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