1/*
2 *  drivers/s390/cio/airq.c
3 *    Support for adapter interruptions
4 *
5 *    Copyright IBM Corp. 1999,2007
6 *    Author(s): Ingo Adlung <adlung@de.ibm.com>
7 *		 Cornelia Huck <cornelia.huck@de.ibm.com>
8 *		 Arnd Bergmann <arndb@de.ibm.com>
9 *		 Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
10 */
11
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/slab.h>
15#include <linux/rcupdate.h>
16
17#include <asm/airq.h>
18#include <asm/isc.h>
19
20#include "cio.h"
21#include "cio_debug.h"
22
23#define NR_AIRQS		32
24#define NR_AIRQS_PER_WORD	sizeof(unsigned long)
25#define NR_AIRQ_WORDS		(NR_AIRQS / NR_AIRQS_PER_WORD)
26
27union indicator_t {
28	unsigned long word[NR_AIRQ_WORDS];
29	unsigned char byte[NR_AIRQS];
30} __attribute__((packed));
31
32struct airq_t {
33	adapter_int_handler_t handler;
34	void *drv_data;
35};
36
37static union indicator_t indicators[MAX_ISC+1];
38static struct airq_t *airqs[MAX_ISC+1][NR_AIRQS];
39
40static int register_airq(struct airq_t *airq, u8 isc)
41{
42	int i;
43
44	for (i = 0; i < NR_AIRQS; i++)
45		if (!cmpxchg(&airqs[isc][i], NULL, airq))
46			return i;
47	return -ENOMEM;
48}
49
50/**
51 * s390_register_adapter_interrupt() - register adapter interrupt handler
52 * @handler: adapter handler to be registered
53 * @drv_data: driver data passed with each call to the handler
54 * @isc: isc for which the handler should be called
55 *
56 * Returns:
57 *  Pointer to the indicator to be used on success
58 *  ERR_PTR() if registration failed
59 */
60void *s390_register_adapter_interrupt(adapter_int_handler_t handler,
61				      void *drv_data, u8 isc)
62{
63	struct airq_t *airq;
64	char dbf_txt[16];
65	int ret;
66
67	if (isc > MAX_ISC)
68		return ERR_PTR(-EINVAL);
69	airq = kmalloc(sizeof(struct airq_t), GFP_KERNEL);
70	if (!airq) {
71		ret = -ENOMEM;
72		goto out;
73	}
74	airq->handler = handler;
75	airq->drv_data = drv_data;
76
77	ret = register_airq(airq, isc);
78out:
79	snprintf(dbf_txt, sizeof(dbf_txt), "rairq:%d", ret);
80	CIO_TRACE_EVENT(4, dbf_txt);
81	if (ret < 0) {
82		kfree(airq);
83		return ERR_PTR(ret);
84	} else
85		return &indicators[isc].byte[ret];
86}
87EXPORT_SYMBOL(s390_register_adapter_interrupt);
88
89/**
90 * s390_unregister_adapter_interrupt - unregister adapter interrupt handler
91 * @ind: indicator for which the handler is to be unregistered
92 * @isc: interruption subclass
93 */
94void s390_unregister_adapter_interrupt(void *ind, u8 isc)
95{
96	struct airq_t *airq;
97	char dbf_txt[16];
98	int i;
99
100	i = (int) ((addr_t) ind) - ((addr_t) &indicators[isc].byte[0]);
101	snprintf(dbf_txt, sizeof(dbf_txt), "urairq:%d", i);
102	CIO_TRACE_EVENT(4, dbf_txt);
103	indicators[isc].byte[i] = 0;
104	airq = xchg(&airqs[isc][i], NULL);
105	/*
106	 * Allow interrupts to complete. This will ensure that the airq handle
107	 * is no longer referenced by any interrupt handler.
108	 */
109	synchronize_sched();
110	kfree(airq);
111}
112EXPORT_SYMBOL(s390_unregister_adapter_interrupt);
113
114#define INDICATOR_MASK	(0xffUL << ((NR_AIRQS_PER_WORD - 1) * 8))
115
116void do_adapter_IO(u8 isc)
117{
118	int w;
119	int i;
120	unsigned long word;
121	struct airq_t *airq;
122
123	/*
124	 * Access indicator array in word-sized chunks to minimize storage
125	 * fetch operations.
126	 */
127	for (w = 0; w < NR_AIRQ_WORDS; w++) {
128		word = indicators[isc].word[w];
129		i = w * NR_AIRQS_PER_WORD;
130		/*
131		 * Check bytes within word for active indicators.
132		 */
133		while (word) {
134			if (word & INDICATOR_MASK) {
135				airq = airqs[isc][i];
136				/* Make sure gcc reads from airqs only once. */
137				barrier();
138				if (likely(airq))
139					airq->handler(&indicators[isc].byte[i],
140						      airq->drv_data);
141				else
142					/*
143					 * Reset ill-behaved indicator.
144					 */
145					indicators[isc].byte[i] = 0;
146			}
147			word <<= 8;
148			i++;
149		}
150	}
151}
152