linux-kernel - [PATCH] driver core: platform: Add an error message to platform_get

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Message-Id: <20181222072452.186726-1-swboyd@chromium.org>
Date:   Fri, 21 Dec 2018 23:24:52 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     robh@...nel.org
Cc:     a.hajda@...sung.com, andy.shevchenko@...il.com,
        b.zolnierkie@...sung.com, broonie@...nel.org,
        gregkh@...uxfoundation.org, javierm@...hat.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux@...linux.org.uk, m.szyprowski@...sung.com, rafael@...nel.org
Subject: [PATCH] driver core: platform: Add an error message to platform_get_irq*()

A grep of the kernel shows that many drivers print an error message if
they fail to get the irq they're looking for. Furthermore, those drivers
all decide to print the device name, or not, and the irq they were
requesting, or not, etc. Let's consolidate all these error messages into
the API itself, allowing us to get rid of the error messages in each
driver.

Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---

Rob Herring wrote:
> Shouldn't platform_get_irq (or what it calls) print the error message
> (like we do for kmalloc), rather than every driver? We could get rid
> of lots of error strings that way. I guess there are cases where no
> irq is not an error and we wouldn't want to always print an error. In
> some cases like that, we have 2 versions of the function.

Yes it should. Just by coincidence, I got around to implementing this
patch yesterday after I bemoaned this on the list a few months ago[1].

> Not what you're addressing here exactly, but what I'd like to see is
> the ability to print the exact locations generating errors in the
> first place. That would require wrapping all the error code
> assignments and returns (or at least the common sources). 

That could be done with some macro magic to add __line__ and __FILE__
into a definition of the "important" functions. In that sense nothing
would really need to change besides the implementation, right?

I also started working on a cocci script to fix up the call sites to
drop the extra prints, but I'm really bad at writing semantic patches so
please help improve the below. My simple grep shows that we can remove
~500 error prints out of the 1500 places the platform_get_irq()
functions are called.

	@@
	expression ret;
	struct platform_device *E;
	@@

	ret =
	(
	platform_get_irq(E, ...)
	|
	platform_get_irq_byname(E, ...)
	);

	if ( \( ret < 0 \| ret <= 0 \) )
	{
	(
	-if (ret != -EPROBE_DEFER)
	-{ ...
	-dev_err(...);
	-... }
	|
	...
	-dev_err(...);
	)
	...
	}

[1] https://lkml.kernel.org/r/153911433511.119890.17831207059115471972@swboyd.mtv.corp.google.com

 drivers/base/platform.c | 52 +++++++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 17 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 1c958eb33ef4..75ceda9f452a 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -79,23 +79,18 @@ struct resource *platform_get_resource(struct platform_device *dev,
 }
 EXPORT_SYMBOL_GPL(platform_get_resource);
 
-/**
- * platform_get_irq - get an IRQ for a device
- * @dev: platform device
- * @num: IRQ number index
- */
-int platform_get_irq(struct platform_device *dev, unsigned int num)
+static int __platform_get_irq(struct platform_device *dev, unsigned int num, bool warn)
 {
+	int ret = -ENXIO;
+
 #ifdef CONFIG_SPARC
 	/* sparc does not have irqs represented as IORESOURCE_IRQ resources */
 	if (!dev || num >= dev->archdata.num_irqs)
-		return -ENXIO;
+		goto error;
 	return dev->archdata.irqs[num];
 #else
 	struct resource *r;
 	if (IS_ENABLED(CONFIG_OF_IRQ) && dev->dev.of_node) {
-		int ret;
-
 		ret = of_irq_get(dev->dev.of_node, num);
 		if (ret > 0 || ret == -EPROBE_DEFER)
 			return ret;
@@ -104,11 +99,11 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
 	r = platform_get_resource(dev, IORESOURCE_IRQ, num);
 	if (has_acpi_companion(&dev->dev)) {
 		if (r && r->flags & IORESOURCE_DISABLED) {
-			int ret;
-
 			ret = acpi_irq_get(ACPI_HANDLE(&dev->dev), num, r);
-			if (ret)
+			if (ret > 0 || ret == -EPROBE_DEFER)
 				return ret;
+			if (ret)
+				goto error;
 		}
 	}
 
@@ -122,13 +117,32 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
 		struct irq_data *irqd;
 
 		irqd = irq_get_irq_data(r->start);
-		if (!irqd)
-			return -ENXIO;
+		if (!irqd) {
+			ret = -ENXIO;
+			goto error;
+		}
+
 		irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
 	}
 
-	return r ? r->start : -ENXIO;
+	if (r)
+		return r->start;
 #endif
+error:
+	if (warn)
+		dev_err(&dev->dev, "IRQ%d not found\n", num);
+
+	return ret;
+}
+
+/**
+ * platform_get_irq - get an IRQ for a device
+ * @dev: platform device
+ * @num: IRQ number index
+ */
+int platform_get_irq(struct platform_device *dev, unsigned int num)
+{
+	return __platform_get_irq(dev, num, true);
 }
 EXPORT_SYMBOL_GPL(platform_get_irq);
 
@@ -142,7 +156,7 @@ int platform_irq_count(struct platform_device *dev)
 {
 	int ret, nr = 0;
 
-	while ((ret = platform_get_irq(dev, nr)) >= 0)
+	while ((ret = __platform_get_irq(dev, nr, false)) >= 0)
 		nr++;
 
 	if (ret == -EPROBE_DEFER)
@@ -195,7 +209,11 @@ int platform_get_irq_byname(struct platform_device *dev, const char *name)
 	}
 
 	r = platform_get_resource_byname(dev, IORESOURCE_IRQ, name);
-	return r ? r->start : -ENXIO;
+	if (r)
+		return r->start;
+
+	dev_err(&dev->dev, "IRQ %s not found\n", name);
+	return -ENXIO;
 }
 EXPORT_SYMBOL_GPL(platform_get_irq_byname);
 
-- 
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