arch/m68k/mac/oss.c

   1 /*
   2  *      Operating System Services (OSS) chip handling
   3  *      Written by Joshua M. Thompson (funaho@jurai.org)
   4  *
   5  *
   6  *      This chip is used in the IIfx in place of VIA #2. It acts like a fancy
   7  *      VIA chip with prorammable interrupt levels.
   8  *
   9  * 990502 (jmt) - Major rewrite for new interrupt architecture as well as some
  10  *                recent insights into OSS operational details.
  11  * 990610 (jmt) - Now taking full advantage of the OSS. Interrupts are mapped
  12  *                to mostly match the A/UX interrupt scheme supported on the
  13  *                VIA side. Also added support for enabling the ISM irq again
  14  *                since we now have a functional IOP manager.
  15  */
  16
  17 #include <linux/types.h>
  18 #include <linux/kernel.h>
  19 #include <linux/mm.h>
  20 #include <linux/delay.h>
  21 #include <linux/init.h>
  22 #include <linux/irq.h>
  23
  24 #include <asm/macintosh.h>
  25 #include <asm/macints.h>
  26 #include <asm/mac_via.h>
  27 #include <asm/mac_oss.h>
  28
  29 int oss_present;
  30 volatile struct mac_oss *oss;
  31
  32 /*
  33  * Initialize the OSS
  34  *
  35  * The OSS "detection" code is actually in via_init() which is always called
  36  * before us. Thus we can count on oss_present being valid on entry.
  37  */
  38
  39 void __init oss_init(void)
  40 {
  41         int i;
  42
  43         if (!oss_present) return;
  44
  45         oss = (struct mac_oss *) OSS_BASE;
  46
  47         /* Disable all interrupts. Unlike a VIA it looks like we    */
  48         /* do this by setting the source's interrupt level to zero. */
  49
  50         for (i = 0; i < OSS_NUM_SOURCES; i++)
  51                 oss->irq_level[i] = 0;
  52 }
  53
  54 /*
  55  * Initialize OSS for Nubus access
  56  */
  57
  58 void __init oss_nubus_init(void)
  59 {
  60 }
  61
  62 /*
  63  * Handle miscellaneous OSS interrupts.
  64  */
  65
  66 static void oss_irq(struct irq_desc *desc)
  67 {
  68         int events = oss->irq_pending &
  69                 (OSS_IP_IOPSCC | OSS_IP_SCSI | OSS_IP_IOPISM);
  70
  71 #ifdef DEBUG_IRQS
  72         if ((console_loglevel == 10) && !(events & OSS_IP_SCSI)) {
  73                 unsigned int irq = irq_desc_get_irq(desc);
  74
  75                 printk("oss_irq: irq %u events = 0x%04X\n", irq,
  76                         (int) oss->irq_pending);
  77         }
  78 #endif
  79
  80         if (events & OSS_IP_IOPSCC) {
  81                 oss->irq_pending &= ~OSS_IP_IOPSCC;
  82                 generic_handle_irq(IRQ_MAC_SCC);
  83         }
  84
  85         if (events & OSS_IP_SCSI) {
  86                 oss->irq_pending &= ~OSS_IP_SCSI;
  87                 generic_handle_irq(IRQ_MAC_SCSI);
  88         }
  89
  90         if (events & OSS_IP_IOPISM) {
  91                 oss->irq_pending &= ~OSS_IP_IOPISM;
  92                 generic_handle_irq(IRQ_MAC_ADB);
  93         }
  94 }
  95
  96 /*
  97  * Nubus IRQ handler, OSS style
  98  *
  99  * Unlike the VIA/RBV this is on its own autovector interrupt level.
 100  */
 101
 102 static void oss_nubus_irq(struct irq_desc *desc)
 103 {
 104         int events, irq_bit, i;
 105
 106         events = oss->irq_pending & OSS_IP_NUBUS;
 107         if (!events)
 108                 return;
 109
 110 #ifdef DEBUG_NUBUS_INT
 111         if (console_loglevel > 7) {
 112                 printk("oss_nubus_irq: events = 0x%04X\n", events);
 113         }
 114 #endif
 115         /* There are only six slots on the OSS, not seven */
 116
 117         i = 6;
 118         irq_bit = 0x40;
 119         do {
 120                 --i;
 121                 irq_bit >>= 1;
 122                 if (events & irq_bit) {
 123                         oss->irq_pending &= ~irq_bit;
 124                         generic_handle_irq(NUBUS_SOURCE_BASE + i);
 125                 }
 126         } while(events & (irq_bit - 1));
 127 }
 128
 129 /*
 130  * Register the OSS and NuBus interrupt dispatchers.
 131  *
 132  * This IRQ mapping is laid out with two things in mind: first, we try to keep
 133  * things on their own levels to avoid having to do double-dispatches. Second,
 134  * the levels match as closely as possible the alternate IRQ mapping mode (aka
 135  * "A/UX mode") available on some VIA machines.
 136  */
 137
 138 #define OSS_IRQLEV_IOPISM    IRQ_AUTO_1
 139 #define OSS_IRQLEV_SCSI      IRQ_AUTO_2
 140 #define OSS_IRQLEV_NUBUS     IRQ_AUTO_3
 141 #define OSS_IRQLEV_IOPSCC    IRQ_AUTO_4
 142 #define OSS_IRQLEV_VIA1      IRQ_AUTO_6
 143
 144 void __init oss_register_interrupts(void)
 145 {
 146         irq_set_chained_handler(OSS_IRQLEV_IOPISM, oss_irq);
 147         irq_set_chained_handler(OSS_IRQLEV_SCSI,   oss_irq);
 148         irq_set_chained_handler(OSS_IRQLEV_NUBUS,  oss_nubus_irq);
 149         irq_set_chained_handler(OSS_IRQLEV_IOPSCC, oss_irq);
 150         irq_set_chained_handler(OSS_IRQLEV_VIA1,   via1_irq);
 151
 152         /* OSS_VIA1 gets enabled here because it has no machspec interrupt. */
 153         oss->irq_level[OSS_VIA1] = IRQ_AUTO_6;
 154 }
 155
 156 /*
 157  * Enable an OSS interrupt
 158  *
 159  * It looks messy but it's rather straightforward. The switch() statement
 160  * just maps the machspec interrupt numbers to the right OSS interrupt
 161  * source (if the OSS handles that interrupt) and then sets the interrupt
 162  * level for that source to nonzero, thus enabling the interrupt.
 163  */
 164
 165 void oss_irq_enable(int irq) {
 166 #ifdef DEBUG_IRQUSE
 167         printk("oss_irq_enable(%d)\n", irq);
 168 #endif
 169         switch(irq) {
 170                 case IRQ_MAC_SCC:
 171                         oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_IOPSCC;
 172                         return;
 173                 case IRQ_MAC_ADB:
 174                         oss->irq_level[OSS_IOPISM] = OSS_IRQLEV_IOPISM;
 175                         return;
 176                 case IRQ_MAC_SCSI:
 177                         oss->irq_level[OSS_SCSI] = OSS_IRQLEV_SCSI;
 178                         return;
 179                 case IRQ_NUBUS_9:
 180                 case IRQ_NUBUS_A:
 181                 case IRQ_NUBUS_B:
 182                 case IRQ_NUBUS_C:
 183                 case IRQ_NUBUS_D:
 184                 case IRQ_NUBUS_E:
 185                         irq -= NUBUS_SOURCE_BASE;
 186                         oss->irq_level[irq] = OSS_IRQLEV_NUBUS;
 187                         return;
 188         }
 189
 190         if (IRQ_SRC(irq) == 1)
 191                 via_irq_enable(irq);
 192 }
 193
 194 /*
 195  * Disable an OSS interrupt
 196  *
 197  * Same as above except we set the source's interrupt level to zero,
 198  * to disable the interrupt.
 199  */
 200
 201 void oss_irq_disable(int irq) {
 202 #ifdef DEBUG_IRQUSE
 203         printk("oss_irq_disable(%d)\n", irq);
 204 #endif
 205         switch(irq) {
 206                 case IRQ_MAC_SCC:
 207                         oss->irq_level[OSS_IOPSCC] = 0;
 208                         return;
 209                 case IRQ_MAC_ADB:
 210                         oss->irq_level[OSS_IOPISM] = 0;
 211                         return;
 212                 case IRQ_MAC_SCSI:
 213                         oss->irq_level[OSS_SCSI] = 0;
 214                         return;
 215                 case IRQ_NUBUS_9:
 216                 case IRQ_NUBUS_A:
 217                 case IRQ_NUBUS_B:
 218                 case IRQ_NUBUS_C:
 219                 case IRQ_NUBUS_D:
 220                 case IRQ_NUBUS_E:
 221                         irq -= NUBUS_SOURCE_BASE;
 222                         oss->irq_level[irq] = 0;
 223                         return;
 224         }
 225
 226         if (IRQ_SRC(irq) == 1)
 227                 via_irq_disable(irq);
 228 }