[PATCH v3 08/16] mn10300: drop dead code

[PATCH v3 08/16] mn10300: drop dead code

[Michael S. Tsirkin]

pci-iomap.c was (apparently, mistakenly) reintroduced as part of
commit 83c2dc15ce824450e7044b9f90cd529c25747ae0
    MN10300: Handle cacheable PCI regions in pci_iomap()
probably as side-effect of forward-porting the patch
from an old kernel.

It's not really needed: the generic pci_iomap does the right thing here.

The new file isn't compiled so it's safe to drop.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Cc: trivial@kernel.org
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Can relevant people please ack this for merging through virtio tree?

 arch/mn10300/unit-asb2305/pci-iomap.c | 35 -----------------------------------
 1 file changed, 35 deletions(-)
 delete mode 100644 arch/mn10300/unit-asb2305/pci-iomap.c

diff --git a/arch/mn10300/unit-asb2305/pci-iomap.c b/arch/mn10300/unit-asb2305/pci-iomap.c
deleted file mode 100644
index bd65dae..0000000
--- a/arch/mn10300/unit-asb2305/pci-iomap.c
+++ /dev/null
@@ -1,35 +0,0 @@
-/* ASB2305 PCI I/O mapping handler
- *
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public Licence
- * as published by the Free Software Foundation; either version
- * 2 of the Licence, or (at your option) any later version.
- */
-#include <linux/pci.h>
-#include <linux/module.h>
-
-/*
- * Create a virtual mapping cookie for a PCI BAR (memory or IO)
- */
-void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
-{
-	resource_size_t start = pci_resource_start(dev, bar);
-	resource_size_t len = pci_resource_len(dev, bar);
-	unsigned long flags = pci_resource_flags(dev, bar);
-
-	if (!len || !start)
-		return NULL;
-
-	if ((flags & IORESOURCE_IO) || (flags & IORESOURCE_MEM)) {
-		if (flags & IORESOURCE_CACHEABLE && !(flags & IORESOURCE_IO))
-			return ioremap(start, len);
-		else
-			return ioremap_nocache(start, len);
-	}
-
-	return NULL;
-}
-EXPORT_SYMBOL(pci_iomap);
-- 
MST

[PATCH v3 09/16] pci: add pci_iomap_range

[Michael S. Tsirkin]

Virtio drivers should map the part of the BAR they need, not necessarily
all of it.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---

Bjorn, can you please ack this for merging through the virtio tree?

 include/asm-generic/pci_iomap.h | 10 ++++++++++
 lib/pci_iomap.c                 | 35 ++++++++++++++++++++++++++++++-----
 2 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h
index ce37349..7389c87 100644
--- a/include/asm-generic/pci_iomap.h
+++ b/include/asm-generic/pci_iomap.h
@@ -15,6 +15,9 @@ 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);
+extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar,
+				     unsigned long offset,
+				     unsigned long maxlen);
 /* 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 */
@@ -30,6 +33,13 @@ static inline void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned lon
 {
 	return NULL;
 }
+
+static inline void __iomem *pci_iomap_range(struct pci_dev *dev, int bar,
+					    unsigned long offset,
+					    unsigned long maxlen)
+{
+	return NULL;
+}
 #endif
 
 #endif /* __ASM_GENERIC_IO_H */
diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c
index 0d83ea8..bcce5f1 100644
--- a/lib/pci_iomap.c
+++ b/lib/pci_iomap.c
@@ -10,10 +10,11 @@
 
 #ifdef CONFIG_PCI
 /**
- * pci_iomap - create a virtual mapping cookie for a PCI BAR
+ * pci_iomap_range - create a virtual mapping cookie for a PCI BAR
  * @dev: PCI device that owns the BAR
  * @bar: BAR number
- * @maxlen: length of the memory to map
+ * @offset: map memory at the given offset in BAR
+ * @maxlen: max length of the memory to map
  *
  * Using this function you will get a __iomem address to your device BAR.
  * You can access it using ioread*() and iowrite*(). These functions hide
@@ -21,16 +22,21 @@
  * you expect from them in the correct way.
  *
  * @maxlen specifies the maximum length to map. If you want to get access to
- * the complete BAR without checking for its length first, pass %0 here.
+ * the complete BAR from offset to the end, pass %0 here.
  * */
-void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
+void __iomem *pci_iomap_range(struct pci_dev *dev,
+			      int bar,
+			      unsigned long offset,
+			      unsigned long maxlen)
 {
 	resource_size_t start = pci_resource_start(dev, bar);
 	resource_size_t len = pci_resource_len(dev, bar);
 	unsigned long flags = pci_resource_flags(dev, bar);
 
-	if (!len || !start)
+	if (len <= offset || !start)
 		return NULL;
+	len -= offset;
+	start += offset;
 	if (maxlen && len > maxlen)
 		len = maxlen;
 	if (flags & IORESOURCE_IO)
@@ -43,6 +49,25 @@ void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
 	/* What? */
 	return NULL;
 }
+EXPORT_SYMBOL(pci_iomap_range);
 
+/**
+ * pci_iomap - create a virtual mapping cookie for a PCI BAR
+ * @dev: PCI device that owns the BAR
+ * @bar: BAR number
+ * @maxlen: length of the memory to map
+ *
+ * Using this function you will get a __iomem address to your device BAR.
+ * You can access it using ioread*() and iowrite*(). These functions hide
+ * the details if this is a MMIO or PIO address space and will just do what
+ * you expect from them in the correct way.
+ *
+ * @maxlen specifies the maximum length to map. If you want to get access to
+ * the complete BAR without checking for its length first, pass %0 here.
+ * */
+void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
+{
+	return pci_iomap_range(dev, bar, 0, maxlen);
+}
 EXPORT_SYMBOL(pci_iomap);
 #endif /* CONFIG_PCI */
-- 
MST

[PATCH v3 10/16] s390: add pci_iomap_range

[Michael S. Tsirkin]

Virtio drivers should map the part of the range they need, not
necessarily all of it.
To this end, support mapping ranges within BAR on s390.
Since multiple ranges can now be mapped within a BAR, we keep track of
the number of mappings created, and only clear out the mapping for a BAR
when this number reaches 0.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Tested-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Heiko, Martin, can you please ack merging this through the virtio tree?
This was lightly tested by Sebastian Ott.

 arch/s390/include/asm/pci_io.h |  1 +
 arch/s390/pci/pci.c            | 34 +++++++++++++++++++++++++++-------
 2 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/arch/s390/include/asm/pci_io.h b/arch/s390/include/asm/pci_io.h
index f664e96..1a9a98d 100644
--- a/arch/s390/include/asm/pci_io.h
+++ b/arch/s390/include/asm/pci_io.h
@@ -16,6 +16,7 @@
 struct zpci_iomap_entry {
 	u32 fh;
 	u8 bar;
+	u16 count;
 };
 
 extern struct zpci_iomap_entry *zpci_iomap_start;
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 3290f11..753a567 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -259,7 +259,10 @@ void __iowrite64_copy(void __iomem *to, const void *from, size_t count)
 }
 
 /* Create a virtual mapping cookie for a PCI BAR */
-void __iomem *pci_iomap(struct pci_dev *pdev, int bar, unsigned long max)
+void __iomem *pci_iomap_range(struct pci_dev *pdev,
+			      int bar,
+			      unsigned long offset,
+			      unsigned long max)
 {
 	struct zpci_dev *zdev =	get_zdev(pdev);
 	u64 addr;
@@ -270,14 +273,27 @@ void __iomem *pci_iomap(struct pci_dev *pdev, int bar, unsigned long max)
 
 	idx = zdev->bars[bar].map_idx;
 	spin_lock(&zpci_iomap_lock);
-	zpci_iomap_start[idx].fh = zdev->fh;
-	zpci_iomap_start[idx].bar = bar;
+	if (zpci_iomap_start[idx].count++) {
+		BUG_ON(zpci_iomap_start[idx].fh != zdev->fh ||
+		       zpci_iomap_start[idx].bar != bar);
+	} else {
+		zpci_iomap_start[idx].fh = zdev->fh;
+		zpci_iomap_start[idx].bar = bar;
+	}
+	/* Detect overrun */
+	BUG_ON(!zpci_iomap_start[idx].count);
 	spin_unlock(&zpci_iomap_lock);
 
 	addr = ZPCI_IOMAP_ADDR_BASE | ((u64) idx << 48);
-	return (void __iomem *) addr;
+	return (void __iomem *) addr + offset;
 }
-EXPORT_SYMBOL_GPL(pci_iomap);
+EXPORT_SYMBOL_GPL(pci_iomap_range);
+
+void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
+{
+	return pci_iomap_range(dev, bar, 0, maxlen);
+}
+EXPORT_SYMBOL(pci_iomap);
 
 void pci_iounmap(struct pci_dev *pdev, void __iomem *addr)
 {
@@ -285,8 +301,12 @@ void pci_iounmap(struct pci_dev *pdev, void __iomem *addr)
 
 	idx = (((__force u64) addr) & ~ZPCI_IOMAP_ADDR_BASE) >> 48;
 	spin_lock(&zpci_iomap_lock);
-	zpci_iomap_start[idx].fh = 0;
-	zpci_iomap_start[idx].bar = 0;
+	/* Detect underrun */
+	BUG_ON(!zpci_iomap_start[idx].count);
+	if (!--zpci_iomap_start[idx].count) {
+		zpci_iomap_start[idx].fh = 0;
+		zpci_iomap_start[idx].bar = 0;
+	}
 	spin_unlock(&zpci_iomap_lock);
 }
 EXPORT_SYMBOL_GPL(pci_iounmap);
-- 
MST

Re: [PATCH v3 10/16] s390: add pci_iomap_range

[Sebastian Ott]

On Wed, 14 Jan 2015, Michael S. Tsirkin wrote:
> Virtio drivers should map the part of the range they need, not
> necessarily all of it.
> To this end, support mapping ranges within BAR on s390.
> Since multiple ranges can now be mapped within a BAR, we keep track of
> the number of mappings created, and only clear out the mapping for a BAR
> when this number reaches 0.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: linux-pci@vger.kernel.org
> Tested-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> 
> Heiko, Martin, can you please ack merging this through the virtio tree?
> This was lightly tested by Sebastian Ott.
> 
>  arch/s390/include/asm/pci_io.h |  1 +
>  arch/s390/pci/pci.c            | 34 +++++++++++++++++++++++++++-------
>  2 files changed, 28 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/s390/include/asm/pci_io.h b/arch/s390/include/asm/pci_io.h
> index f664e96..1a9a98d 100644
> --- a/arch/s390/include/asm/pci_io.h
> +++ b/arch/s390/include/asm/pci_io.h
> @@ -16,6 +16,7 @@
>  struct zpci_iomap_entry {
>  	u32 fh;
>  	u8 bar;
> +	u16 count;
>  };
> 
>  extern struct zpci_iomap_entry *zpci_iomap_start;
> diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
> index 3290f11..753a567 100644
> --- a/arch/s390/pci/pci.c
> +++ b/arch/s390/pci/pci.c
> @@ -259,7 +259,10 @@ void __iowrite64_copy(void __iomem *to, const void *from, size_t count)
>  }
> 
>  /* Create a virtual mapping cookie for a PCI BAR */
> -void __iomem *pci_iomap(struct pci_dev *pdev, int bar, unsigned long max)
> +void __iomem *pci_iomap_range(struct pci_dev *pdev,
> +			      int bar,
> +			      unsigned long offset,
> +			      unsigned long max)
>  {
>  	struct zpci_dev *zdev =	get_zdev(pdev);
>  	u64 addr;
> @@ -270,14 +273,27 @@ void __iomem *pci_iomap(struct pci_dev *pdev, int bar, unsigned long max)
> 
>  	idx = zdev->bars[bar].map_idx;
>  	spin_lock(&zpci_iomap_lock);
> -	zpci_iomap_start[idx].fh = zdev->fh;
> -	zpci_iomap_start[idx].bar = bar;
> +	if (zpci_iomap_start[idx].count++) {
> +		BUG_ON(zpci_iomap_start[idx].fh != zdev->fh ||
> +		       zpci_iomap_start[idx].bar != bar);
> +	} else {
> +		zpci_iomap_start[idx].fh = zdev->fh;
> +		zpci_iomap_start[idx].bar = bar;
> +	}
> +	/* Detect overrun */
> +	BUG_ON(!zpci_iomap_start[idx].count);
>  	spin_unlock(&zpci_iomap_lock);
> 
>  	addr = ZPCI_IOMAP_ADDR_BASE | ((u64) idx << 48);
> -	return (void __iomem *) addr;
> +	return (void __iomem *) addr + offset;
>  }
> -EXPORT_SYMBOL_GPL(pci_iomap);
> +EXPORT_SYMBOL_GPL(pci_iomap_range);
> +
> +void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
> +{
> +	return pci_iomap_range(dev, bar, 0, maxlen);
> +}
> +EXPORT_SYMBOL(pci_iomap);

As discussed earlier, could you please leave that as EXPORT_SYMBOL_GPL.
If there's a reason to have these interfaces as EXPORT_SYMBOL, we could
change all of them in an extra patch.

With this change integrated you can add
Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com>

Regards,
Sebastian

> 
>  void pci_iounmap(struct pci_dev *pdev, void __iomem *addr)
>  {
> @@ -285,8 +301,12 @@ void pci_iounmap(struct pci_dev *pdev, void __iomem *addr)
> 
>  	idx = (((__force u64) addr) & ~ZPCI_IOMAP_ADDR_BASE) >> 48;
>  	spin_lock(&zpci_iomap_lock);
> -	zpci_iomap_start[idx].fh = 0;
> -	zpci_iomap_start[idx].bar = 0;
> +	/* Detect underrun */
> +	BUG_ON(!zpci_iomap_start[idx].count);
> +	if (!--zpci_iomap_start[idx].count) {
> +		zpci_iomap_start[idx].fh = 0;
> +		zpci_iomap_start[idx].bar = 0;
> +	}
>  	spin_unlock(&zpci_iomap_lock);
>  }
>  EXPORT_SYMBOL_GPL(pci_iounmap);
> -- 
> MST
> 
> 

Re: [PATCH v3 10/16] s390: add pci_iomap_range

[Rusty Russell]

Sebastian Ott <sebott@linux.vnet.ibm.com> writes:
> On Wed, 14 Jan 2015, Michael S. Tsirkin wrote:
>>  }
>> -EXPORT_SYMBOL_GPL(pci_iomap);
>> +EXPORT_SYMBOL_GPL(pci_iomap_range);
>> +
>> +void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
>> +{
>> +	return pci_iomap_range(dev, bar, 0, maxlen);
>> +}
>> +EXPORT_SYMBOL(pci_iomap);
>
> As discussed earlier, could you please leave that as EXPORT_SYMBOL_GPL.
> If there's a reason to have these interfaces as EXPORT_SYMBOL, we could
> change all of them in an extra patch.
>
> With this change integrated you can add
> Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com>

OK, I've gone back and rebased virtio-next to fix this (I don't really
want to think too hard about the legal consequences of having a version
which isn't EXPORT_SYMBOL_GPL).

Thanks,
Rusty.

Re: [PATCH v3 08/16] mn10300: drop dead code

[Bjorn Helgaas]

On Wed, Jan 14, 2015 at 07:27:48PM +0200, Michael S. Tsirkin wrote:
> pci-iomap.c was (apparently, mistakenly) reintroduced as part of
> commit 83c2dc15ce824450e7044b9f90cd529c25747ae0
>     MN10300: Handle cacheable PCI regions in pci_iomap()
> probably as side-effect of forward-porting the patch
> from an old kernel.
> 
> It's not really needed: the generic pci_iomap does the right thing here.
> 
> The new file isn't compiled so it's safe to drop.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: linux-pci@vger.kernel.org
> Cc: trivial@kernel.org
> Cc: David Howells <dhowells@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
> 
> Can relevant people please ack this for merging through virtio tree?
> 
>  arch/mn10300/unit-asb2305/pci-iomap.c | 35 -----------------------------------
>  1 file changed, 35 deletions(-)
>  delete mode 100644 arch/mn10300/unit-asb2305/pci-iomap.c
> 
> diff --git a/arch/mn10300/unit-asb2305/pci-iomap.c b/arch/mn10300/unit-asb2305/pci-iomap.c
> deleted file mode 100644
> index bd65dae..0000000
> --- a/arch/mn10300/unit-asb2305/pci-iomap.c
> +++ /dev/null
> @@ -1,35 +0,0 @@
> -/* ASB2305 PCI I/O mapping handler
> - *
> - * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
> - * Written by David Howells (dhowells@redhat.com)
> - *
> - * This program is free software; you can redistribute it and/or
> - * modify it under the terms of the GNU General Public Licence
> - * as published by the Free Software Foundation; either version
> - * 2 of the Licence, or (at your option) any later version.
> - */
> -#include <linux/pci.h>
> -#include <linux/module.h>
> -
> -/*
> - * Create a virtual mapping cookie for a PCI BAR (memory or IO)
> - */
> -void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
> -{
> -	resource_size_t start = pci_resource_start(dev, bar);
> -	resource_size_t len = pci_resource_len(dev, bar);
> -	unsigned long flags = pci_resource_flags(dev, bar);
> -
> -	if (!len || !start)
> -		return NULL;
> -
> -	if ((flags & IORESOURCE_IO) || (flags & IORESOURCE_MEM)) {
> -		if (flags & IORESOURCE_CACHEABLE && !(flags & IORESOURCE_IO))
> -			return ioremap(start, len);
> -		else
> -			return ioremap_nocache(start, len);
> -	}
> -
> -	return NULL;
> -}
> -EXPORT_SYMBOL(pci_iomap);
> -- 
> MST
> 

Re: [PATCH v3 09/16] pci: add pci_iomap_range

[Bjorn Helgaas]

On Wed, Jan 14, 2015 at 07:27:54PM +0200, Michael S. Tsirkin wrote:
> Virtio drivers should map the part of the BAR they need, not necessarily
> all of it.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: linux-pci@vger.kernel.org
> Acked-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

Sorry it took so long for me to notice these!

> ---
> 
> Bjorn, can you please ack this for merging through the virtio tree?
> 
>  include/asm-generic/pci_iomap.h | 10 ++++++++++
>  lib/pci_iomap.c                 | 35 ++++++++++++++++++++++++++++++-----
>  2 files changed, 40 insertions(+), 5 deletions(-)
> 
> diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h
> index ce37349..7389c87 100644
> --- a/include/asm-generic/pci_iomap.h
> +++ b/include/asm-generic/pci_iomap.h
> @@ -15,6 +15,9 @@ 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);
> +extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar,
> +				     unsigned long offset,
> +				     unsigned long maxlen);
>  /* 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 */
> @@ -30,6 +33,13 @@ static inline void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned lon
>  {
>  	return NULL;
>  }
> +
> +static inline void __iomem *pci_iomap_range(struct pci_dev *dev, int bar,
> +					    unsigned long offset,
> +					    unsigned long maxlen)
> +{
> +	return NULL;
> +}
>  #endif
>  
>  #endif /* __ASM_GENERIC_IO_H */
> diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c
> index 0d83ea8..bcce5f1 100644
> --- a/lib/pci_iomap.c
> +++ b/lib/pci_iomap.c
> @@ -10,10 +10,11 @@
>  
>  #ifdef CONFIG_PCI
>  /**
> - * pci_iomap - create a virtual mapping cookie for a PCI BAR
> + * pci_iomap_range - create a virtual mapping cookie for a PCI BAR
>   * @dev: PCI device that owns the BAR
>   * @bar: BAR number
> - * @maxlen: length of the memory to map
> + * @offset: map memory at the given offset in BAR
> + * @maxlen: max length of the memory to map
>   *
>   * Using this function you will get a __iomem address to your device BAR.
>   * You can access it using ioread*() and iowrite*(). These functions hide
> @@ -21,16 +22,21 @@
>   * you expect from them in the correct way.
>   *
>   * @maxlen specifies the maximum length to map. If you want to get access to
> - * the complete BAR without checking for its length first, pass %0 here.
> + * the complete BAR from offset to the end, pass %0 here.
>   * */
> -void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
> +void __iomem *pci_iomap_range(struct pci_dev *dev,
> +			      int bar,
> +			      unsigned long offset,
> +			      unsigned long maxlen)
>  {
>  	resource_size_t start = pci_resource_start(dev, bar);
>  	resource_size_t len = pci_resource_len(dev, bar);
>  	unsigned long flags = pci_resource_flags(dev, bar);
>  
> -	if (!len || !start)
> +	if (len <= offset || !start)
>  		return NULL;
> +	len -= offset;
> +	start += offset;
>  	if (maxlen && len > maxlen)
>  		len = maxlen;
>  	if (flags & IORESOURCE_IO)
> @@ -43,6 +49,25 @@ void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
>  	/* What? */
>  	return NULL;
>  }
> +EXPORT_SYMBOL(pci_iomap_range);
>  
> +/**
> + * pci_iomap - create a virtual mapping cookie for a PCI BAR
> + * @dev: PCI device that owns the BAR
> + * @bar: BAR number
> + * @maxlen: length of the memory to map
> + *
> + * Using this function you will get a __iomem address to your device BAR.
> + * You can access it using ioread*() and iowrite*(). These functions hide
> + * the details if this is a MMIO or PIO address space and will just do what
> + * you expect from them in the correct way.
> + *
> + * @maxlen specifies the maximum length to map. If you want to get access to
> + * the complete BAR without checking for its length first, pass %0 here.
> + * */
> +void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
> +{
> +	return pci_iomap_range(dev, bar, 0, maxlen);
> +}
>  EXPORT_SYMBOL(pci_iomap);
>  #endif /* CONFIG_PCI */
> -- 
> MST
>