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/*
* linux/kernel/irq/ipi.c
*
* Copyright (C) 2015 Imagination Technologies Ltd
* Author: Qais Yousef <qais.yousef@imgtec.com>
*
* This file contains driver APIs to the IPI subsystem.
*/
#define pr_fmt(fmt) "genirq/ipi: " fmt
#include <linux/irqdomain.h>
#include <linux/irq.h>
/**
* irq_reserve_ipi() - Setup an IPI to destination cpumask
* @domain: IPI domain
* @dest: cpumask of cpus which can receive the IPI
*
* Allocate a virq that can be used to send IPI to any CPU in dest mask.
*
* On success it'll return linux irq number and 0 on failure
*/
unsigned int irq_reserve_ipi(struct irq_domain *domain,
const struct cpumask *dest)
{
unsigned int nr_irqs, offset;
struct irq_data *data;
int virq, i;
if (!domain ||!irq_domain_is_ipi(domain)) {
pr_warn("Reservation on a non IPI domain\n");
return 0;
}
if (!cpumask_subset(dest, cpu_possible_mask)) {
pr_warn("Reservation is not in possible_cpu_mask\n");
return 0;
}
nr_irqs = cpumask_weight(dest);
if (!nr_irqs) {
pr_warn("Reservation for empty destination mask\n");
return 0;
}
if (irq_domain_is_ipi_single(domain)) {
/*
* If the underlying implementation uses a single HW irq on
* all cpus then we only need a single Linux irq number for
* it. We have no restrictions vs. the destination mask. The
* underlying implementation can deal with holes nicely.
*/
nr_irqs = 1;
offset = 0;
} else {
unsigned int next;
/*
* The IPI requires a seperate HW irq on each CPU. We require
* that the destination mask is consecutive. If an
* implementation needs to support holes, it can reserve
* several IPI ranges.
*/
offset = cpumask_first(dest);
/*
* Find a hole and if found look for another set bit after the
* hole. For now we don't support this scenario.
*/
next = cpumask_next_zero(offset, dest);
if (next < nr_cpu_ids)
next = cpumask_next(next, dest);
if (next < nr_cpu_ids) {
pr_warn("Destination mask has holes\n");
return 0;
}
}
virq = irq_domain_alloc_descs(-1, nr_irqs, 0, NUMA_NO_NODE);
if (virq <= 0) {
pr_warn("Can't reserve IPI, failed to alloc descs\n");
return 0;
}
virq = __irq_domain_alloc_irqs(domain, virq, nr_irqs, NUMA_NO_NODE,
(void *) dest, true);
if (virq <= 0) {
pr_warn("Can't reserve IPI, failed to alloc hw irqs\n");
goto free_descs;
}
for (i = 0; i < nr_irqs; i++) {
data = irq_get_irq_data(virq + i);
cpumask_copy(data->common->affinity, dest);
data->common->ipi_offset = offset;
}
return virq;
free_descs:
irq_free_descs(virq, nr_irqs);
return 0;
}
/**
* irq_destroy_ipi() - unreserve an IPI that was previously allocated
* @irq: linux irq number to be destroyed
*
* Return the IPIs allocated with irq_reserve_ipi() to the system destroying
* all virqs associated with them.
*/
void irq_destroy_ipi(unsigned int irq)
{
struct irq_data *data = irq_get_irq_data(irq);
struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
struct irq_domain *domain;
unsigned int nr_irqs;
if (!irq || !data || !ipimask)
return;
domain = data->domain;
if (WARN_ON(domain == NULL))
return;
if (!irq_domain_is_ipi(domain)) {
pr_warn("Trying to destroy a non IPI domain!\n");
return;
}
if (irq_domain_is_ipi_per_cpu(domain))
nr_irqs = cpumask_weight(ipimask);
else
nr_irqs = 1;
irq_domain_free_irqs(irq, nr_irqs);
}
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