openrisc: mm: convert to GENERIC_IOREMAP

By taking GENERIC_IOREMAP method, the generic generic_ioremap_prot(),
generic_iounmap(), and their generic wrapper ioremap_prot(), ioremap() and
iounmap() are all visible and available to arch. Arch needs to provide
wrapper functions to override the generic versions if there's arch
specific handling in its ioremap_prot(), ioremap() or iounmap(). This
change will simplify implementation by removing duplicated code with
generic_ioremap_prot() and generic_iounmap(), and has the equivalent
functioality as before.

For openrisc, the current ioremap() and iounmap() are the same as generic
version. After taking GENERIC_IOREMAP way, the old ioremap() and
iounmap() can be completely removed.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Baoquan He <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Mike Rapoport (IBM) <[e-mail]>
Cc: Stafford Horne <[e-mail]>
Cc: Jonas Bonn <[e-mail]>
Cc: Stefan Kristiansson <[e-mail]>
Cc: Alexander Gordeev <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Brian Cain <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Christian Borntraeger <[e-mail]>
Cc: Christophe Leroy <[e-mail]>
Cc: Chris Zankel <[e-mail]>
Cc: David Laight <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Cc: Gerald Schaefer <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Helge Deller <[e-mail]>
Cc: "James E.J. Bottomley" <[e-mail]>
Cc: John Paul Adrian Glaubitz <[e-mail]>
Cc: Kefeng Wang <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Max Filippov <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Nathan Chancellor <[e-mail]>
Cc: Nicholas Piggin <[e-mail]>
Cc: Niklas Schnelle <[e-mail]>
Cc: Rich Felker <[e-mail]>
Cc: Sven Schnelle <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Cc: Vineet Gupta <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Yoshinori Sato <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

arch/openrisc/Kconfig

···
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_PCI_IOMAP
+	select GENERIC_IOREMAP
 	select GENERIC_CPU_DEVICES
 	select HAVE_PCI
 	select HAVE_UID16

arch/openrisc/include/asm/io.h

···
 #define __ASM_OPENRISC_IO_H
 
 #include <linux/types.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
 
 /*
  * PCI: We do not use IO ports in OpenRISC
···
 #define PIO_OFFSET		0
 #define PIO_MASK		0
 
-#define ioremap ioremap
-void __iomem *ioremap(phys_addr_t offset, unsigned long size);
-
-#define iounmap iounmap
-extern void iounmap(volatile void __iomem *addr);
+/*
+ * I/O memory mapping functions.
+ */
+#define _PAGE_IOREMAP (pgprot_val(PAGE_KERNEL) | _PAGE_CI)
 
 #include <asm-generic/io.h>
 

arch/openrisc/mm/ioremap.c

···
 
 extern int mem_init_done;
 
-/*
- * Remap an arbitrary physical address space into the kernel virtual
- * address space. Needed when the kernel wants to access high addresses
- * directly.
- *
- * NOTE! We need to allow non-page-aligned mappings too: we will obviously
- * have to convert them into an offset in a page-aligned mapping, but the
- * caller shouldn't need to know that small detail.
- */
-void __iomem *__ref ioremap(phys_addr_t addr, unsigned long size)
-{
-	phys_addr_t p;
-	unsigned long v;
-	unsigned long offset, last_addr;
-	struct vm_struct *area = NULL;
-
-	/* Don't allow wraparound or zero size */
-	last_addr = addr + size - 1;
-	if (!size || last_addr < addr)
-		return NULL;
-
-	/*
-	 * Mappings have to be page-aligned
-	 */
-	offset = addr & ~PAGE_MASK;
-	p = addr & PAGE_MASK;
-	size = PAGE_ALIGN(last_addr + 1) - p;
-
-	area = get_vm_area(size, VM_IOREMAP);
-	if (!area)
-		return NULL;
-	v = (unsigned long)area->addr;
-
-	if (ioremap_page_range(v, v + size, p,
-			__pgprot(pgprot_val(PAGE_KERNEL) | _PAGE_CI))) {
-		vfree(area->addr);
-		return NULL;
-	}
-
-	return (void __iomem *)(offset + (char *)v);
-}
-EXPORT_SYMBOL(ioremap);
-
-void iounmap(volatile void __iomem *addr)
-{
-	return vfree((void *)(PAGE_MASK & (unsigned long)addr));
-}
-EXPORT_SYMBOL(iounmap);
-
 /**
  * OK, this one's a bit tricky... ioremap can get called before memory is
  * initialized (early serial console does this) and will want to alloc a page