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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2015 Imagination Technologies Ltd
4 * Author: Qais Yousef <[email protected]>
5 *
6 * This file contains driver APIs to the IPI subsystem.
7 */
8
9#define pr_fmt(fmt) "genirq/ipi: " fmt
10
11#include <linux/irqdomain.h>
12#include <linux/irq.h>
13
14/**
15 * irq_reserve_ipi() - Setup an IPI to destination cpumask
16 * @domain: IPI domain
17 * @dest: cpumask of CPUs which can receive the IPI
18 *
19 * Allocate a virq that can be used to send IPI to any CPU in dest mask.
20 *
21 * Return: Linux IRQ number on success or error code on failure
22 */
23int irq_reserve_ipi(struct irq_domain *domain,
24 const struct cpumask *dest)
25{
26 unsigned int nr_irqs, offset;
27 struct irq_data *data;
28 int virq, i;
29
30 if (!domain ||!irq_domain_is_ipi(domain)) {
31 pr_warn("Reservation on a non IPI domain\n");
32 return -EINVAL;
33 }
34
35 if (!cpumask_subset(dest, cpu_possible_mask)) {
36 pr_warn("Reservation is not in possible_cpu_mask\n");
37 return -EINVAL;
38 }
39
40 nr_irqs = cpumask_weight(dest);
41 if (!nr_irqs) {
42 pr_warn("Reservation for empty destination mask\n");
43 return -EINVAL;
44 }
45
46 if (irq_domain_is_ipi_single(domain)) {
47 /*
48 * If the underlying implementation uses a single HW irq on
49 * all cpus then we only need a single Linux irq number for
50 * it. We have no restrictions vs. the destination mask. The
51 * underlying implementation can deal with holes nicely.
52 */
53 nr_irqs = 1;
54 offset = 0;
55 } else {
56 unsigned int next;
57
58 /*
59 * The IPI requires a separate HW irq on each CPU. We require
60 * that the destination mask is consecutive. If an
61 * implementation needs to support holes, it can reserve
62 * several IPI ranges.
63 */
64 offset = cpumask_first(dest);
65 /*
66 * Find a hole and if found look for another set bit after the
67 * hole. For now we don't support this scenario.
68 */
69 next = cpumask_next_zero(offset, dest);
70 if (next < nr_cpu_ids)
71 next = cpumask_next(next, dest);
72 if (next < nr_cpu_ids) {
73 pr_warn("Destination mask has holes\n");
74 return -EINVAL;
75 }
76 }
77
78 virq = irq_domain_alloc_descs(-1, nr_irqs, 0, NUMA_NO_NODE, NULL);
79 if (virq <= 0) {
80 pr_warn("Can't reserve IPI, failed to alloc descs\n");
81 return -ENOMEM;
82 }
83
84 virq = __irq_domain_alloc_irqs(domain, virq, nr_irqs, NUMA_NO_NODE,
85 (void *) dest, true, NULL);
86
87 if (virq <= 0) {
88 pr_warn("Can't reserve IPI, failed to alloc hw irqs\n");
89 goto free_descs;
90 }
91
92 for (i = 0; i < nr_irqs; i++) {
93 data = irq_get_irq_data(virq + i);
94 cpumask_copy(data->common->affinity, dest);
95 data->common->ipi_offset = offset;
96 irq_set_status_flags(virq + i, IRQ_NO_BALANCING);
97 }
98 return virq;
99
100free_descs:
101 irq_free_descs(virq, nr_irqs);
102 return -EBUSY;
103}
104
105/**
106 * irq_destroy_ipi() - unreserve an IPI that was previously allocated
107 * @irq: Linux IRQ number to be destroyed
108 * @dest: cpumask of CPUs which should have the IPI removed
109 *
110 * The IPIs allocated with irq_reserve_ipi() are returned to the system
111 * destroying all virqs associated with them.
112 *
113 * Return: %0 on success or error code on failure.
114 */
115int irq_destroy_ipi(unsigned int irq, const struct cpumask *dest)
116{
117 struct irq_data *data = irq_get_irq_data(irq);
118 const struct cpumask *ipimask;
119 struct irq_domain *domain;
120 unsigned int nr_irqs;
121
122 if (!irq || !data)
123 return -EINVAL;
124
125 domain = data->domain;
126 if (WARN_ON(domain == NULL))
127 return -EINVAL;
128
129 if (!irq_domain_is_ipi(domain)) {
130 pr_warn("Trying to destroy a non IPI domain!\n");
131 return -EINVAL;
132 }
133
134 ipimask = irq_data_get_affinity_mask(data);
135 if (!ipimask || WARN_ON(!cpumask_subset(dest, ipimask)))
136 /*
137 * Must be destroying a subset of CPUs to which this IPI
138 * was set up to target
139 */
140 return -EINVAL;
141
142 if (irq_domain_is_ipi_per_cpu(domain)) {
143 irq = irq + cpumask_first(dest) - data->common->ipi_offset;
144 nr_irqs = cpumask_weight(dest);
145 } else {
146 nr_irqs = 1;
147 }
148
149 irq_domain_free_irqs(irq, nr_irqs);
150 return 0;
151}
152
153/**
154 * ipi_get_hwirq - Get the hwirq associated with an IPI to a CPU
155 * @irq: Linux IRQ number
156 * @cpu: the target CPU
157 *
158 * When dealing with coprocessors IPI, we need to inform the coprocessor of
159 * the hwirq it needs to use to receive and send IPIs.
160 *
161 * Return: hwirq value on success or INVALID_HWIRQ on failure.
162 */
163irq_hw_number_t ipi_get_hwirq(unsigned int irq, unsigned int cpu)
164{
165 struct irq_data *data = irq_get_irq_data(irq);
166 const struct cpumask *ipimask;
167
168 if (!data || cpu >= nr_cpu_ids)
169 return INVALID_HWIRQ;
170
171 ipimask = irq_data_get_affinity_mask(data);
172 if (!ipimask || !cpumask_test_cpu(cpu, ipimask))
173 return INVALID_HWIRQ;
174
175 /*
176 * Get the real hardware irq number if the underlying implementation
177 * uses a separate irq per cpu. If the underlying implementation uses
178 * a single hardware irq for all cpus then the IPI send mechanism
179 * needs to take care of the cpu destinations.
180 */
181 if (irq_domain_is_ipi_per_cpu(data->domain))
182 data = irq_get_irq_data(irq + cpu - data->common->ipi_offset);
183
184 return data ? irqd_to_hwirq(data) : INVALID_HWIRQ;
185}
186EXPORT_SYMBOL_GPL(ipi_get_hwirq);
187
188static int ipi_send_verify(struct irq_chip *chip, struct irq_data *data,
189 const struct cpumask *dest, unsigned int cpu)
190{
191 const struct cpumask *ipimask;
192
193 if (!chip || !data)
194 return -EINVAL;
195
196 if (!chip->ipi_send_single && !chip->ipi_send_mask)
197 return -EINVAL;
198
199 if (cpu >= nr_cpu_ids)
200 return -EINVAL;
201
202 ipimask = irq_data_get_affinity_mask(data);
203 if (!ipimask)
204 return -EINVAL;
205
206 if (dest) {
207 if (!cpumask_subset(dest, ipimask))
208 return -EINVAL;
209 } else {
210 if (!cpumask_test_cpu(cpu, ipimask))
211 return -EINVAL;
212 }
213 return 0;
214}
215
216/**
217 * __ipi_send_single - send an IPI to a target Linux SMP CPU
218 * @desc: pointer to irq_desc of the IRQ
219 * @cpu: destination CPU, must in the destination mask passed to
220 * irq_reserve_ipi()
221 *
222 * This function is for architecture or core code to speed up IPI sending. Not
223 * usable from driver code.
224 *
225 * Return: %0 on success or negative error number on failure.
226 */
227int __ipi_send_single(struct irq_desc *desc, unsigned int cpu)
228{
229 struct irq_data *data = irq_desc_get_irq_data(desc);
230 struct irq_chip *chip = irq_data_get_irq_chip(data);
231
232#ifdef DEBUG
233 /*
234 * Minimise the overhead by omitting the checks for Linux SMP IPIs.
235 * Since the callers should be arch or core code which is generally
236 * trusted, only check for errors when debugging.
237 */
238 if (WARN_ON_ONCE(ipi_send_verify(chip, data, NULL, cpu)))
239 return -EINVAL;
240#endif
241 if (!chip->ipi_send_single) {
242 chip->ipi_send_mask(data, cpumask_of(cpu));
243 return 0;
244 }
245
246 /* FIXME: Store this information in irqdata flags */
247 if (irq_domain_is_ipi_per_cpu(data->domain) &&
248 cpu != data->common->ipi_offset) {
249 /* use the correct data for that cpu */
250 unsigned irq = data->irq + cpu - data->common->ipi_offset;
251
252 data = irq_get_irq_data(irq);
253 }
254 chip->ipi_send_single(data, cpu);
255 return 0;
256}
257
258/**
259 * __ipi_send_mask - send an IPI to target Linux SMP CPU(s)
260 * @desc: pointer to irq_desc of the IRQ
261 * @dest: dest CPU(s), must be a subset of the mask passed to
262 * irq_reserve_ipi()
263 *
264 * This function is for architecture or core code to speed up IPI sending. Not
265 * usable from driver code.
266 *
267 * Return: %0 on success or negative error number on failure.
268 */
269int __ipi_send_mask(struct irq_desc *desc, const struct cpumask *dest)
270{
271 struct irq_data *data = irq_desc_get_irq_data(desc);
272 struct irq_chip *chip = irq_data_get_irq_chip(data);
273 unsigned int cpu;
274
275#ifdef DEBUG
276 /*
277 * Minimise the overhead by omitting the checks for Linux SMP IPIs.
278 * Since the callers should be arch or core code which is generally
279 * trusted, only check for errors when debugging.
280 */
281 if (WARN_ON_ONCE(ipi_send_verify(chip, data, dest, 0)))
282 return -EINVAL;
283#endif
284 if (chip->ipi_send_mask) {
285 chip->ipi_send_mask(data, dest);
286 return 0;
287 }
288
289 if (irq_domain_is_ipi_per_cpu(data->domain)) {
290 unsigned int base = data->irq;
291
292 for_each_cpu(cpu, dest) {
293 unsigned irq = base + cpu - data->common->ipi_offset;
294
295 data = irq_get_irq_data(irq);
296 chip->ipi_send_single(data, cpu);
297 }
298 } else {
299 for_each_cpu(cpu, dest)
300 chip->ipi_send_single(data, cpu);
301 }
302 return 0;
303}
304
305/**
306 * ipi_send_single - Send an IPI to a single CPU
307 * @virq: Linux IRQ number from irq_reserve_ipi()
308 * @cpu: destination CPU, must in the destination mask passed to
309 * irq_reserve_ipi()
310 *
311 * Return: %0 on success or negative error number on failure.
312 */
313int ipi_send_single(unsigned int virq, unsigned int cpu)
314{
315 struct irq_desc *desc = irq_to_desc(virq);
316 struct irq_data *data = desc ? irq_desc_get_irq_data(desc) : NULL;
317 struct irq_chip *chip = data ? irq_data_get_irq_chip(data) : NULL;
318
319 if (WARN_ON_ONCE(ipi_send_verify(chip, data, NULL, cpu)))
320 return -EINVAL;
321
322 return __ipi_send_single(desc, cpu);
323}
324EXPORT_SYMBOL_GPL(ipi_send_single);
325
326/**
327 * ipi_send_mask - Send an IPI to target CPU(s)
328 * @virq: Linux IRQ number from irq_reserve_ipi()
329 * @dest: dest CPU(s), must be a subset of the mask passed to
330 * irq_reserve_ipi()
331 *
332 * Return: %0 on success or negative error number on failure.
333 */
334int ipi_send_mask(unsigned int virq, const struct cpumask *dest)
335{
336 struct irq_desc *desc = irq_to_desc(virq);
337 struct irq_data *data = desc ? irq_desc_get_irq_data(desc) : NULL;
338 struct irq_chip *chip = data ? irq_data_get_irq_chip(data) : NULL;
339
340 if (WARN_ON_ONCE(ipi_send_verify(chip, data, dest, 0)))
341 return -EINVAL;
342
343 return __ipi_send_mask(desc, dest);
344}
345EXPORT_SYMBOL_GPL(ipi_send_mask);