1 /*
2 * This file implements an irqchip for OPAL events. Whenever there is
3 * an interrupt that is handled by OPAL we get passed a list of events
4 * that Linux needs to do something about. These basically look like
5 * interrupts to Linux so we implement an irqchip to handle them.
6 *
7 * Copyright Alistair Popple, IBM Corporation 2014.
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version.
13 */
14 #include <linux/bitops.h>
15 #include <linux/irq.h>
16 #include <linux/irqchip.h>
17 #include <linux/irqdomain.h>
18 #include <linux/interrupt.h>
19 #include <linux/module.h>
20 #include <linux/of.h>
21 #include <linux/platform_device.h>
22 #include <linux/kthread.h>
23 #include <linux/delay.h>
24 #include <linux/slab.h>
25 #include <linux/irq_work.h>
26
27 #include <asm/machdep.h>
28 #include <asm/opal.h>
29
30 #include "powernv.h"
31
32 /* Maximum number of events supported by OPAL firmware */
33 #define MAX_NUM_EVENTS 64
34
35 struct opal_event_irqchip {
36 struct irq_chip irqchip;
37 struct irq_domain *domain;
38 unsigned long mask;
39 };
40 static struct opal_event_irqchip opal_event_irqchip;
41
42 static unsigned int opal_irq_count;
43 static unsigned int *opal_irqs;
44
45 static void opal_handle_irq_work(struct irq_work *work);
46 static u64 last_outstanding_events;
47 static struct irq_work opal_event_irq_work = {
48 .func = opal_handle_irq_work,
49 };
50
opal_handle_events(uint64_t events)51 void opal_handle_events(uint64_t events)
52 {
53 int virq, hwirq = 0;
54 u64 mask = opal_event_irqchip.mask;
55
56 if (!in_irq() && (events & mask)) {
57 last_outstanding_events = events;
58 irq_work_queue(&opal_event_irq_work);
59 return;
60 }
61
62 while (events & mask) {
63 hwirq = fls64(events) - 1;
64 if (BIT_ULL(hwirq) & mask) {
65 virq = irq_find_mapping(opal_event_irqchip.domain,
66 hwirq);
67 if (virq)
68 generic_handle_irq(virq);
69 }
70 events &= ~BIT_ULL(hwirq);
71 }
72 }
73
opal_event_mask(struct irq_data * d)74 static void opal_event_mask(struct irq_data *d)
75 {
76 clear_bit(d->hwirq, &opal_event_irqchip.mask);
77 }
78
opal_event_unmask(struct irq_data * d)79 static void opal_event_unmask(struct irq_data *d)
80 {
81 __be64 events;
82
83 set_bit(d->hwirq, &opal_event_irqchip.mask);
84
85 opal_poll_events(&events);
86 last_outstanding_events = be64_to_cpu(events);
87
88 /*
89 * We can't just handle the events now with opal_handle_events().
90 * If we did we would deadlock when opal_event_unmask() is called from
91 * handle_level_irq() with the irq descriptor lock held, because
92 * calling opal_handle_events() would call generic_handle_irq() and
93 * then handle_level_irq() which would try to take the descriptor lock
94 * again. Instead queue the events for later.
95 */
96 if (last_outstanding_events & opal_event_irqchip.mask)
97 /* Need to retrigger the interrupt */
98 irq_work_queue(&opal_event_irq_work);
99 }
100
opal_event_set_type(struct irq_data * d,unsigned int flow_type)101 static int opal_event_set_type(struct irq_data *d, unsigned int flow_type)
102 {
103 /*
104 * For now we only support level triggered events. The irq
105 * handler will be called continuously until the event has
106 * been cleared in OPAL.
107 */
108 if (flow_type != IRQ_TYPE_LEVEL_HIGH)
109 return -EINVAL;
110
111 return 0;
112 }
113
114 static struct opal_event_irqchip opal_event_irqchip = {
115 .irqchip = {
116 .name = "OPAL EVT",
117 .irq_mask = opal_event_mask,
118 .irq_unmask = opal_event_unmask,
119 .irq_set_type = opal_event_set_type,
120 },
121 .mask = 0,
122 };
123
opal_event_map(struct irq_domain * d,unsigned int irq,irq_hw_number_t hwirq)124 static int opal_event_map(struct irq_domain *d, unsigned int irq,
125 irq_hw_number_t hwirq)
126 {
127 irq_set_chip_data(irq, &opal_event_irqchip);
128 irq_set_chip_and_handler(irq, &opal_event_irqchip.irqchip,
129 handle_level_irq);
130
131 return 0;
132 }
133
opal_interrupt(int irq,void * data)134 static irqreturn_t opal_interrupt(int irq, void *data)
135 {
136 __be64 events;
137
138 opal_handle_interrupt(virq_to_hw(irq), &events);
139 opal_handle_events(be64_to_cpu(events));
140
141 return IRQ_HANDLED;
142 }
143
opal_handle_irq_work(struct irq_work * work)144 static void opal_handle_irq_work(struct irq_work *work)
145 {
146 opal_handle_events(last_outstanding_events);
147 }
148
opal_event_match(struct irq_domain * h,struct device_node * node,enum irq_domain_bus_token bus_token)149 static int opal_event_match(struct irq_domain *h, struct device_node *node,
150 enum irq_domain_bus_token bus_token)
151 {
152 return irq_domain_get_of_node(h) == node;
153 }
154
opal_event_xlate(struct irq_domain * h,struct device_node * np,const u32 * intspec,unsigned int intsize,irq_hw_number_t * out_hwirq,unsigned int * out_flags)155 static int opal_event_xlate(struct irq_domain *h, struct device_node *np,
156 const u32 *intspec, unsigned int intsize,
157 irq_hw_number_t *out_hwirq, unsigned int *out_flags)
158 {
159 *out_hwirq = intspec[0];
160 *out_flags = IRQ_TYPE_LEVEL_HIGH;
161
162 return 0;
163 }
164
165 static const struct irq_domain_ops opal_event_domain_ops = {
166 .match = opal_event_match,
167 .map = opal_event_map,
168 .xlate = opal_event_xlate,
169 };
170
opal_event_shutdown(void)171 void opal_event_shutdown(void)
172 {
173 unsigned int i;
174
175 /* First free interrupts, which will also mask them */
176 for (i = 0; i < opal_irq_count; i++) {
177 if (opal_irqs[i])
178 free_irq(opal_irqs[i], NULL);
179 opal_irqs[i] = 0;
180 }
181 }
182
opal_event_init(void)183 int __init opal_event_init(void)
184 {
185 struct device_node *dn, *opal_node;
186 const __be32 *irqs;
187 int i, irqlen, rc = 0;
188
189 opal_node = of_find_node_by_path("/ibm,opal");
190 if (!opal_node) {
191 pr_warn("opal: Node not found\n");
192 return -ENODEV;
193 }
194
195 /* If dn is NULL it means the domain won't be linked to a DT
196 * node so therefore irq_of_parse_and_map(...) wont work. But
197 * that shouldn't be problem because if we're running a
198 * version of skiboot that doesn't have the dn then the
199 * devices won't have the correct properties and will have to
200 * fall back to the legacy method (opal_event_request(...))
201 * anyway. */
202 dn = of_find_compatible_node(NULL, NULL, "ibm,opal-event");
203 opal_event_irqchip.domain = irq_domain_add_linear(dn, MAX_NUM_EVENTS,
204 &opal_event_domain_ops, &opal_event_irqchip);
205 of_node_put(dn);
206 if (!opal_event_irqchip.domain) {
207 pr_warn("opal: Unable to create irq domain\n");
208 rc = -ENOMEM;
209 goto out;
210 }
211
212 /* Get interrupt property */
213 irqs = of_get_property(opal_node, "opal-interrupts", &irqlen);
214 opal_irq_count = irqs ? (irqlen / 4) : 0;
215 pr_debug("Found %d interrupts reserved for OPAL\n", opal_irq_count);
216
217 /* Install interrupt handlers */
218 opal_irqs = kcalloc(opal_irq_count, sizeof(*opal_irqs), GFP_KERNEL);
219 for (i = 0; irqs && i < opal_irq_count; i++, irqs++) {
220 unsigned int irq, virq;
221
222 /* Get hardware and virtual IRQ */
223 irq = be32_to_cpup(irqs);
224 virq = irq_create_mapping(NULL, irq);
225 if (virq == NO_IRQ) {
226 pr_warn("Failed to map irq 0x%x\n", irq);
227 continue;
228 }
229
230 /* Install interrupt handler */
231 rc = request_irq(virq, opal_interrupt, 0, "opal", NULL);
232 if (rc) {
233 irq_dispose_mapping(virq);
234 pr_warn("Error %d requesting irq %d (0x%x)\n",
235 rc, virq, irq);
236 continue;
237 }
238
239 /* Cache IRQ */
240 opal_irqs[i] = virq;
241 }
242
243 out:
244 of_node_put(opal_node);
245 return rc;
246 }
247 machine_arch_initcall(powernv, opal_event_init);
248
249 /**
250 * opal_event_request(unsigned int opal_event_nr) - Request an event
251 * @opal_event_nr: the opal event number to request
252 *
253 * This routine can be used to find the linux virq number which can
254 * then be passed to request_irq to assign a handler for a particular
255 * opal event. This should only be used by legacy devices which don't
256 * have proper device tree bindings. Most devices should use
257 * irq_of_parse_and_map() instead.
258 */
opal_event_request(unsigned int opal_event_nr)259 int opal_event_request(unsigned int opal_event_nr)
260 {
261 if (WARN_ON_ONCE(!opal_event_irqchip.domain))
262 return NO_IRQ;
263
264 return irq_create_mapping(opal_event_irqchip.domain, opal_event_nr);
265 }
266 EXPORT_SYMBOL(opal_event_request);
267