Patchwork [RFC] powerpc: add ioremap_wt

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Submitter Michael Moese
Date Feb. 3, 2014, 7:16 a.m.
Message ID <1391411809-1845-1-git-send-email-michael.moese@men.de>
Download mbox | patch
Permalink /patch/316071/
State New
Headers show

Comments

Michael Moese - Feb. 3, 2014, 7:16 a.m.
Allow for IO memory to be mapped cacheable for performing
PCI read bursts.

Signed-off-by: Michael Moese <michael.moese@men.de>
---
 arch/powerpc/include/asm/io.h | 3 +++
 arch/powerpc/mm/pgtable_32.c  | 8 ++++++++
 2 files changed, 11 insertions(+)
Gabriel Paubert - Feb. 3, 2014, 8:32 a.m.
On Mon, Feb 03, 2014 at 08:16:49AM +0100, Michael Moese wrote:
> Allow for IO memory to be mapped cacheable for performing
> PCI read bursts.
> 
> Signed-off-by: Michael Moese <michael.moese@men.de>
> ---
>  arch/powerpc/include/asm/io.h | 3 +++
>  arch/powerpc/mm/pgtable_32.c  | 8 ++++++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
> index 45698d5..9591fff 100644
> --- a/arch/powerpc/include/asm/io.h
> +++ b/arch/powerpc/include/asm/io.h
> @@ -631,6 +631,8 @@ static inline void iosync(void)
>   *
>   * * ioremap_wc enables write combining
>   *
> + * * ioremap_wc enables write thru

Typo: _wc -> _wt

Looks fine in principle, but there is a significant difference with wc
on x86, where read accesses always go to the bus (no read caching).

	Gabriel

> + *
>   * * iounmap undoes such a mapping and can be hooked
>   *
>   * * __ioremap_at (and the pending __iounmap_at) are low level functions to
> @@ -652,6 +654,7 @@ extern void __iomem *ioremap(phys_addr_t address, unsigned long size);
>  extern void __iomem *ioremap_prot(phys_addr_t address, unsigned long size,
>  				  unsigned long flags);
>  extern void __iomem *ioremap_wc(phys_addr_t address, unsigned long size);
> +extern void __iomem *ioremap_wt(phys_addr_t address, unsigned long size);
>  #define ioremap_nocache(addr, size)	ioremap((addr), (size))
>  
>  extern void iounmap(volatile void __iomem *addr);
> diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
> index 51f8795..9ab0a54 100644
> --- a/arch/powerpc/mm/pgtable_32.c
> +++ b/arch/powerpc/mm/pgtable_32.c
> @@ -141,6 +141,14 @@ ioremap_wc(phys_addr_t addr, unsigned long size)
>  EXPORT_SYMBOL(ioremap_wc);
>  
>  void __iomem *
> +ioremap_wt(phys_addr_t addr, unsigned long size)
> +{
> +	return __ioremap_caller(addr, size, _PAGE_WRITETHRU,
> +				__builtin_return_address(0));
> +}
> +EXPORT_SYMBOL(ioremap_wt);
> +
> +void __iomem *
>  ioremap_prot(phys_addr_t addr, unsigned long size, unsigned long flags)
>  {
>  	/* writeable implies dirty for kernel addresses */
> -- 
> 1.8.5.3
> 
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

Patch

diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
index 45698d5..9591fff 100644
--- a/arch/powerpc/include/asm/io.h
+++ b/arch/powerpc/include/asm/io.h
@@ -631,6 +631,8 @@  static inline void iosync(void)
  *
  * * ioremap_wc enables write combining
  *
+ * * ioremap_wc enables write thru
+ *
  * * iounmap undoes such a mapping and can be hooked
  *
  * * __ioremap_at (and the pending __iounmap_at) are low level functions to
@@ -652,6 +654,7 @@  extern void __iomem *ioremap(phys_addr_t address, unsigned long size);
 extern void __iomem *ioremap_prot(phys_addr_t address, unsigned long size,
 				  unsigned long flags);
 extern void __iomem *ioremap_wc(phys_addr_t address, unsigned long size);
+extern void __iomem *ioremap_wt(phys_addr_t address, unsigned long size);
 #define ioremap_nocache(addr, size)	ioremap((addr), (size))
 
 extern void iounmap(volatile void __iomem *addr);
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 51f8795..9ab0a54 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -141,6 +141,14 @@  ioremap_wc(phys_addr_t addr, unsigned long size)
 EXPORT_SYMBOL(ioremap_wc);
 
 void __iomem *
+ioremap_wt(phys_addr_t addr, unsigned long size)
+{
+	return __ioremap_caller(addr, size, _PAGE_WRITETHRU,
+				__builtin_return_address(0));
+}
+EXPORT_SYMBOL(ioremap_wt);
+
+void __iomem *
 ioremap_prot(phys_addr_t addr, unsigned long size, unsigned long flags)
 {
 	/* writeable implies dirty for kernel addresses */