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Commit 4559fbb3 authored by Yun Wu's avatar Yun Wu Committed by Jason Cooper
Browse files

irqchip: gicv3-its: Support safe initialization 



It's unsafe to change the configurations of an activated ITS directly
since this will lead to unpredictable results. This patch guarantees
the ITSes being initialized are quiescent.

Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarYun Wu <wuyun.wu@huawei.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1425659870-11832-12-git-send-email-marc.zyngier@arm.com


Signed-off-by: default avatarJason Cooper <jason@lakedaemon.net>
parent 7cb99116

drivers/irqchip/irq-gic-v3-its.c

+35 −0
Original line number Diff line number Diff line
@@ -1320,6 +1320,34 @@ static const struct irq_domain_ops its_domain_ops = { 
	.deactivate		= its_irq_domain_deactivate,

};



static int its_force_quiescent(void __iomem *base)

{

	u32 count = 1000000;	/* 1s */

	u32 val;



	val = readl_relaxed(base + GITS_CTLR);

	if (val & GITS_CTLR_QUIESCENT)

		return 0;



	/* Disable the generation of all interrupts to this ITS */

	val &= ~GITS_CTLR_ENABLE;

	writel_relaxed(val, base + GITS_CTLR);



	/* Poll GITS_CTLR and wait until ITS becomes quiescent */

	while (1) {

		val = readl_relaxed(base + GITS_CTLR);

		if (val & GITS_CTLR_QUIESCENT)

			return 0;



		count--;

		if (!count)

			return -EBUSY;



		cpu_relax();

		udelay(1);

	}

}



static int its_probe(struct device_node *node, struct irq_domain *parent)

{

	struct resource res;
@@ -1348,6 +1376,13 @@ static int its_probe(struct device_node *node, struct irq_domain *parent) 
		goto out_unmap;

	}



	err = its_force_quiescent(its_base);

	if (err) {

		pr_warn("%s: failed to quiesce, giving up\n",

			node->full_name);

		goto out_unmap;

	}



	pr_info("ITS: %s\n", node->full_name);



	its = kzalloc(sizeof(*its), GFP_KERNEL);