linux-kernel - [PATCH] drivers: platform: parse IRQ flags from resources

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Date:	Wed, 18 Feb 2015 17:12:18 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Grant Likely <grant.likely@...aro.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Robert Jarzmik <robert.jarzmik@...e.fr>,
	"David S. Miller" <davem@...emloft.net>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: [PATCH] drivers: platform: parse IRQ flags from resources

This fixes a regression from the net subsystem:
After commit d52fdbb735c36a209f36a628d40ca9185b349ba7
"smc91x: retrieve IRQ and trigger flags in a modern way"
a regression would appear on some legacy platforms such
as the ARM PXA Zylonite that specify IRQ resources like
this:

static struct resource r = {
       .start  = X,
       .end    = X,
       .flags  = IORESOURCE_IRQ | IORESOURCE_IRQ_HIGHEDGE,
};

The previous code would retrieve the resource and parse
the high edge setting in the SMC91x driver, a use pattern
that means every driver specifying an IRQ flag from a
static resource need to parse resource flags and apply
them at runtime.

As we switched the code to use IRQ descriptors to retrieve
the the trigger type like this:

  irqd_get_trigger_type(irq_get_irq_data(...));

the code would work for new platforms using e.g. device
tree as the backing irq descriptor would have its flags
properly set, whereas this kind of oldstyle static
resources at no point assign the trigger flags to the
corresponding IRQ descriptor.

To make the behaviour identical on modern device tree
and legacy static platform data platforms, modify
platform_get_irq() to assign the trigger flags to the
irq descriptor when a client looks up an IRQ from static
resources.

Fixes: d52fdbb735c3 ("smc91x: retrieve IRQ and trigger flags in a modern way")
Tested-by: Robert Jarzmik <robert.jarzmik@...e.fr>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
---
Greg/Grant: I'm a bit uncertain here. It's kind of
unintuitive that the platform_get_irq() function go around
setting trigger flags on IRQ descriptors, but it is *also*
unintuitive that the descriptor has all the right flags
from a device tree but not from an identical static
resource. And it is bloated to have resource parsing in
each and every driver. The alternative is to revert
the offending patch and live with some resource parsing
all over the place. (Such a patch is posted.)
---
 drivers/base/platform.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 9421fed40905..e68ab79df28b 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -101,6 +101,15 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
 	}
 
 	r = platform_get_resource(dev, IORESOURCE_IRQ, num);
+	/*
+	 * The resources may pass trigger flags to the irqs that need
+	 * to be set up. It so happens that the trigger flags for
+	 * IORESOURCE_BITS correspond 1-to-1 to the IRQF_TRIGGER*
+	 * settings.
+	 */
+	if (r && r->flags & IORESOURCE_BITS)
+		irqd_set_trigger_type(irq_get_irq_data(r->start),
+				      r->flags & IORESOURCE_BITS);
 
 	return r ? r->start : -ENXIO;
 #endif
-- 
1.9.3

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