fbdev: Move framebuffer I/O helpers into <asm/fb.h>

Implement framebuffer I/O helpers, such as fb_read*() and fb_write*(),
in the architecture's <asm/fb.h> header file or the generic one.

The common case has been the use of regular I/O functions, such as
__raw_readb() or memset_io(). A few architectures used plain system-
memory reads and writes. Sparc used helpers for its SBus.

The architectures that used special cases provide the same code in
their __raw_*() I/O helpers. So the patch replaces this code with the
__raw_*() functions and moves it to <asm-generic/fb.h> for all
architectures.

v8:
	* remove garbage after commit-message tags
v6:
	* fix fb_readq()/fb_writeq() on 64-bit mips (kernel test robot)
v5:
	* include <linux/io.h> in <asm-generic/fb>; fix s390 build
v4:
	* ia64, loongarch, sparc64: add fb_mem*() to arch headers
	  to keep current semantics (Arnd)
v3:
	* implement all architectures with generic helpers
	* support reordering and native byte order (Geert, Arnd)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Sui Jingfeng <suijingfeng@loongson.cn>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230512102444.5438-7-tzimmermann@suse.de

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/ia64/include/asm/fb.h b/arch/ia64/include/asm/fb.h
index 0208f64a0da0..bcf982043a5c 100644
--- a/arch/ia64/include/asm/fb.h
+++ b/arch/ia64/include/asm/fb.h
@@ -2,7 +2,9 @@
 #ifndef _ASM_FB_H_
 #define _ASM_FB_H_
 
+#include <linux/compiler.h>
 #include <linux/efi.h>
+#include <linux/string.h>
 
 #include <asm/page.h>
 
@@ -18,6 +20,24 @@ static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
 }
 #define fb_pgprotect fb_pgprotect
 
+static inline void fb_memcpy_fromfb(void *to, const volatile void __iomem *from, size_t n)
+{
+	memcpy(to, (void __force *)from, n);
+}
+#define fb_memcpy_fromfb fb_memcpy_fromfb
+
+static inline void fb_memcpy_tofb(volatile void __iomem *to, const void *from, size_t n)
+{
+	memcpy((void __force *)to, from, n);
+}
+#define fb_memcpy_tofb fb_memcpy_tofb
+
+static inline void fb_memset(volatile void __iomem *addr, int c, size_t n)
+{
+	memset((void __force *)addr, c, n);
+}
+#define fb_memset fb_memset
+
 #include <asm-generic/fb.h>
 
 #endif /* _ASM_FB_H_ */