m68k: Mac via cleanup and commentry

No behavioural changes, just cleanups and better documentation.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

1 files changed, 32 insertions, 47 deletions

diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c
index 1bdb03c73c0..125404788e8 100644
--- a/arch/m68k/mac/via.c
+++ b/arch/m68k/mac/via.c
@@ -37,10 +37,6 @@
 #include <asm/mac_psc.h>
 
 volatile __u8 *via1, *via2;
-#if 0
-/* See note in mac_via.h about how this is possibly not useful */
-volatile long *via_memory_bogon=(long *)&via_memory_bogon;
-#endif
 int rbv_present;
 int via_alt_mapping;
 EXPORT_SYMBOL(via_alt_mapping);
@@ -66,7 +62,7 @@ static int gIER,gIFR,gBufA,gBufB;
 #define MAC_CLOCK_LOW           (MAC_CLOCK_TICK&0xFF)
 #define MAC_CLOCK_HIGH          (MAC_CLOCK_TICK>>8)
 
-/* To disable a NuBus slot on Quadras we make the slot IRQ lines outputs, set
+/* To disable a NuBus slot on Quadras we make that slot IRQ line an output set
  * high. On RBV we just use the slot interrupt enable register. On Macs with
  * genuine VIA chips we must use nubus_disabled to keep track of disabled slot
  * interrupts. When any slot IRQ is disabled we mask the (edge triggered) CA1
@@ -180,7 +176,7 @@ void __init via_init(void)
         via1[vT1CH] = 0;
         via1[vT2CL] = 0;
         via1[vT2CH] = 0;
-        via1[vACR] &= 0x3F;
+        via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
         via1[vACR] &= ~0x03; /* disable port A & B latches */
 
         /*
@@ -203,40 +199,41 @@ void __init via_init(void)
 
         /* Everything below this point is VIA2/RBV only... */
 
-        if (oss_present) return;
+        if (oss_present)
+                return;
 
-#if 1
         /* Some machines support an alternate IRQ mapping that spreads  */
         /* Ethernet and Sound out to their own autolevel IRQs and moves */
         /* VIA1 to level 6. A/UX uses this mapping and we do too.  Note */
         /* that the IIfx emulates this alternate mapping using the OSS. */
 
-        switch(macintosh_config->ident) {
-                case MAC_MODEL_P475:
-                case MAC_MODEL_P475F:
-                case MAC_MODEL_P575:
-                case MAC_MODEL_Q605:
-                case MAC_MODEL_Q605_ACC:
-                case MAC_MODEL_C610:
-                case MAC_MODEL_Q610:
-                case MAC_MODEL_Q630:
-                case MAC_MODEL_C650:
-                case MAC_MODEL_Q650:
-                case MAC_MODEL_Q700:
-                case MAC_MODEL_Q800:
-                case MAC_MODEL_Q900:
-                case MAC_MODEL_Q950:
+        via_alt_mapping = 0;
+        if (macintosh_config->via_type == MAC_VIA_QUADRA)
+                switch (macintosh_config->ident) {
+                case MAC_MODEL_C660:
+                case MAC_MODEL_Q840:
+                        /* not applicable */
+                        break;
+                case MAC_MODEL_P588:
+                case MAC_MODEL_TV:
+                case MAC_MODEL_PB140:
+                case MAC_MODEL_PB145:
+                case MAC_MODEL_PB160:
+                case MAC_MODEL_PB165:
+                case MAC_MODEL_PB165C:
+                case MAC_MODEL_PB170:
+                case MAC_MODEL_PB180:
+                case MAC_MODEL_PB180C:
+                case MAC_MODEL_PB190:
+                case MAC_MODEL_PB520:
+                        /* not yet tested */
+                        break;
+                default:
                         via_alt_mapping = 1;
                         via1[vDirB] |= 0x40;
                         via1[vBufB] &= ~0x40;
                         break;
-                default:
-                        via_alt_mapping = 0;
-                        break;
-        }
-#else
-        via_alt_mapping = 0;
-#endif
+                }
 
         /*
          * Now initialize VIA2. For RBV we just kill all interrupts;
@@ -252,14 +249,17 @@ void __init via_init(void)
                 via2[vT1CH] = 0;
                 via2[vT2CL] = 0;
                 via2[vT2CH] = 0;
-                via2[vACR] &= 0x3F;
+                via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
                 via2[vACR] &= ~0x03; /* disable port A & B latches */
         }
 
         /*
-         * Set vPCR for SCSI interrupts (but not on RBV)
+         * Set vPCR for control line interrupts (but not on RBV)
          */
         if (!rbv_present) {
+                /* For all VIA types, CA1 (SLOTS IRQ) and CB1 (ASC IRQ)
+                 * are made negative edge triggered here.
+                 */
                 if (macintosh_config->scsi_type == MAC_SCSI_OLD) {
                         /* CB2 (IRQ) indep. input, positive edge */
                         /* CA2 (DRQ) indep. input, positive edge */
@@ -466,21 +466,6 @@ irqreturn_t via1_irq(int irq, void *dev_id)
                 ++irq_num;
                 irq_bit <<= 1;
         } while (events >= irq_bit);
-
-#if 0 /* freakin' pmu is doing weird stuff */
-        if (!oss_present) {
-                /* This (still) seems to be necessary to get IDE
-                   working.  However, if you enable VBL interrupts,
-                   you're screwed... */
-                /* FIXME: should we check the SLOTIRQ bit before
-                   pulling this stunt? */
-                /* No, it won't be set. that's why we're doing this. */
-                via_irq_disable(IRQ_MAC_NUBUS);
-                via_irq_clear(IRQ_MAC_NUBUS);
-                m68k_handle_int(IRQ_MAC_NUBUS);
-                via_irq_enable(IRQ_MAC_NUBUS);
-        }
-#endif
         return IRQ_HANDLED;
 }