1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/arch/alpha/kernel/irq_pyxis.c
4 *
5 * Based on code written by David A Rusling (david.rusling@reo.mts.dec.com).
6 *
7 * IRQ Code common to all PYXIS core logic chips.
8 */
9
10 #include <linux/init.h>
11 #include <linux/sched.h>
12 #include <linux/irq.h>
13
14 #include <asm/io.h>
15 #include <asm/core_cia.h>
16
17 #include "proto.h"
18 #include "irq_impl.h"
19
20
21 /* Note mask bit is true for ENABLED irqs. */
22 static unsigned long cached_irq_mask;
23
24 static inline void
25 pyxis_update_irq_hw(unsigned long mask)
26 {
27 *(vulp)PYXIS_INT_MASK = mask;
28 mb();
29 *(vulp)PYXIS_INT_MASK;
30 }
31
32 static inline void
33 pyxis_enable_irq(struct irq_data *d)
34 {
35 pyxis_update_irq_hw(cached_irq_mask |= 1UL << (d->irq - 16));
36 }
37
38 static void
39 pyxis_disable_irq(struct irq_data *d)
40 {
41 pyxis_update_irq_hw(cached_irq_mask &= ~(1UL << (d->irq - 16)));
42 }
43
44 static void
45 pyxis_mask_and_ack_irq(struct irq_data *d)
46 {
47 unsigned long bit = 1UL << (d->irq - 16);
48 unsigned long mask = cached_irq_mask &= ~bit;
49
50 /* Disable the interrupt. */
51 *(vulp)PYXIS_INT_MASK = mask;
52 wmb();
53 /* Ack PYXIS PCI interrupt. */
54 *(vulp)PYXIS_INT_REQ = bit;
55 mb();
56 /* Re-read to force both writes. */
57 *(vulp)PYXIS_INT_MASK;
58 }
59
60 static struct irq_chip pyxis_irq_type = {
61 .name = "PYXIS",
62 .irq_mask_ack = pyxis_mask_and_ack_irq,
63 .irq_mask = pyxis_disable_irq,
64 .irq_unmask = pyxis_enable_irq,
65 };
66
67 void
68 pyxis_device_interrupt(unsigned long vector)
69 {
70 unsigned long pld;
71 unsigned int i;
72
73 /* Read the interrupt summary register of PYXIS */
74 pld = *(vulp)PYXIS_INT_REQ;
75 pld &= cached_irq_mask;
76
77 /*
78 * Now for every possible bit set, work through them and call
79 * the appropriate interrupt handler.
80 */
81 while (pld) {
82 i = ffz(~pld);
83 pld &= pld - 1; /* clear least bit set */
84 if (i == 7)
85 isa_device_interrupt(vector);
86 else
87 handle_irq(16+i);
88 }
89 }
90
91 void __init
92 init_pyxis_irqs(unsigned long ignore_mask)
93 {
94 long i;
95
96 *(vulp)PYXIS_INT_MASK = 0; /* disable all */
97 *(vulp)PYXIS_INT_REQ = -1; /* flush all */
98 mb();
99
100 /* Send -INTA pulses to clear any pending interrupts ...*/
101 *(vuip) CIA_IACK_SC;
102
103 for (i = 16; i < 48; ++i) {
104 if ((ignore_mask >> i) & 1)
105 continue;
106 irq_set_chip_and_handler(i, &pyxis_irq_type, handle_level_irq);
107 irq_set_status_flags(i, IRQ_LEVEL);
108 }
109
110 if (request_irq(16 + 7, no_action, 0, "isa-cascade", NULL))
111 pr_err("Failed to register isa-cascade interrupt\n");
112 }
113
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