1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright IBM Corp. 2000, 2009
4 * Author(s): Utz Bacher <utz.bacher@de.ibm.com>
5 *	      Cornelia Huck <cornelia.huck@de.ibm.com>
6 *	      Jan Glauber <jang@linux.vnet.ibm.com>
7 */
8#include <linux/io.h>
9#include <linux/slab.h>
10#include <linux/kernel_stat.h>
11#include <linux/atomic.h>
12#include <linux/rculist.h>
13
14#include <asm/debug.h>
15#include <asm/qdio.h>
16#include <asm/airq.h>
17#include <asm/isc.h>
18#include <asm/tpi.h>
19
20#include "cio.h"
21#include "ioasm.h"
22#include "qdio.h"
23#include "qdio_debug.h"
24
25/*
26 * Restriction: only 63 iqdio subchannels would have its own indicator,
27 * after that, subsequent subchannels share one indicator
28 */
29#define TIQDIO_NR_NONSHARED_IND		63
30#define TIQDIO_NR_INDICATORS		(TIQDIO_NR_NONSHARED_IND + 1)
31#define TIQDIO_SHARED_IND		63
32
33/* device state change indicators */
34struct indicator_t {
35	u32 ind;	/* u32 because of compare-and-swap performance */
36	atomic_t count; /* use count, 0 or 1 for non-shared indicators */
37};
38
39/* list of thin interrupt input queues */
40static LIST_HEAD(tiq_list);
41static DEFINE_MUTEX(tiq_list_lock);
42
43static struct indicator_t *q_indicators;
44
45u64 last_ai_time;
46
47/* returns addr for the device state change indicator */
48static u32 *get_indicator(void)
49{
50	int i;
51
52	for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
53		if (!atomic_cmpxchg(&q_indicators[i].count, 0, 1))
54			return &q_indicators[i].ind;
55
56	/* use the shared indicator */
57	atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
58	return &q_indicators[TIQDIO_SHARED_IND].ind;
59}
60
61static void put_indicator(u32 *addr)
62{
63	struct indicator_t *ind = container_of(addr, struct indicator_t, ind);
64
65	if (!addr)
66		return;
67	atomic_dec(&ind->count);
68}
69
70static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
71{
72	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
73}
74
75int test_nonshared_ind(struct qdio_irq *irq_ptr)
76{
77	if (!is_thinint_irq(irq_ptr))
78		return 0;
79	if (references_shared_dsci(irq_ptr))
80		return 0;
81	if (*irq_ptr->dsci)
82		return 1;
83	else
84		return 0;
85}
86
87static inline u32 clear_shared_ind(void)
88{
89	if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
90		return 0;
91	return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
92}
93
94/**
95 * tiqdio_thinint_handler - thin interrupt handler for qdio
96 * @airq: pointer to adapter interrupt descriptor
97 * @tpi_info: interrupt information (e.g. floating vs directed -- unused)
98 */
99static void tiqdio_thinint_handler(struct airq_struct *airq,
100				   struct tpi_info *tpi_info)
101{
102	u64 irq_time = S390_lowcore.int_clock;
103	u32 si_used = clear_shared_ind();
104	struct qdio_irq *irq;
105
106	last_ai_time = irq_time;
107	inc_irq_stat(IRQIO_QAI);
108
109	/* protect tiq_list entries, only changed in activate or shutdown */
110	rcu_read_lock();
111
112	list_for_each_entry_rcu(irq, &tiq_list, entry) {
113		/* only process queues from changed sets */
114		if (unlikely(references_shared_dsci(irq))) {
115			if (!si_used)
116				continue;
117		} else {
118			if (!*irq->dsci)
119				continue;
120
121			xchg(irq->dsci, 0);
122		}
123
124		qdio_deliver_irq(irq);
125		irq->last_data_irq_time = irq_time;
126
127		QDIO_PERF_STAT_INC(irq, adapter_int);
128	}
129	rcu_read_unlock();
130}
131
132static struct airq_struct tiqdio_airq = {
133	.handler = tiqdio_thinint_handler,
134	.isc = QDIO_AIRQ_ISC,
135};
136
137static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
138{
139	struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
140	dma64_t summary_indicator_addr, subchannel_indicator_addr;
141	int rc;
142
143	if (reset) {
144		summary_indicator_addr = 0;
145		subchannel_indicator_addr = 0;
146	} else {
147		summary_indicator_addr = virt_to_dma64(tiqdio_airq.lsi_ptr);
148		subchannel_indicator_addr = virt_to_dma64(irq_ptr->dsci);
149	}
150
151	rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
152		       subchannel_indicator_addr, tiqdio_airq.isc);
153	if (rc) {
154		DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
155			  scssc->response.code);
156		goto out;
157	}
158
159	DBF_EVENT("setscind");
160	DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
161	DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
162out:
163	return rc;
164}
165
166int qdio_establish_thinint(struct qdio_irq *irq_ptr)
167{
168	int rc;
169
170	if (!is_thinint_irq(irq_ptr))
171		return 0;
172
173	irq_ptr->dsci = get_indicator();
174	DBF_HEX(&irq_ptr->dsci, sizeof(void *));
175
176	rc = set_subchannel_ind(irq_ptr, 0);
177	if (rc) {
178		put_indicator(irq_ptr->dsci);
179		return rc;
180	}
181
182	mutex_lock(&tiq_list_lock);
183	list_add_rcu(&irq_ptr->entry, &tiq_list);
184	mutex_unlock(&tiq_list_lock);
185	return 0;
186}
187
188void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
189{
190	if (!is_thinint_irq(irq_ptr))
191		return;
192
193	mutex_lock(&tiq_list_lock);
194	list_del_rcu(&irq_ptr->entry);
195	mutex_unlock(&tiq_list_lock);
196	synchronize_rcu();
197
198	/* reset adapter interrupt indicators */
199	set_subchannel_ind(irq_ptr, 1);
200	put_indicator(irq_ptr->dsci);
201}
202
203int __init qdio_thinint_init(void)
204{
205	int rc;
206
207	q_indicators = kcalloc(TIQDIO_NR_INDICATORS, sizeof(struct indicator_t),
208			       GFP_KERNEL);
209	if (!q_indicators)
210		return -ENOMEM;
211
212	rc = register_adapter_interrupt(&tiqdio_airq);
213	if (rc) {
214		DBF_EVENT("RTI:%x", rc);
215		kfree(q_indicators);
216		return rc;
217	}
218	return 0;
219}
220
221void __exit qdio_thinint_exit(void)
222{
223	WARN_ON(!list_empty(&tiq_list));
224	unregister_adapter_interrupt(&tiqdio_airq);
225	kfree(q_indicators);
226}
227