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irqchip: gicv3-its: Support safe initialization

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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: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Yun Wu <wuyun.wu@huawei.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1425659870-11832-12-git-send-email-marc.zyngier@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
This commit is contained in:
Yun Wu 2015-03-06 16:37:50 +00:00 committed by Jason Cooper
parent 7cb991164a
commit 4559fbb3a9
1 changed files with 35 additions and 0 deletions
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35
drivers/irqchip/irq-gic-v3-its.c
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@ -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);