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