xref: /openbmc/linux/drivers/s390/cio/qdio_thinint.c (revision 94cdda6b) 
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 */
30 struct 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 */
36 static LIST_HEAD(tiq_list);
37 static DEFINE_MUTEX(tiq_list_lock);
38 
39 /* Adapter interrupt definitions */
40 static void tiqdio_thinint_handler(struct airq_struct *airq);
41 
42 static struct airq_struct tiqdio_airq = {
43 	.handler = tiqdio_thinint_handler,
44 	.isc = QDIO_AIRQ_ISC,
45 };
46 
47 static struct indicator_t *q_indicators;
48 
49 u64 last_ai_time;
50 
51 /* returns addr for the device state change indicator */
52 static 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 
67 static 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 
78 void 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 
86 void 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 
101 static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
102 {
103 	return irq_ptr->nr_input_qs > 1;
104 }
105 
106 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
107 {
108 	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
109 }
110 
111 static 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 
117 void 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 
126 int 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 
138 static 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 
145 static 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  */
184 static 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 
214 static 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));
239 out:
240 	return rc;
241 }
242 
243 /* allocate non-shared indicators and shared indicator */
244 int __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 
253 void tiqdio_free_memory(void)
254 {
255 	kfree(q_indicators);
256 }
257 
258 int __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 
270 int 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 
277 void 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 
285 void 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 
295 void __exit tiqdio_unregister_thinints(void)
296 {
297 	WARN_ON(!list_empty(&tiq_list));
298 	unregister_adapter_interrupt(&tiqdio_airq);
299 }
300