![Qais Yousef](/assets/img/avatar_default.png)
Add a generic mechanism to dynamically allocate an IPI. Depending on the underlying implementation this creates either a single Linux irq or a consective range of Linux irqs. The Linux irq is used later to send IPIs to other CPUs. [ tglx: Massaged the code and removed the 'consecutive mask' restriction for the single IRQ case ] Signed-off-by: Qais Yousef <qais.yousef@imgtec.com> Cc: <jason@lakedaemon.net> Cc: <marc.zyngier@arm.com> Cc: <jiang.liu@linux.intel.com> Cc: <ralf@linux-mips.org> Cc: <linux-mips@linux-mips.org> Cc: <lisa.parratt@imgtec.com> Cc: Qais Yousef <qsyousef@gmail.com> Link: http://lkml.kernel.org/r/1449580830-23652-9-git-send-email-qais.yousef@imgtec.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
138 lines
3.3 KiB
C
138 lines
3.3 KiB
C
/*
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* linux/kernel/irq/ipi.c
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*
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* Copyright (C) 2015 Imagination Technologies Ltd
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* Author: Qais Yousef <qais.yousef@imgtec.com>
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*
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* This file contains driver APIs to the IPI subsystem.
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*/
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#define pr_fmt(fmt) "genirq/ipi: " fmt
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#include <linux/irqdomain.h>
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#include <linux/irq.h>
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/**
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* irq_reserve_ipi() - Setup an IPI to destination cpumask
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* @domain: IPI domain
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* @dest: cpumask of cpus which can receive the IPI
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*
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* Allocate a virq that can be used to send IPI to any CPU in dest mask.
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*
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* On success it'll return linux irq number and 0 on failure
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*/
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unsigned int irq_reserve_ipi(struct irq_domain *domain,
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const struct cpumask *dest)
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{
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unsigned int nr_irqs, offset;
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struct irq_data *data;
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int virq, i;
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if (!domain ||!irq_domain_is_ipi(domain)) {
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pr_warn("Reservation on a non IPI domain\n");
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return 0;
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}
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if (!cpumask_subset(dest, cpu_possible_mask)) {
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pr_warn("Reservation is not in possible_cpu_mask\n");
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return 0;
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}
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nr_irqs = cpumask_weight(dest);
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if (!nr_irqs) {
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pr_warn("Reservation for empty destination mask\n");
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return 0;
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}
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if (irq_domain_is_ipi_single(domain)) {
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/*
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* If the underlying implementation uses a single HW irq on
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* all cpus then we only need a single Linux irq number for
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* it. We have no restrictions vs. the destination mask. The
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* underlying implementation can deal with holes nicely.
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*/
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nr_irqs = 1;
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offset = 0;
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} else {
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unsigned int next;
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/*
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* The IPI requires a seperate HW irq on each CPU. We require
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* that the destination mask is consecutive. If an
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* implementation needs to support holes, it can reserve
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* several IPI ranges.
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*/
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offset = cpumask_first(dest);
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/*
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* Find a hole and if found look for another set bit after the
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* hole. For now we don't support this scenario.
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*/
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next = cpumask_next_zero(offset, dest);
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if (next < nr_cpu_ids)
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next = cpumask_next(next, dest);
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if (next < nr_cpu_ids) {
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pr_warn("Destination mask has holes\n");
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return 0;
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}
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}
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virq = irq_domain_alloc_descs(-1, nr_irqs, 0, NUMA_NO_NODE);
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if (virq <= 0) {
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pr_warn("Can't reserve IPI, failed to alloc descs\n");
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return 0;
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}
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virq = __irq_domain_alloc_irqs(domain, virq, nr_irqs, NUMA_NO_NODE,
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(void *) dest, true);
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if (virq <= 0) {
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pr_warn("Can't reserve IPI, failed to alloc hw irqs\n");
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goto free_descs;
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}
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for (i = 0; i < nr_irqs; i++) {
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data = irq_get_irq_data(virq + i);
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cpumask_copy(data->common->affinity, dest);
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data->common->ipi_offset = offset;
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}
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return virq;
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free_descs:
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irq_free_descs(virq, nr_irqs);
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return 0;
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}
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/**
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* irq_destroy_ipi() - unreserve an IPI that was previously allocated
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* @irq: linux irq number to be destroyed
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*
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* Return the IPIs allocated with irq_reserve_ipi() to the system destroying
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* all virqs associated with them.
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*/
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void irq_destroy_ipi(unsigned int irq)
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{
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struct irq_data *data = irq_get_irq_data(irq);
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struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
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struct irq_domain *domain;
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unsigned int nr_irqs;
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if (!irq || !data || !ipimask)
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return;
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domain = data->domain;
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if (WARN_ON(domain == NULL))
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return;
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if (!irq_domain_is_ipi(domain)) {
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pr_warn("Trying to destroy a non IPI domain!\n");
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return;
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}
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if (irq_domain_is_ipi_per_cpu(domain))
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nr_irqs = cpumask_weight(ipimask);
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else
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nr_irqs = 1;
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irq_domain_free_irqs(irq, nr_irqs);
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}
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