unsigned int irq,
unsigned int prio)
void _irq_priority_set(unsigned int irq, unsigned int prio, uint32_t flags)
{
__ASSERT(prio > 0 && prio < 256, "invalid priority!");
/* Hardware priority levels 0 and 1 reserved for Kernel use.
* So we add 2 to the requested priority level. If we support
* ZLI, 2 is also reserved so we add 3.
*/
#if CONFIG_ZERO_LATENCY_IRQS
#define IRQ_PRIORITY_OFFSET 3
/* If we have zero latency interrupts, that makes priority level 2
* a case with special semantics; it is not masked by irq_lock().
* Our policy is to express priority levels with special properties
* via flags
*/
if (flags | IRQ_ZERO_LATENCY) {
prio = 2;
} else {
prio += IRQ_PRIORITY_OFFSET;
}
#else
#define IRQ_PRIORITY_OFFSET 2
ARG_UNUSED(flags);
prio += IRQ_PRIORITY_OFFSET;
#endif
/* Last priority level reserved for PendSV exception */
__ASSERT(prio < ((1 << CONFIG_NUM_IRQ_PRIO_BITS) - 1),
"invalid priority %d! values must be less than %d\n",
prio - IRQ_PRIORITY_OFFSET,
(1 << CONFIG_NUM_IRQ_PRIO_BITS) - (IRQ_PRIORITY_OFFSET + 1));
_NvicIrqPrioSet(irq, _EXC_PRIO(prio));
}
@ -146,7 +168,7 @@ int irq_connect_dynamic(unsigned int irq,
{
ARG_UNUSED(flags);
_irq_handler_set(irq, isr, arg);
_irq_priority_set(irq, prio);
_irq_priority_set(irq, prio, flags);
return irq;
}