1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *	Apple Peripheral System Controller (PSC)
4  *
5  *	The PSC is used on the AV Macs to control IO functions not handled
6  *	by the VIAs (Ethernet, DSP, SCC).
7  *
8  * TO DO:
9  *
10  * Try to figure out what's going on in pIFR5 and pIFR6. There seem to be
11  * persisant interrupt conditions in those registers and I have no idea what
12  * they are. Granted it doesn't affect since we're not enabling any interrupts
13  * on those levels at the moment, but it would be nice to know. I have a feeling
14  * they aren't actually interrupt lines but data lines (to the DSP?)
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/traps.h>
25 #include <asm/macintosh.h>
26 #include <asm/macints.h>
27 #include <asm/mac_psc.h>
28 
29 #define DEBUG_PSC
30 
31 volatile __u8 *psc;
32 EXPORT_SYMBOL_GPL(psc);
33 
34 /*
35  * Debugging dump, used in various places to see what's going on.
36  */
37 
psc_debug_dump(void)38 static void psc_debug_dump(void)
39 {
40 	int	i;
41 
42 	if (!psc)
43 		return;
44 
45 	for (i = 0x30 ; i < 0x70 ; i += 0x10) {
46 		printk(KERN_DEBUG "PSC #%d:  IFR = 0x%02X IER = 0x%02X\n",
47 			i >> 4,
48 			(int) psc_read_byte(pIFRbase + i),
49 			(int) psc_read_byte(pIERbase + i));
50 	}
51 }
52 
53 /*
54  * Try to kill all DMA channels on the PSC. Not sure how this his
55  * supposed to work; this is code lifted from macmace.c and then
56  * expanded to cover what I think are the other 7 channels.
57  */
58 
psc_dma_die_die_die(void)59 static __init void psc_dma_die_die_die(void)
60 {
61 	int i;
62 
63 	for (i = 0 ; i < 9 ; i++) {
64 		psc_write_word(PSC_CTL_BASE + (i << 4), 0x8800);
65 		psc_write_word(PSC_CTL_BASE + (i << 4), 0x1000);
66 		psc_write_word(PSC_CMD_BASE + (i << 5), 0x1100);
67 		psc_write_word(PSC_CMD_BASE + (i << 5) + 0x10, 0x1100);
68 	}
69 }
70 
71 /*
72  * Initialize the PSC. For now this just involves shutting down all
73  * interrupt sources using the IERs.
74  */
75 
psc_init(void)76 void __init psc_init(void)
77 {
78 	int i;
79 
80 	if (macintosh_config->ident != MAC_MODEL_C660
81 	 && macintosh_config->ident != MAC_MODEL_Q840)
82 	{
83 		psc = NULL;
84 		return;
85 	}
86 
87 	/*
88 	 * The PSC is always at the same spot, but using psc
89 	 * keeps things consistent with the psc_xxxx functions.
90 	 */
91 
92 	psc = (void *) PSC_BASE;
93 
94 	pr_debug("PSC detected at %p\n", psc);
95 
96 	psc_dma_die_die_die();
97 
98 #ifdef DEBUG_PSC
99 	psc_debug_dump();
100 #endif
101 	/*
102 	 * Mask and clear all possible interrupts
103 	 */
104 
105 	for (i = 0x30 ; i < 0x70 ; i += 0x10) {
106 		psc_write_byte(pIERbase + i, 0x0F);
107 		psc_write_byte(pIFRbase + i, 0x0F);
108 	}
109 }
110 
111 /*
112  * PSC interrupt handler. It's a lot like the VIA interrupt handler.
113  */
114 
psc_irq(struct irq_desc * desc)115 static void psc_irq(struct irq_desc *desc)
116 {
117 	unsigned int offset = (unsigned int)irq_desc_get_handler_data(desc);
118 	unsigned int irq = irq_desc_get_irq(desc);
119 	int pIFR	= pIFRbase + offset;
120 	int pIER	= pIERbase + offset;
121 	int irq_num;
122 	unsigned char irq_bit, events;
123 
124 	events = psc_read_byte(pIFR) & psc_read_byte(pIER) & 0xF;
125 	if (!events)
126 		return;
127 
128 	irq_num = irq << 3;
129 	irq_bit = 1;
130 	do {
131 		if (events & irq_bit) {
132 			psc_write_byte(pIFR, irq_bit);
133 			generic_handle_irq(irq_num);
134 		}
135 		irq_num++;
136 		irq_bit <<= 1;
137 	} while (events >= irq_bit);
138 }
139 
140 /*
141  * Register the PSC interrupt dispatchers for autovector interrupts 3-6.
142  */
143 
psc_register_interrupts(void)144 void __init psc_register_interrupts(void)
145 {
146 	irq_set_chained_handler_and_data(IRQ_AUTO_3, psc_irq, (void *)0x30);
147 	irq_set_chained_handler_and_data(IRQ_AUTO_4, psc_irq, (void *)0x40);
148 	irq_set_chained_handler_and_data(IRQ_AUTO_5, psc_irq, (void *)0x50);
149 	irq_set_chained_handler_and_data(IRQ_AUTO_6, psc_irq, (void *)0x60);
150 }
151 
psc_irq_enable(int irq)152 void psc_irq_enable(int irq) {
153 	int irq_src	= IRQ_SRC(irq);
154 	int irq_idx	= IRQ_IDX(irq);
155 	int pIER	= pIERbase + (irq_src << 4);
156 
157 	psc_write_byte(pIER, (1 << irq_idx) | 0x80);
158 }
159 
psc_irq_disable(int irq)160 void psc_irq_disable(int irq) {
161 	int irq_src	= IRQ_SRC(irq);
162 	int irq_idx	= IRQ_IDX(irq);
163 	int pIER	= pIERbase + (irq_src << 4);
164 
165 	psc_write_byte(pIER, 1 << irq_idx);
166 }
167