linux-kernel - Re: [PATCH 1/3] lib: add NO_GENERIC_PCI_IOPORT

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Date:	Tue, 31 Jan 2012 02:22:05 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Kevin Cernekee <cernekee@...il.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Paul Mundt <lethal@...ux-sh.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Myron Stowe <myron.stowe@...hat.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Lucas De Marchi <lucas.demarchi@...fusion.mobi>,
	Dmitry Kasatkin <dmitry.kasatkin@...el.com>,
	James Morris <jmorris@...ei.org>,
	"John W. Linville" <linville@...driver.com>,
	Michael Witten <mfwitten@...il.com>, linux-mips@...ux-mips.org,
	linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH 1/3] lib: add NO_GENERIC_PCI_IOPORT_MAP

On Mon, Jan 30, 2012 at 08:04:32PM +0000, Arnd Bergmann wrote:
> On Monday 30 January 2012, Michael S. Tsirkin wrote:
> > > 
> > > +/*
> > > + * Create a virtual mapping cookie for a port on a given PCI device.
> > > + * Do not call this directly, it exists to make it easier for architectures
> > > + * to override.
> > > + */
> > > +#ifdef CONFIG_NO_GENERIC_PCI_IOPORT_MAP
> > > +extern void __iomem *__pci_ioport_map(struct pci_dev *dev, unsigned long port,
> > > +                                     unsigned int nr);
> > > +#else
> > > +static inline void __iomem *__pci_ioport_map(struct pci_dev *dev,
> > > +                              unsigned long port, unsigned int nr)
> > > +{
> > > +       return ioport_map(port, nr);
> > > +}
> > > +#endif
> > > 
> > >       Arnd
> > 
> > It would be nicer in that it would
> > make the kernel a bit smaller for generic architectures
> > but this would need to go into a separate header:
> > it depends on io.h and io.h depends on pci_iomap.h.
> 
> Adding extra dependencies is not good here, I agree.
> Maybe  a better solution is to use a macro instead of an inline
> function then:
> 
> #define  __pci_ioport_map(dev, port, nr) ioport_map(port, nr)
> 
> In general, macros should be avoided, but I think it's the
> best tradeoff in this case.
> 
> 	Arnd

I have an idea: we can make the generic one inline
if we keep it in the .c file. So something like
the below on top of my patch will probably work.
Ack?

diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h
index 2aff58e..2ec1bdb 100644
--- a/include/asm-generic/pci_iomap.h
+++ b/include/asm-generic/pci_iomap.h
@@ -15,11 +15,6 @@ struct pci_dev;
 #ifdef CONFIG_PCI
 /* Create a virtual mapping cookie for a PCI BAR (memory or IO) */
 extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max);
-/* Create a virtual mapping cookie for a port on a given PCI device.
- * Do not call this directly, it exists to make it easier for architectures
- * to override. */
-extern void __iomem *__pci_ioport_map(struct pci_dev *dev, unsigned long port,
-				      unsigned int nr);
 #else
 static inline void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max)
 {
@@ -27,4 +22,12 @@ static inline void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned lon
 }
 #endif
 
+#ifdef CONFIG_NO_GENERIC_PCI_IOPORT_MAP
+/* Create a virtual mapping cookie for a port on a given PCI device.
+ * Do not call this directly, it exists to make it easier for architectures
+ * to override. */
+extern void __iomem *__pci_ioport_map(struct pci_dev *dev, unsigned long port,
+				      unsigned int nr);
+#endif
+
 #endif /* __ASM_GENERIC_IO_H */
diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c
index 1dfda29..8102f28 100644
--- a/lib/pci_iomap.c
+++ b/lib/pci_iomap.c
@@ -12,9 +12,9 @@
 #ifndef CONFIG_NO_GENERIC_PCI_IOPORT_MAP
 /* Architectures can override ioport mapping while
  * still using the rest of the generic infrastructure. */
-void __iomem *__pci_ioport_map(struct pci_dev *dev,
-			       unsigned long port,
-			       unsigned int nr)
+static inline void __iomem *__pci_ioport_map(struct pci_dev *dev,
+					     unsigned long port,
+					     unsigned int nr)
 {
 	return ioport_map(port, nr);
 }
--
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