sh: interrupt exception handling rework

Kill off interrupt_table for all of the CPU subtypes, we now
default in to stepping in to do_IRQ() for _all_ IRQ exceptions
and counting the spurious ones, rather than simply flipping on
the ones we cared about. This and enabling the IRQ by default
automatically has already uncovered a couple of bugs and IRQs
that weren't being caught, as well as some that are being
generated far too often (SCI Tx Data Empty, for example).

The general rationale is to use a marker for interrupt exceptions,
test for it in the handle_exception() path, and skip out to
do_IRQ() if it's found. Everything else follows the same behaviour
of finding the cached EXPEVT value in r2/r2_bank, we just rip out
the INTEVT read from entry.S entirely (except for in the kGDB NMI
case, which is another matter).

Note that while this changes the do_IRQ() semantics regarding r4
handling, they were fundamentally broken anyways (relying entirely
on r2_bank for the cached code). With this, we do the INTEVT read
from do_IRQ() itself (in the CONFIG_CPU_HAS_INTEVT case), or fall
back on r4 for the muxed IRQ number, which should also be closer
to what SH-2 and SH-2A want anyways.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 7 insertions, 16 deletions

diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
index 3b93682bf18..acf2602569c 100644
--- a/arch/sh/kernel/irq.c
+++ b/arch/sh/kernel/irq.c
@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/kernel_stat.h>
 #include <linux/seq_file.h>
+#include <linux/io.h>
 #include <asm/irq.h>
 #include <asm/processor.h>
 #include <asm/uaccess.h>
@@ -26,6 +27,7 @@ atomic_t irq_err_count;
  */
 void ack_bad_irq(unsigned int irq)
 {
+        atomic_inc(&irq_err_count);
         printk("unexpected IRQ trap at vector %02x\n", irq);
 }
 
@@ -85,7 +87,7 @@ asmlinkage int do_IRQ(unsigned long r4, unsigned long r5,
                       struct pt_regs regs)
 {
         struct pt_regs *old_regs = set_irq_regs(&regs);
-        int irq = r4;
+        int irq;
 #ifdef CONFIG_4KSTACKS
         union irq_ctx *curctx, *irqctx;
 #endif
@@ -109,20 +111,9 @@ asmlinkage int do_IRQ(unsigned long r4, unsigned long r5,
 #endif
 
 #ifdef CONFIG_CPU_HAS_INTEVT
-        __asm__ __volatile__ (
-#ifdef CONFIG_CPU_HAS_SR_RB
-                "stc    r2_bank, %0\n\t"
+        irq = (ctrl_inl(INTEVT) >> 5) - 16;
 #else
-                "mov.l  @%1, %0\n\t"
-#endif
-                "shlr2  %0\n\t"
-                "shlr2  %0\n\t"
-                "shlr   %0\n\t"
-                "add    #-16, %0\n\t"
-                : "=z" (irq), "=r" (r4)
-                : "1" (INTEVT)
-                : "memory"
-        );
+        irq = r4;
 #endif
 
         irq = irq_demux(irq);
@@ -147,9 +138,9 @@ asmlinkage int do_IRQ(unsigned long r4, unsigned long r5,
                 __asm__ __volatile__ (
                         "mov    %0, r4          \n"
                         "mov    r15, r9         \n"
-                        "jsr    @%2             \n"
+                        "jsr    @%1             \n"
                         /* swith to the irq stack */
-                        " mov   %3, r15         \n"
+                        " mov   %2, r15         \n"
                         /* restore the stack (ring zero) */
                         "mov    r9, r15         \n"
                         : /* no outputs */