xref: /linux/drivers/s390/cio/qdio_thinint.c (revision b2d0f5d5dc53532e6f07bc546a476a55ebdfe0f3) 
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);
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_read(&q_indicators[i].count)) {
61 			atomic_set(&q_indicators[i].count, 1);
62 			return &q_indicators[i].ind;
63 		}
64 
65 	/* use the shared indicator */
66 	atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
67 	return &q_indicators[TIQDIO_SHARED_IND].ind;
68 }
69 
70 static void put_indicator(u32 *addr)
71 {
72 	int i;
73 
74 	if (!addr)
75 		return;
76 	i = ((unsigned long)addr - (unsigned long)q_indicators) /
77 		sizeof(struct indicator_t);
78 	atomic_dec(&q_indicators[i].count);
79 }
80 
81 void tiqdio_add_input_queues(struct qdio_irq *irq_ptr)
82 {
83 	mutex_lock(&tiq_list_lock);
84 	list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);
85 	mutex_unlock(&tiq_list_lock);
86 	xchg(irq_ptr->dsci, 1 << 7);
87 }
88 
89 void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
90 {
91 	struct qdio_q *q;
92 
93 	q = irq_ptr->input_qs[0];
94 	/* if establish triggered an error */
95 	if (!q || !q->entry.prev || !q->entry.next)
96 		return;
97 
98 	mutex_lock(&tiq_list_lock);
99 	list_del_rcu(&q->entry);
100 	mutex_unlock(&tiq_list_lock);
101 	synchronize_rcu();
102 }
103 
104 static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
105 {
106 	return irq_ptr->nr_input_qs > 1;
107 }
108 
109 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
110 {
111 	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
112 }
113 
114 static inline int shared_ind(struct qdio_irq *irq_ptr)
115 {
116 	return references_shared_dsci(irq_ptr) ||
117 		has_multiple_inq_on_dsci(irq_ptr);
118 }
119 
120 void clear_nonshared_ind(struct qdio_irq *irq_ptr)
121 {
122 	if (!is_thinint_irq(irq_ptr))
123 		return;
124 	if (shared_ind(irq_ptr))
125 		return;
126 	xchg(irq_ptr->dsci, 0);
127 }
128 
129 int test_nonshared_ind(struct qdio_irq *irq_ptr)
130 {
131 	if (!is_thinint_irq(irq_ptr))
132 		return 0;
133 	if (shared_ind(irq_ptr))
134 		return 0;
135 	if (*irq_ptr->dsci)
136 		return 1;
137 	else
138 		return 0;
139 }
140 
141 static inline u32 clear_shared_ind(void)
142 {
143 	if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
144 		return 0;
145 	return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
146 }
147 
148 static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
149 {
150 	struct qdio_q *q;
151 	int i;
152 
153 	if (!references_shared_dsci(irq) &&
154 	    has_multiple_inq_on_dsci(irq))
155 		xchg(irq->dsci, 0);
156 
157 	for_each_input_queue(irq, q, i) {
158 		if (q->u.in.queue_start_poll) {
159 			/* skip if polling is enabled or already in work */
160 			if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
161 					     &q->u.in.queue_irq_state)) {
162 				qperf_inc(q, int_discarded);
163 				continue;
164 			}
165 
166 			/* avoid dsci clear here, done after processing */
167 			q->u.in.queue_start_poll(irq->cdev, q->nr,
168 						 irq->int_parm);
169 		} else {
170 			if (!shared_ind(irq))
171 				xchg(irq->dsci, 0);
172 
173 			/*
174 			 * Call inbound processing but not directly
175 			 * since that could starve other thinint queues.
176 			 */
177 			tasklet_schedule(&q->tasklet);
178 		}
179 	}
180 }
181 
182 /**
183  * tiqdio_thinint_handler - thin interrupt handler for qdio
184  * @airq: pointer to adapter interrupt descriptor
185  */
186 static void tiqdio_thinint_handler(struct airq_struct *airq)
187 {
188 	u32 si_used = clear_shared_ind();
189 	struct qdio_q *q;
190 
191 	last_ai_time = S390_lowcore.int_clock;
192 	inc_irq_stat(IRQIO_QAI);
193 
194 	/* protect tiq_list entries, only changed in activate or shutdown */
195 	rcu_read_lock();
196 
197 	/* check for work on all inbound thinint queues */
198 	list_for_each_entry_rcu(q, &tiq_list, entry) {
199 		struct qdio_irq *irq;
200 
201 		/* only process queues from changed sets */
202 		irq = q->irq_ptr;
203 		if (unlikely(references_shared_dsci(irq))) {
204 			if (!si_used)
205 				continue;
206 		} else if (!*irq->dsci)
207 			continue;
208 
209 		tiqdio_call_inq_handlers(irq);
210 
211 		qperf_inc(q, adapter_int);
212 	}
213 	rcu_read_unlock();
214 }
215 
216 static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
217 {
218 	struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
219 	u64 summary_indicator_addr, subchannel_indicator_addr;
220 	int rc;
221 
222 	if (reset) {
223 		summary_indicator_addr = 0;
224 		subchannel_indicator_addr = 0;
225 	} else {
226 		summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
227 		subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
228 	}
229 
230 	rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
231 		       subchannel_indicator_addr);
232 	if (rc) {
233 		DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
234 			  scssc->response.code);
235 		goto out;
236 	}
237 
238 	DBF_EVENT("setscind");
239 	DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
240 	DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
241 out:
242 	return rc;
243 }
244 
245 /* allocate non-shared indicators and shared indicator */
246 int __init tiqdio_allocate_memory(void)
247 {
248 	q_indicators = kzalloc(sizeof(struct indicator_t) * TIQDIO_NR_INDICATORS,
249 			     GFP_KERNEL);
250 	if (!q_indicators)
251 		return -ENOMEM;
252 	return 0;
253 }
254 
255 void tiqdio_free_memory(void)
256 {
257 	kfree(q_indicators);
258 }
259 
260 int __init tiqdio_register_thinints(void)
261 {
262 	int rc;
263 
264 	rc = register_adapter_interrupt(&tiqdio_airq);
265 	if (rc) {
266 		DBF_EVENT("RTI:%x", rc);
267 		return rc;
268 	}
269 	return 0;
270 }
271 
272 int qdio_establish_thinint(struct qdio_irq *irq_ptr)
273 {
274 	if (!is_thinint_irq(irq_ptr))
275 		return 0;
276 	return set_subchannel_ind(irq_ptr, 0);
277 }
278 
279 void qdio_setup_thinint(struct qdio_irq *irq_ptr)
280 {
281 	if (!is_thinint_irq(irq_ptr))
282 		return;
283 	irq_ptr->dsci = get_indicator();
284 	DBF_HEX(&irq_ptr->dsci, sizeof(void *));
285 }
286 
287 void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
288 {
289 	if (!is_thinint_irq(irq_ptr))
290 		return;
291 
292 	/* reset adapter interrupt indicators */
293 	set_subchannel_ind(irq_ptr, 1);
294 	put_indicator(irq_ptr->dsci);
295 }
296 
297 void __exit tiqdio_unregister_thinints(void)
298 {
299 	WARN_ON(!list_empty(&tiq_list));
300 	unregister_adapter_interrupt(&tiqdio_airq);
301 }
302