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 ENABLE_BASE 0x2000
48 #define ENABLE_PER_HART 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_PER_HART 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 struct plic_priv {
64 struct cpumask lmask;
65 struct irq_domain *irqdomain;
66 void __iomem *regs;
67 };
68
69 struct plic_handler {
70 bool present;
71 void __iomem *hart_base;
72 /*
73 * Protect mask operations on the registers given that we can't
74 * assume atomic memory operations work on them.
75 */
76 raw_spinlock_t enable_lock;
77 void __iomem *enable_base;
78 struct plic_priv *priv;
79 };
80 static int plic_parent_irq;
81 static bool plic_cpuhp_setup_done;
82 static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
83
plic_toggle(struct plic_handler * handler,int hwirq,int enable)84 static inline void plic_toggle(struct plic_handler *handler,
85 int hwirq, int enable)
86 {
87 u32 __iomem *reg = handler->enable_base + (hwirq / 32) * sizeof(u32);
88 u32 hwirq_mask = 1 << (hwirq % 32);
89
90 raw_spin_lock(&handler->enable_lock);
91 if (enable)
92 writel(readl(reg) | hwirq_mask, reg);
93 else
94 writel(readl(reg) & ~hwirq_mask, reg);
95 raw_spin_unlock(&handler->enable_lock);
96 }
97
plic_irq_toggle(const struct cpumask * mask,struct irq_data * d,int enable)98 static inline void plic_irq_toggle(const struct cpumask *mask,
99 struct irq_data *d, int enable)
100 {
101 int cpu;
102 struct plic_priv *priv = irq_data_get_irq_chip_data(d);
103
104 writel(enable, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
105 for_each_cpu(cpu, mask) {
106 struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
107
108 if (handler->present &&
109 cpumask_test_cpu(cpu, &handler->priv->lmask))
110 plic_toggle(handler, d->hwirq, enable);
111 }
112 }
113
plic_irq_unmask(struct irq_data * d)114 static void plic_irq_unmask(struct irq_data *d)
115 {
116 struct cpumask amask;
117 unsigned int cpu;
118 struct plic_priv *priv = irq_data_get_irq_chip_data(d);
119
120 cpumask_and(&amask, &priv->lmask, cpu_online_mask);
121 cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
122 &amask);
123 if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
124 return;
125 plic_irq_toggle(cpumask_of(cpu), d, 1);
126 }
127
plic_irq_mask(struct irq_data * d)128 static void plic_irq_mask(struct irq_data *d)
129 {
130 struct plic_priv *priv = irq_data_get_irq_chip_data(d);
131
132 plic_irq_toggle(&priv->lmask, d, 0);
133 }
134
135 #ifdef CONFIG_SMP
plic_set_affinity(struct irq_data * d,const struct cpumask * mask_val,bool force)136 static int plic_set_affinity(struct irq_data *d,
137 const struct cpumask *mask_val, bool force)
138 {
139 unsigned int cpu;
140 struct cpumask amask;
141 struct plic_priv *priv = irq_data_get_irq_chip_data(d);
142
143 cpumask_and(&amask, &priv->lmask, mask_val);
144
145 if (force)
146 cpu = cpumask_first(&amask);
147 else
148 cpu = cpumask_any_and(&amask, cpu_online_mask);
149
150 if (cpu >= nr_cpu_ids)
151 return -EINVAL;
152
153 plic_irq_toggle(&priv->lmask, d, 0);
154 plic_irq_toggle(cpumask_of(cpu), d, !irqd_irq_masked(d));
155
156 irq_data_update_effective_affinity(d, cpumask_of(cpu));
157
158 return IRQ_SET_MASK_OK_DONE;
159 }
160 #endif
161
plic_irq_eoi(struct irq_data * d)162 static void plic_irq_eoi(struct irq_data *d)
163 {
164 struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
165
166 if (irqd_irq_masked(d)) {
167 plic_irq_unmask(d);
168 writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
169 plic_irq_mask(d);
170 } else {
171 writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
172 }
173 }
174
175 static struct irq_chip plic_chip = {
176 .name = "SiFive PLIC",
177 .irq_mask = plic_irq_mask,
178 .irq_unmask = plic_irq_unmask,
179 .irq_eoi = plic_irq_eoi,
180 #ifdef CONFIG_SMP
181 .irq_set_affinity = plic_set_affinity,
182 #endif
183 };
184
plic_irqdomain_map(struct irq_domain * d,unsigned int irq,irq_hw_number_t hwirq)185 static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
186 irq_hw_number_t hwirq)
187 {
188 struct plic_priv *priv = d->host_data;
189
190 irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
191 handle_fasteoi_irq, NULL, NULL);
192 irq_set_noprobe(irq);
193 irq_set_affinity(irq, &priv->lmask);
194 return 0;
195 }
196
plic_irq_domain_alloc(struct irq_domain * domain,unsigned int virq,unsigned int nr_irqs,void * arg)197 static int plic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
198 unsigned int nr_irqs, void *arg)
199 {
200 int i, ret;
201 irq_hw_number_t hwirq;
202 unsigned int type;
203 struct irq_fwspec *fwspec = arg;
204
205 ret = irq_domain_translate_onecell(domain, fwspec, &hwirq, &type);
206 if (ret)
207 return ret;
208
209 for (i = 0; i < nr_irqs; i++) {
210 ret = plic_irqdomain_map(domain, virq + i, hwirq + i);
211 if (ret)
212 return ret;
213 }
214
215 return 0;
216 }
217
218 static const struct irq_domain_ops plic_irqdomain_ops = {
219 .translate = irq_domain_translate_onecell,
220 .alloc = plic_irq_domain_alloc,
221 .free = irq_domain_free_irqs_top,
222 };
223
224 /*
225 * Handling an interrupt is a two-step process: first you claim the interrupt
226 * by reading the claim register, then you complete the interrupt by writing
227 * that source ID back to the same claim register. This automatically enables
228 * and disables the interrupt, so there's nothing else to do.
229 */
plic_handle_irq(struct irq_desc * desc)230 static void plic_handle_irq(struct irq_desc *desc)
231 {
232 struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
233 struct irq_chip *chip = irq_desc_get_chip(desc);
234 void __iomem *claim = handler->hart_base + CONTEXT_CLAIM;
235 irq_hw_number_t hwirq;
236
237 WARN_ON_ONCE(!handler->present);
238
239 chained_irq_enter(chip, desc);
240
241 while ((hwirq = readl(claim))) {
242 int irq = irq_find_mapping(handler->priv->irqdomain, hwirq);
243
244 if (unlikely(irq <= 0))
245 pr_warn_ratelimited("can't find mapping for hwirq %lu\n",
246 hwirq);
247 else
248 generic_handle_irq(irq);
249 }
250
251 chained_irq_exit(chip, desc);
252 }
253
plic_set_threshold(struct plic_handler * handler,u32 threshold)254 static void plic_set_threshold(struct plic_handler *handler, u32 threshold)
255 {
256 /* priority must be > threshold to trigger an interrupt */
257 writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);
258 }
259
plic_dying_cpu(unsigned int cpu)260 static int plic_dying_cpu(unsigned int cpu)
261 {
262 if (plic_parent_irq)
263 disable_percpu_irq(plic_parent_irq);
264
265 return 0;
266 }
267
plic_starting_cpu(unsigned int cpu)268 static int plic_starting_cpu(unsigned int cpu)
269 {
270 struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
271
272 if (plic_parent_irq)
273 enable_percpu_irq(plic_parent_irq,
274 irq_get_trigger_type(plic_parent_irq));
275 else
276 pr_warn("cpu%d: parent irq not available\n", cpu);
277 plic_set_threshold(handler, PLIC_ENABLE_THRESHOLD);
278
279 return 0;
280 }
281
plic_init(struct device_node * node,struct device_node * parent)282 static int __init plic_init(struct device_node *node,
283 struct device_node *parent)
284 {
285 int error = 0, nr_contexts, nr_handlers = 0, i;
286 u32 nr_irqs;
287 struct plic_priv *priv;
288 struct plic_handler *handler;
289
290 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
291 if (!priv)
292 return -ENOMEM;
293
294 priv->regs = of_iomap(node, 0);
295 if (WARN_ON(!priv->regs)) {
296 error = -EIO;
297 goto out_free_priv;
298 }
299
300 error = -EINVAL;
301 of_property_read_u32(node, "riscv,ndev", &nr_irqs);
302 if (WARN_ON(!nr_irqs))
303 goto out_iounmap;
304
305 nr_contexts = of_irq_count(node);
306 if (WARN_ON(!nr_contexts))
307 goto out_iounmap;
308
309 error = -ENOMEM;
310 priv->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
311 &plic_irqdomain_ops, priv);
312 if (WARN_ON(!priv->irqdomain))
313 goto out_iounmap;
314
315 for (i = 0; i < nr_contexts; i++) {
316 struct of_phandle_args parent;
317 irq_hw_number_t hwirq;
318 int cpu, hartid;
319
320 if (of_irq_parse_one(node, i, &parent)) {
321 pr_err("failed to parse parent for context %d.\n", i);
322 continue;
323 }
324
325 /*
326 * Skip contexts other than external interrupts for our
327 * privilege level.
328 */
329 if (parent.args[0] != RV_IRQ_EXT)
330 continue;
331
332 hartid = riscv_of_parent_hartid(parent.np);
333 if (hartid < 0) {
334 pr_warn("failed to parse hart ID for context %d.\n", i);
335 continue;
336 }
337
338 cpu = riscv_hartid_to_cpuid(hartid);
339 if (cpu < 0) {
340 pr_warn("Invalid cpuid for context %d\n", i);
341 continue;
342 }
343
344 /* Find parent domain and register chained handler */
345 if (!plic_parent_irq && irq_find_host(parent.np)) {
346 plic_parent_irq = irq_of_parse_and_map(node, i);
347 if (plic_parent_irq)
348 irq_set_chained_handler(plic_parent_irq,
349 plic_handle_irq);
350 }
351
352 /*
353 * When running in M-mode we need to ignore the S-mode handler.
354 * Here we assume it always comes later, but that might be a
355 * little fragile.
356 */
357 handler = per_cpu_ptr(&plic_handlers, cpu);
358 if (handler->present) {
359 pr_warn("handler already present for context %d.\n", i);
360 plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
361 goto done;
362 }
363
364 cpumask_set_cpu(cpu, &priv->lmask);
365 handler->present = true;
366 handler->hart_base =
367 priv->regs + CONTEXT_BASE + i * CONTEXT_PER_HART;
368 raw_spin_lock_init(&handler->enable_lock);
369 handler->enable_base =
370 priv->regs + ENABLE_BASE + i * ENABLE_PER_HART;
371 handler->priv = priv;
372 done:
373 for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
374 plic_toggle(handler, hwirq, 0);
375 nr_handlers++;
376 }
377
378 /*
379 * We can have multiple PLIC instances so setup cpuhp state only
380 * when context handler for current/boot CPU is present.
381 */
382 handler = this_cpu_ptr(&plic_handlers);
383 if (handler->present && !plic_cpuhp_setup_done) {
384 cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
385 "irqchip/sifive/plic:starting",
386 plic_starting_cpu, plic_dying_cpu);
387 plic_cpuhp_setup_done = true;
388 }
389
390 pr_info("%pOFP: mapped %d interrupts with %d handlers for"
391 " %d contexts.\n", node, nr_irqs, nr_handlers, nr_contexts);
392 return 0;
393
394 out_iounmap:
395 iounmap(priv->regs);
396 out_free_priv:
397 kfree(priv);
398 return error;
399 }
400
401 IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
402 IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */
403 IRQCHIP_DECLARE(thead_c900_plic, "thead,c900-plic", plic_init); /* for firmware driver */
404