From d5d50d196a18a79e812ac4008a5d752a1337ca2e Mon Sep 17 00:00:00 2001 From: Yun Wu Date: Fri, 6 Mar 2015 16:37:50 +0000 Subject: 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 (cherry picked from commit 4559fbb3a9b1bde46afc739fa6c300826acdc19c) Signed-off-by: Alex Shi --- 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 3c82d8119c29..17262c18ca0d 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); -- cgit v1.2.3