1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * This file implements an irqchip for OPAL events. Whenever there is
4 * an interrupt that is handled by OPAL we get passed a list of events
5 * that Linux needs to do something about. These basically look like
6 * interrupts to Linux so we implement an irqchip to handle them.
7 *
8 * Copyright Alistair Popple, IBM Corporation 2014.
9 */
10#include <linux/bitops.h>
11#include <linux/irq.h>
12#include <linux/irqchip.h>
13#include <linux/irqdomain.h>
14#include <linux/interrupt.h>
15#include <linux/module.h>
16#include <linux/of.h>
17#include <linux/platform_device.h>
18#include <linux/kthread.h>
19#include <linux/delay.h>
20#include <linux/slab.h>
21#include <linux/of_irq.h>
22
23#include <asm/machdep.h>
24#include <asm/opal.h>
25
26#include "powernv.h"
27
28/* Maximum number of events supported by OPAL firmware */
29#define MAX_NUM_EVENTS 64
30
31struct opal_event_irqchip {
32	struct irq_chip irqchip;
33	struct irq_domain *domain;
34	unsigned long mask;
35};
36static struct opal_event_irqchip opal_event_irqchip;
37static u64 last_outstanding_events;
38static int opal_irq_count;
39static struct resource *opal_irqs;
40
41void opal_handle_events(void)
42{
43	__be64 events = 0;
44	u64 e;
45
46	e = READ_ONCE(last_outstanding_events) & opal_event_irqchip.mask;
47again:
48	while (e) {
49		int virq, hwirq;
50
51		hwirq = fls64(e) - 1;
52		e &= ~BIT_ULL(hwirq);
53
54		local_irq_disable();
55		virq = irq_find_mapping(opal_event_irqchip.domain, hwirq);
56		if (virq) {
57			irq_enter();
58			generic_handle_irq(virq);
59			irq_exit();
60		}
61		local_irq_enable();
62
63		cond_resched();
64	}
65	last_outstanding_events = 0;
66	if (opal_poll_events(&events) != OPAL_SUCCESS)
67		return;
68	e = be64_to_cpu(events) & opal_event_irqchip.mask;
69	if (e)
70		goto again;
71}
72
73bool opal_have_pending_events(void)
74{
75	if (last_outstanding_events & opal_event_irqchip.mask)
76		return true;
77	return false;
78}
79
80static void opal_event_mask(struct irq_data *d)
81{
82	clear_bit(d->hwirq, &opal_event_irqchip.mask);
83}
84
85static void opal_event_unmask(struct irq_data *d)
86{
87	set_bit(d->hwirq, &opal_event_irqchip.mask);
88	if (opal_have_pending_events())
89		opal_wake_poller();
90}
91
92static int opal_event_set_type(struct irq_data *d, unsigned int flow_type)
93{
94	/*
95	 * For now we only support level triggered events. The irq
96	 * handler will be called continuously until the event has
97	 * been cleared in OPAL.
98	 */
99	if (flow_type != IRQ_TYPE_LEVEL_HIGH)
100		return -EINVAL;
101
102	return 0;
103}
104
105static struct opal_event_irqchip opal_event_irqchip = {
106	.irqchip = {
107		.name = "OPAL EVT",
108		.irq_mask = opal_event_mask,
109		.irq_unmask = opal_event_unmask,
110		.irq_set_type = opal_event_set_type,
111	},
112	.mask = 0,
113};
114
115static int opal_event_map(struct irq_domain *d, unsigned int irq,
116			irq_hw_number_t hwirq)
117{
118	irq_set_chip_data(irq, &opal_event_irqchip);
119	irq_set_chip_and_handler(irq, &opal_event_irqchip.irqchip,
120				handle_level_irq);
121
122	return 0;
123}
124
125static irqreturn_t opal_interrupt(int irq, void *data)
126{
127	__be64 events;
128
129	opal_handle_interrupt(virq_to_hw(irq), &events);
130	last_outstanding_events = be64_to_cpu(events);
131	if (opal_have_pending_events())
132		opal_wake_poller();
133
134	return IRQ_HANDLED;
135}
136
137static int opal_event_match(struct irq_domain *h, struct device_node *node,
138			    enum irq_domain_bus_token bus_token)
139{
140	return irq_domain_get_of_node(h) == node;
141}
142
143static int opal_event_xlate(struct irq_domain *h, struct device_node *np,
144			   const u32 *intspec, unsigned int intsize,
145			   irq_hw_number_t *out_hwirq, unsigned int *out_flags)
146{
147	*out_hwirq = intspec[0];
148	*out_flags = IRQ_TYPE_LEVEL_HIGH;
149
150	return 0;
151}
152
153static const struct irq_domain_ops opal_event_domain_ops = {
154	.match	= opal_event_match,
155	.map	= opal_event_map,
156	.xlate	= opal_event_xlate,
157};
158
159void opal_event_shutdown(void)
160{
161	unsigned int i;
162
163	/* First free interrupts, which will also mask them */
164	for (i = 0; i < opal_irq_count; i++) {
165		if (!opal_irqs || !opal_irqs[i].start)
166			continue;
167
168		if (in_interrupt() || irqs_disabled())
169			disable_irq_nosync(opal_irqs[i].start);
170		else
171			free_irq(opal_irqs[i].start, NULL);
172
173		opal_irqs[i].start = 0;
174	}
175}
176
177int __init opal_event_init(void)
178{
179	struct device_node *dn, *opal_node;
180	bool old_style = false;
181	int i, rc = 0;
182
183	opal_node = of_find_node_by_path("/ibm,opal");
184	if (!opal_node) {
185		pr_warn("opal: Node not found\n");
186		return -ENODEV;
187	}
188
189	/* If dn is NULL it means the domain won't be linked to a DT
190	 * node so therefore irq_of_parse_and_map(...) wont work. But
191	 * that shouldn't be problem because if we're running a
192	 * version of skiboot that doesn't have the dn then the
193	 * devices won't have the correct properties and will have to
194	 * fall back to the legacy method (opal_event_request(...))
195	 * anyway. */
196	dn = of_find_compatible_node(NULL, NULL, "ibm,opal-event");
197	opal_event_irqchip.domain = irq_domain_add_linear(dn, MAX_NUM_EVENTS,
198				&opal_event_domain_ops, &opal_event_irqchip);
199	of_node_put(dn);
200	if (!opal_event_irqchip.domain) {
201		pr_warn("opal: Unable to create irq domain\n");
202		rc = -ENOMEM;
203		goto out;
204	}
205
206	/* Look for new-style (standard) "interrupts" property */
207	opal_irq_count = of_irq_count(opal_node);
208
209	/* Absent ? Look for the old one */
210	if (opal_irq_count < 1) {
211		/* Get opal-interrupts property and names if present */
212		rc = of_property_count_u32_elems(opal_node, "opal-interrupts");
213		if (rc > 0)
214			opal_irq_count = rc;
215		old_style = true;
216	}
217
218	/* No interrupts ? Bail out */
219	if (!opal_irq_count)
220		goto out;
221
222	pr_debug("OPAL: Found %d interrupts reserved for OPAL using %s scheme\n",
223		 opal_irq_count, old_style ? "old" : "new");
224
225	/* Allocate an IRQ resources array */
226	opal_irqs = kcalloc(opal_irq_count, sizeof(struct resource), GFP_KERNEL);
227	if (WARN_ON(!opal_irqs)) {
228		rc = -ENOMEM;
229		goto out;
230	}
231
232	/* Build the resources array */
233	if (old_style) {
234		/* Old style "opal-interrupts" property */
235		for (i = 0; i < opal_irq_count; i++) {
236			struct resource *r = &opal_irqs[i];
237			const char *name = NULL;
238			u32 hw_irq;
239			int virq;
240
241			rc = of_property_read_u32_index(opal_node, "opal-interrupts",
242							i, &hw_irq);
243			if (WARN_ON(rc < 0)) {
244				opal_irq_count = i;
245				break;
246			}
247			of_property_read_string_index(opal_node, "opal-interrupts-names",
248						      i, &name);
249			virq = irq_create_mapping(NULL, hw_irq);
250			if (!virq) {
251				pr_warn("Failed to map OPAL irq 0x%x\n", hw_irq);
252				continue;
253			}
254			r->start = r->end = virq;
255			r->flags = IORESOURCE_IRQ | IRQ_TYPE_LEVEL_LOW;
256			r->name = name;
257		}
258	} else {
259		/* new style standard "interrupts" property */
260		rc = of_irq_to_resource_table(opal_node, opal_irqs, opal_irq_count);
261		if (WARN_ON(rc < 0)) {
262			opal_irq_count = 0;
263			kfree(opal_irqs);
264			goto out;
265		}
266		if (WARN_ON(rc < opal_irq_count))
267			opal_irq_count = rc;
268	}
269
270	/* Install interrupt handlers */
271	for (i = 0; i < opal_irq_count; i++) {
272		struct resource *r = &opal_irqs[i];
273		const char *name;
274
275		/* Prefix name */
276		if (r->name && strlen(r->name))
277			name = kasprintf(GFP_KERNEL, "opal-%s", r->name);
278		else
279			name = kasprintf(GFP_KERNEL, "opal");
280
281		if (!name)
282			continue;
283		/* Install interrupt handler */
284		rc = request_irq(r->start, opal_interrupt, r->flags & IRQD_TRIGGER_MASK,
285				 name, NULL);
286		if (rc) {
287			pr_warn("Error %d requesting OPAL irq %d\n", rc, (int)r->start);
288			continue;
289		}
290	}
291	rc = 0;
292 out:
293	of_node_put(opal_node);
294	return rc;
295}
296machine_arch_initcall(powernv, opal_event_init);
297
298/**
299 * opal_event_request(unsigned int opal_event_nr) - Request an event
300 * @opal_event_nr: the opal event number to request
301 *
302 * This routine can be used to find the linux virq number which can
303 * then be passed to request_irq to assign a handler for a particular
304 * opal event. This should only be used by legacy devices which don't
305 * have proper device tree bindings. Most devices should use
306 * irq_of_parse_and_map() instead.
307 */
308int opal_event_request(unsigned int opal_event_nr)
309{
310	if (WARN_ON_ONCE(!opal_event_irqchip.domain))
311		return 0;
312
313	return irq_create_mapping(opal_event_irqchip.domain, opal_event_nr);
314}
315EXPORT_SYMBOL(opal_event_request);
316