pci-dma: add include/linux/pci-dma.h

This patch adds include/linux/pci-dma.h that defines the pci_unmap state
API:

DECLARE_PCI_UNMAP_ADDR(ADDR_NAME)
DECLARE_PCI_UNMAP_LEN(LEN_NAME)
pci_unmap_addr(PTR, ADDR_NAME)
pci_unmap_addr_set(PTR, ADDR_NAME, VAL)
pci_unmap_len(PTR, LEN_NAME)
pci_unmap_len_set(PTR, LEN_NAME, VAL)

This enables us to remove lots of the duplication in architecture
implementations since there are only two ways to define the API.

If architectures define CONFIG_NEED_DMA_MAP_STATE, they get the real
definition of pci_unmap state API.  If not, they get the noop definition.

In the long term, it's better to replace the API with the generic device
model API such as DECLARE_DMA_UNMAP_ADDR.  We can map the API to the
generic one (like dma-mapping-compat.h does).  This patch also makes the
migration process easier.  We can remove this file after the migration.

It might be simpler to add the API to include/linux/pci.h but looks it's
already too large.  We'll remove pci-dma.h after finishing moving to the
generic device model.  So I put the API to a separate file.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: James Bottomley <James.Bottomley@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Chris Zankel <chris@zankel.net>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/pci-dma.h

+#ifndef _LINUX_PCI_DMA_H
+#define _LINUX_PCI_DMA_H
+
+#ifdef CONFIG_NEED_DMA_MAP_STATE
+#define DECLARE_PCI_UNMAP_ADDR(ADDR_NAME)        dma_addr_t ADDR_NAME;
+#define DECLARE_PCI_UNMAP_LEN(LEN_NAME)          __u32 LEN_NAME;
+#define pci_unmap_addr(PTR, ADDR_NAME)           ((PTR)->ADDR_NAME)
+#define pci_unmap_addr_set(PTR, ADDR_NAME, VAL)  (((PTR)->ADDR_NAME) = (VAL))
+#define pci_unmap_len(PTR, LEN_NAME)             ((PTR)->LEN_NAME)
+#define pci_unmap_len_set(PTR, LEN_NAME, VAL)    (((PTR)->LEN_NAME) = (VAL))
+#else
+#define DECLARE_PCI_UNMAP_ADDR(ADDR_NAME)
+#define DECLARE_PCI_UNMAP_LEN(LEN_NAME)
+#define pci_unmap_addr(PTR, ADDR_NAME)           (0)
+#define pci_unmap_addr_set(PTR, ADDR_NAME, VAL)  do { } while (0)
+#define pci_unmap_len(PTR, LEN_NAME)             (0)
+#define pci_unmap_len_set(PTR, LEN_NAME, VAL)    do { } while (0)
+#endif
+
+#endif