m68k: Mac IRQ prep

Make sure that there are no slot IRQs asserted before leaving the nubus
handler. If there are and we don't then the nubus gets wedged because this
prevents a CA1 transition, which means no more nubus IRQs.

Make the interrupt dispatch loops terminate sooner.

Explicitly initialise the VIA latches to make the code more easily understood.

Also some cleanups.

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

1 files changed, 87 insertions, 54 deletions

diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c
index 21b03180d9f4..0c1cc45c570d 100644
--- a/arch/m68k/mac/via.c
+++ b/arch/m68k/mac/via.c
@@ -13,6 +13,10 @@
  * for info.  A full-text web search on 6522 AND VIA will probably also
  * net some usefulness. <cananian@alumni.princeton.edu> 20apr1999
  *
+ * Additional data is here (the SY6522 was used in the Mac II etc):
+ *     http://www.6502.org/documents/datasheets/synertek/synertek_sy6522.pdf
+ *     http://www.6502.org/documents/datasheets/synertek/synertek_sy6522_programming_reference.pdf
+ *
  * PRAM/RTC access algorithms are from the NetBSD RTC toolkit version 1.08b
  * by Erik Vogan and adapted to Linux by Joshua M. Thompson (funaho@jurai.org)
  *
@@ -37,7 +41,7 @@ volatile __u8 *via1, *via2;
 /* 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,via_alt_mapping;
+int rbv_present, via_alt_mapping;
 __u8 rbv_clear;
 
 /*
@@ -138,11 +142,11 @@ void __init via_init(void)
 
         printk(KERN_INFO "VIA2 at %p is ", via2);
         if (rbv_present) {
-                printk(KERN_INFO "an RBV\n");
+                printk("an RBV\n");
         } else if (oss_present) {
-                printk(KERN_INFO "an OSS\n");
+                printk("an OSS\n");
         } else {
-                printk(KERN_INFO "a 6522 or clone\n");
+                printk("a 6522 or clone\n");
         }
 
 #ifdef DEBUG_VIA
@@ -163,6 +167,7 @@ void __init via_init(void)
         via1[vT2CL] = 0;
         via1[vT2CH] = 0;
         via1[vACR] &= 0x3F;
+        via1[vACR] &= ~0x03; /* disable port A & B latches */
 
         /*
          * SE/30: disable video IRQ
@@ -234,6 +239,22 @@ void __init via_init(void)
                 via2[vT2CL] = 0;
                 via2[vT2CH] = 0;
                 via2[vACR] &= 0x3F;
+                via2[vACR] &= ~0x03; /* disable port A & B latches */
+        }
+
+        /*
+         * Set vPCR for SCSI interrupts (but not on RBV)
+         */
+        if (!rbv_present) {
+                if (macintosh_config->scsi_type == MAC_SCSI_OLD) {
+                        /* CB2 (IRQ) indep. input, positive edge */
+                        /* CA2 (DRQ) indep. input, positive edge */
+                        via2[vPCR] = 0x66;
+                } else {
+                        /* CB2 (IRQ) indep. input, negative edge */
+                        /* CA2 (DRQ) indep. input, negative edge */
+                        via2[vPCR] = 0x22;
+                }
         }
 }
 
@@ -367,19 +388,14 @@ void __init via_nubus_init(void)
 
         /* unlock nubus transactions */
 
-        if (!rbv_present) {
+        if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
+            (macintosh_config->adb_type != MAC_ADB_PB2)) {
                 /* set the line to be an output on non-RBV machines */
-                if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
-                   (macintosh_config->adb_type != MAC_ADB_PB2)) {
+                if (!rbv_present)
                         via2[vDirB] |= 0x02;
-                }
-        }
-
-        /* this seems to be an ADB bit on PMU machines */
-        /* according to MkLinux.  -- jmt               */
 
-        if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
-            (macintosh_config->adb_type != MAC_ADB_PB2)) {
+                /* this seems to be an ADB bit on PMU machines */
+                /* according to MkLinux.  -- jmt               */
                 via2[gBufB] |= 0x02;
         }
 
@@ -420,20 +436,25 @@ void __init via_nubus_init(void)
 
 irqreturn_t via1_irq(int irq, void *dev_id)
 {
-        int irq_bit, i;
-        unsigned char events, mask;
+        int irq_num;
+        unsigned char irq_bit, events;
 
-        mask = via1[vIER] & 0x7F;
-        if (!(events = via1[vIFR] & mask))
+        events = via1[vIFR] & via1[vIER] & 0x7F;
+        if (!events)
                 return IRQ_NONE;
 
-        for (i = 0, irq_bit = 1 ; i < 7 ; i++, irq_bit <<= 1)
+        irq_num = VIA1_SOURCE_BASE;
+        irq_bit = 1;
+        do {
                 if (events & irq_bit) {
                         via1[vIER] = irq_bit;
                         via1[vIFR] = irq_bit;
-                        m68k_handle_int(VIA1_SOURCE_BASE + i);
+                        m68k_handle_int(irq_num);
                         via1[vIER] = irq_bit | 0x80;
                 }
+                ++irq_num;
+                irq_bit <<= 1;
+        } while (events >= irq_bit);
 
 #if 0 /* freakin' pmu is doing weird stuff */
         if (!oss_present) {
@@ -454,20 +475,25 @@ irqreturn_t via1_irq(int irq, void *dev_id)
 
 irqreturn_t via2_irq(int irq, void *dev_id)
 {
-        int irq_bit, i;
-        unsigned char events, mask;
+        int irq_num;
+        unsigned char irq_bit, events;
 
-        mask = via2[gIER] & 0x7F;
-        if (!(events = via2[gIFR] & mask))
+        events = via2[gIFR] & via2[gIER] & 0x7F;
+        if (!events)
                 return IRQ_NONE;
 
-        for (i = 0, irq_bit = 1 ; i < 7 ; i++, irq_bit <<= 1)
+        irq_num = VIA2_SOURCE_BASE;
+        irq_bit = 1;
+        do {
                 if (events & irq_bit) {
                         via2[gIER] = irq_bit;
                         via2[gIFR] = irq_bit | rbv_clear;
-                        m68k_handle_int(VIA2_SOURCE_BASE + i);
+                        m68k_handle_int(irq_num);
                         via2[gIER] = irq_bit | 0x80;
                 }
+                ++irq_num;
+                irq_bit <<= 1;
+        } while (events >= irq_bit);
         return IRQ_HANDLED;
 }
 
@@ -478,19 +504,37 @@ irqreturn_t via2_irq(int irq, void *dev_id)
 
 irqreturn_t via_nubus_irq(int irq, void *dev_id)
 {
-        int irq_bit, i;
-        unsigned char events;
-
-        if (!(events = ~via2[gBufA] & nubus_active))
+        int slot_irq;
+        unsigned char slot_bit, events;
+
+        events = ~via2[gBufA] & 0x7F;
+        if (rbv_present)
+                events &= via2[rSIER];
+        else
+                events &= nubus_active;
+        if (!events)
                 return IRQ_NONE;
 
-        for (i = 0, irq_bit = 1 ; i < 7 ; i++, irq_bit <<= 1) {
-                if (events & irq_bit) {
-                        via_irq_disable(NUBUS_SOURCE_BASE + i);
-                        m68k_handle_int(NUBUS_SOURCE_BASE + i);
-                        via_irq_enable(NUBUS_SOURCE_BASE + i);
-                }
-        }
+        do {
+                slot_irq = IRQ_NUBUS_F;
+                slot_bit = 0x40;
+                do {
+                        if (events & slot_bit) {
+                                events &= ~slot_bit;
+                                m68k_handle_int(slot_irq);
+                        }
+                        --slot_irq;
+                        slot_bit >>= 1;
+                } while (events);
+
+                /* clear the CA1 interrupt and make certain there's no more. */
+                via2[gIFR] = 0x02 | rbv_clear;
+                events = ~via2[gBufA] & 0x7F;
+                if (rbv_present)
+                        events &= via2[rSIER];
+                else
+                        events &= nubus_active;
+        } while (events);
         return IRQ_HANDLED;
 }
 
@@ -506,20 +550,6 @@ void via_irq_enable(int irq) {
         if (irq_src == 1) {
                 via1[vIER] = irq_bit | 0x80;
         } else if (irq_src == 2) {
-                /*
-                 * Set vPCR for SCSI interrupts (but not on RBV)
-                 */
-                if ((irq_idx == 0) && !rbv_present) {
-                        if (macintosh_config->scsi_type == MAC_SCSI_OLD) {
-                                /* CB2 (IRQ) indep. input, positive edge */
-                                /* CA2 (DRQ) indep. input, positive edge */
-                                via2[vPCR] = 0x66;
-                        } else {
-                                /* CB2 (IRQ) indep. input, negative edge */
-                                /* CA2 (DRQ) indep. input, negative edge */
-                                via2[vPCR] = 0x22;
-                        }
-                }
                 via2[gIER] = irq_bit | 0x80;
         } else if (irq_src == 7) {
                 nubus_active |= irq_bit;
@@ -557,9 +587,9 @@ void via_irq_disable(int irq) {
 #endif
 
         if (irq_src == 1) {
-                via1[vIER] = irq_bit;
+                via1[vIER] = irq_bit & 0x7F;
         } else if (irq_src == 2) {
-                via2[gIER] = irq_bit;
+                via2[gIER] = irq_bit & 0x7F;
         } else if (irq_src == 7) {
                 if (rbv_present) {
                         /* disable the slot interrupt.  SIER works like IER. */
@@ -586,7 +616,9 @@ void via_irq_clear(int irq) {
         } else if (irq_src == 2) {
                 via2[gIFR] = irq_bit | rbv_clear;
         } else if (irq_src == 7) {
-                /* FIXME: hmm.. */
+                /* FIXME: There is no way to clear an individual nubus slot
+                 * IRQ flag, other than getting the device to do it.
+                 */
         }
 }
 
@@ -606,6 +638,7 @@ int via_irq_pending(int irq)
         } else if (irq_src == 2) {
                 return via2[gIFR] & irq_bit;
         } else if (irq_src == 7) {
+                /* FIXME: this can't work while a slot irq is disabled! */
                 return ~via2[gBufA] & irq_bit;
         }
         return 0;