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
oss_init(void)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
oss_nubus_init(void)59 void __init oss_nubus_init(void)
60 {
61 }
62
63 /*
64 * Handle miscellaneous OSS interrupts.
65 */
66
oss_irq(struct irq_desc * desc)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
oss_nubus_irq(struct irq_desc * desc)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
oss_register_interrupts(void)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
oss_irq_enable(int irq)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
oss_irq_disable(int irq)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