1/*
2 * Copyright IBM Corp. 2000, 2009
3 * Author(s): Utz Bacher <utz.bacher@de.ibm.com>
4 *	      Cornelia Huck <cornelia.huck@de.ibm.com>
5 *	      Jan Glauber <jang@linux.vnet.ibm.com>
6 */
7#include <linux/io.h>
8#include <linux/slab.h>
9#include <linux/kernel_stat.h>
10#include <linux/atomic.h>
11#include <asm/debug.h>
12#include <asm/qdio.h>
13#include <asm/airq.h>
14#include <asm/isc.h>
15
16#include "cio.h"
17#include "ioasm.h"
18#include "qdio.h"
19#include "qdio_debug.h"
20
21/*
22 * Restriction: only 63 iqdio subchannels would have its own indicator,
23 * after that, subsequent subchannels share one indicator
24 */
25#define TIQDIO_NR_NONSHARED_IND		63
26#define TIQDIO_NR_INDICATORS		(TIQDIO_NR_NONSHARED_IND + 1)
27#define TIQDIO_SHARED_IND		63
28
29/* device state change indicators */
30struct indicator_t {
31	u32 ind;	/* u32 because of compare-and-swap performance */
32	atomic_t count; /* use count, 0 or 1 for non-shared indicators */
33};
34
35/* list of thin interrupt input queues */
36static LIST_HEAD(tiq_list);
37static DEFINE_MUTEX(tiq_list_lock);
38
39/* Adapter interrupt definitions */
40static void tiqdio_thinint_handler(struct airq_struct *airq);
41
42static struct airq_struct tiqdio_airq = {
43	.handler = tiqdio_thinint_handler,
44	.isc = QDIO_AIRQ_ISC,
45};
46
47static struct indicator_t *q_indicators;
48
49u64 last_ai_time;
50
51/* returns addr for the device state change indicator */
52static u32 *get_indicator(void)
53{
54	int i;
55
56	for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
57		if (!atomic_read(&q_indicators[i].count)) {
58			atomic_set(&q_indicators[i].count, 1);
59			return &q_indicators[i].ind;
60		}
61
62	/* use the shared indicator */
63	atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
64	return &q_indicators[TIQDIO_SHARED_IND].ind;
65}
66
67static void put_indicator(u32 *addr)
68{
69	int i;
70
71	if (!addr)
72		return;
73	i = ((unsigned long)addr - (unsigned long)q_indicators) /
74		sizeof(struct indicator_t);
75	atomic_dec(&q_indicators[i].count);
76}
77
78void tiqdio_add_input_queues(struct qdio_irq *irq_ptr)
79{
80	mutex_lock(&tiq_list_lock);
81	list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);
82	mutex_unlock(&tiq_list_lock);
83	xchg(irq_ptr->dsci, 1 << 7);
84}
85
86void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
87{
88	struct qdio_q *q;
89
90	q = irq_ptr->input_qs[0];
91	/* if establish triggered an error */
92	if (!q || !q->entry.prev || !q->entry.next)
93		return;
94
95	mutex_lock(&tiq_list_lock);
96	list_del_rcu(&q->entry);
97	mutex_unlock(&tiq_list_lock);
98	synchronize_rcu();
99}
100
101static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
102{
103	return irq_ptr->nr_input_qs > 1;
104}
105
106static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
107{
108	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
109}
110
111static inline int shared_ind(struct qdio_irq *irq_ptr)
112{
113	return references_shared_dsci(irq_ptr) ||
114		has_multiple_inq_on_dsci(irq_ptr);
115}
116
117void clear_nonshared_ind(struct qdio_irq *irq_ptr)
118{
119	if (!is_thinint_irq(irq_ptr))
120		return;
121	if (shared_ind(irq_ptr))
122		return;
123	xchg(irq_ptr->dsci, 0);
124}
125
126int test_nonshared_ind(struct qdio_irq *irq_ptr)
127{
128	if (!is_thinint_irq(irq_ptr))
129		return 0;
130	if (shared_ind(irq_ptr))
131		return 0;
132	if (*irq_ptr->dsci)
133		return 1;
134	else
135		return 0;
136}
137
138static inline u32 clear_shared_ind(void)
139{
140	if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
141		return 0;
142	return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
143}
144
145static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
146{
147	struct qdio_q *q;
148	int i;
149
150	for_each_input_queue(irq, q, i) {
151		if (!references_shared_dsci(irq) &&
152		    has_multiple_inq_on_dsci(irq))
153			xchg(q->irq_ptr->dsci, 0);
154
155		if (q->u.in.queue_start_poll) {
156			/* skip if polling is enabled or already in work */
157			if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
158					     &q->u.in.queue_irq_state)) {
159				qperf_inc(q, int_discarded);
160				continue;
161			}
162
163			/* avoid dsci clear here, done after processing */
164			q->u.in.queue_start_poll(q->irq_ptr->cdev, q->nr,
165						 q->irq_ptr->int_parm);
166		} else {
167			if (!shared_ind(q->irq_ptr))
168				xchg(q->irq_ptr->dsci, 0);
169
170			/*
171			 * Call inbound processing but not directly
172			 * since that could starve other thinint queues.
173			 */
174			tasklet_schedule(&q->tasklet);
175		}
176	}
177}
178
179/**
180 * tiqdio_thinint_handler - thin interrupt handler for qdio
181 * @alsi: pointer to adapter local summary indicator
182 * @data: NULL
183 */
184static void tiqdio_thinint_handler(struct airq_struct *airq)
185{
186	u32 si_used = clear_shared_ind();
187	struct qdio_q *q;
188
189	last_ai_time = S390_lowcore.int_clock;
190	inc_irq_stat(IRQIO_QAI);
191
192	/* protect tiq_list entries, only changed in activate or shutdown */
193	rcu_read_lock();
194
195	/* check for work on all inbound thinint queues */
196	list_for_each_entry_rcu(q, &tiq_list, entry) {
197		struct qdio_irq *irq;
198
199		/* only process queues from changed sets */
200		irq = q->irq_ptr;
201		if (unlikely(references_shared_dsci(irq))) {
202			if (!si_used)
203				continue;
204		} else if (!*irq->dsci)
205			continue;
206
207		tiqdio_call_inq_handlers(irq);
208
209		qperf_inc(q, adapter_int);
210	}
211	rcu_read_unlock();
212}
213
214static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
215{
216	struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
217	u64 summary_indicator_addr, subchannel_indicator_addr;
218	int rc;
219
220	if (reset) {
221		summary_indicator_addr = 0;
222		subchannel_indicator_addr = 0;
223	} else {
224		summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
225		subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
226	}
227
228	rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
229		       subchannel_indicator_addr);
230	if (rc) {
231		DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
232			  scssc->response.code);
233		goto out;
234	}
235
236	DBF_EVENT("setscind");
237	DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
238	DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
239out:
240	return rc;
241}
242
243/* allocate non-shared indicators and shared indicator */
244int __init tiqdio_allocate_memory(void)
245{
246	q_indicators = kzalloc(sizeof(struct indicator_t) * TIQDIO_NR_INDICATORS,
247			     GFP_KERNEL);
248	if (!q_indicators)
249		return -ENOMEM;
250	return 0;
251}
252
253void tiqdio_free_memory(void)
254{
255	kfree(q_indicators);
256}
257
258int __init tiqdio_register_thinints(void)
259{
260	int rc;
261
262	rc = register_adapter_interrupt(&tiqdio_airq);
263	if (rc) {
264		DBF_EVENT("RTI:%x", rc);
265		return rc;
266	}
267	return 0;
268}
269
270int qdio_establish_thinint(struct qdio_irq *irq_ptr)
271{
272	if (!is_thinint_irq(irq_ptr))
273		return 0;
274	return set_subchannel_ind(irq_ptr, 0);
275}
276
277void qdio_setup_thinint(struct qdio_irq *irq_ptr)
278{
279	if (!is_thinint_irq(irq_ptr))
280		return;
281	irq_ptr->dsci = get_indicator();
282	DBF_HEX(&irq_ptr->dsci, sizeof(void *));
283}
284
285void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
286{
287	if (!is_thinint_irq(irq_ptr))
288		return;
289
290	/* reset adapter interrupt indicators */
291	set_subchannel_ind(irq_ptr, 1);
292	put_indicator(irq_ptr->dsci);
293}
294
295void __exit tiqdio_unregister_thinints(void)
296{
297	WARN_ON(!list_empty(&tiq_list));
298	unregister_adapter_interrupt(&tiqdio_airq);
299}
300