irqchip: gic: Allow interrupt level to be set for PPIs

During a recent cleanup of the arm64 DTs it has become clear that
the handling of PPIs in xxxx_set_type() is incorrect. The ARM TRMs
for GICv2 and later allow for "implementation defined" support for
setting the edge or level type of the PPI interrupts and don't restrict
the activation level of the signal. Current ARM implementations
do restrict the PPI level type to IRQ_TYPE_LEVEL_LOW, but licensees
of the IP can decide to shoot themselves in the foot at any time.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Acked-by: Marc Zyngier <Marc.Zyngier@arm.com>
Cc: LAKML <linux-arm-kernel@lists.infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Haojian Zhuang <haojian.zhuang@linaro.org>
Link: http://lkml.kernel.org/r/1421772779-25764-1-git-send-email-Liviu.Dudau@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 12 insertions, 6 deletions

diff --git a/drivers/irqchip/irq-gic-common.c b/drivers/irqchip/irq-gic-common.c
index 61541ff24397..ad96ebb0c7ab 100644
--- a/drivers/irqchip/irq-gic-common.c
+++ b/drivers/irqchip/irq-gic-common.c
@@ -21,7 +21,7 @@
 
 #include "irq-gic-common.h"
 
-void gic_configure_irq(unsigned int irq, unsigned int type,
+int gic_configure_irq(unsigned int irq, unsigned int type,
 		       void __iomem *base, void (*sync_access)(void))
 {
 	u32 enablemask = 1 << (irq % 32);
@@ -29,16 +29,17 @@ void gic_configure_irq(unsigned int irq, unsigned int type,
 	u32 confmask = 0x2 << ((irq % 16) * 2);
 	u32 confoff = (irq / 16) * 4;
 	bool enabled = false;
-	u32 val;
+	u32 val, oldval;
+	int ret = 0;
 
 	/*
 	 * Read current configuration register, and insert the config
 	 * for "irq", depending on "type".
 	 */
-	val = readl_relaxed(base + GIC_DIST_CONFIG + confoff);
-	if (type == IRQ_TYPE_LEVEL_HIGH)
+	val = oldval = readl_relaxed(base + GIC_DIST_CONFIG + confoff);
+	if (type & IRQ_TYPE_LEVEL_MASK)
 		val &= ~confmask;
-	else if (type == IRQ_TYPE_EDGE_RISING)
+	else if (type & IRQ_TYPE_EDGE_BOTH)
 		val |= confmask;
 
 	/*
@@ -54,15 +55,20 @@ void gic_configure_irq(unsigned int irq, unsigned int type,
 
 	/*
 	 * Write back the new configuration, and possibly re-enable
-	 * the interrupt.
+	 * the interrupt. If we tried to write a new configuration and failed,
+	 * return an error.
 	 */
 	writel_relaxed(val, base + GIC_DIST_CONFIG + confoff);
+	if (readl_relaxed(base + GIC_DIST_CONFIG + confoff) != val && val != oldval)
+		ret = -EINVAL;
 
 	if (enabled)
 		writel_relaxed(enablemask, base + GIC_DIST_ENABLE_SET + enableoff);
 
 	if (sync_access)
 		sync_access();
+
+	return ret;
 }
 
 void __init gic_dist_config(void __iomem *base, int gic_irqs,