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
32int oss_present;
33volatile struct mac_oss *oss;
34
35/*
36 * Initialize the OSS
37 */
38
39void __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
62static void oss_iopism_irq(struct irq_desc *desc)
63{
64	generic_handle_irq(IRQ_MAC_ADB);
65}
66
67static void oss_scsi_irq(struct irq_desc *desc)
68{
69	generic_handle_irq(IRQ_MAC_SCSI);
70}
71
72static 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
90static 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
110void __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
131void 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
164void 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