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Commit d17bf24e authored by Qais Yousef's avatar Qais Yousef Committed by Thomas Gleixner
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genirq: Add a new generic IPI reservation code to irq core 



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: default avatarQais 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent ac0a0cd2

include/linux/irq.h

+3 −0
Original line number Diff line number Diff line
@@ -940,4 +940,7 @@ static inline u32 irq_reg_readl(struct irq_chip_generic *gc, 
		return readl(gc->reg_base + reg_offset);

}



/* Contrary to Linux irqs, for hardware irqs the irq number 0 is valid */

#define INVALID_HWIRQ	(~0UL)



#endif /* _LINUX_IRQ_H */

include/linux/irqdomain.h

+5 −0
Original line number Diff line number Diff line
@@ -344,6 +344,11 @@ int irq_domain_xlate_onetwocell(struct irq_domain *d, struct device_node *ctrlr, 
			const u32 *intspec, unsigned int intsize,

			irq_hw_number_t *out_hwirq, unsigned int *out_type);



/* IPI functions */

unsigned int irq_reserve_ipi(struct irq_domain *domain,

			     const struct cpumask *dest);

void irq_destroy_ipi(unsigned int irq);



/* V2 interfaces to support hierarchy IRQ domains. */

extern struct irq_data *irq_domain_get_irq_data(struct irq_domain *domain,

						unsigned int virq);

kernel/irq/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -8,3 +8,4 @@ obj-$(CONFIG_GENERIC_PENDING_IRQ) += migration.o 
obj-$(CONFIG_GENERIC_IRQ_MIGRATION) += cpuhotplug.o

obj-$(CONFIG_PM_SLEEP) += pm.o

obj-$(CONFIG_GENERIC_MSI_IRQ) += msi.o

obj-$(CONFIG_GENERIC_IRQ_IPI) += ipi.o

kernel/irq/ipi.c

0 → 100644
+137 −0
Original line number Diff line number Diff line 
/*

 * 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);

}