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 #include "mac.h" 31 32 int oss_present; 33 volatile struct mac_oss *oss; 34 35 /* 36 * Initialize the OSS 37 */ 38 39 void __init oss_init(void) 40 { 41 int i; 42 43 if (macintosh_config->ident != MAC_MODEL_IIFX) 44 return; 45 46 oss = (struct mac_oss *) OSS_BASE; 47 pr_debug("OSS detected at %p", oss); 48 oss_present = 1; 49 50 /* Disable all interrupts. Unlike a VIA it looks like we */ 51 /* do this by setting the source's interrupt level to zero. */ 52 53 for (i = 0; i < OSS_NUM_SOURCES; i++) 54 oss->irq_level[i] = 0; 55 } 56 57 /* 58 * Handle OSS interrupts. 59 * XXX how do you clear a pending IRQ? is it even necessary? 60 */ 61 62 static void oss_iopism_irq(struct irq_desc *desc) 63 { 64 generic_handle_irq(IRQ_MAC_ADB); 65 } 66 67 static void oss_scsi_irq(struct irq_desc *desc) 68 { 69 generic_handle_irq(IRQ_MAC_SCSI); 70 } 71 72 static void oss_nubus_irq(struct irq_desc *desc) 73 { 74 u16 events, irq_bit; 75 int irq_num; 76 77 events = oss->irq_pending & OSS_IP_NUBUS; 78 irq_num = NUBUS_SOURCE_BASE + 5; 79 irq_bit = OSS_IP_NUBUS5; 80 do { 81 if (events & irq_bit) { 82 events &= ~irq_bit; 83 generic_handle_irq(irq_num); 84 } 85 --irq_num; 86 irq_bit >>= 1; 87 } while (events); 88 } 89 90 static void oss_iopscc_irq(struct irq_desc *desc) 91 { 92 generic_handle_irq(IRQ_MAC_SCC); 93 } 94 95 /* 96 * Register the OSS and NuBus interrupt dispatchers. 97 * 98 * This IRQ mapping is laid out with two things in mind: first, we try to keep 99 * things on their own levels to avoid having to do double-dispatches. Second, 100 * the levels match as closely as possible the alternate IRQ mapping mode (aka 101 * "A/UX mode") available on some VIA machines. 102 */ 103 104 #define OSS_IRQLEV_IOPISM IRQ_AUTO_1 105 #define OSS_IRQLEV_SCSI IRQ_AUTO_2 106 #define OSS_IRQLEV_NUBUS IRQ_AUTO_3 107 #define OSS_IRQLEV_IOPSCC IRQ_AUTO_4 108 #define OSS_IRQLEV_VIA1 IRQ_AUTO_6 109 110 void __init oss_register_interrupts(void) 111 { 112 irq_set_chained_handler(OSS_IRQLEV_IOPISM, oss_iopism_irq); 113 irq_set_chained_handler(OSS_IRQLEV_SCSI, oss_scsi_irq); 114 irq_set_chained_handler(OSS_IRQLEV_NUBUS, oss_nubus_irq); 115 irq_set_chained_handler(OSS_IRQLEV_IOPSCC, oss_iopscc_irq); 116 irq_set_chained_handler(OSS_IRQLEV_VIA1, via1_irq); 117 118 /* OSS_VIA1 gets enabled here because it has no machspec interrupt. */ 119 oss->irq_level[OSS_VIA1] = OSS_IRQLEV_VIA1; 120 } 121 122 /* 123 * Enable an OSS interrupt 124 * 125 * It looks messy but it's rather straightforward. The switch() statement 126 * just maps the machspec interrupt numbers to the right OSS interrupt 127 * source (if the OSS handles that interrupt) and then sets the interrupt 128 * level for that source to nonzero, thus enabling the interrupt. 129 */ 130 131 void oss_irq_enable(int irq) { 132 switch(irq) { 133 case IRQ_MAC_SCC: 134 oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_IOPSCC; 135 return; 136 case IRQ_MAC_ADB: 137 oss->irq_level[OSS_IOPISM] = OSS_IRQLEV_IOPISM; 138 return; 139 case IRQ_MAC_SCSI: 140 oss->irq_level[OSS_SCSI] = OSS_IRQLEV_SCSI; 141 return; 142 case IRQ_NUBUS_9: 143 case IRQ_NUBUS_A: 144 case IRQ_NUBUS_B: 145 case IRQ_NUBUS_C: 146 case IRQ_NUBUS_D: 147 case IRQ_NUBUS_E: 148 irq -= NUBUS_SOURCE_BASE; 149 oss->irq_level[irq] = OSS_IRQLEV_NUBUS; 150 return; 151 } 152 153 if (IRQ_SRC(irq) == 1) 154 via_irq_enable(irq); 155 } 156 157 /* 158 * Disable an OSS interrupt 159 * 160 * Same as above except we set the source's interrupt level to zero, 161 * to disable the interrupt. 162 */ 163 164 void oss_irq_disable(int irq) { 165 switch(irq) { 166 case IRQ_MAC_SCC: 167 oss->irq_level[OSS_IOPSCC] = 0; 168 return; 169 case IRQ_MAC_ADB: 170 oss->irq_level[OSS_IOPISM] = 0; 171 return; 172 case IRQ_MAC_SCSI: 173 oss->irq_level[OSS_SCSI] = 0; 174 return; 175 case IRQ_NUBUS_9: 176 case IRQ_NUBUS_A: 177 case IRQ_NUBUS_B: 178 case IRQ_NUBUS_C: 179 case IRQ_NUBUS_D: 180 case IRQ_NUBUS_E: 181 irq -= NUBUS_SOURCE_BASE; 182 oss->irq_level[irq] = 0; 183 return; 184 } 185 186 if (IRQ_SRC(irq) == 1) 187 via_irq_disable(irq); 188 } 189