diff mbox

[v11,6/12] x86, mm, asm-gen: Add ioremap_wt() for WT

Message ID 1432940350-1802-7-git-send-email-toshi.kani@hp.com
State Superseded
Headers show

Commit Message

Toshi Kani May 29, 2015, 10:59 p.m. UTC
From: Toshi Kani <toshi.kani@hp.com>

This patch adds ioremap_wt() for creating WT mapping on x86.
It follows the same model as ioremap_wc() for multi-architecture
support.  ARCH_HAS_IOREMAP_WT is defined in the x86 version of
io.h to indicate that ioremap_wt() is implemented on x86.

Also update the PAT documentation file to cover ioremap_wt().

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---
 Documentation/x86/pat.txt   |    4 +++-
 arch/x86/include/asm/io.h   |    2 ++
 arch/x86/mm/ioremap.c       |   21 +++++++++++++++++++++
 include/asm-generic/io.h    |    9 +++++++++
 include/asm-generic/iomap.h |    4 ++++
 5 files changed, 39 insertions(+), 1 deletion(-)

Comments

Geert Uytterhoeven May 30, 2015, 9:18 a.m. UTC | #1
On Sat, May 30, 2015 at 12:59 AM, Toshi Kani <toshi.kani@hp.com> wrote:
> --- a/include/asm-generic/io.h
> +++ b/include/asm-generic/io.h
> @@ -785,8 +785,17 @@ static inline void __iomem *ioremap_wc(phys_addr_t offset, size_t size)
>  }
>  #endif
>
> +#ifndef ioremap_wt
> +#define ioremap_wt ioremap_wt
> +static inline void __iomem *ioremap_wt(phys_addr_t offset, size_t size)
> +{
> +       return ioremap_nocache(offset, size);
> +}
> +#endif
> +
>  #ifndef iounmap
>  #define iounmap iounmap
> +
>  static inline void iounmap(void __iomem *addr)
>  {
>  }
> diff --git a/include/asm-generic/iomap.h b/include/asm-generic/iomap.h
> index 1b41011..d8f8622 100644
> --- a/include/asm-generic/iomap.h
> +++ b/include/asm-generic/iomap.h
> @@ -66,6 +66,10 @@ extern void ioport_unmap(void __iomem *);
>  #define ioremap_wc ioremap_nocache
>  #endif
>
> +#ifndef ARCH_HAS_IOREMAP_WT
> +#define ioremap_wt ioremap_nocache
> +#endif

Defining ioremap_wt in two different places in asm-generic looks fishy to me.

If <asm/io.h> already provides it (either through asm-generic/io.h or
arch/<arch>/include/asm/io.h), why does asm-generic/iomap.h need to define
its own version?

I see this pattern already exists for ioremap_wc...

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
Toshi Kani May 31, 2015, 12:58 a.m. UTC | #2
On Sat, 2015-05-30 at 11:18 +0200, Geert Uytterhoeven wrote:
> On Sat, May 30, 2015 at 12:59 AM, Toshi Kani <toshi.kani@hp.com> wrote:
> > --- a/include/asm-generic/io.h
> > +++ b/include/asm-generic/io.h
> > @@ -785,8 +785,17 @@ static inline void __iomem *ioremap_wc(phys_addr_t offset, size_t size)
> >  }
> >  #endif
> >
> > +#ifndef ioremap_wt
> > +#define ioremap_wt ioremap_wt
> > +static inline void __iomem *ioremap_wt(phys_addr_t offset, size_t size)
> > +{
> > +       return ioremap_nocache(offset, size);
> > +}
> > +#endif
> > +
> >  #ifndef iounmap
> >  #define iounmap iounmap
> > +
> >  static inline void iounmap(void __iomem *addr)
> >  {
> >  }
> > diff --git a/include/asm-generic/iomap.h b/include/asm-generic/iomap.h
> > index 1b41011..d8f8622 100644
> > --- a/include/asm-generic/iomap.h
> > +++ b/include/asm-generic/iomap.h
> > @@ -66,6 +66,10 @@ extern void ioport_unmap(void __iomem *);
> >  #define ioremap_wc ioremap_nocache
> >  #endif
> >
> > +#ifndef ARCH_HAS_IOREMAP_WT
> > +#define ioremap_wt ioremap_nocache
> > +#endif
> 
> Defining ioremap_wt in two different places in asm-generic looks fishy to me.
> 
> If <asm/io.h> already provides it (either through asm-generic/io.h or
> arch/<arch>/include/asm/io.h), why does asm-generic/iomap.h need to define
> its own version?
> 
> I see this pattern already exists for ioremap_wc...

Yes, this patchset follows the model of ioremap_wc.  This duplication
was introduced by 9216efafc52 "asm-generic/io.h: Reconcile I/O accessor
overrides", while the original ioremap_wc support changed
asm-generic/iomap.h (1526a756fba).  As described in patch 07, some
architectures define ioremap_xxx() locally as well.

It is too risky to do everything in one short.  I will look into the
duplication issue as a separate item after this patchset is settled.

Thanks,
-Toshi
diff mbox

Patch

diff --git a/Documentation/x86/pat.txt b/Documentation/x86/pat.txt
index 521bd8a..db0de6c 100644
--- a/Documentation/x86/pat.txt
+++ b/Documentation/x86/pat.txt
@@ -12,7 +12,7 @@  virtual addresses.
 
 PAT allows for different types of memory attributes. The most commonly used
 ones that will be supported at this time are Write-back, Uncached,
-Write-combined and Uncached Minus.
+Write-combined, Write-through and Uncached Minus.
 
 
 PAT APIs
@@ -40,6 +40,8 @@  ioremap_nocache        |    --    |    UC-     |       UC-        |
                        |          |            |                  |
 ioremap_wc             |    --    |    --      |       WC         |
                        |          |            |                  |
+ioremap_wt             |    --    |    --      |       WT         |
+                       |          |            |                  |
 set_memory_uc          |    UC-   |    --      |       --         |
  set_memory_wb         |          |            |                  |
                        |          |            |                  |
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index a2b9740..6c3a130 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -35,6 +35,7 @@ 
   */
 
 #define ARCH_HAS_IOREMAP_WC
+#define ARCH_HAS_IOREMAP_WT
 
 #include <linux/string.h>
 #include <linux/compiler.h>
@@ -321,6 +322,7 @@  extern void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr);
 extern int ioremap_change_attr(unsigned long vaddr, unsigned long size,
 				enum page_cache_mode pcm);
 extern void __iomem *ioremap_wc(resource_size_t offset, unsigned long size);
+extern void __iomem *ioremap_wt(resource_size_t offset, unsigned long size);
 
 extern bool is_early_ioremap_ptep(pte_t *ptep);
 
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 078c270..779b1a2 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -172,6 +172,10 @@  static void __iomem *__ioremap_caller(resource_size_t phys_addr,
 		prot = __pgprot(pgprot_val(prot) |
 				cachemode2protval(_PAGE_CACHE_MODE_WC));
 		break;
+	case _PAGE_CACHE_MODE_WT:
+		prot = __pgprot(pgprot_val(prot) |
+				cachemode2protval(_PAGE_CACHE_MODE_WT));
+		break;
 	case _PAGE_CACHE_MODE_WB:
 		break;
 	}
@@ -297,6 +301,23 @@  void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size)
 }
 EXPORT_SYMBOL(ioremap_wc);
 
+/**
+ * ioremap_wt	-	map memory into CPU space write through
+ * @phys_addr:	bus address of the memory
+ * @size:	size of the resource to map
+ *
+ * This version of ioremap ensures that the memory is marked write through.
+ * Write through stores data into memory while keeping the cache up-to-date.
+ *
+ * Must be freed with iounmap.
+ */
+void __iomem *ioremap_wt(resource_size_t phys_addr, unsigned long size)
+{
+	return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WT,
+					__builtin_return_address(0));
+}
+EXPORT_SYMBOL(ioremap_wt);
+
 void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size)
 {
 	return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB,
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 90ccba7..f56094c 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -785,8 +785,17 @@  static inline void __iomem *ioremap_wc(phys_addr_t offset, size_t size)
 }
 #endif
 
+#ifndef ioremap_wt
+#define ioremap_wt ioremap_wt
+static inline void __iomem *ioremap_wt(phys_addr_t offset, size_t size)
+{
+	return ioremap_nocache(offset, size);
+}
+#endif
+
 #ifndef iounmap
 #define iounmap iounmap
+
 static inline void iounmap(void __iomem *addr)
 {
 }
diff --git a/include/asm-generic/iomap.h b/include/asm-generic/iomap.h
index 1b41011..d8f8622 100644
--- a/include/asm-generic/iomap.h
+++ b/include/asm-generic/iomap.h
@@ -66,6 +66,10 @@  extern void ioport_unmap(void __iomem *);
 #define ioremap_wc ioremap_nocache
 #endif
 
+#ifndef ARCH_HAS_IOREMAP_WT
+#define ioremap_wt ioremap_nocache
+#endif
+
 #ifdef CONFIG_PCI
 /* Destroy a virtual mapping cookie for a PCI BAR (memory or IO) */
 struct pci_dev;