Linux Kernel  3.7.1
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oss.c
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1 /*
2  * Operating System Services (OSS) chip handling
3  * Written by Joshua M. Thompson ([email protected])
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 
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 
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 
61 {
62 }
63 
64 /*
65  * Handle miscellaneous OSS interrupts.
66  */
67 
68 static void oss_irq(unsigned int irq, struct irq_desc *desc)
69 {
70  int events = oss->irq_pending &
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;
83  }
84 
85  if (events & OSS_IP_SCSI) {
86  oss->irq_pending &= ~OSS_IP_SCSI;
88  }
89 
90  if (events & OSS_IP_IOPISM) {
91  oss->irq_pending &= ~OSS_IP_IOPISM;
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 
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;
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 
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 
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:
172  return;
173  case IRQ_MAC_ADB:
175  return;
176  case IRQ_MAC_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 
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 }