2 * linux/kernel/irq/ipi.c
4 * Copyright (C) 2015 Imagination Technologies Ltd
5 * Author: Qais Yousef <qais.yousef@imgtec.com>
7 * This file contains driver APIs to the IPI subsystem.
10 #define pr_fmt(fmt) "genirq/ipi: " fmt
12 #include <linux/irqdomain.h>
13 #include <linux/irq.h>
16 * irq_reserve_ipi() - Setup an IPI to destination cpumask
18 * @dest: cpumask of cpus which can receive the IPI
20 * Allocate a virq that can be used to send IPI to any CPU in dest mask.
22 * On success it'll return linux irq number and 0 on failure
24 unsigned int irq_reserve_ipi(struct irq_domain *domain,
25 const struct cpumask *dest)
27 unsigned int nr_irqs, offset;
28 struct irq_data *data;
31 if (!domain ||!irq_domain_is_ipi(domain)) {
32 pr_warn("Reservation on a non IPI domain\n");
36 if (!cpumask_subset(dest, cpu_possible_mask)) {
37 pr_warn("Reservation is not in possible_cpu_mask\n");
41 nr_irqs = cpumask_weight(dest);
43 pr_warn("Reservation for empty destination mask\n");
47 if (irq_domain_is_ipi_single(domain)) {
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.
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
65 offset = cpumask_first(dest);
67 * Find a hole and if found look for another set bit after the
68 * hole. For now we don't support this scenario.
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");
79 virq = irq_domain_alloc_descs(-1, nr_irqs, 0, NUMA_NO_NODE);
81 pr_warn("Can't reserve IPI, failed to alloc descs\n");
85 virq = __irq_domain_alloc_irqs(domain, virq, nr_irqs, NUMA_NO_NODE,
89 pr_warn("Can't reserve IPI, failed to alloc hw irqs\n");
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;
101 irq_free_descs(virq, nr_irqs);
106 * irq_destroy_ipi() - unreserve an IPI that was previously allocated
107 * @irq: linux irq number to be destroyed
109 * Return the IPIs allocated with irq_reserve_ipi() to the system destroying
110 * all virqs associated with them.
112 void irq_destroy_ipi(unsigned int irq)
114 struct irq_data *data = irq_get_irq_data(irq);
115 struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
116 struct irq_domain *domain;
117 unsigned int nr_irqs;
119 if (!irq || !data || !ipimask)
122 domain = data->domain;
123 if (WARN_ON(domain == NULL))
126 if (!irq_domain_is_ipi(domain)) {
127 pr_warn("Trying to destroy a non IPI domain!\n");
131 if (irq_domain_is_ipi_per_cpu(domain))
132 nr_irqs = cpumask_weight(ipimask);
136 irq_domain_free_irqs(irq, nr_irqs);
140 * ipi_get_hwirq - Get the hwirq associated with an IPI to a cpu
141 * @irq: linux irq number
142 * @cpu: the target cpu
144 * When dealing with coprocessors IPI, we need to inform the coprocessor of
145 * the hwirq it needs to use to receive and send IPIs.
147 * Returns hwirq value on success and INVALID_HWIRQ on failure.
149 irq_hw_number_t ipi_get_hwirq(unsigned int irq, unsigned int cpu)
151 struct irq_data *data = irq_get_irq_data(irq);
152 struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
154 if (!data || !ipimask || cpu > nr_cpu_ids)
155 return INVALID_HWIRQ;
157 if (!cpumask_test_cpu(cpu, ipimask))
158 return INVALID_HWIRQ;
161 * Get the real hardware irq number if the underlying implementation
162 * uses a seperate irq per cpu. If the underlying implementation uses
163 * a single hardware irq for all cpus then the IPI send mechanism
164 * needs to take care of this.
166 if (irq_domain_is_ipi_per_cpu(data->domain))
167 data = irq_get_irq_data(irq + cpu - data->common->ipi_offset);
169 return data ? irqd_to_hwirq(data) : INVALID_HWIRQ;
171 EXPORT_SYMBOL_GPL(ipi_get_hwirq);