Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754989AbbBOJev (ORCPT ); Sun, 15 Feb 2015 04:34:51 -0500 Received: from szxga01-in.huawei.com ([119.145.14.64]:61992 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754550AbbBOJd2 (ORCPT ); Sun, 15 Feb 2015 04:33:28 -0500 From: Yun Wu To: , , CC: , , Yun Wu Subject: [PATCH v2 5/6] irqchip: gicv3-its: add support for power down Date: Sun, 15 Feb 2015 17:32:02 +0800 Message-ID: <1423992723-5028-6-git-send-email-wuyun.wu@huawei.com> X-Mailer: git-send-email 1.9.4.msysgit.1 In-Reply-To: <1423992723-5028-1-git-send-email-wuyun.wu@huawei.com> References: <1423992723-5028-1-git-send-email-wuyun.wu@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.177.24.136] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1934 Lines: 68 It's unsafe to change the configurations of an activated ITS directly since this will lead to unpredictable results. This patch guarantees a safe quiescent status before initializing an ITS. Signed-off-by: Yun Wu --- drivers/irqchip/irq-gic-v3-its.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 42c03b2..29eb665 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -1321,6 +1321,31 @@ static const struct irq_domain_ops its_domain_ops = { .deactivate = its_irq_domain_deactivate, }; +static int its_check_quiesced(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 (count--) { + val = readl_relaxed(base + GITS_CTLR); + if (val & GITS_CTLR_QUIESCENT) + return 0; + cpu_relax(); + udelay(1); + } + + return -EBUSY; +} + static int its_probe(struct device_node *node, struct irq_domain *parent) { struct resource res; @@ -1349,6 +1374,13 @@ static int its_probe(struct device_node *node, struct irq_domain *parent) goto out_unmap; } + err = its_check_quiesced(its_base); + if (err) { + pr_warn("%s: failed to quiesce, behaviour unpredictable\n", + node->full_name); + goto out_unmap; + } + pr_info("ITS: %s\n", node->full_name); its = kzalloc(sizeof(*its), GFP_KERNEL); -- 1.8.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/