Linux kernel mirror (for testing)
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linux
1/*
2 * Operating System Services (OSS) chip handling
3 * Written by Joshua M. Thompson (funaho@jurai.org)
4 *
5 *
6 * This chip is used in the IIfx in place of VIA #2. It acts like a fancy
7 * VIA chip with prorammable interrupt levels.
8 *
9 * 990502 (jmt) - Major rewrite for new interrupt architecture as well as some
10 * recent insights into OSS operational details.
11 * 990610 (jmt) - Now taking full advantage of the OSS. Interrupts are mapped
12 * to mostly match the A/UX interrupt scheme supported on the
13 * VIA side. Also added support for enabling the ISM irq again
14 * since we now have a functional IOP manager.
15 */
16
17#include <linux/types.h>
18#include <linux/kernel.h>
19#include <linux/mm.h>
20#include <linux/delay.h>
21#include <linux/init.h>
22#include <linux/irq.h>
23
24#include <asm/macintosh.h>
25#include <asm/macints.h>
26#include <asm/mac_via.h>
27#include <asm/mac_oss.h>
28
29int oss_present;
30volatile struct mac_oss *oss;
31
32/*
33 * Initialize the OSS
34 *
35 * The OSS "detection" code is actually in via_init() which is always called
36 * before us. Thus we can count on oss_present being valid on entry.
37 */
38
39void __init oss_init(void)
40{
41 int i;
42
43 if (!oss_present) return;
44
45 oss = (struct mac_oss *) OSS_BASE;
46
47 /* Disable all interrupts. Unlike a VIA it looks like we */
48 /* do this by setting the source's interrupt level to zero. */
49
50 for (i = 0; i < OSS_NUM_SOURCES; i++)
51 oss->irq_level[i] = 0;
52}
53
54/*
55 * Initialize OSS for Nubus access
56 */
57
58void __init oss_nubus_init(void)
59{
60}
61
62/*
63 * Handle miscellaneous OSS interrupts.
64 */
65
66static void oss_irq(struct irq_desc *desc)
67{
68 int events = oss->irq_pending &
69 (OSS_IP_IOPSCC | OSS_IP_SCSI | OSS_IP_IOPISM);
70
71 if (events & OSS_IP_IOPSCC) {
72 oss->irq_pending &= ~OSS_IP_IOPSCC;
73 generic_handle_irq(IRQ_MAC_SCC);
74 }
75
76 if (events & OSS_IP_SCSI) {
77 oss->irq_pending &= ~OSS_IP_SCSI;
78 generic_handle_irq(IRQ_MAC_SCSI);
79 }
80
81 if (events & OSS_IP_IOPISM) {
82 oss->irq_pending &= ~OSS_IP_IOPISM;
83 generic_handle_irq(IRQ_MAC_ADB);
84 }
85}
86
87/*
88 * Nubus IRQ handler, OSS style
89 *
90 * Unlike the VIA/RBV this is on its own autovector interrupt level.
91 */
92
93static void oss_nubus_irq(struct irq_desc *desc)
94{
95 int events, irq_bit, i;
96
97 events = oss->irq_pending & OSS_IP_NUBUS;
98 if (!events)
99 return;
100
101 /* There are only six slots on the OSS, not seven */
102
103 i = 6;
104 irq_bit = 0x40;
105 do {
106 --i;
107 irq_bit >>= 1;
108 if (events & irq_bit) {
109 oss->irq_pending &= ~irq_bit;
110 generic_handle_irq(NUBUS_SOURCE_BASE + i);
111 }
112 } while(events & (irq_bit - 1));
113}
114
115/*
116 * Register the OSS and NuBus interrupt dispatchers.
117 *
118 * This IRQ mapping is laid out with two things in mind: first, we try to keep
119 * things on their own levels to avoid having to do double-dispatches. Second,
120 * the levels match as closely as possible the alternate IRQ mapping mode (aka
121 * "A/UX mode") available on some VIA machines.
122 */
123
124#define OSS_IRQLEV_IOPISM IRQ_AUTO_1
125#define OSS_IRQLEV_SCSI IRQ_AUTO_2
126#define OSS_IRQLEV_NUBUS IRQ_AUTO_3
127#define OSS_IRQLEV_IOPSCC IRQ_AUTO_4
128#define OSS_IRQLEV_VIA1 IRQ_AUTO_6
129
130void __init oss_register_interrupts(void)
131{
132 irq_set_chained_handler(OSS_IRQLEV_IOPISM, oss_irq);
133 irq_set_chained_handler(OSS_IRQLEV_SCSI, oss_irq);
134 irq_set_chained_handler(OSS_IRQLEV_NUBUS, oss_nubus_irq);
135 irq_set_chained_handler(OSS_IRQLEV_IOPSCC, oss_irq);
136 irq_set_chained_handler(OSS_IRQLEV_VIA1, via1_irq);
137
138 /* OSS_VIA1 gets enabled here because it has no machspec interrupt. */
139 oss->irq_level[OSS_VIA1] = IRQ_AUTO_6;
140}
141
142/*
143 * Enable an OSS interrupt
144 *
145 * It looks messy but it's rather straightforward. The switch() statement
146 * just maps the machspec interrupt numbers to the right OSS interrupt
147 * source (if the OSS handles that interrupt) and then sets the interrupt
148 * level for that source to nonzero, thus enabling the interrupt.
149 */
150
151void oss_irq_enable(int irq) {
152 switch(irq) {
153 case IRQ_MAC_SCC:
154 oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_IOPSCC;
155 return;
156 case IRQ_MAC_ADB:
157 oss->irq_level[OSS_IOPISM] = OSS_IRQLEV_IOPISM;
158 return;
159 case IRQ_MAC_SCSI:
160 oss->irq_level[OSS_SCSI] = OSS_IRQLEV_SCSI;
161 return;
162 case IRQ_NUBUS_9:
163 case IRQ_NUBUS_A:
164 case IRQ_NUBUS_B:
165 case IRQ_NUBUS_C:
166 case IRQ_NUBUS_D:
167 case IRQ_NUBUS_E:
168 irq -= NUBUS_SOURCE_BASE;
169 oss->irq_level[irq] = OSS_IRQLEV_NUBUS;
170 return;
171 }
172
173 if (IRQ_SRC(irq) == 1)
174 via_irq_enable(irq);
175}
176
177/*
178 * Disable an OSS interrupt
179 *
180 * Same as above except we set the source's interrupt level to zero,
181 * to disable the interrupt.
182 */
183
184void oss_irq_disable(int irq) {
185 switch(irq) {
186 case IRQ_MAC_SCC:
187 oss->irq_level[OSS_IOPSCC] = 0;
188 return;
189 case IRQ_MAC_ADB:
190 oss->irq_level[OSS_IOPISM] = 0;
191 return;
192 case IRQ_MAC_SCSI:
193 oss->irq_level[OSS_SCSI] = 0;
194 return;
195 case IRQ_NUBUS_9:
196 case IRQ_NUBUS_A:
197 case IRQ_NUBUS_B:
198 case IRQ_NUBUS_C:
199 case IRQ_NUBUS_D:
200 case IRQ_NUBUS_E:
201 irq -= NUBUS_SOURCE_BASE;
202 oss->irq_level[irq] = 0;
203 return;
204 }
205
206 if (IRQ_SRC(irq) == 1)
207 via_irq_disable(irq);
208}