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Linux/arch/powerpc/platforms/powernv/opal-irqchip.c

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  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 
 26 #include <asm/machdep.h>
 27 #include <asm/opal.h>
 28 
 29 #include "powernv.h"
 30 
 31 /* Maximum number of events supported by OPAL firmware */
 32 #define MAX_NUM_EVENTS 64
 33 
 34 struct opal_event_irqchip {
 35         struct irq_chip irqchip;
 36         struct irq_domain *domain;
 37         unsigned long mask;
 38 };
 39 static struct opal_event_irqchip opal_event_irqchip;
 40 static u64 last_outstanding_events;
 41 static unsigned int opal_irq_count;
 42 static unsigned int *opal_irqs;
 43 
 44 void opal_handle_events(void)
 45 {
 46         __be64 events = 0;
 47         u64 e;
 48 
 49         e = READ_ONCE(last_outstanding_events) & opal_event_irqchip.mask;
 50 again:
 51         while (e) {
 52                 int virq, hwirq;
 53 
 54                 hwirq = fls64(e) - 1;
 55                 e &= ~BIT_ULL(hwirq);
 56 
 57                 local_irq_disable();
 58                 virq = irq_find_mapping(opal_event_irqchip.domain, hwirq);
 59                 if (virq) {
 60                         irq_enter();
 61                         generic_handle_irq(virq);
 62                         irq_exit();
 63                 }
 64                 local_irq_enable();
 65 
 66                 cond_resched();
 67         }
 68         last_outstanding_events = 0;
 69         if (opal_poll_events(&events) != OPAL_SUCCESS)
 70                 return;
 71         e = be64_to_cpu(events) & opal_event_irqchip.mask;
 72         if (e)
 73                 goto again;
 74 }
 75 
 76 bool opal_have_pending_events(void)
 77 {
 78         if (last_outstanding_events & opal_event_irqchip.mask)
 79                 return true;
 80         return false;
 81 }
 82 
 83 static void opal_event_mask(struct irq_data *d)
 84 {
 85         clear_bit(d->hwirq, &opal_event_irqchip.mask);
 86 }
 87 
 88 static void opal_event_unmask(struct irq_data *d)
 89 {
 90         set_bit(d->hwirq, &opal_event_irqchip.mask);
 91         if (opal_have_pending_events())
 92                 opal_wake_poller();
 93 }
 94 
 95 static int opal_event_set_type(struct irq_data *d, unsigned int flow_type)
 96 {
 97         /*
 98          * For now we only support level triggered events. The irq
 99          * handler will be called continuously until the event has
100          * been cleared in OPAL.
101          */
102         if (flow_type != IRQ_TYPE_LEVEL_HIGH)
103                 return -EINVAL;
104 
105         return 0;
106 }
107 
108 static struct opal_event_irqchip opal_event_irqchip = {
109         .irqchip = {
110                 .name = "OPAL EVT",
111                 .irq_mask = opal_event_mask,
112                 .irq_unmask = opal_event_unmask,
113                 .irq_set_type = opal_event_set_type,
114         },
115         .mask = 0,
116 };
117 
118 static int opal_event_map(struct irq_domain *d, unsigned int irq,
119                         irq_hw_number_t hwirq)
120 {
121         irq_set_chip_data(irq, &opal_event_irqchip);
122         irq_set_chip_and_handler(irq, &opal_event_irqchip.irqchip,
123                                 handle_level_irq);
124 
125         return 0;
126 }
127 
128 static irqreturn_t opal_interrupt(int irq, void *data)
129 {
130         __be64 events;
131 
132         opal_handle_interrupt(virq_to_hw(irq), &events);
133         last_outstanding_events = be64_to_cpu(events);
134         if (opal_have_pending_events())
135                 opal_wake_poller();
136 
137         return IRQ_HANDLED;
138 }
139 
140 static int opal_event_match(struct irq_domain *h, struct device_node *node,
141                             enum irq_domain_bus_token bus_token)
142 {
143         return irq_domain_get_of_node(h) == node;
144 }
145 
146 static int opal_event_xlate(struct irq_domain *h, struct device_node *np,
147                            const u32 *intspec, unsigned int intsize,
148                            irq_hw_number_t *out_hwirq, unsigned int *out_flags)
149 {
150         *out_hwirq = intspec[0];
151         *out_flags = IRQ_TYPE_LEVEL_HIGH;
152 
153         return 0;
154 }
155 
156 static const struct irq_domain_ops opal_event_domain_ops = {
157         .match  = opal_event_match,
158         .map    = opal_event_map,
159         .xlate  = opal_event_xlate,
160 };
161 
162 void opal_event_shutdown(void)
163 {
164         unsigned int i;
165 
166         /* First free interrupts, which will also mask them */
167         for (i = 0; i < opal_irq_count; i++) {
168                 if (!opal_irqs[i])
169                         continue;
170 
171                 if (in_interrupt() || irqs_disabled())
172                         disable_irq_nosync(opal_irqs[i]);
173                 else
174                         free_irq(opal_irqs[i], NULL);
175 
176                 opal_irqs[i] = 0;
177         }
178 }
179 
180 int __init opal_event_init(void)
181 {
182         struct device_node *dn, *opal_node;
183         const char **names;
184         u32 *irqs;
185         int i, rc;
186 
187         opal_node = of_find_node_by_path("/ibm,opal");
188         if (!opal_node) {
189                 pr_warn("opal: Node not found\n");
190                 return -ENODEV;
191         }
192 
193         /* If dn is NULL it means the domain won't be linked to a DT
194          * node so therefore irq_of_parse_and_map(...) wont work. But
195          * that shouldn't be problem because if we're running a
196          * version of skiboot that doesn't have the dn then the
197          * devices won't have the correct properties and will have to
198          * fall back to the legacy method (opal_event_request(...))
199          * anyway. */
200         dn = of_find_compatible_node(NULL, NULL, "ibm,opal-event");
201         opal_event_irqchip.domain = irq_domain_add_linear(dn, MAX_NUM_EVENTS,
202                                 &opal_event_domain_ops, &opal_event_irqchip);
203         of_node_put(dn);
204         if (!opal_event_irqchip.domain) {
205                 pr_warn("opal: Unable to create irq domain\n");
206                 rc = -ENOMEM;
207                 goto out;
208         }
209 
210         /* Get opal-interrupts property and names if present */
211         rc = of_property_count_u32_elems(opal_node, "opal-interrupts");
212         if (rc < 0)
213                 goto out;
214 
215         opal_irq_count = rc;
216         pr_debug("Found %d interrupts reserved for OPAL\n", opal_irq_count);
217 
218         irqs = kcalloc(opal_irq_count, sizeof(*irqs), GFP_KERNEL);
219         names = kcalloc(opal_irq_count, sizeof(*names), GFP_KERNEL);
220         opal_irqs = kcalloc(opal_irq_count, sizeof(*opal_irqs), GFP_KERNEL);
221 
222         if (WARN_ON(!irqs || !names || !opal_irqs))
223                 goto out_free;
224 
225         rc = of_property_read_u32_array(opal_node, "opal-interrupts",
226                                         irqs, opal_irq_count);
227         if (rc < 0) {
228                 pr_err("Error %d reading opal-interrupts array\n", rc);
229                 goto out_free;
230         }
231 
232         /* It's not an error for the names to be missing */
233         of_property_read_string_array(opal_node, "opal-interrupts-names",
234                                       names, opal_irq_count);
235 
236         /* Install interrupt handlers */
237         for (i = 0; i < opal_irq_count; i++) {
238                 unsigned int virq;
239                 char *name;
240 
241                 /* Get hardware and virtual IRQ */
242                 virq = irq_create_mapping(NULL, irqs[i]);
243                 if (!virq) {
244                         pr_warn("Failed to map irq 0x%x\n", irqs[i]);
245                         continue;
246                 }
247 
248                 if (names[i] && strlen(names[i]))
249                         name = kasprintf(GFP_KERNEL, "opal-%s", names[i]);
250                 else
251                         name = kasprintf(GFP_KERNEL, "opal");
252 
253                 /* Install interrupt handler */
254                 rc = request_irq(virq, opal_interrupt, IRQF_TRIGGER_LOW,
255                                  name, NULL);
256                 if (rc) {
257                         irq_dispose_mapping(virq);
258                         pr_warn("Error %d requesting irq %d (0x%x)\n",
259                                  rc, virq, irqs[i]);
260                         continue;
261                 }
262 
263                 /* Cache IRQ */
264                 opal_irqs[i] = virq;
265         }
266 
267 out_free:
268         kfree(irqs);
269         kfree(names);
270 out:
271         of_node_put(opal_node);
272         return rc;
273 }
274 machine_arch_initcall(powernv, opal_event_init);
275 
276 /**
277  * opal_event_request(unsigned int opal_event_nr) - Request an event
278  * @opal_event_nr: the opal event number to request
279  *
280  * This routine can be used to find the linux virq number which can
281  * then be passed to request_irq to assign a handler for a particular
282  * opal event. This should only be used by legacy devices which don't
283  * have proper device tree bindings. Most devices should use
284  * irq_of_parse_and_map() instead.
285  */
286 int opal_event_request(unsigned int opal_event_nr)
287 {
288         if (WARN_ON_ONCE(!opal_event_irqchip.domain))
289                 return 0;
290 
291         return irq_create_mapping(opal_event_irqchip.domain, opal_event_nr);
292 }
293 EXPORT_SYMBOL(opal_event_request);
294 

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