1 // SPDX-License-Identifier: GPL-2.0
3 * Operating System Services (OSS) chip handling
4 * Written by Joshua M. Thompson (funaho@jurai.org)
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.
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.
18 #include <linux/types.h>
19 #include <linux/kernel.h>
21 #include <linux/delay.h>
22 #include <linux/init.h>
23 #include <linux/irq.h>
25 #include <asm/macintosh.h>
26 #include <asm/macints.h>
27 #include <asm/mac_via.h>
28 #include <asm/mac_oss.h>
31 volatile struct mac_oss *oss;
37 void __init oss_init(void)
41 if (macintosh_config->ident != MAC_MODEL_IIFX)
44 oss = (struct mac_oss *) OSS_BASE;
45 pr_debug("OSS detected at %p", oss);
48 /* Disable all interrupts. Unlike a VIA it looks like we */
49 /* do this by setting the source's interrupt level to zero. */
51 for (i = 0; i < OSS_NUM_SOURCES; i++)
52 oss->irq_level[i] = 0;
56 * Handle miscellaneous OSS interrupts.
59 static void oss_irq(struct irq_desc *desc)
61 int events = oss->irq_pending &
62 (OSS_IP_IOPSCC | OSS_IP_SCSI | OSS_IP_IOPISM);
64 if (events & OSS_IP_IOPSCC) {
65 oss->irq_pending &= ~OSS_IP_IOPSCC;
66 generic_handle_irq(IRQ_MAC_SCC);
69 if (events & OSS_IP_SCSI) {
70 oss->irq_pending &= ~OSS_IP_SCSI;
71 generic_handle_irq(IRQ_MAC_SCSI);
74 if (events & OSS_IP_IOPISM) {
75 oss->irq_pending &= ~OSS_IP_IOPISM;
76 generic_handle_irq(IRQ_MAC_ADB);
81 * Nubus IRQ handler, OSS style
83 * Unlike the VIA/RBV this is on its own autovector interrupt level.
86 static void oss_nubus_irq(struct irq_desc *desc)
88 int events, irq_bit, i;
90 events = oss->irq_pending & OSS_IP_NUBUS;
94 /* There are only six slots on the OSS, not seven */
101 if (events & irq_bit) {
102 oss->irq_pending &= ~irq_bit;
103 generic_handle_irq(NUBUS_SOURCE_BASE + i);
105 } while(events & (irq_bit - 1));
109 * Register the OSS and NuBus interrupt dispatchers.
111 * This IRQ mapping is laid out with two things in mind: first, we try to keep
112 * things on their own levels to avoid having to do double-dispatches. Second,
113 * the levels match as closely as possible the alternate IRQ mapping mode (aka
114 * "A/UX mode") available on some VIA machines.
117 #define OSS_IRQLEV_IOPISM IRQ_AUTO_1
118 #define OSS_IRQLEV_SCSI IRQ_AUTO_2
119 #define OSS_IRQLEV_NUBUS IRQ_AUTO_3
120 #define OSS_IRQLEV_IOPSCC IRQ_AUTO_4
121 #define OSS_IRQLEV_VIA1 IRQ_AUTO_6
123 void __init oss_register_interrupts(void)
125 irq_set_chained_handler(OSS_IRQLEV_IOPISM, oss_irq);
126 irq_set_chained_handler(OSS_IRQLEV_SCSI, oss_irq);
127 irq_set_chained_handler(OSS_IRQLEV_NUBUS, oss_nubus_irq);
128 irq_set_chained_handler(OSS_IRQLEV_IOPSCC, oss_irq);
129 irq_set_chained_handler(OSS_IRQLEV_VIA1, via1_irq);
131 /* OSS_VIA1 gets enabled here because it has no machspec interrupt. */
132 oss->irq_level[OSS_VIA1] = IRQ_AUTO_6;
136 * Enable an OSS interrupt
138 * It looks messy but it's rather straightforward. The switch() statement
139 * just maps the machspec interrupt numbers to the right OSS interrupt
140 * source (if the OSS handles that interrupt) and then sets the interrupt
141 * level for that source to nonzero, thus enabling the interrupt.
144 void oss_irq_enable(int irq) {
147 oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_IOPSCC;
150 oss->irq_level[OSS_IOPISM] = OSS_IRQLEV_IOPISM;
153 oss->irq_level[OSS_SCSI] = OSS_IRQLEV_SCSI;
161 irq -= NUBUS_SOURCE_BASE;
162 oss->irq_level[irq] = OSS_IRQLEV_NUBUS;
166 if (IRQ_SRC(irq) == 1)
171 * Disable an OSS interrupt
173 * Same as above except we set the source's interrupt level to zero,
174 * to disable the interrupt.
177 void oss_irq_disable(int irq) {
180 oss->irq_level[OSS_IOPSCC] = 0;
183 oss->irq_level[OSS_IOPISM] = 0;
186 oss->irq_level[OSS_SCSI] = 0;
194 irq -= NUBUS_SOURCE_BASE;
195 oss->irq_level[irq] = 0;
199 if (IRQ_SRC(irq) == 1)
200 via_irq_disable(irq);