sh: Inhibit mapping PCI apertures through page tables.

Inhibit mapping through page tables in __ioremap() for PCI memory
apertures on SH7751 and SH7780-style PCI controllers, translation is
not possible for these areas. For other users that map a small window
in P1/P2 space, ioremap() traps that already, and should never make
it to __ioremap().
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/drivers/pci/pci.c

@@ -195,7 +195,7 @@ void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
 	unsigned long len = pci_resource_len(dev, bar);
 	unsigned long flags = pci_resource_flags(dev, bar);
 
-	if (!len || !start)
+	if (unlikely(!len || !start))
 		return NULL;
 	if (maxlen && len > maxlen)
 		len = maxlen;
@@ -204,18 +204,16 @@ void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
 	 * Presently the IORESOURCE_MEM case is a bit special, most
 	 * SH7751 style PCI controllers have PCI memory at a fixed
 	 * location in the address space where no remapping is desired
-	 * (traditionally at 0xfd000000). Once this changes, the
-	 * IORESOURCE_MEM case will have to switch to using ioremap() and
-	 * more care will have to be taken to inhibit page table mapping
-	 * for legacy cores.
-	 *
-	 * For now everything wraps to ioport_map(), since boards that
-	 * have PCI will be able to check the address range properly on
-	 * their own.
-	 *			-- PFM.
+	 * (typically at 0xfd000000, but is_pci_memaddr() will know
+	 * best). With the IORESOURCE_MEM case more care has to be taken
+	 * to inhibit page table mapping for legacy cores, but this is
+	 * punted off to __ioremap().
+	 *					-- PFM.
 	 */
-	if (flags & (IORESOURCE_IO | IORESOURCE_MEM))
+	if (flags & IORESOURCE_IO)
 		return ioport_map(start, len);
+	if (flags & IORESOURCE_MEM)
+		return ioremap(start, len);
 
 	return NULL;
 }

arch/sh/mm/ioremap.c

@@ -15,6 +15,7 @@
 #include <linux/vmalloc.h>
 #include <linux/module.h>
 #include <linux/mm.h>
+#include <linux/pci.h>
 #include <asm/io.h>
 #include <asm/page.h>
 #include <asm/pgalloc.h>
@@ -134,6 +135,20 @@ void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
 	if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 		return (void __iomem *)phys_to_virt(phys_addr);
 
+	/*
+	 * If we're on an SH7751 or SH7780 PCI controller, PCI memory is
+	 * mapped at the end of the address space (typically 0xfd000000)
+	 * in a non-translatable area, so mapping through page tables for
+	 * this area is not only pointless, but also fundamentally
+	 * broken. Just return the physical address instead.
+	 *
+	 * For boards that map a small PCI memory aperture somewhere in
+	 * P1/P2 space, ioremap() will already do the right thing,
+	 * and we'll never get this far.
+	 */
+	if (is_pci_memaddr(phys_addr) && is_pci_memaddr(last_addr))
+		return (void __iomem *)phys_addr;
+
 	/*
 	 * Don't allow anybody to remap normal RAM that we're using..
 	 */
@@ -192,7 +207,7 @@ void __iounmap(void __iomem *addr)
 	unsigned long vaddr = (unsigned long __force)addr;
 	struct vm_struct *p;
 
-	if (PXSEG(vaddr) < P3SEG)
+	if (PXSEG(vaddr) < P3SEG || is_pci_memaddr(vaddr))
 		return;
 
 #ifdef CONFIG_32BIT