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/irqdomain.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/of_address.h>
  16 #include <linux/of_irq.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/spinlock.h>
  19 #include <asm/smp.h>
  20
  21 /*
  22  * This driver implements a version of the RISC-V PLIC with the actual layout
  23  * specified in chapter 8 of the SiFive U5 Coreplex Series Manual:
  24  *
  25  *     https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf
  26  *
  27  * The largest number supported by devices marked as 'sifive,plic-1.0.0', is
  28  * 1024, of which device 0 is defined as non-existent by the RISC-V Privileged
  29  * Spec.
  30  */
  31
  32 #define MAX_DEVICES                     1024
  33 #define MAX_CONTEXTS                    15872
  34
  35 /*
  36  * Each interrupt source has a priority register associated with it.
  37  * We always hardwire it to one in Linux.
  38  */
  39 #define PRIORITY_BASE                   0
  40 #define     PRIORITY_PER_ID             4
  41
  42 /*
  43  * Each hart context has a vector of interrupt enable bits associated with it.
  44  * There's one bit for each interrupt source.
  45  */
  46 #define ENABLE_BASE                     0x2000
  47 #define     ENABLE_PER_HART             0x80
  48
  49 /*
  50  * Each hart context has a set of control registers associated with it.  Right
  51  * now there's only two: a source priority threshold over which the hart will
  52  * take an interrupt, and a register to claim interrupts.
  53  */
  54 #define CONTEXT_BASE                    0x200000
  55 #define     CONTEXT_PER_HART            0x1000
  56 #define     CONTEXT_THRESHOLD           0x00
  57 #define     CONTEXT_CLAIM               0x04
  58
  59 #define PLIC_DISABLE_THRESHOLD          0xf
  60 #define PLIC_ENABLE_THRESHOLD           0
  61
  62 struct plic_priv {
  63         struct cpumask lmask;
  64         struct irq_domain *irqdomain;
  65         void __iomem *regs;
  66 };
  67
  68 struct plic_handler {
  69         bool                    present;
  70         void __iomem            *hart_base;
  71         /*
  72          * Protect mask operations on the registers given that we can't
  73          * assume atomic memory operations work on them.
  74          */
  75         raw_spinlock_t          enable_lock;
  76         void __iomem            *enable_base;
  77         struct plic_priv        *priv;
  78 };
  79 static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
  80
  81 static inline void plic_toggle(struct plic_handler *handler,
  82                                 int hwirq, int enable)
  83 {
  84         u32 __iomem *reg = handler->enable_base + (hwirq / 32) * sizeof(u32);
  85         u32 hwirq_mask = 1 << (hwirq % 32);
  86
  87         raw_spin_lock(&handler->enable_lock);
  88         if (enable)
  89                 writel(readl(reg) | hwirq_mask, reg);
  90         else
  91                 writel(readl(reg) & ~hwirq_mask, reg);
  92         raw_spin_unlock(&handler->enable_lock);
  93 }
  94
  95 static inline void plic_irq_toggle(const struct cpumask *mask,
  96                                    struct irq_data *d, int enable)
  97 {
  98         int cpu;
  99         struct plic_priv *priv = irq_get_chip_data(d->irq);
 100
 101         writel(enable, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
 102         for_each_cpu(cpu, mask) {
 103                 struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
 104
 105                 if (handler->present &&
 106                     cpumask_test_cpu(cpu, &handler->priv->lmask))
 107                         plic_toggle(handler, d->hwirq, enable);
 108         }
 109 }
 110
 111 static void plic_irq_unmask(struct irq_data *d)
 112 {
 113         struct cpumask amask;
 114         unsigned int cpu;
 115         struct plic_priv *priv = irq_get_chip_data(d->irq);
 116
 117         cpumask_and(&amask, &priv->lmask, cpu_online_mask);
 118         cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
 119                                            &amask);
 120         if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
 121                 return;
 122         plic_irq_toggle(cpumask_of(cpu), d, 1);
 123 }
 124
 125 static void plic_irq_mask(struct irq_data *d)
 126 {
 127         struct plic_priv *priv = irq_get_chip_data(d->irq);
 128
 129         plic_irq_toggle(&priv->lmask, d, 0);
 130 }
 131
 132 #ifdef CONFIG_SMP
 133 static int plic_set_affinity(struct irq_data *d,
 134                              const struct cpumask *mask_val, bool force)
 135 {
 136         unsigned int cpu;
 137         struct cpumask amask;
 138         struct plic_priv *priv = irq_get_chip_data(d->irq);
 139
 140         cpumask_and(&amask, &priv->lmask, mask_val);
 141
 142         if (force)
 143                 cpu = cpumask_first(&amask);
 144         else
 145                 cpu = cpumask_any_and(&amask, cpu_online_mask);
 146
 147         if (cpu >= nr_cpu_ids)
 148                 return -EINVAL;
 149
 150         plic_irq_toggle(&priv->lmask, d, 0);
 151         plic_irq_toggle(cpumask_of(cpu), d, 1);
 152
 153         irq_data_update_effective_affinity(d, cpumask_of(cpu));
 154
 155         return IRQ_SET_MASK_OK_DONE;
 156 }
 157 #endif
 158
 159 static void plic_irq_eoi(struct irq_data *d)
 160 {
 161         struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
 162
 163         writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
 164 }
 165
 166 static struct irq_chip plic_chip = {
 167         .name           = "SiFive PLIC",
 168         .irq_mask       = plic_irq_mask,
 169         .irq_unmask     = plic_irq_unmask,
 170         .irq_eoi        = plic_irq_eoi,
 171 #ifdef CONFIG_SMP
 172         .irq_set_affinity = plic_set_affinity,
 173 #endif
 174 };
 175
 176 static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
 177                               irq_hw_number_t hwirq)
 178 {
 179         irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
 180                             handle_fasteoi_irq, NULL, NULL);
 181         irq_set_noprobe(irq);
 182         return 0;
 183 }
 184
 185 static int plic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 186                                  unsigned int nr_irqs, void *arg)
 187 {
 188         int i, ret;
 189         irq_hw_number_t hwirq;
 190         unsigned int type;
 191         struct irq_fwspec *fwspec = arg;
 192
 193         ret = irq_domain_translate_onecell(domain, fwspec, &hwirq, &type);
 194         if (ret)
 195                 return ret;
 196
 197         for (i = 0; i < nr_irqs; i++) {
 198                 ret = plic_irqdomain_map(domain, virq + i, hwirq + i);
 199                 if (ret)
 200                         return ret;
 201         }
 202
 203         return 0;
 204 }
 205
 206 static const struct irq_domain_ops plic_irqdomain_ops = {
 207         .translate      = irq_domain_translate_onecell,
 208         .alloc          = plic_irq_domain_alloc,
 209         .free           = irq_domain_free_irqs_top,
 210 };
 211
 212 /*
 213  * Handling an interrupt is a two-step process: first you claim the interrupt
 214  * by reading the claim register, then you complete the interrupt by writing
 215  * that source ID back to the same claim register.  This automatically enables
 216  * and disables the interrupt, so there's nothing else to do.
 217  */
 218 static void plic_handle_irq(struct pt_regs *regs)
 219 {
 220         struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
 221         void __iomem *claim = handler->hart_base + CONTEXT_CLAIM;
 222         irq_hw_number_t hwirq;
 223
 224         WARN_ON_ONCE(!handler->present);
 225
 226         csr_clear(CSR_IE, IE_EIE);
 227         while ((hwirq = readl(claim))) {
 228                 int irq = irq_find_mapping(handler->priv->irqdomain, hwirq);
 229
 230                 if (unlikely(irq <= 0))
 231                         pr_warn_ratelimited("can't find mapping for hwirq %lu\n",
 232                                         hwirq);
 233                 else
 234                         generic_handle_irq(irq);
 235         }
 236         csr_set(CSR_IE, IE_EIE);
 237 }
 238
 239 /*
 240  * Walk up the DT tree until we find an active RISC-V core (HART) node and
 241  * extract the cpuid from it.
 242  */
 243 static int plic_find_hart_id(struct device_node *node)
 244 {
 245         for (; node; node = node->parent) {
 246                 if (of_device_is_compatible(node, "riscv"))
 247                         return riscv_of_processor_hartid(node);
 248         }
 249
 250         return -1;
 251 }
 252
 253 static void plic_set_threshold(struct plic_handler *handler, u32 threshold)
 254 {
 255         /* priority must be > threshold to trigger an interrupt */
 256         writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);
 257 }
 258
 259 static int plic_dying_cpu(unsigned int cpu)
 260 {
 261         struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
 262
 263         csr_clear(CSR_IE, IE_EIE);
 264         plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
 265
 266         return 0;
 267 }
 268
 269 static int plic_starting_cpu(unsigned int cpu)
 270 {
 271         struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
 272
 273         csr_set(CSR_IE, IE_EIE);
 274         plic_set_threshold(handler, PLIC_ENABLE_THRESHOLD);
 275
 276         return 0;
 277 }
 278
 279 static int __init plic_init(struct device_node *node,
 280                 struct device_node *parent)
 281 {
 282         int error = 0, nr_contexts, nr_handlers = 0, i;
 283         u32 nr_irqs;
 284         struct plic_priv *priv;
 285
 286         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 287         if (!priv)
 288                 return -ENOMEM;
 289
 290         priv->regs = of_iomap(node, 0);
 291         if (WARN_ON(!priv->regs)) {
 292                 error = -EIO;
 293                 goto out_free_priv;
 294         }
 295
 296         error = -EINVAL;
 297         of_property_read_u32(node, "riscv,ndev", &nr_irqs);
 298         if (WARN_ON(!nr_irqs))
 299                 goto out_iounmap;
 300
 301         nr_contexts = of_irq_count(node);
 302         if (WARN_ON(!nr_contexts))
 303                 goto out_iounmap;
 304         if (WARN_ON(nr_contexts < num_possible_cpus()))
 305                 goto out_iounmap;
 306
 307         error = -ENOMEM;
 308         priv->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
 309                         &plic_irqdomain_ops, priv);
 310         if (WARN_ON(!priv->irqdomain))
 311                 goto out_iounmap;
 312
 313         for (i = 0; i < nr_contexts; i++) {
 314                 struct of_phandle_args parent;
 315                 struct plic_handler *handler;
 316                 irq_hw_number_t hwirq;
 317                 int cpu, hartid;
 318
 319                 if (of_irq_parse_one(node, i, &parent)) {
 320                         pr_err("failed to parse parent for context %d.\n", i);
 321                         continue;
 322                 }
 323
 324                 /*
 325                  * Skip contexts other than external interrupts for our
 326                  * privilege level.
 327                  */
 328                 if (parent.args[0] != RV_IRQ_EXT)
 329                         continue;
 330
 331                 hartid = plic_find_hart_id(parent.np);
 332                 if (hartid < 0) {
 333                         pr_warn("failed to parse hart ID for context %d.\n", i);
 334                         continue;
 335                 }
 336
 337                 cpu = riscv_hartid_to_cpuid(hartid);
 338                 if (cpu < 0) {
 339                         pr_warn("Invalid cpuid for context %d\n", i);
 340                         continue;
 341                 }
 342
 343                 /*
 344                  * When running in M-mode we need to ignore the S-mode handler.
 345                  * Here we assume it always comes later, but that might be a
 346                  * little fragile.
 347                  */
 348                 handler = per_cpu_ptr(&plic_handlers, cpu);
 349                 if (handler->present) {
 350                         pr_warn("handler already present for context %d.\n", i);
 351                         plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
 352                         goto done;
 353                 }
 354
 355                 cpumask_set_cpu(cpu, &priv->lmask);
 356                 handler->present = true;
 357                 handler->hart_base =
 358                         priv->regs + CONTEXT_BASE + i * CONTEXT_PER_HART;
 359                 raw_spin_lock_init(&handler->enable_lock);
 360                 handler->enable_base =
 361                         priv->regs + ENABLE_BASE + i * ENABLE_PER_HART;
 362                 handler->priv = priv;
 363 done:
 364                 for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
 365                         plic_toggle(handler, hwirq, 0);
 366                 nr_handlers++;
 367         }
 368
 369         cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
 370                                   "irqchip/sifive/plic:starting",
 371                                   plic_starting_cpu, plic_dying_cpu);
 372         pr_info("mapped %d interrupts with %d handlers for %d contexts.\n",
 373                 nr_irqs, nr_handlers, nr_contexts);
 374         set_handle_irq(plic_handle_irq);
 375         return 0;
 376
 377 out_iounmap:
 378         iounmap(priv->regs);
 379 out_free_priv:
 380         kfree(priv);
 381         return error;
 382 }
 383
 384 IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
 385 IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */