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