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MIPS: DEC: Implement FPU interrupt counter

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Implement a cheap way to count FPU interrupts for R2k/R3k DECstation
systems.  Do this manually in handcoded assembly, rather than calling
`kstat_incr_irq_this_cpu' that would require setting up a stack frame
and a lot of redirection.  This is not going to be a problem because the
FPU interrupt is local to the CPU and also there is one CPU only anyway.

So at bootstrap determine the address of the correct location within
`struct irq_desc', and then only refer to it directly in the interrupt
handler.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9713/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Maciej W. Rozycki 2015-04-03 23:32:08 +01:00 committed by Ralf Baechle
parent 7aecd5ca80
commit f02cf4691e
2 changed files with 19 additions and 4 deletions
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7
arch/mips/dec/int-handler.S
View File

@ -267,8 +267,13 @@ handle_it:
#ifdef CONFIG_32BIT
fpu:
lw t0,fpu_kstat_irq
nop
lw t1,(t0)
nop
addu t1,1
j handle_fpe_int
nop
sw t1,(t0)
#endif
spurious:

16
arch/mips/dec/setup.c
View File

@ -12,13 +12,15 @@
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/irq.h>
#include <linux/irqnr.h>
#include <linux/module.h>
#include <linux/param.h>
#include <linux/percpu-defs.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/pm.h>
#include <linux/irq.h>
#include <asm/bootinfo.h>
#include <asm/cpu.h>
@ -98,6 +100,7 @@ int_ptr asic_mask_nr_tbl[DEC_MAX_ASIC_INTS][2] = {
{ { .i = ~0 }, { .p = asic_intr_unimplemented } },
};
int cpu_fpu_mask = DEC_CPU_IRQ_MASK(DEC_CPU_INR_FPU);
int *fpu_kstat_irq;
static struct irqaction ioirq = {
.handler = no_action,
@ -755,8 +758,15 @@ void __init arch_init_irq(void)
dec_interrupt[DEC_IRQ_HALT] = -1;
/* Register board interrupts: FPU and cascade. */
if (dec_interrupt[DEC_IRQ_FPU] >= 0)
setup_irq(dec_interrupt[DEC_IRQ_FPU], &fpuirq);
if (dec_interrupt[DEC_IRQ_FPU] >= 0) {
struct irq_desc *desc_fpu;
int irq_fpu;
irq_fpu = dec_interrupt[DEC_IRQ_FPU];
setup_irq(irq_fpu, &fpuirq);
desc_fpu = irq_to_desc(irq_fpu);
fpu_kstat_irq = this_cpu_ptr(desc_fpu->kstat_irqs);
}
if (dec_interrupt[DEC_IRQ_CASCADE] >= 0)
setup_irq(dec_interrupt[DEC_IRQ_CASCADE], &ioirq);