From 4559fbb3a9b1bde46afc739fa6c300826acdc19c Mon Sep 17 00:00:00 2001 From: Yun Wu Date: Fri, 6 Mar 2015 16:37:50 +0000 Subject: [PATCH] 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: Marc Zyngier Signed-off-by: Yun Wu Signed-off-by: Marc Zyngier Link: https://lkml.kernel.org/r/1425659870-11832-12-git-send-email-marc.zyngier@arm.com Signed-off-by: Jason Cooper --- drivers/irqchip/irq-gic-v3-its.c | 35 ++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 826da706be4b..596b0a9eee99 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -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);