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