Loading...
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 | // SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2017 SiFive
* Copyright (C) 2018 Christoph Hellwig
*/
#define pr_fmt(fmt) "plic: " fmt
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/irqchip.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 <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 ENABLE_BASE 0x2000
#define ENABLE_PER_HART 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_PER_HART 0x1000
#define CONTEXT_THRESHOLD 0x00
#define CONTEXT_CLAIM 0x04
static void __iomem *plic_regs;
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;
};
static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
static inline void plic_toggle(struct plic_handler *handler,
int hwirq, int enable)
{
u32 __iomem *reg = handler->enable_base + (hwirq / 32) * sizeof(u32);
u32 hwirq_mask = 1 << (hwirq % 32);
raw_spin_lock(&handler->enable_lock);
if (enable)
writel(readl(reg) | hwirq_mask, reg);
else
writel(readl(reg) & ~hwirq_mask, reg);
raw_spin_unlock(&handler->enable_lock);
}
static inline void plic_irq_toggle(const struct cpumask *mask,
int hwirq, int enable)
{
int cpu;
writel(enable, plic_regs + PRIORITY_BASE + hwirq * PRIORITY_PER_ID);
for_each_cpu(cpu, mask) {
struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
if (handler->present)
plic_toggle(handler, hwirq, enable);
}
}
static void plic_irq_unmask(struct irq_data *d)
{
unsigned int cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
cpu_online_mask);
if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
return;
plic_irq_toggle(cpumask_of(cpu), d->hwirq, 1);
}
static void plic_irq_mask(struct irq_data *d)
{
plic_irq_toggle(cpu_possible_mask, d->hwirq, 0);
}
#ifdef CONFIG_SMP
static int plic_set_affinity(struct irq_data *d,
const struct cpumask *mask_val, bool force)
{
unsigned int cpu;
if (force)
cpu = cpumask_first(mask_val);
else
cpu = cpumask_any_and(mask_val, cpu_online_mask);
if (cpu >= nr_cpu_ids)
return -EINVAL;
plic_irq_toggle(cpu_possible_mask, d->hwirq, 0);
plic_irq_toggle(cpumask_of(cpu), d->hwirq, 1);
irq_data_update_effective_affinity(d, cpumask_of(cpu));
return IRQ_SET_MASK_OK_DONE;
}
#endif
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);
}
static struct irq_chip plic_chip = {
.name = "SiFive PLIC",
.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
};
static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hwirq)
{
irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
handle_fasteoi_irq, NULL, NULL);
irq_set_noprobe(irq);
return 0;
}
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 = irq_domain_translate_onecell(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 = irq_domain_translate_onecell,
.alloc = plic_irq_domain_alloc,
.free = irq_domain_free_irqs_top,
};
static struct irq_domain *plic_irqdomain;
/*
* 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 pt_regs *regs)
{
struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
void __iomem *claim = handler->hart_base + CONTEXT_CLAIM;
irq_hw_number_t hwirq;
WARN_ON_ONCE(!handler->present);
csr_clear(CSR_IE, IE_EIE);
while ((hwirq = readl(claim))) {
int irq = irq_find_mapping(plic_irqdomain, hwirq);
if (unlikely(irq <= 0))
pr_warn_ratelimited("can't find mapping for hwirq %lu\n",
hwirq);
else
generic_handle_irq(irq);
}
csr_set(CSR_IE, IE_EIE);
}
/*
* Walk up the DT tree until we find an active RISC-V core (HART) node and
* extract the cpuid from it.
*/
static int plic_find_hart_id(struct device_node *node)
{
for (; node; node = node->parent) {
if (of_device_is_compatible(node, "riscv"))
return riscv_of_processor_hartid(node);
}
return -1;
}
static int __init plic_init(struct device_node *node,
struct device_node *parent)
{
int error = 0, nr_contexts, nr_handlers = 0, i;
u32 nr_irqs;
if (plic_regs) {
pr_warn("PLIC already present.\n");
return -ENXIO;
}
plic_regs = of_iomap(node, 0);
if (WARN_ON(!plic_regs))
return -EIO;
error = -EINVAL;
of_property_read_u32(node, "riscv,ndev", &nr_irqs);
if (WARN_ON(!nr_irqs))
goto out_iounmap;
nr_contexts = of_irq_count(node);
if (WARN_ON(!nr_contexts))
goto out_iounmap;
if (WARN_ON(nr_contexts < num_possible_cpus()))
goto out_iounmap;
error = -ENOMEM;
plic_irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
&plic_irqdomain_ops, NULL);
if (WARN_ON(!plic_irqdomain))
goto out_iounmap;
for (i = 0; i < nr_contexts; i++) {
struct of_phandle_args parent;
struct plic_handler *handler;
irq_hw_number_t hwirq;
int cpu, hartid;
u32 threshold = 0;
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)
continue;
hartid = plic_find_hart_id(parent.np);
if (hartid < 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;
}
/*
* 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);
threshold = 0xffffffff;
goto done;
}
handler->present = true;
handler->hart_base =
plic_regs + CONTEXT_BASE + i * CONTEXT_PER_HART;
raw_spin_lock_init(&handler->enable_lock);
handler->enable_base =
plic_regs + ENABLE_BASE + i * ENABLE_PER_HART;
done:
/* priority must be > threshold to trigger an interrupt */
writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);
for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
plic_toggle(handler, hwirq, 0);
nr_handlers++;
}
pr_info("mapped %d interrupts with %d handlers for %d contexts.\n",
nr_irqs, nr_handlers, nr_contexts);
set_handle_irq(plic_handle_irq);
return 0;
out_iounmap:
iounmap(plic_regs);
return error;
}
IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */
|