xref: /linux/drivers/s390/cio/qdio_thinint.c (revision 9a6b55ac) 
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 static struct indicator_t *q_indicators;
43 
44 u64 last_ai_time;
45 
46 /* returns addr for the device state change indicator */
47 static u32 *get_indicator(void)
48 {
49 	int i;
50 
51 	for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
52 		if (!atomic_cmpxchg(&q_indicators[i].count, 0, 1))
53 			return &q_indicators[i].ind;
54 
55 	/* use the shared indicator */
56 	atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
57 	return &q_indicators[TIQDIO_SHARED_IND].ind;
58 }
59 
60 static void put_indicator(u32 *addr)
61 {
62 	struct indicator_t *ind = container_of(addr, struct indicator_t, ind);
63 
64 	if (!addr)
65 		return;
66 	atomic_dec(&ind->count);
67 }
68 
69 void tiqdio_add_device(struct qdio_irq *irq_ptr)
70 {
71 	mutex_lock(&tiq_list_lock);
72 	list_add_rcu(&irq_ptr->entry, &tiq_list);
73 	mutex_unlock(&tiq_list_lock);
74 }
75 
76 void tiqdio_remove_device(struct qdio_irq *irq_ptr)
77 {
78 	mutex_lock(&tiq_list_lock);
79 	list_del_rcu(&irq_ptr->entry);
80 	mutex_unlock(&tiq_list_lock);
81 	synchronize_rcu();
82 	INIT_LIST_HEAD(&irq_ptr->entry);
83 }
84 
85 static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
86 {
87 	return irq_ptr->nr_input_qs > 1;
88 }
89 
90 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
91 {
92 	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
93 }
94 
95 static inline int shared_ind(struct qdio_irq *irq_ptr)
96 {
97 	return references_shared_dsci(irq_ptr) ||
98 		has_multiple_inq_on_dsci(irq_ptr);
99 }
100 
101 void clear_nonshared_ind(struct qdio_irq *irq_ptr)
102 {
103 	if (!is_thinint_irq(irq_ptr))
104 		return;
105 	if (shared_ind(irq_ptr))
106 		return;
107 	xchg(irq_ptr->dsci, 0);
108 }
109 
110 int test_nonshared_ind(struct qdio_irq *irq_ptr)
111 {
112 	if (!is_thinint_irq(irq_ptr))
113 		return 0;
114 	if (shared_ind(irq_ptr))
115 		return 0;
116 	if (*irq_ptr->dsci)
117 		return 1;
118 	else
119 		return 0;
120 }
121 
122 static inline u32 clear_shared_ind(void)
123 {
124 	if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
125 		return 0;
126 	return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
127 }
128 
129 static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
130 {
131 	struct qdio_q *q;
132 	int i;
133 
134 	if (!references_shared_dsci(irq) &&
135 	    has_multiple_inq_on_dsci(irq))
136 		xchg(irq->dsci, 0);
137 
138 	for_each_input_queue(irq, q, i) {
139 		if (q->u.in.queue_start_poll) {
140 			/* skip if polling is enabled or already in work */
141 			if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
142 					     &q->u.in.queue_irq_state)) {
143 				QDIO_PERF_STAT_INC(irq, int_discarded);
144 				continue;
145 			}
146 
147 			/* avoid dsci clear here, done after processing */
148 			q->u.in.queue_start_poll(irq->cdev, q->nr,
149 						 irq->int_parm);
150 		} else {
151 			if (!shared_ind(irq))
152 				xchg(irq->dsci, 0);
153 
154 			/*
155 			 * Call inbound processing but not directly
156 			 * since that could starve other thinint queues.
157 			 */
158 			tasklet_schedule(&q->tasklet);
159 		}
160 	}
161 }
162 
163 /**
164  * tiqdio_thinint_handler - thin interrupt handler for qdio
165  * @airq: pointer to adapter interrupt descriptor
166  * @floating: flag to recognize floating vs. directed interrupts (unused)
167  */
168 static void tiqdio_thinint_handler(struct airq_struct *airq, bool floating)
169 {
170 	u32 si_used = clear_shared_ind();
171 	struct qdio_irq *irq;
172 
173 	last_ai_time = S390_lowcore.int_clock;
174 	inc_irq_stat(IRQIO_QAI);
175 
176 	/* protect tiq_list entries, only changed in activate or shutdown */
177 	rcu_read_lock();
178 
179 	list_for_each_entry_rcu(irq, &tiq_list, entry) {
180 		/* only process queues from changed sets */
181 		if (unlikely(references_shared_dsci(irq))) {
182 			if (!si_used)
183 				continue;
184 		} else if (!*irq->dsci)
185 			continue;
186 
187 		tiqdio_call_inq_handlers(irq);
188 
189 		QDIO_PERF_STAT_INC(irq, adapter_int);
190 	}
191 	rcu_read_unlock();
192 }
193 
194 static struct airq_struct tiqdio_airq = {
195 	.handler = tiqdio_thinint_handler,
196 	.isc = QDIO_AIRQ_ISC,
197 };
198 
199 static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
200 {
201 	struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
202 	u64 summary_indicator_addr, subchannel_indicator_addr;
203 	int rc;
204 
205 	if (reset) {
206 		summary_indicator_addr = 0;
207 		subchannel_indicator_addr = 0;
208 	} else {
209 		summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
210 		subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
211 	}
212 
213 	rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
214 		       subchannel_indicator_addr);
215 	if (rc) {
216 		DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
217 			  scssc->response.code);
218 		goto out;
219 	}
220 
221 	DBF_EVENT("setscind");
222 	DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
223 	DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
224 out:
225 	return rc;
226 }
227 
228 /* allocate non-shared indicators and shared indicator */
229 int __init tiqdio_allocate_memory(void)
230 {
231 	q_indicators = kcalloc(TIQDIO_NR_INDICATORS,
232 			       sizeof(struct indicator_t),
233 			       GFP_KERNEL);
234 	if (!q_indicators)
235 		return -ENOMEM;
236 	return 0;
237 }
238 
239 void tiqdio_free_memory(void)
240 {
241 	kfree(q_indicators);
242 }
243 
244 int __init tiqdio_register_thinints(void)
245 {
246 	int rc;
247 
248 	rc = register_adapter_interrupt(&tiqdio_airq);
249 	if (rc) {
250 		DBF_EVENT("RTI:%x", rc);
251 		return rc;
252 	}
253 	return 0;
254 }
255 
256 int qdio_establish_thinint(struct qdio_irq *irq_ptr)
257 {
258 	if (!is_thinint_irq(irq_ptr))
259 		return 0;
260 	return set_subchannel_ind(irq_ptr, 0);
261 }
262 
263 void qdio_setup_thinint(struct qdio_irq *irq_ptr)
264 {
265 	if (!is_thinint_irq(irq_ptr))
266 		return;
267 	irq_ptr->dsci = get_indicator();
268 	DBF_HEX(&irq_ptr->dsci, sizeof(void *));
269 }
270 
271 void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
272 {
273 	if (!is_thinint_irq(irq_ptr))
274 		return;
275 
276 	/* reset adapter interrupt indicators */
277 	set_subchannel_ind(irq_ptr, 1);
278 	put_indicator(irq_ptr->dsci);
279 }
280 
281 void __exit tiqdio_unregister_thinints(void)
282 {
283 	WARN_ON(!list_empty(&tiq_list));
284 	unregister_adapter_interrupt(&tiqdio_airq);
285 }
286