xref: /linux/drivers/s390/cio/qdio_thinint.c (revision 8795a739e5c72abeec51caf36b6df2b37e5720c5) 
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 
19 #include "cio.h"
20 #include "ioasm.h"
21 #include "qdio.h"
22 #include "qdio_debug.h"
23 
24 /*
25  * Restriction: only 63 iqdio subchannels would have its own indicator,
26  * after that, subsequent subchannels share one indicator
27  */
28 #define TIQDIO_NR_NONSHARED_IND		63
29 #define TIQDIO_NR_INDICATORS		(TIQDIO_NR_NONSHARED_IND + 1)
30 #define TIQDIO_SHARED_IND		63
31 
32 /* device state change indicators */
33 struct indicator_t {
34 	u32 ind;	/* u32 because of compare-and-swap performance */
35 	atomic_t count; /* use count, 0 or 1 for non-shared indicators */
36 };
37 
38 /* list of thin interrupt input queues */
39 static LIST_HEAD(tiq_list);
40 static DEFINE_MUTEX(tiq_list_lock);
41 
42 /* Adapter interrupt definitions */
43 static void tiqdio_thinint_handler(struct airq_struct *airq, bool floating);
44 
45 static struct airq_struct tiqdio_airq = {
46 	.handler = tiqdio_thinint_handler,
47 	.isc = QDIO_AIRQ_ISC,
48 };
49 
50 static struct indicator_t *q_indicators;
51 
52 u64 last_ai_time;
53 
54 /* returns addr for the device state change indicator */
55 static u32 *get_indicator(void)
56 {
57 	int i;
58 
59 	for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
60 		if (!atomic_cmpxchg(&q_indicators[i].count, 0, 1))
61 			return &q_indicators[i].ind;
62 
63 	/* use the shared indicator */
64 	atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
65 	return &q_indicators[TIQDIO_SHARED_IND].ind;
66 }
67 
68 static void put_indicator(u32 *addr)
69 {
70 	struct indicator_t *ind = container_of(addr, struct indicator_t, ind);
71 
72 	if (!addr)
73 		return;
74 	atomic_dec(&ind->count);
75 }
76 
77 void tiqdio_add_input_queues(struct qdio_irq *irq_ptr)
78 {
79 	mutex_lock(&tiq_list_lock);
80 	list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);
81 	mutex_unlock(&tiq_list_lock);
82 }
83 
84 void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
85 {
86 	struct qdio_q *q;
87 
88 	q = irq_ptr->input_qs[0];
89 	if (!q)
90 		return;
91 
92 	mutex_lock(&tiq_list_lock);
93 	list_del_rcu(&q->entry);
94 	mutex_unlock(&tiq_list_lock);
95 	synchronize_rcu();
96 	INIT_LIST_HEAD(&q->entry);
97 }
98 
99 static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
100 {
101 	return irq_ptr->nr_input_qs > 1;
102 }
103 
104 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
105 {
106 	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
107 }
108 
109 static inline int shared_ind(struct qdio_irq *irq_ptr)
110 {
111 	return references_shared_dsci(irq_ptr) ||
112 		has_multiple_inq_on_dsci(irq_ptr);
113 }
114 
115 void clear_nonshared_ind(struct qdio_irq *irq_ptr)
116 {
117 	if (!is_thinint_irq(irq_ptr))
118 		return;
119 	if (shared_ind(irq_ptr))
120 		return;
121 	xchg(irq_ptr->dsci, 0);
122 }
123 
124 int test_nonshared_ind(struct qdio_irq *irq_ptr)
125 {
126 	if (!is_thinint_irq(irq_ptr))
127 		return 0;
128 	if (shared_ind(irq_ptr))
129 		return 0;
130 	if (*irq_ptr->dsci)
131 		return 1;
132 	else
133 		return 0;
134 }
135 
136 static inline u32 clear_shared_ind(void)
137 {
138 	if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
139 		return 0;
140 	return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
141 }
142 
143 static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
144 {
145 	struct qdio_q *q;
146 	int i;
147 
148 	if (!references_shared_dsci(irq) &&
149 	    has_multiple_inq_on_dsci(irq))
150 		xchg(irq->dsci, 0);
151 
152 	for_each_input_queue(irq, q, i) {
153 		if (q->u.in.queue_start_poll) {
154 			/* skip if polling is enabled or already in work */
155 			if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
156 					     &q->u.in.queue_irq_state)) {
157 				qperf_inc(q, int_discarded);
158 				continue;
159 			}
160 
161 			/* avoid dsci clear here, done after processing */
162 			q->u.in.queue_start_poll(irq->cdev, q->nr,
163 						 irq->int_parm);
164 		} else {
165 			if (!shared_ind(irq))
166 				xchg(irq->dsci, 0);
167 
168 			/*
169 			 * Call inbound processing but not directly
170 			 * since that could starve other thinint queues.
171 			 */
172 			tasklet_schedule(&q->tasklet);
173 		}
174 	}
175 }
176 
177 /**
178  * tiqdio_thinint_handler - thin interrupt handler for qdio
179  * @airq: pointer to adapter interrupt descriptor
180  * @floating: flag to recognize floating vs. directed interrupts (unused)
181  */
182 static void tiqdio_thinint_handler(struct airq_struct *airq, bool floating)
183 {
184 	u32 si_used = clear_shared_ind();
185 	struct qdio_q *q;
186 
187 	last_ai_time = S390_lowcore.int_clock;
188 	inc_irq_stat(IRQIO_QAI);
189 
190 	/* protect tiq_list entries, only changed in activate or shutdown */
191 	rcu_read_lock();
192 
193 	/* check for work on all inbound thinint queues */
194 	list_for_each_entry_rcu(q, &tiq_list, entry) {
195 		struct qdio_irq *irq;
196 
197 		/* only process queues from changed sets */
198 		irq = q->irq_ptr;
199 		if (unlikely(references_shared_dsci(irq))) {
200 			if (!si_used)
201 				continue;
202 		} else if (!*irq->dsci)
203 			continue;
204 
205 		tiqdio_call_inq_handlers(irq);
206 
207 		qperf_inc(q, adapter_int);
208 	}
209 	rcu_read_unlock();
210 }
211 
212 static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
213 {
214 	struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
215 	u64 summary_indicator_addr, subchannel_indicator_addr;
216 	int rc;
217 
218 	if (reset) {
219 		summary_indicator_addr = 0;
220 		subchannel_indicator_addr = 0;
221 	} else {
222 		summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
223 		subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
224 	}
225 
226 	rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
227 		       subchannel_indicator_addr);
228 	if (rc) {
229 		DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
230 			  scssc->response.code);
231 		goto out;
232 	}
233 
234 	DBF_EVENT("setscind");
235 	DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
236 	DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
237 out:
238 	return rc;
239 }
240 
241 /* allocate non-shared indicators and shared indicator */
242 int __init tiqdio_allocate_memory(void)
243 {
244 	q_indicators = kcalloc(TIQDIO_NR_INDICATORS,
245 			       sizeof(struct indicator_t),
246 			       GFP_KERNEL);
247 	if (!q_indicators)
248 		return -ENOMEM;
249 	return 0;
250 }
251 
252 void tiqdio_free_memory(void)
253 {
254 	kfree(q_indicators);
255 }
256 
257 int __init tiqdio_register_thinints(void)
258 {
259 	int rc;
260 
261 	rc = register_adapter_interrupt(&tiqdio_airq);
262 	if (rc) {
263 		DBF_EVENT("RTI:%x", rc);
264 		return rc;
265 	}
266 	return 0;
267 }
268 
269 int qdio_establish_thinint(struct qdio_irq *irq_ptr)
270 {
271 	if (!is_thinint_irq(irq_ptr))
272 		return 0;
273 	return set_subchannel_ind(irq_ptr, 0);
274 }
275 
276 void qdio_setup_thinint(struct qdio_irq *irq_ptr)
277 {
278 	if (!is_thinint_irq(irq_ptr))
279 		return;
280 	irq_ptr->dsci = get_indicator();
281 	DBF_HEX(&irq_ptr->dsci, sizeof(void *));
282 }
283 
284 void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
285 {
286 	if (!is_thinint_irq(irq_ptr))
287 		return;
288 
289 	/* reset adapter interrupt indicators */
290 	set_subchannel_ind(irq_ptr, 1);
291 	put_indicator(irq_ptr->dsci);
292 }
293 
294 void __exit tiqdio_unregister_thinints(void)
295 {
296 	WARN_ON(!list_empty(&tiq_list));
297 	unregister_adapter_interrupt(&tiqdio_airq);
298 }
299