lkml.org 
[lkml]   [2015]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v4 5/5] irqchip: gicv3-its: support safe initialization
Date
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>
---
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 d13c24e..9e09aa0 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);
--
1.8.0



\
 
 \ /
  Last update: 2015-03-06 05:21    [W:0.068 / U:21.992 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site