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
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