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/bootinfo.h>
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 /*
57 * Initialize OSS for Nubus access
58 */
59
oss_nubus_init(void)60 void __init oss_nubus_init(void)
61 {
62 }
63
64 /*
65 * Handle miscellaneous OSS interrupts.
66 */
67
oss_irq(unsigned int irq,struct irq_desc * desc)68 static void oss_irq(unsigned int irq, struct irq_desc *desc)
69 {
70 int events = oss->irq_pending &
71 (OSS_IP_IOPSCC | OSS_IP_SCSI | OSS_IP_IOPISM);
72
73 #ifdef DEBUG_IRQS
74 if ((console_loglevel == 10) && !(events & OSS_IP_SCSI)) {
75 printk("oss_irq: irq %u events = 0x%04X\n", irq,
76 (int) oss->irq_pending);
77 }
78 #endif
79
80 if (events & OSS_IP_IOPSCC) {
81 oss->irq_pending &= ~OSS_IP_IOPSCC;
82 generic_handle_irq(IRQ_MAC_SCC);
83 }
84
85 if (events & OSS_IP_SCSI) {
86 oss->irq_pending &= ~OSS_IP_SCSI;
87 generic_handle_irq(IRQ_MAC_SCSI);
88 }
89
90 if (events & OSS_IP_IOPISM) {
91 oss->irq_pending &= ~OSS_IP_IOPISM;
92 generic_handle_irq(IRQ_MAC_ADB);
93 }
94 }
95
96 /*
97 * Nubus IRQ handler, OSS style
98 *
99 * Unlike the VIA/RBV this is on its own autovector interrupt level.
100 */
101
oss_nubus_irq(unsigned int irq,struct irq_desc * desc)102 static void oss_nubus_irq(unsigned int irq, struct irq_desc *desc)
103 {
104 int events, irq_bit, i;
105
106 events = oss->irq_pending & OSS_IP_NUBUS;
107 if (!events)
108 return;
109
110 #ifdef DEBUG_NUBUS_INT
111 if (console_loglevel > 7) {
112 printk("oss_nubus_irq: events = 0x%04X\n", events);
113 }
114 #endif
115 /* There are only six slots on the OSS, not seven */
116
117 i = 6;
118 irq_bit = 0x40;
119 do {
120 --i;
121 irq_bit >>= 1;
122 if (events & irq_bit) {
123 oss->irq_pending &= ~irq_bit;
124 generic_handle_irq(NUBUS_SOURCE_BASE + i);
125 }
126 } while(events & (irq_bit - 1));
127 }
128
129 /*
130 * Register the OSS and NuBus interrupt dispatchers.
131 *
132 * This IRQ mapping is laid out with two things in mind: first, we try to keep
133 * things on their own levels to avoid having to do double-dispatches. Second,
134 * the levels match as closely as possible the alternate IRQ mapping mode (aka
135 * "A/UX mode") available on some VIA machines.
136 */
137
138 #define OSS_IRQLEV_IOPISM IRQ_AUTO_1
139 #define OSS_IRQLEV_SCSI IRQ_AUTO_2
140 #define OSS_IRQLEV_NUBUS IRQ_AUTO_3
141 #define OSS_IRQLEV_IOPSCC IRQ_AUTO_4
142 #define OSS_IRQLEV_VIA1 IRQ_AUTO_6
143
oss_register_interrupts(void)144 void __init oss_register_interrupts(void)
145 {
146 irq_set_chained_handler(OSS_IRQLEV_IOPISM, oss_irq);
147 irq_set_chained_handler(OSS_IRQLEV_SCSI, oss_irq);
148 irq_set_chained_handler(OSS_IRQLEV_NUBUS, oss_nubus_irq);
149 irq_set_chained_handler(OSS_IRQLEV_IOPSCC, oss_irq);
150 irq_set_chained_handler(OSS_IRQLEV_VIA1, via1_irq);
151
152 /* OSS_VIA1 gets enabled here because it has no machspec interrupt. */
153 oss->irq_level[OSS_VIA1] = IRQ_AUTO_6;
154 }
155
156 /*
157 * Enable an OSS interrupt
158 *
159 * It looks messy but it's rather straightforward. The switch() statement
160 * just maps the machspec interrupt numbers to the right OSS interrupt
161 * source (if the OSS handles that interrupt) and then sets the interrupt
162 * level for that source to nonzero, thus enabling the interrupt.
163 */
164
oss_irq_enable(int irq)165 void oss_irq_enable(int irq) {
166 #ifdef DEBUG_IRQUSE
167 printk("oss_irq_enable(%d)\n", irq);
168 #endif
169 switch(irq) {
170 case IRQ_MAC_SCC:
171 oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_IOPSCC;
172 return;
173 case IRQ_MAC_ADB:
174 oss->irq_level[OSS_IOPISM] = OSS_IRQLEV_IOPISM;
175 return;
176 case IRQ_MAC_SCSI:
177 oss->irq_level[OSS_SCSI] = OSS_IRQLEV_SCSI;
178 return;
179 case IRQ_NUBUS_9:
180 case IRQ_NUBUS_A:
181 case IRQ_NUBUS_B:
182 case IRQ_NUBUS_C:
183 case IRQ_NUBUS_D:
184 case IRQ_NUBUS_E:
185 irq -= NUBUS_SOURCE_BASE;
186 oss->irq_level[irq] = OSS_IRQLEV_NUBUS;
187 return;
188 }
189
190 if (IRQ_SRC(irq) == 1)
191 via_irq_enable(irq);
192 }
193
194 /*
195 * Disable an OSS interrupt
196 *
197 * Same as above except we set the source's interrupt level to zero,
198 * to disable the interrupt.
199 */
200
oss_irq_disable(int irq)201 void oss_irq_disable(int irq) {
202 #ifdef DEBUG_IRQUSE
203 printk("oss_irq_disable(%d)\n", irq);
204 #endif
205 switch(irq) {
206 case IRQ_MAC_SCC:
207 oss->irq_level[OSS_IOPSCC] = 0;
208 return;
209 case IRQ_MAC_ADB:
210 oss->irq_level[OSS_IOPISM] = 0;
211 return;
212 case IRQ_MAC_SCSI:
213 oss->irq_level[OSS_SCSI] = 0;
214 return;
215 case IRQ_NUBUS_9:
216 case IRQ_NUBUS_A:
217 case IRQ_NUBUS_B:
218 case IRQ_NUBUS_C:
219 case IRQ_NUBUS_D:
220 case IRQ_NUBUS_E:
221 irq -= NUBUS_SOURCE_BASE;
222 oss->irq_level[irq] = 0;
223 return;
224 }
225
226 if (IRQ_SRC(irq) == 1)
227 via_irq_disable(irq);
228 }
229