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ARCv2: intc: default all interrupts to priority 1

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ARC HS Cores support configurable multiple interrupt priorities of upto
16 levels. In commit dec2b2849c ("ARCv2: intc: Allow interruption by
lowest priority interrupt") we switched to 15 which seems a bit
excessive given that there would be rare hardware implementing so many
preemption levels AND running Linux. It would seem that 2 levels will be
more common so switch to 1 as the default priority level. This will be
the "lower" priority level saving 0 for implementing NMI style support.

This scheme also works in systems with more than 2 prioity levels as
well.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2016-09-30 16:13:28 -07:00
parent 78833e79d5
commit 107177b14d
2 changed files with 7 additions and 9 deletions
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6
arch/arc/include/asm/irqflags-arcv2.h
View File

@ -38,10 +38,10 @@
#define AUX_IRQ_ACT_BIT_U 31
/*
* User space should be interruptable even by lowest prio interrupt
* Safe even if actual interrupt priorities is fewer or even one
* Hardware supports 16 priorities (0 highest, 15 lowest)
* Linux by default runs at 1, priority 0 reserved for NMI style interrupts
*/
#define ARCV2_IRQ_DEF_PRIO 15
#define ARCV2_IRQ_DEF_PRIO 1
/* seed value for status register */
#define ISA_INIT_STATUS_BITS (STATUS_IE_MASK | STATUS_AD_MASK | \

10
arch/arc/kernel/intc-arcv2.c
View File

@ -14,8 +14,6 @@
#include <linux/irqchip.h>
#include <asm/irq.h>
static int irq_prio;
/*
* Early Hardware specific Interrupt setup
* -Called very early (start_kernel -> setup_arch -> setup_processor)
@ -24,7 +22,7 @@ static int irq_prio;
*/
void arc_init_IRQ(void)
{
unsigned int tmp;
unsigned int tmp, irq_prio;
struct irq_build {
#ifdef CONFIG_CPU_BIG_ENDIAN
@ -67,12 +65,12 @@ void arc_init_IRQ(void)
irq_prio = irq_bcr.prio; /* Encoded as N-1 for N levels */
pr_info("archs-intc\t: %d priority levels (default %d)%s\n",
irq_prio + 1, irq_prio,
irq_prio + 1, ARCV2_IRQ_DEF_PRIO,
irq_bcr.firq ? " FIRQ (not used)":"");
/* setup status32, don't enable intr yet as kernel doesn't want */
tmp = read_aux_reg(0xa);
tmp |= STATUS_AD_MASK | (irq_prio << 1);
tmp |= STATUS_AD_MASK | (ARCV2_IRQ_DEF_PRIO << 1);
tmp &= ~STATUS_IE_MASK;
asm volatile("kflag %0 \n"::"r"(tmp));
}
@ -93,7 +91,7 @@ void arcv2_irq_enable(struct irq_data *data)
{
/* set default priority */
write_aux_reg(AUX_IRQ_SELECT, data->irq);
write_aux_reg(AUX_IRQ_PRIORITY, irq_prio);
write_aux_reg(AUX_IRQ_PRIORITY, ARCV2_IRQ_DEF_PRIO);
/*
* hw auto enables (linux unmask) all by default