Add a simple mini-driver for the ELCR register. Originally, the ELCR

register controlled the trigger mode and polarity of EISA interrupts.
However, it appears that most (all?) PCI systems use the ELCR to manage
the trigger mode and polarity of ISA interrupts as well since ISA IRQs used
to route PCI interrupts need to be level triggered with active low
polarity.  We check to see if the ELCR exists by sanity checking the value
we get back ensuring that IRQS 0 (8254), 1 (atkbd), 2 (the link from the
slave PIC), and 8 (RTC) are all clear indicating edge trigger and active
high polarity.

This mini-driver will be used by the atpic driver to manage the trigger and
polarity of ISA IRQs.  Also, the mptable parsing code will use this mini
driver rather than examining the ELCR directly.

1 files changed, 5 insertions, 0 deletions

diff --git a/sys/i386/include/intr_machdep.h b/sys/i386/include/intr_machdep.h
index 0aacd91..6794751 100644
--- a/sys/i386/include/intr_machdep.h
+++ b/sys/i386/include/intr_machdep.h
@@ -77,6 +77,11 @@ struct intrframe;
 
 extern struct mtx icu_lock;
 
+/* XXX: The elcr_* prototypes probably belong somewhere else. */
+int	elcr_probe(void);
+enum intr_trigger elcr_read_trigger(u_int irq);
+void	elcr_resume(void);
+void	elcr_write_trigger(u_int irq, enum intr_trigger trigger);
 int	intr_add_handler(const char *name, int vector, driver_intr_t handler,
     void *arg, enum intr_type flags, void **cookiep);
 void	intr_execute_handlers(struct intsrc *isrc, struct intrframe *iframe);