xref: /openbmc/linux/drivers/s390/cio/qdio_thinint.c (revision d2197485)
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 #include <asm/tpi.h>
19 
20 #include "cio.h"
21 #include "ioasm.h"
22 #include "qdio.h"
23 #include "qdio_debug.h"
24 
25 /*
26  * Restriction: only 63 iqdio subchannels would have its own indicator,
27  * after that, subsequent subchannels share one indicator
28  */
29 #define TIQDIO_NR_NONSHARED_IND		63
30 #define TIQDIO_NR_INDICATORS		(TIQDIO_NR_NONSHARED_IND + 1)
31 #define TIQDIO_SHARED_IND		63
32 
33 /* device state change indicators */
34 struct indicator_t {
35 	u32 ind;	/* u32 because of compare-and-swap performance */
36 	atomic_t count; /* use count, 0 or 1 for non-shared indicators */
37 };
38 
39 /* list of thin interrupt input queues */
40 static LIST_HEAD(tiq_list);
41 static DEFINE_MUTEX(tiq_list_lock);
42 
43 static struct indicator_t *q_indicators;
44 
45 u64 last_ai_time;
46 
47 /* returns addr for the device state change indicator */
get_indicator(void)48 static u32 *get_indicator(void)
49 {
50 	int i;
51 
52 	for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
53 		if (!atomic_cmpxchg(&q_indicators[i].count, 0, 1))
54 			return &q_indicators[i].ind;
55 
56 	/* use the shared indicator */
57 	atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
58 	return &q_indicators[TIQDIO_SHARED_IND].ind;
59 }
60 
put_indicator(u32 * addr)61 static void put_indicator(u32 *addr)
62 {
63 	struct indicator_t *ind = container_of(addr, struct indicator_t, ind);
64 
65 	if (!addr)
66 		return;
67 	atomic_dec(&ind->count);
68 }
69 
references_shared_dsci(struct qdio_irq * irq_ptr)70 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
71 {
72 	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
73 }
74 
test_nonshared_ind(struct qdio_irq * irq_ptr)75 int test_nonshared_ind(struct qdio_irq *irq_ptr)
76 {
77 	if (!is_thinint_irq(irq_ptr))
78 		return 0;
79 	if (references_shared_dsci(irq_ptr))
80 		return 0;
81 	if (*irq_ptr->dsci)
82 		return 1;
83 	else
84 		return 0;
85 }
86 
clear_shared_ind(void)87 static inline u32 clear_shared_ind(void)
88 {
89 	if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
90 		return 0;
91 	return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
92 }
93 
94 /**
95  * tiqdio_thinint_handler - thin interrupt handler for qdio
96  * @airq: pointer to adapter interrupt descriptor
97  * @tpi_info: interrupt information (e.g. floating vs directed -- unused)
98  */
tiqdio_thinint_handler(struct airq_struct * airq,struct tpi_info * tpi_info)99 static void tiqdio_thinint_handler(struct airq_struct *airq,
100 				   struct tpi_info *tpi_info)
101 {
102 	u64 irq_time = S390_lowcore.int_clock;
103 	u32 si_used = clear_shared_ind();
104 	struct qdio_irq *irq;
105 
106 	last_ai_time = irq_time;
107 	inc_irq_stat(IRQIO_QAI);
108 
109 	/* protect tiq_list entries, only changed in activate or shutdown */
110 	rcu_read_lock();
111 
112 	list_for_each_entry_rcu(irq, &tiq_list, entry) {
113 		/* only process queues from changed sets */
114 		if (unlikely(references_shared_dsci(irq))) {
115 			if (!si_used)
116 				continue;
117 		} else {
118 			if (!*irq->dsci)
119 				continue;
120 
121 			xchg(irq->dsci, 0);
122 		}
123 
124 		qdio_deliver_irq(irq);
125 		irq->last_data_irq_time = irq_time;
126 
127 		QDIO_PERF_STAT_INC(irq, adapter_int);
128 	}
129 	rcu_read_unlock();
130 }
131 
132 static struct airq_struct tiqdio_airq = {
133 	.handler = tiqdio_thinint_handler,
134 	.isc = QDIO_AIRQ_ISC,
135 };
136 
set_subchannel_ind(struct qdio_irq * irq_ptr,int reset)137 static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
138 {
139 	struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
140 	u64 summary_indicator_addr, subchannel_indicator_addr;
141 	int rc;
142 
143 	if (reset) {
144 		summary_indicator_addr = 0;
145 		subchannel_indicator_addr = 0;
146 	} else {
147 		summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
148 		subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
149 	}
150 
151 	rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
152 		       subchannel_indicator_addr, tiqdio_airq.isc);
153 	if (rc) {
154 		DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
155 			  scssc->response.code);
156 		goto out;
157 	}
158 
159 	DBF_EVENT("setscind");
160 	DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
161 	DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
162 out:
163 	return rc;
164 }
165 
qdio_establish_thinint(struct qdio_irq * irq_ptr)166 int qdio_establish_thinint(struct qdio_irq *irq_ptr)
167 {
168 	int rc;
169 
170 	if (!is_thinint_irq(irq_ptr))
171 		return 0;
172 
173 	irq_ptr->dsci = get_indicator();
174 	DBF_HEX(&irq_ptr->dsci, sizeof(void *));
175 
176 	rc = set_subchannel_ind(irq_ptr, 0);
177 	if (rc) {
178 		put_indicator(irq_ptr->dsci);
179 		return rc;
180 	}
181 
182 	mutex_lock(&tiq_list_lock);
183 	list_add_rcu(&irq_ptr->entry, &tiq_list);
184 	mutex_unlock(&tiq_list_lock);
185 	return 0;
186 }
187 
qdio_shutdown_thinint(struct qdio_irq * irq_ptr)188 void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
189 {
190 	if (!is_thinint_irq(irq_ptr))
191 		return;
192 
193 	mutex_lock(&tiq_list_lock);
194 	list_del_rcu(&irq_ptr->entry);
195 	mutex_unlock(&tiq_list_lock);
196 	synchronize_rcu();
197 
198 	/* reset adapter interrupt indicators */
199 	set_subchannel_ind(irq_ptr, 1);
200 	put_indicator(irq_ptr->dsci);
201 }
202 
qdio_thinint_init(void)203 int __init qdio_thinint_init(void)
204 {
205 	int rc;
206 
207 	q_indicators = kcalloc(TIQDIO_NR_INDICATORS, sizeof(struct indicator_t),
208 			       GFP_KERNEL);
209 	if (!q_indicators)
210 		return -ENOMEM;
211 
212 	rc = register_adapter_interrupt(&tiqdio_airq);
213 	if (rc) {
214 		DBF_EVENT("RTI:%x", rc);
215 		kfree(q_indicators);
216 		return rc;
217 	}
218 	return 0;
219 }
220 
qdio_thinint_exit(void)221 void __exit qdio_thinint_exit(void)
222 {
223 	WARN_ON(!list_empty(&tiq_list));
224 	unregister_adapter_interrupt(&tiqdio_airq);
225 	kfree(q_indicators);
226 }
227