1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Operating System Services (OSS) chip handling 4 * Written by Joshua M. Thompson (funaho@jurai.org) 5 * 6 * 7 * This chip is used in the IIfx in place of VIA #2. It acts like a fancy 8 * VIA chip with prorammable interrupt levels. 9 * 10 * 990502 (jmt) - Major rewrite for new interrupt architecture as well as some 11 * recent insights into OSS operational details. 12 * 990610 (jmt) - Now taking full advantage of the OSS. Interrupts are mapped 13 * to mostly match the A/UX interrupt scheme supported on the 14 * VIA side. Also added support for enabling the ISM irq again 15 * since we now have a functional IOP manager. 16 */ 17 18 #include <linux/types.h> 19 #include <linux/kernel.h> 20 #include <linux/mm.h> 21 #include <linux/delay.h> 22 #include <linux/init.h> 23 #include <linux/irq.h> 24 25 #include <asm/macintosh.h> 26 #include <asm/macints.h> 27 #include <asm/mac_via.h> 28 #include <asm/mac_oss.h> 29 30 int oss_present; 31 volatile struct mac_oss *oss; 32 33 /* 34 * Initialize the OSS 35 * 36 * The OSS "detection" code is actually in via_init() which is always called 37 * before us. Thus we can count on oss_present being valid on entry. 38 */ 39 40 void __init oss_init(void) 41 { 42 int i; 43 44 if (!oss_present) return; 45 46 oss = (struct mac_oss *) OSS_BASE; 47 48 /* Disable all interrupts. Unlike a VIA it looks like we */ 49 /* do this by setting the source's interrupt level to zero. */ 50 51 for (i = 0; i < OSS_NUM_SOURCES; i++) 52 oss->irq_level[i] = 0; 53 } 54 55 /* 56 * Initialize OSS for Nubus access 57 */ 58 59 void __init oss_nubus_init(void) 60 { 61 } 62 63 /* 64 * Handle miscellaneous OSS interrupts. 65 */ 66 67 static void oss_irq(struct irq_desc *desc) 68 { 69 int events = oss->irq_pending & 70 (OSS_IP_IOPSCC | OSS_IP_SCSI | OSS_IP_IOPISM); 71 72 if (events & OSS_IP_IOPSCC) { 73 oss->irq_pending &= ~OSS_IP_IOPSCC; 74 generic_handle_irq(IRQ_MAC_SCC); 75 } 76 77 if (events & OSS_IP_SCSI) { 78 oss->irq_pending &= ~OSS_IP_SCSI; 79 generic_handle_irq(IRQ_MAC_SCSI); 80 } 81 82 if (events & OSS_IP_IOPISM) { 83 oss->irq_pending &= ~OSS_IP_IOPISM; 84 generic_handle_irq(IRQ_MAC_ADB); 85 } 86 } 87 88 /* 89 * Nubus IRQ handler, OSS style 90 * 91 * Unlike the VIA/RBV this is on its own autovector interrupt level. 92 */ 93 94 static void oss_nubus_irq(struct irq_desc *desc) 95 { 96 int events, irq_bit, i; 97 98 events = oss->irq_pending & OSS_IP_NUBUS; 99 if (!events) 100 return; 101 102 /* There are only six slots on the OSS, not seven */ 103 104 i = 6; 105 irq_bit = 0x40; 106 do { 107 --i; 108 irq_bit >>= 1; 109 if (events & irq_bit) { 110 oss->irq_pending &= ~irq_bit; 111 generic_handle_irq(NUBUS_SOURCE_BASE + i); 112 } 113 } while(events & (irq_bit - 1)); 114 } 115 116 /* 117 * Register the OSS and NuBus interrupt dispatchers. 118 * 119 * This IRQ mapping is laid out with two things in mind: first, we try to keep 120 * things on their own levels to avoid having to do double-dispatches. Second, 121 * the levels match as closely as possible the alternate IRQ mapping mode (aka 122 * "A/UX mode") available on some VIA machines. 123 */ 124 125 #define OSS_IRQLEV_IOPISM IRQ_AUTO_1 126 #define OSS_IRQLEV_SCSI IRQ_AUTO_2 127 #define OSS_IRQLEV_NUBUS IRQ_AUTO_3 128 #define OSS_IRQLEV_IOPSCC IRQ_AUTO_4 129 #define OSS_IRQLEV_VIA1 IRQ_AUTO_6 130 131 void __init oss_register_interrupts(void) 132 { 133 irq_set_chained_handler(OSS_IRQLEV_IOPISM, oss_irq); 134 irq_set_chained_handler(OSS_IRQLEV_SCSI, oss_irq); 135 irq_set_chained_handler(OSS_IRQLEV_NUBUS, oss_nubus_irq); 136 irq_set_chained_handler(OSS_IRQLEV_IOPSCC, oss_irq); 137 irq_set_chained_handler(OSS_IRQLEV_VIA1, via1_irq); 138 139 /* OSS_VIA1 gets enabled here because it has no machspec interrupt. */ 140 oss->irq_level[OSS_VIA1] = IRQ_AUTO_6; 141 } 142 143 /* 144 * Enable an OSS interrupt 145 * 146 * It looks messy but it's rather straightforward. The switch() statement 147 * just maps the machspec interrupt numbers to the right OSS interrupt 148 * source (if the OSS handles that interrupt) and then sets the interrupt 149 * level for that source to nonzero, thus enabling the interrupt. 150 */ 151 152 void oss_irq_enable(int irq) { 153 switch(irq) { 154 case IRQ_MAC_SCC: 155 oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_IOPSCC; 156 return; 157 case IRQ_MAC_ADB: 158 oss->irq_level[OSS_IOPISM] = OSS_IRQLEV_IOPISM; 159 return; 160 case IRQ_MAC_SCSI: 161 oss->irq_level[OSS_SCSI] = OSS_IRQLEV_SCSI; 162 return; 163 case IRQ_NUBUS_9: 164 case IRQ_NUBUS_A: 165 case IRQ_NUBUS_B: 166 case IRQ_NUBUS_C: 167 case IRQ_NUBUS_D: 168 case IRQ_NUBUS_E: 169 irq -= NUBUS_SOURCE_BASE; 170 oss->irq_level[irq] = OSS_IRQLEV_NUBUS; 171 return; 172 } 173 174 if (IRQ_SRC(irq) == 1) 175 via_irq_enable(irq); 176 } 177 178 /* 179 * Disable an OSS interrupt 180 * 181 * Same as above except we set the source's interrupt level to zero, 182 * to disable the interrupt. 183 */ 184 185 void oss_irq_disable(int irq) { 186 switch(irq) { 187 case IRQ_MAC_SCC: 188 oss->irq_level[OSS_IOPSCC] = 0; 189 return; 190 case IRQ_MAC_ADB: 191 oss->irq_level[OSS_IOPISM] = 0; 192 return; 193 case IRQ_MAC_SCSI: 194 oss->irq_level[OSS_SCSI] = 0; 195 return; 196 case IRQ_NUBUS_9: 197 case IRQ_NUBUS_A: 198 case IRQ_NUBUS_B: 199 case IRQ_NUBUS_C: 200 case IRQ_NUBUS_D: 201 case IRQ_NUBUS_E: 202 irq -= NUBUS_SOURCE_BASE; 203 oss->irq_level[irq] = 0; 204 return; 205 } 206 207 if (IRQ_SRC(irq) == 1) 208 via_irq_disable(irq); 209 } 210