drivers/irqchip/irq-sifive-plic.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2017 SiFive
   4  * Copyright (C) 2018 Christoph Hellwig
   5  */
   6 #define pr_fmt(fmt) "plic: " fmt
   7 #include <linux/cpu.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/io.h>
  10 #include <linux/irq.h>
  11 #include <linux/irqchip.h>
  12 #include <linux/irqchip/chained_irq.h>
  13 #include <linux/irqdomain.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/of_address.h>
  17 #include <linux/of_irq.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/syscore_ops.h>
  21 #include <asm/smp.h>
  22
  23 /*
  24  * This driver implements a version of the RISC-V PLIC with the actual layout
  25  * specified in chapter 8 of the SiFive U5 Coreplex Series Manual:
  26  *
  27  *     https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf
  28  *
  29  * The largest number supported by devices marked as 'sifive,plic-1.0.0', is
  30  * 1024, of which device 0 is defined as non-existent by the RISC-V Privileged
  31  * Spec.
  32  */
  33
  34 #define MAX_DEVICES                     1024
  35 #define MAX_CONTEXTS                    15872
  36
  37 /*
  38  * Each interrupt source has a priority register associated with it.
  39  * We always hardwire it to one in Linux.
  40  */
  41 #define PRIORITY_BASE                   0
  42 #define     PRIORITY_PER_ID             4
  43
  44 /*
  45  * Each hart context has a vector of interrupt enable bits associated with it.
  46  * There's one bit for each interrupt source.
  47  */
  48 #define CONTEXT_ENABLE_BASE             0x2000
  49 #define     CONTEXT_ENABLE_SIZE         0x80
  50
  51 /*
  52  * Each hart context has a set of control registers associated with it.  Right
  53  * now there's only two: a source priority threshold over which the hart will
  54  * take an interrupt, and a register to claim interrupts.
  55  */
  56 #define CONTEXT_BASE                    0x200000
  57 #define     CONTEXT_SIZE                0x1000
  58 #define     CONTEXT_THRESHOLD           0x00
  59 #define     CONTEXT_CLAIM               0x04
  60
  61 #define PLIC_DISABLE_THRESHOLD          0x7
  62 #define PLIC_ENABLE_THRESHOLD           0
  63
  64 #define PLIC_QUIRK_EDGE_INTERRUPT       0
  65
  66 struct plic_priv {
  67         struct cpumask lmask;
  68         struct irq_domain *irqdomain;
  69         void __iomem *regs;
  70         unsigned long plic_quirks;
  71         unsigned int nr_irqs;
  72         unsigned long *prio_save;
  73 };
  74
  75 struct plic_handler {
  76         bool                    present;
  77         void __iomem            *hart_base;
  78         /*
  79          * Protect mask operations on the registers given that we can't
  80          * assume atomic memory operations work on them.
  81          */
  82         raw_spinlock_t          enable_lock;
  83         void __iomem            *enable_base;
  84         u32                     *enable_save;
  85         struct plic_priv        *priv;
  86 };
  87 static int plic_parent_irq __ro_after_init;
  88 static bool plic_cpuhp_setup_done __ro_after_init;
  89 static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
  90
  91 static int plic_irq_set_type(struct irq_data *d, unsigned int type);
  92
  93 static void __plic_toggle(void __iomem *enable_base, int hwirq, int enable)
  94 {
  95         u32 __iomem *reg = enable_base + (hwirq / 32) * sizeof(u32);
  96         u32 hwirq_mask = 1 << (hwirq % 32);
  97
  98         if (enable)
  99                 writel(readl(reg) | hwirq_mask, reg);
 100         else
 101                 writel(readl(reg) & ~hwirq_mask, reg);
 102 }
 103
 104 static void plic_toggle(struct plic_handler *handler, int hwirq, int enable)
 105 {
 106         raw_spin_lock(&handler->enable_lock);
 107         __plic_toggle(handler->enable_base, hwirq, enable);
 108         raw_spin_unlock(&handler->enable_lock);
 109 }
 110
 111 static inline void plic_irq_toggle(const struct cpumask *mask,
 112                                    struct irq_data *d, int enable)
 113 {
 114         int cpu;
 115
 116         for_each_cpu(cpu, mask) {
 117                 struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
 118
 119                 plic_toggle(handler, d->hwirq, enable);
 120         }
 121 }
 122
 123 static void plic_irq_enable(struct irq_data *d)
 124 {
 125         plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 1);
 126 }
 127
 128 static void plic_irq_disable(struct irq_data *d)
 129 {
 130         plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 0);
 131 }
 132
 133 static void plic_irq_unmask(struct irq_data *d)
 134 {
 135         struct plic_priv *priv = irq_data_get_irq_chip_data(d);
 136
 137         writel(1, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
 138 }
 139
 140 static void plic_irq_mask(struct irq_data *d)
 141 {
 142         struct plic_priv *priv = irq_data_get_irq_chip_data(d);
 143
 144         writel(0, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
 145 }
 146
 147 static void plic_irq_eoi(struct irq_data *d)
 148 {
 149         struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
 150
 151         writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
 152 }
 153
 154 #ifdef CONFIG_SMP
 155 static int plic_set_affinity(struct irq_data *d,
 156                              const struct cpumask *mask_val, bool force)
 157 {
 158         unsigned int cpu;
 159         struct cpumask amask;
 160         struct plic_priv *priv = irq_data_get_irq_chip_data(d);
 161
 162         cpumask_and(&amask, &priv->lmask, mask_val);
 163
 164         if (force)
 165                 cpu = cpumask_first(&amask);
 166         else
 167                 cpu = cpumask_any_and(&amask, cpu_online_mask);
 168
 169         if (cpu >= nr_cpu_ids)
 170                 return -EINVAL;
 171
 172         plic_irq_disable(d);
 173
 174         irq_data_update_effective_affinity(d, cpumask_of(cpu));
 175
 176         if (!irqd_irq_disabled(d))
 177                 plic_irq_enable(d);
 178
 179         return IRQ_SET_MASK_OK_DONE;
 180 }
 181 #endif
 182
 183 static struct irq_chip plic_edge_chip = {
 184         .name           = "SiFive PLIC",
 185         .irq_enable     = plic_irq_enable,
 186         .irq_disable    = plic_irq_disable,
 187         .irq_ack        = plic_irq_eoi,
 188         .irq_mask       = plic_irq_mask,
 189         .irq_unmask     = plic_irq_unmask,
 190 #ifdef CONFIG_SMP
 191         .irq_set_affinity = plic_set_affinity,
 192 #endif
 193         .irq_set_type   = plic_irq_set_type,
 194         .flags          = IRQCHIP_SKIP_SET_WAKE |
 195                           IRQCHIP_AFFINITY_PRE_STARTUP,
 196 };
 197
 198 static struct irq_chip plic_chip = {
 199         .name           = "SiFive PLIC",
 200         .irq_enable     = plic_irq_enable,
 201         .irq_disable    = plic_irq_disable,
 202         .irq_mask       = plic_irq_mask,
 203         .irq_unmask     = plic_irq_unmask,
 204         .irq_eoi        = plic_irq_eoi,
 205 #ifdef CONFIG_SMP
 206         .irq_set_affinity = plic_set_affinity,
 207 #endif
 208         .irq_set_type   = plic_irq_set_type,
 209         .flags          = IRQCHIP_SKIP_SET_WAKE |
 210                           IRQCHIP_AFFINITY_PRE_STARTUP,
 211 };
 212
 213 static int plic_irq_set_type(struct irq_data *d, unsigned int type)
 214 {
 215         struct plic_priv *priv = irq_data_get_irq_chip_data(d);
 216
 217         if (!test_bit(PLIC_QUIRK_EDGE_INTERRUPT, &priv->plic_quirks))
 218                 return IRQ_SET_MASK_OK_NOCOPY;
 219
 220         switch (type) {
 221         case IRQ_TYPE_EDGE_RISING:
 222                 irq_set_chip_handler_name_locked(d, &plic_edge_chip,
 223                                                  handle_edge_irq, NULL);
 224                 break;
 225         case IRQ_TYPE_LEVEL_HIGH:
 226                 irq_set_chip_handler_name_locked(d, &plic_chip,
 227                                                  handle_fasteoi_irq, NULL);
 228                 break;
 229         default:
 230                 return -EINVAL;
 231         }
 232
 233         return IRQ_SET_MASK_OK;
 234 }
 235
 236 static int plic_irq_suspend(void)
 237 {
 238         unsigned int i, cpu;
 239         u32 __iomem *reg;
 240         struct plic_priv *priv;
 241
 242         priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv;
 243
 244         for (i = 0; i < priv->nr_irqs; i++)
 245                 if (readl(priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID))
 246                         __set_bit(i, priv->prio_save);
 247                 else
 248                         __clear_bit(i, priv->prio_save);
 249
 250         for_each_cpu(cpu, cpu_present_mask) {
 251                 struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
 252
 253                 if (!handler->present)
 254                         continue;
 255
 256                 raw_spin_lock(&handler->enable_lock);
 257                 for (i = 0; i < DIV_ROUND_UP(priv->nr_irqs, 32); i++) {
 258                         reg = handler->enable_base + i * sizeof(u32);
 259                         handler->enable_save[i] = readl(reg);
 260                 }
 261                 raw_spin_unlock(&handler->enable_lock);
 262         }
 263
 264         return 0;
 265 }
 266
 267 static void plic_irq_resume(void)
 268 {
 269         unsigned int i, index, cpu;
 270         u32 __iomem *reg;
 271         struct plic_priv *priv;
 272
 273         priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv;
 274
 275         for (i = 0; i < priv->nr_irqs; i++) {
 276                 index = BIT_WORD(i);
 277                 writel((priv->prio_save[index] & BIT_MASK(i)) ? 1 : 0,
 278                        priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID);
 279         }
 280
 281         for_each_cpu(cpu, cpu_present_mask) {
 282                 struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
 283
 284                 if (!handler->present)
 285                         continue;
 286
 287                 raw_spin_lock(&handler->enable_lock);
 288                 for (i = 0; i < DIV_ROUND_UP(priv->nr_irqs, 32); i++) {
 289                         reg = handler->enable_base + i * sizeof(u32);
 290                         writel(handler->enable_save[i], reg);
 291                 }
 292                 raw_spin_unlock(&handler->enable_lock);
 293         }
 294 }
 295
 296 static struct syscore_ops plic_irq_syscore_ops = {
 297         .suspend        = plic_irq_suspend,
 298         .resume         = plic_irq_resume,
 299 };
 300
 301 static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
 302                               irq_hw_number_t hwirq)
 303 {
 304         struct plic_priv *priv = d->host_data;
 305
 306         irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
 307                             handle_fasteoi_irq, NULL, NULL);
 308         irq_set_noprobe(irq);
 309         irq_set_affinity(irq, &priv->lmask);
 310         return 0;
 311 }
 312
 313 static int plic_irq_domain_translate(struct irq_domain *d,
 314                                      struct irq_fwspec *fwspec,
 315                                      unsigned long *hwirq,
 316                                      unsigned int *type)
 317 {
 318         struct plic_priv *priv = d->host_data;
 319
 320         if (test_bit(PLIC_QUIRK_EDGE_INTERRUPT, &priv->plic_quirks))
 321                 return irq_domain_translate_twocell(d, fwspec, hwirq, type);
 322
 323         return irq_domain_translate_onecell(d, fwspec, hwirq, type);
 324 }
 325
 326 static int plic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 327                                  unsigned int nr_irqs, void *arg)
 328 {
 329         int i, ret;
 330         irq_hw_number_t hwirq;
 331         unsigned int type;
 332         struct irq_fwspec *fwspec = arg;
 333
 334         ret = plic_irq_domain_translate(domain, fwspec, &hwirq, &type);
 335         if (ret)
 336                 return ret;
 337
 338         for (i = 0; i < nr_irqs; i++) {
 339                 ret = plic_irqdomain_map(domain, virq + i, hwirq + i);
 340                 if (ret)
 341                         return ret;
 342         }
 343
 344         return 0;
 345 }
 346
 347 static const struct irq_domain_ops plic_irqdomain_ops = {
 348         .translate      = plic_irq_domain_translate,
 349         .alloc          = plic_irq_domain_alloc,
 350         .free           = irq_domain_free_irqs_top,
 351 };
 352
 353 /*
 354  * Handling an interrupt is a two-step process: first you claim the interrupt
 355  * by reading the claim register, then you complete the interrupt by writing
 356  * that source ID back to the same claim register.  This automatically enables
 357  * and disables the interrupt, so there's nothing else to do.
 358  */
 359 static void plic_handle_irq(struct irq_desc *desc)
 360 {
 361         struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
 362         struct irq_chip *chip = irq_desc_get_chip(desc);
 363         void __iomem *claim = handler->hart_base + CONTEXT_CLAIM;
 364         irq_hw_number_t hwirq;
 365
 366         WARN_ON_ONCE(!handler->present);
 367
 368         chained_irq_enter(chip, desc);
 369
 370         while ((hwirq = readl(claim))) {
 371                 int err = generic_handle_domain_irq(handler->priv->irqdomain,
 372                                                     hwirq);
 373                 if (unlikely(err))
 374                         pr_warn_ratelimited("can't find mapping for hwirq %lu\n",
 375                                         hwirq);
 376         }
 377
 378         chained_irq_exit(chip, desc);
 379 }
 380
 381 static void plic_set_threshold(struct plic_handler *handler, u32 threshold)
 382 {
 383         /* priority must be > threshold to trigger an interrupt */
 384         writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);
 385 }
 386
 387 static int plic_dying_cpu(unsigned int cpu)
 388 {
 389         if (plic_parent_irq)
 390                 disable_percpu_irq(plic_parent_irq);
 391
 392         return 0;
 393 }
 394
 395 static int plic_starting_cpu(unsigned int cpu)
 396 {
 397         struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
 398
 399         if (plic_parent_irq)
 400                 enable_percpu_irq(plic_parent_irq,
 401                                   irq_get_trigger_type(plic_parent_irq));
 402         else
 403                 pr_warn("cpu%d: parent irq not available\n", cpu);
 404         plic_set_threshold(handler, PLIC_ENABLE_THRESHOLD);
 405
 406         return 0;
 407 }
 408
 409 static int __init __plic_init(struct device_node *node,
 410                               struct device_node *parent,
 411                               unsigned long plic_quirks)
 412 {
 413         int error = 0, nr_contexts, nr_handlers = 0, i;
 414         u32 nr_irqs;
 415         struct plic_priv *priv;
 416         struct plic_handler *handler;
 417         unsigned int cpu;
 418
 419         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 420         if (!priv)
 421                 return -ENOMEM;
 422
 423         priv->plic_quirks = plic_quirks;
 424
 425         priv->regs = of_iomap(node, 0);
 426         if (WARN_ON(!priv->regs)) {
 427                 error = -EIO;
 428                 goto out_free_priv;
 429         }
 430
 431         error = -EINVAL;
 432         of_property_read_u32(node, "riscv,ndev", &nr_irqs);
 433         if (WARN_ON(!nr_irqs))
 434                 goto out_iounmap;
 435
 436         priv->nr_irqs = nr_irqs;
 437
 438         priv->prio_save = bitmap_alloc(nr_irqs, GFP_KERNEL);
 439         if (!priv->prio_save)
 440                 goto out_free_priority_reg;
 441
 442         nr_contexts = of_irq_count(node);
 443         if (WARN_ON(!nr_contexts))
 444                 goto out_free_priority_reg;
 445
 446         error = -ENOMEM;
 447         priv->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
 448                         &plic_irqdomain_ops, priv);
 449         if (WARN_ON(!priv->irqdomain))
 450                 goto out_free_priority_reg;
 451
 452         for (i = 0; i < nr_contexts; i++) {
 453                 struct of_phandle_args parent;
 454                 irq_hw_number_t hwirq;
 455                 int cpu;
 456                 unsigned long hartid;
 457
 458                 if (of_irq_parse_one(node, i, &parent)) {
 459                         pr_err("failed to parse parent for context %d.\n", i);
 460                         continue;
 461                 }
 462
 463                 /*
 464                  * Skip contexts other than external interrupts for our
 465                  * privilege level.
 466                  */
 467                 if (parent.args[0] != RV_IRQ_EXT) {
 468                         /* Disable S-mode enable bits if running in M-mode. */
 469                         if (IS_ENABLED(CONFIG_RISCV_M_MODE)) {
 470                                 void __iomem *enable_base = priv->regs +
 471                                         CONTEXT_ENABLE_BASE +
 472                                         i * CONTEXT_ENABLE_SIZE;
 473
 474                                 for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
 475                                         __plic_toggle(enable_base, hwirq, 0);
 476                         }
 477                         continue;
 478                 }
 479
 480                 error = riscv_of_parent_hartid(parent.np, &hartid);
 481                 if (error < 0) {
 482                         pr_warn("failed to parse hart ID for context %d.\n", i);
 483                         continue;
 484                 }
 485
 486                 cpu = riscv_hartid_to_cpuid(hartid);
 487                 if (cpu < 0) {
 488                         pr_warn("Invalid cpuid for context %d\n", i);
 489                         continue;
 490                 }
 491
 492                 /* Find parent domain and register chained handler */
 493                 if (!plic_parent_irq && irq_find_host(parent.np)) {
 494                         plic_parent_irq = irq_of_parse_and_map(node, i);
 495                         if (plic_parent_irq)
 496                                 irq_set_chained_handler(plic_parent_irq,
 497                                                         plic_handle_irq);
 498                 }
 499
 500                 /*
 501                  * When running in M-mode we need to ignore the S-mode handler.
 502                  * Here we assume it always comes later, but that might be a
 503                  * little fragile.
 504                  */
 505                 handler = per_cpu_ptr(&plic_handlers, cpu);
 506                 if (handler->present) {
 507                         pr_warn("handler already present for context %d.\n", i);
 508                         plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
 509                         goto done;
 510                 }
 511
 512                 cpumask_set_cpu(cpu, &priv->lmask);
 513                 handler->present = true;
 514                 handler->hart_base = priv->regs + CONTEXT_BASE +
 515                         i * CONTEXT_SIZE;
 516                 raw_spin_lock_init(&handler->enable_lock);
 517                 handler->enable_base = priv->regs + CONTEXT_ENABLE_BASE +
 518                         i * CONTEXT_ENABLE_SIZE;
 519                 handler->priv = priv;
 520
 521                 handler->enable_save =  kcalloc(DIV_ROUND_UP(nr_irqs, 32),
 522                                                 sizeof(*handler->enable_save), GFP_KERNEL);
 523                 if (!handler->enable_save)
 524                         goto out_free_enable_reg;
 525 done:
 526                 for (hwirq = 1; hwirq <= nr_irqs; hwirq++) {
 527                         plic_toggle(handler, hwirq, 0);
 528                         writel(1, priv->regs + PRIORITY_BASE +
 529                                   hwirq * PRIORITY_PER_ID);
 530                 }
 531                 nr_handlers++;
 532         }
 533
 534         /*
 535          * We can have multiple PLIC instances so setup cpuhp state
 536          * and register syscore operations only when context handler
 537          * for current/boot CPU is present.
 538          */
 539         handler = this_cpu_ptr(&plic_handlers);
 540         if (handler->present && !plic_cpuhp_setup_done) {
 541                 cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
 542                                   "irqchip/sifive/plic:starting",
 543                                   plic_starting_cpu, plic_dying_cpu);
 544                 register_syscore_ops(&plic_irq_syscore_ops);
 545                 plic_cpuhp_setup_done = true;
 546         }
 547
 548         pr_info("%pOFP: mapped %d interrupts with %d handlers for"
 549                 " %d contexts.\n", node, nr_irqs, nr_handlers, nr_contexts);
 550         return 0;
 551
 552 out_free_enable_reg:
 553         for_each_cpu(cpu, cpu_present_mask) {
 554                 handler = per_cpu_ptr(&plic_handlers, cpu);
 555                 kfree(handler->enable_save);
 556         }
 557 out_free_priority_reg:
 558         kfree(priv->prio_save);
 559 out_iounmap:
 560         iounmap(priv->regs);
 561 out_free_priv:
 562         kfree(priv);
 563         return error;
 564 }
 565
 566 static int __init plic_init(struct device_node *node,
 567                             struct device_node *parent)
 568 {
 569         return __plic_init(node, parent, 0);
 570 }
 571
 572 IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
 573 IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */
 574
 575 static int __init plic_edge_init(struct device_node *node,
 576                                  struct device_node *parent)
 577 {
 578         return __plic_init(node, parent, BIT(PLIC_QUIRK_EDGE_INTERRUPT));
 579 }
 580
 581 IRQCHIP_DECLARE(andestech_nceplic100, "andestech,nceplic100", plic_edge_init);
 582 IRQCHIP_DECLARE(thead_c900_plic, "thead,c900-plic", plic_edge_init);