summaryrefslogtreecommitdiffstats
path: root/drivers/irqchip/irq-sifive-plic.c
blob: 5b7bc4fd9517c8972680ad7a503eebf2ca47a518 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2017 SiFive
 * Copyright (C) 2018 Christoph Hellwig
 */
#define pr_fmt(fmt) "plic: " fmt
#include <linux/cpu.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/syscore_ops.h>
#include <asm/smp.h>

/*
 * This driver implements a version of the RISC-V PLIC with the actual layout
 * specified in chapter 8 of the SiFive U5 Coreplex Series Manual:
 *
 *     https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf
 *
 * The largest number supported by devices marked as 'sifive,plic-1.0.0', is
 * 1024, of which device 0 is defined as non-existent by the RISC-V Privileged
 * Spec.
 */

#define MAX_DEVICES			1024
#define MAX_CONTEXTS			15872

/*
 * Each interrupt source has a priority register associated with it.
 * We always hardwire it to one in Linux.
 */
#define PRIORITY_BASE			0
#define     PRIORITY_PER_ID		4

/*
 * Each hart context has a vector of interrupt enable bits associated with it.
 * There's one bit for each interrupt source.
 */
#define CONTEXT_ENABLE_BASE		0x2000
#define     CONTEXT_ENABLE_SIZE		0x80

/*
 * Each hart context has a set of control registers associated with it.  Right
 * now there's only two: a source priority threshold over which the hart will
 * take an interrupt, and a register to claim interrupts.
 */
#define CONTEXT_BASE			0x200000
#define     CONTEXT_SIZE		0x1000
#define     CONTEXT_THRESHOLD		0x00
#define     CONTEXT_CLAIM		0x04

#define	PLIC_DISABLE_THRESHOLD		0x7
#define	PLIC_ENABLE_THRESHOLD		0

#define PLIC_QUIRK_EDGE_INTERRUPT	0

struct plic_priv {
	struct cpumask lmask;
	struct irq_domain *irqdomain;
	void __iomem *regs;
	unsigned long plic_quirks;
	unsigned int nr_irqs;
	unsigned long *prio_save;
};

struct plic_handler {
	bool			present;
	void __iomem		*hart_base;
	/*
	 * Protect mask operations on the registers given that we can't
	 * assume atomic memory operations work on them.
	 */
	raw_spinlock_t		enable_lock;
	void __iomem		*enable_base;
	u32			*enable_save;
	struct plic_priv	*priv;
};
static int plic_parent_irq __ro_after_init;
static bool plic_cpuhp_setup_done __ro_after_init;
static DEFINE_PER_CPU(struct plic_handler, plic_handlers);

static int plic_irq_set_type(struct irq_data *d, unsigned int type);

static void __plic_toggle(void __iomem *enable_base, int hwirq, int enable)
{
	u32 __iomem *reg = enable_base + (hwirq / 32) * sizeof(u32);
	u32 hwirq_mask = 1 << (hwirq % 32);

	if (enable)
		writel(readl(reg) | hwirq_mask, reg);
	else
		writel(readl(reg) & ~hwirq_mask, reg);
}

static void plic_toggle(struct plic_handler *handler, int hwirq, int enable)
{
	raw_spin_lock(&handler->enable_lock);
	__plic_toggle(handler->enable_base, hwirq, enable);
	raw_spin_unlock(&handler->enable_lock);
}

static inline void plic_irq_toggle(const struct cpumask *mask,
				   struct irq_data *d, int enable)
{
	int cpu;

	for_each_cpu(cpu, mask) {
		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);

		plic_toggle(handler, d->hwirq, enable);
	}
}

static void plic_irq_enable(struct irq_data *d)
{
	plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 1);
}

static void plic_irq_disable(struct irq_data *d)
{
	plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 0);
}

static void plic_irq_unmask(struct irq_data *d)
{
	struct plic_priv *priv = irq_data_get_irq_chip_data(d);

	writel(1, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
}

static void plic_irq_mask(struct irq_data *d)
{
	struct plic_priv *priv = irq_data_get_irq_chip_data(d);

	writel(0, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
}

static void plic_irq_eoi(struct irq_data *d)
{
	struct plic_handler *handler = this_cpu_ptr(&plic_handlers);

	writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
}

#ifdef CONFIG_SMP
static int plic_set_affinity(struct irq_data *d,
			     const struct cpumask *mask_val, bool force)
{
	unsigned int cpu;
	struct cpumask amask;
	struct plic_priv *priv = irq_data_get_irq_chip_data(d);

	cpumask_and(&amask, &priv->lmask, mask_val);

	if (force)
		cpu = cpumask_first(&amask);
	else
		cpu = cpumask_any_and(&amask, cpu_online_mask);

	if (cpu >= nr_cpu_ids)
		return -EINVAL;

	plic_irq_disable(d);

	irq_data_update_effective_affinity(d, cpumask_of(cpu));

	if (!irqd_irq_disabled(d))
		plic_irq_enable(d);

	return IRQ_SET_MASK_OK_DONE;
}
#endif

static struct irq_chip plic_edge_chip = {
	.name		= "SiFive PLIC",
	.irq_enable	= plic_irq_enable,
	.irq_disable	= plic_irq_disable,
	.irq_ack	= plic_irq_eoi,
	.irq_mask	= plic_irq_mask,
	.irq_unmask	= plic_irq_unmask,
#ifdef CONFIG_SMP
	.irq_set_affinity = plic_set_affinity,
#endif
	.irq_set_type	= plic_irq_set_type,
	.flags		= IRQCHIP_SKIP_SET_WAKE |
			  IRQCHIP_AFFINITY_PRE_STARTUP,
};

static struct irq_chip plic_chip = {
	.name		= "SiFive PLIC",
	.irq_enable	= plic_irq_enable,
	.irq_disable	= plic_irq_disable,
	.irq_mask	= plic_irq_mask,
	.irq_unmask	= plic_irq_unmask,
	.irq_eoi	= plic_irq_eoi,
#ifdef CONFIG_SMP
	.irq_set_affinity = plic_set_affinity,
#endif
	.irq_set_type	= plic_irq_set_type,
	.flags		= IRQCHIP_SKIP_SET_WAKE |
			  IRQCHIP_AFFINITY_PRE_STARTUP,
};

static int plic_irq_set_type(struct irq_data *d, unsigned int type)
{
	struct plic_priv *priv = irq_data_get_irq_chip_data(d);

	if (!test_bit(PLIC_QUIRK_EDGE_INTERRUPT, &priv->plic_quirks))
		return IRQ_SET_MASK_OK_NOCOPY;

	switch (type) {
	case IRQ_TYPE_EDGE_RISING:
		irq_set_chip_handler_name_locked(d, &plic_edge_chip,
						 handle_edge_irq, NULL);
		break;
	case IRQ_TYPE_LEVEL_HIGH:
		irq_set_chip_handler_name_locked(d, &plic_chip,
						 handle_fasteoi_irq, NULL);
		break;
	default:
		return -EINVAL;
	}

	return IRQ_SET_MASK_OK;
}

static int plic_irq_suspend(void)
{
	unsigned int i, cpu;
	u32 __iomem *reg;
	struct plic_priv *priv;

	priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv;

	for (i = 0; i < priv->nr_irqs; i++)
		if (readl(priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID))
			__set_bit(i, priv->prio_save);
		else
			__clear_bit(i, priv->prio_save);

	for_each_cpu(cpu, cpu_present_mask) {
		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);

		if (!handler->present)
			continue;

		raw_spin_lock(&handler->enable_lock);
		for (i = 0; i < DIV_ROUND_UP(priv->nr_irqs, 32); i++) {
			reg = handler->enable_base + i * sizeof(u32);
			handler->enable_save[i] = readl(reg);
		}
		raw_spin_unlock(&handler->enable_lock);
	}

	return 0;
}

static void plic_irq_resume(void)
{
	unsigned int i, index, cpu;
	u32 __iomem *reg;
	struct plic_priv *priv;

	priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv;

	for (i = 0; i < priv->nr_irqs; i++) {
		index = BIT_WORD(i);
		writel((priv->prio_save[index] & BIT_MASK(i)) ? 1 : 0,
		       priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID);
	}

	for_each_cpu(cpu, cpu_present_mask) {
		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);

		if (!handler->present)
			continue;

		raw_spin_lock(&handler->enable_lock);
		for (i = 0; i < DIV_ROUND_UP(priv->nr_irqs, 32); i++) {
			reg = handler->enable_base + i * sizeof(u32);
			writel(handler->enable_save[i], reg);
		}
		raw_spin_unlock(&handler->enable_lock);
	}
}

static struct syscore_ops plic_irq_syscore_ops = {
	.suspend	= plic_irq_suspend,
	.resume		= plic_irq_resume,
};

static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
			      irq_hw_number_t hwirq)
{
	struct plic_priv *priv = d->host_data;

	irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
			    handle_fasteoi_irq, NULL, NULL);
	irq_set_noprobe(irq);
	irq_set_affinity(irq, &priv->lmask);
	return 0;
}

static int plic_irq_domain_translate(struct irq_domain *d,
				     struct irq_fwspec *fwspec,
				     unsigned long *hwirq,
				     unsigned int *type)
{
	struct plic_priv *priv = d->host_data;

	if (test_bit(PLIC_QUIRK_EDGE_INTERRUPT, &priv->plic_quirks))
		return irq_domain_translate_twocell(d, fwspec, hwirq, type);

	return irq_domain_translate_onecell(d, fwspec, hwirq, type);
}

static int plic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
				 unsigned int nr_irqs, void *arg)
{
	int i, ret;
	irq_hw_number_t hwirq;
	unsigned int type;
	struct irq_fwspec *fwspec = arg;

	ret = plic_irq_domain_translate(domain, fwspec, &hwirq, &type);
	if (ret)
		return ret;

	for (i = 0; i < nr_irqs; i++) {
		ret = plic_irqdomain_map(domain, virq + i, hwirq + i);
		if (ret)
			return ret;
	}

	return 0;
}

static const struct irq_domain_ops plic_irqdomain_ops = {
	.translate	= plic_irq_domain_translate,
	.alloc		= plic_irq_domain_alloc,
	.free		= irq_domain_free_irqs_top,
};

/*
 * Handling an interrupt is a two-step process: first you claim the interrupt
 * by reading the claim register, then you complete the interrupt by writing
 * that source ID back to the same claim register.  This automatically enables
 * and disables the interrupt, so there's nothing else to do.
 */
static void plic_handle_irq(struct irq_desc *desc)
{
	struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
	struct irq_chip *chip = irq_desc_get_chip(desc);
	void __iomem *claim = handler->hart_base + CONTEXT_CLAIM;
	irq_hw_number_t hwirq;

	WARN_ON_ONCE(!handler->present);

	chained_irq_enter(chip, desc);

	while ((hwirq = readl(claim))) {
		int err = generic_handle_domain_irq(handler->priv->irqdomain,
						    hwirq);
		if (unlikely(err))
			pr_warn_ratelimited("can't find mapping for hwirq %lu\n",
					hwirq);
	}

	chained_irq_exit(chip, desc);
}

static void plic_set_threshold(struct plic_handler *handler, u32 threshold)
{
	/* priority must be > threshold to trigger an interrupt */
	writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);
}

static int plic_dying_cpu(unsigned int cpu)
{
	if (plic_parent_irq)
		disable_percpu_irq(plic_parent_irq);

	return 0;
}

static int plic_starting_cpu(unsigned int cpu)
{
	struct plic_handler *handler = this_cpu_ptr(&plic_handlers);

	if (plic_parent_irq)
		enable_percpu_irq(plic_parent_irq,
				  irq_get_trigger_type(plic_parent_irq));
	else
		pr_warn("cpu%d: parent irq not available\n", cpu);
	plic_set_threshold(handler, PLIC_ENABLE_THRESHOLD);

	return 0;
}

static int __init __plic_init(struct device_node *node,
			      struct device_node *parent,
			      unsigned long plic_quirks)
{
	int error = 0, nr_contexts, nr_handlers = 0, i;
	u32 nr_irqs;
	struct plic_priv *priv;
	struct plic_handler *handler;
	unsigned int cpu;

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	priv->plic_quirks = plic_quirks;

	priv->regs = of_iomap(node, 0);
	if (WARN_ON(!priv->regs)) {
		error = -EIO;
		goto out_free_priv;
	}

	error = -EINVAL;
	of_property_read_u32(node, "riscv,ndev", &nr_irqs);
	if (WARN_ON(!nr_irqs))
		goto out_iounmap;

	priv->nr_irqs = nr_irqs;

	priv->prio_save = bitmap_alloc(nr_irqs, GFP_KERNEL);
	if (!priv->prio_save)
		goto out_free_priority_reg;

	nr_contexts = of_irq_count(node);
	if (WARN_ON(!nr_contexts))
		goto out_free_priority_reg;

	error = -ENOMEM;
	priv->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
			&plic_irqdomain_ops, priv);
	if (WARN_ON(!priv->irqdomain))
		goto out_free_priority_reg;

	for (i = 0; i < nr_contexts; i++) {
		struct of_phandle_args parent;
		irq_hw_number_t hwirq;
		int cpu;
		unsigned long hartid;

		if (of_irq_parse_one(node, i, &parent)) {
			pr_err("failed to parse parent for context %d.\n", i);
			continue;
		}

		/*
		 * Skip contexts other than external interrupts for our
		 * privilege level.
		 */
		if (parent.args[0] != RV_IRQ_EXT) {
			/* Disable S-mode enable bits if running in M-mode. */
			if (IS_ENABLED(CONFIG_RISCV_M_MODE)) {
				void __iomem *enable_base = priv->regs +
					CONTEXT_ENABLE_BASE +
					i * CONTEXT_ENABLE_SIZE;

				for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
					__plic_toggle(enable_base, hwirq, 0);
			}
			continue;
		}

		error = riscv_of_parent_hartid(parent.np, &hartid);
		if (error < 0) {
			pr_warn("failed to parse hart ID for context %d.\n", i);
			continue;
		}

		cpu = riscv_hartid_to_cpuid(hartid);
		if (cpu < 0) {
			pr_warn("Invalid cpuid for context %d\n", i);
			continue;
		}

		/* Find parent domain and register chained handler */
		if (!plic_parent_irq && irq_find_host(parent.np)) {
			plic_parent_irq = irq_of_parse_and_map(node, i);
			if (plic_parent_irq)
				irq_set_chained_handler(plic_parent_irq,
							plic_handle_irq);
		}

		/*
		 * When running in M-mode we need to ignore the S-mode handler.
		 * Here we assume it always comes later, but that might be a
		 * little fragile.
		 */
		handler = per_cpu_ptr(&plic_handlers, cpu);
		if (handler->present) {
			pr_warn("handler already present for context %d.\n", i);
			plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
			goto done;
		}

		cpumask_set_cpu(cpu, &priv->lmask);
		handler->present = true;
		handler->hart_base = priv->regs + CONTEXT_BASE +
			i * CONTEXT_SIZE;
		raw_spin_lock_init(&handler->enable_lock);
		handler->enable_base = priv->regs + CONTEXT_ENABLE_BASE +
			i * CONTEXT_ENABLE_SIZE;
		handler->priv = priv;

		handler->enable_save =  kcalloc(DIV_ROUND_UP(nr_irqs, 32),
						sizeof(*handler->enable_save), GFP_KERNEL);
		if (!handler->enable_save)
			goto out_free_enable_reg;
done:
		for (hwirq = 1; hwirq <= nr_irqs; hwirq++) {
			plic_toggle(handler, hwirq, 0);
			writel(1, priv->regs + PRIORITY_BASE +
				  hwirq * PRIORITY_PER_ID);
		}
		nr_handlers++;
	}

	/*
	 * We can have multiple PLIC instances so setup cpuhp state
	 * and register syscore operations only when context handler
	 * for current/boot CPU is present.
	 */
	handler = this_cpu_ptr(&plic_handlers);
	if (handler->present && !plic_cpuhp_setup_done) {
		cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
				  "irqchip/sifive/plic:starting",
				  plic_starting_cpu, plic_dying_cpu);
		register_syscore_ops(&plic_irq_syscore_ops);
		plic_cpuhp_setup_done = true;
	}

	pr_info("%pOFP: mapped %d interrupts with %d handlers for"
		" %d contexts.\n", node, nr_irqs, nr_handlers, nr_contexts);
	return 0;

out_free_enable_reg:
	for_each_cpu(cpu, cpu_present_mask) {
		handler = per_cpu_ptr(&plic_handlers, cpu);
		kfree(handler->enable_save);
	}
out_free_priority_reg:
	kfree(priv->prio_save);
out_iounmap:
	iounmap(priv->regs);
out_free_priv:
	kfree(priv);
	return error;
}

static int __init plic_init(struct device_node *node,
			    struct device_node *parent)
{
	return __plic_init(node, parent, 0);
}

IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */

static int __init plic_edge_init(struct device_node *node,
				 struct device_node *parent)
{
	return __plic_init(node, parent, BIT(PLIC_QUIRK_EDGE_INTERRUPT));
}

IRQCHIP_DECLARE(andestech_nceplic100, "andestech,nceplic100", plic_edge_init);
IRQCHIP_DECLARE(thead_c900_plic, "thead,c900-plic", plic_edge_init);