diff mbox series

[v2,2/5] fbdev: Replace fb_pgprotect() with fb_pgprot_device()

Message ID 20230906144801.25297-3-tzimmermann@suse.de
State New
Headers show
Series ppc, fbdev: Clean up fbdev mmap helper | expand

Commit Message

Thomas Zimmermann Sept. 6, 2023, 2:35 p.m. UTC 
Rename the fbdev mmap helper fb_pgprotect() to fb_pgprot_device().
The helper sets VMA page-access flags for framebuffers in device I/O
memory. The new name follows pgprot_device(), which does the same for
arbitrary devices.

Also clean up the helper's parameters and return value. Instead of
the VMA instance, pass the individial parameters separately: existing
page-access flags, the VMAs start and end addresses and the offset
in the underlying device memory rsp file. Return the new page-access
flags. These changes align fb_pgprot_device() closer with pgprot_device.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 arch/ia64/include/asm/fb.h           | 15 +++++++--------
 arch/m68k/include/asm/fb.h           | 19 ++++++++++---------
 arch/mips/include/asm/fb.h           | 11 +++++------
 arch/powerpc/include/asm/fb.h        | 13 +++++--------
 arch/sparc/include/asm/fb.h          | 15 +++++++++------
 arch/x86/include/asm/fb.h            | 10 ++++++----
 arch/x86/video/fbdev.c               | 15 ++++++++-------
 drivers/video/fbdev/core/fb_chrdev.c |  3 ++-
 include/asm-generic/fb.h             | 12 ++++++------
 9 files changed, 58 insertions(+), 55 deletions(-)

Comments

Arnd Bergmann Sept. 6, 2023, 7:53 p.m. UTC | #1 
On Wed, Sep 6, 2023, at 10:35, Thomas Zimmermann wrote:
> Rename the fbdev mmap helper fb_pgprotect() to fb_pgprot_device().
> The helper sets VMA page-access flags for framebuffers in device I/O
> memory. The new name follows pgprot_device(), which does the same for
> arbitrary devices.
>
> Also clean up the helper's parameters and return value. Instead of
> the VMA instance, pass the individial parameters separately: existing
> page-access flags, the VMAs start and end addresses and the offset
> in the underlying device memory rsp file. Return the new page-access
> flags. These changes align fb_pgprot_device() closer with pgprot_device.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

This makes sense as a cleanup, but I'm not sure the new naming is helpful.

The 'pgprot_device' permissions are based on Arm's memory attributes,
which have slightly different behavior for "device", "uncached" and
"writecombine" mappings. I think simply calling this one pgprot_fb()
or fb_pgprot() would be less confusing, since depending on the architecture
it appears to give either uncached or writecombine mappings but not
"device" on the architectures where this is different.

      Arnd
Thomas Zimmermann Sept. 7, 2023, 6:49 a.m. UTC | #2 
Hi Arnd

Am 06.09.23 um 21:53 schrieb Arnd Bergmann:
> On Wed, Sep 6, 2023, at 10:35, Thomas Zimmermann wrote:
>> Rename the fbdev mmap helper fb_pgprotect() to fb_pgprot_device().
>> The helper sets VMA page-access flags for framebuffers in device I/O
>> memory. The new name follows pgprot_device(), which does the same for
>> arbitrary devices.
>>
>> Also clean up the helper's parameters and return value. Instead of
>> the VMA instance, pass the individial parameters separately: existing
>> page-access flags, the VMAs start and end addresses and the offset
>> in the underlying device memory rsp file. Return the new page-access
>> flags. These changes align fb_pgprot_device() closer with pgprot_device.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> 
> This makes sense as a cleanup, but I'm not sure the new naming is helpful.
> 
> The 'pgprot_device' permissions are based on Arm's memory attributes,
> which have slightly different behavior for "device", "uncached" and
> "writecombine" mappings. I think simply calling this one pgprot_fb()
> or fb_pgprot() would be less confusing, since depending on the architecture
> it appears to give either uncached or writecombine mappings but not
> "device" on the architectures where this is different.

I see. Thanks for the info. I like pgprot_fb() maybe 
pgprot_framebuffer(). I'll update the patchset.

One thing I've been wondering is whether I should attempt to integrate 
the helpers in <asm/fb.h> in the regular asm headers. So the pgprot code 
would go into pgtable.h, the I/O functions would go into io.h. The I/O 
functions could then be called readb_fb(), writel_fb(), memcpy_tofb() 
and so on. Would you prefer that or rather not?

Best regards
Thomas

> 
>        Arnd
diff mbox series

Patch

diff --git a/arch/ia64/include/asm/fb.h b/arch/ia64/include/asm/fb.h
index 1717b26fd423..2fbad4a9fc15 100644
--- a/arch/ia64/include/asm/fb.h
+++ b/arch/ia64/include/asm/fb.h
@@ -8,17 +8,16 @@ 
 
 #include <asm/page.h>
 
-struct file;
-
-static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
-				unsigned long off)
+static inline pgprot_t fb_pgprot_device(pgprot_t prot,
+					unsigned long vm_start, unsigned long vm_end,
+					unsigned long offset)
 {
-	if (efi_range_is_wc(vma->vm_start, vma->vm_end - vma->vm_start))
-		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
+	if (efi_range_is_wc(vm_start, vm_end - vm_start))
+		return pgprot_writecombine(prot);
 	else
-		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+		return pgprot_noncached(prot);
 }
-#define fb_pgprotect fb_pgprotect
+#define fb_pgprot_device fb_pgprot_device
 
 static inline void fb_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
 {
diff --git a/arch/m68k/include/asm/fb.h b/arch/m68k/include/asm/fb.h
index 24273fc7ad91..4acdf5b62871 100644
--- a/arch/m68k/include/asm/fb.h
+++ b/arch/m68k/include/asm/fb.h
@@ -5,26 +5,27 @@ 
 #include <asm/page.h>
 #include <asm/setup.h>
 
-struct file;
-
-static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
-				unsigned long off)
+static inline pgprot_t fb_pgprot_device(pgprot_t prot,
+					unsigned long vm_start, unsigned long vm_end,
+					unsigned long offset)
 {
 #ifdef CONFIG_MMU
 #ifdef CONFIG_SUN3
-	pgprot_val(vma->vm_page_prot) |= SUN3_PAGE_NOCACHE;
+	pgprot_val(prot) |= SUN3_PAGE_NOCACHE;
 #else
 	if (CPU_IS_020_OR_030)
-		pgprot_val(vma->vm_page_prot) |= _PAGE_NOCACHE030;
+		pgprot_val(prot) |= _PAGE_NOCACHE030;
 	if (CPU_IS_040_OR_060) {
-		pgprot_val(vma->vm_page_prot) &= _CACHEMASK040;
+		pgprot_val(prot) &= _CACHEMASK040;
 		/* Use no-cache mode, serialized */
-		pgprot_val(vma->vm_page_prot) |= _PAGE_NOCACHE_S;
+		pgprot_val(prot) |= _PAGE_NOCACHE_S;
 	}
 #endif /* CONFIG_SUN3 */
 #endif /* CONFIG_MMU */
+
+	return prot;
 }
-#define fb_pgprotect fb_pgprotect
+#define fb_pgprot_device fb_pgprot_device
 
 #include <asm-generic/fb.h>
 
diff --git a/arch/mips/include/asm/fb.h b/arch/mips/include/asm/fb.h
index 18b7226403ba..98e63d14a71f 100644
--- a/arch/mips/include/asm/fb.h
+++ b/arch/mips/include/asm/fb.h
@@ -3,14 +3,13 @@ 
 
 #include <asm/page.h>
 
-struct file;
-
-static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
-				unsigned long off)
+static inline pgprot_t fb_pgprot_device(pgprot_t prot,
+					unsigned long vm_start, unsigned long vm_end,
+					unsigned long offset)
 {
-	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	return pgprot_noncached(prot);
 }
-#define fb_pgprotect fb_pgprotect
+#define fb_pgprot_device fb_pgprot_device
 
 /*
  * MIPS doesn't define __raw_ I/O macros, so the helpers
diff --git a/arch/powerpc/include/asm/fb.h b/arch/powerpc/include/asm/fb.h
index 61e3b8806db6..3c7486323178 100644
--- a/arch/powerpc/include/asm/fb.h
+++ b/arch/powerpc/include/asm/fb.h
@@ -2,23 +2,20 @@ 
 #ifndef _ASM_FB_H_
 #define _ASM_FB_H_
 
-#include <linux/fs.h>
-
 #include <asm/page.h>
 
-static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
-				unsigned long off)
+static inline pgprot_t fb_pgprot_device(pgprot_t prot,
+					unsigned long vm_start, unsigned long vm_end,
+					unsigned long offset)
 {
 	/*
 	 * PowerPC's implementation of phys_mem_access_prot() does
 	 * not use the file argument. Set it to NULL in preparation
 	 * of later updates to the interface.
 	 */
-	vma->vm_page_prot = phys_mem_access_prot(NULL, PHYS_PFN(off),
-						 vma->vm_end - vma->vm_start,
-						 vma->vm_page_prot);
+	return phys_mem_access_prot(NULL, PHYS_PFN(offset), vm_end - vm_start, prot);
 }
-#define fb_pgprotect fb_pgprotect
+#define fb_pgprot_device fb_pgprot_device
 
 #include <asm-generic/fb.h>
 
diff --git a/arch/sparc/include/asm/fb.h b/arch/sparc/include/asm/fb.h
index 572ecd3e1cc4..dc0fa30d11f3 100644
--- a/arch/sparc/include/asm/fb.h
+++ b/arch/sparc/include/asm/fb.h
@@ -4,15 +4,18 @@ 
 
 #include <linux/io.h>
 
+#include <asm/page.h>
+
 struct fb_info;
-struct file;
-struct vm_area_struct;
 
 #ifdef CONFIG_SPARC32
-static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
-				unsigned long off)
-{ }
-#define fb_pgprotect fb_pgprotect
+static inline pgprot_t fb_pgprot_device(pgprot_t prot,
+					unsigned long vm_start, unsigned long vm_end,
+					unsigned long offset)
+{
+	return prot;
+}
+#define fb_pgprot_device fb_pgprot_device
 #endif
 
 int fb_is_primary_device(struct fb_info *info);
diff --git a/arch/x86/include/asm/fb.h b/arch/x86/include/asm/fb.h
index 23873da8fb77..511aedb23d66 100644
--- a/arch/x86/include/asm/fb.h
+++ b/arch/x86/include/asm/fb.h
@@ -2,12 +2,14 @@ 
 #ifndef _ASM_X86_FB_H
 #define _ASM_X86_FB_H
 
+#include <asm/page.h>
+
 struct fb_info;
-struct file;
-struct vm_area_struct;
 
-void fb_pgprotect(struct file *file, struct vm_area_struct *vma, unsigned long off);
-#define fb_pgprotect fb_pgprotect
+pgprot_t fb_pgprot_device(pgprot_t prot,
+			  unsigned long vm_start, unsigned long vm_end,
+			  unsigned long offset);
+#define fb_pgprot_device fb_pgprot_device
 
 int fb_is_primary_device(struct fb_info *info);
 #define fb_is_primary_device fb_is_primary_device
diff --git a/arch/x86/video/fbdev.c b/arch/x86/video/fbdev.c
index 49a0452402e9..c7f247d91386 100644
--- a/arch/x86/video/fbdev.c
+++ b/arch/x86/video/fbdev.c
@@ -13,16 +13,17 @@ 
 #include <linux/vgaarb.h>
 #include <asm/fb.h>
 
-void fb_pgprotect(struct file *file, struct vm_area_struct *vma, unsigned long off)
+pgprot_t fb_pgprot_device(pgprot_t prot,
+			  unsigned long vm_start, unsigned long vm_end,
+			  unsigned long offset)
 {
-	unsigned long prot;
-
-	prot = pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK;
+	pgprot_val(prot) &= ~_PAGE_CACHE_MASK;
 	if (boot_cpu_data.x86 > 3)
-		pgprot_val(vma->vm_page_prot) =
-			prot | cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS);
+		pgprot_val(prot) |= cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS);
+
+	return prot;
 }
-EXPORT_SYMBOL(fb_pgprotect);
+EXPORT_SYMBOL(fb_pgprot_device);
 
 int fb_is_primary_device(struct fb_info *info)
 {
diff --git a/drivers/video/fbdev/core/fb_chrdev.c b/drivers/video/fbdev/core/fb_chrdev.c
index eadb81f53a82..100a92b2c3b7 100644
--- a/drivers/video/fbdev/core/fb_chrdev.c
+++ b/drivers/video/fbdev/core/fb_chrdev.c
@@ -365,7 +365,8 @@  static int fb_mmap(struct file *file, struct vm_area_struct *vma)
 	mutex_unlock(&info->mm_lock);
 
 	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
-	fb_pgprotect(file, vma, start);
+	vma->vm_page_prot = fb_pgprot_device(vma->vm_page_prot, vma->vm_start,
+					     vma->vm_end, start);
 
 	return vm_iomap_memory(vma, start, len);
 }
diff --git a/include/asm-generic/fb.h b/include/asm-generic/fb.h
index bb7ee9c70e60..876e1bef7859 100644
--- a/include/asm-generic/fb.h
+++ b/include/asm-generic/fb.h
@@ -12,14 +12,14 @@ 
 #include <linux/pgtable.h>
 
 struct fb_info;
-struct file;
 
-#ifndef fb_pgprotect
-#define fb_pgprotect fb_pgprotect
-static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
-				unsigned long off)
+#ifndef fb_pgprot_device
+#define fb_pgprot_device fb_pgprot_device
+static inline pgprot_t fb_pgprot_device(pgprot_t prot,
+					unsigned long vm_start, unsigned long vm_end,
+					unsigned long offset)
 {
-	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
+	return pgprot_writecombine(prot);
 }
 #endif