[PATCH/RFC 4/6] mm: Add NO_DMA dummies for DMA pool API

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Add dummies for dma{,m}_pool_{create,destroy,alloc,free}(), to allow
compile-testing if NO_DMA=y.

This prevents the following from showing up later:

    ERROR: "dma_pool_destroy" [drivers/usb/mtu3/mtu3.ko] undefined!
    ERROR: "dma_pool_free" [drivers/usb/mtu3/mtu3.ko] undefined!
    ERROR: "dma_pool_alloc" [drivers/usb/mtu3/mtu3.ko] undefined!
    ERROR: "dma_pool_create" [drivers/usb/mtu3/mtu3.ko] undefined!
    ERROR: "dma_pool_destroy" [drivers/scsi/hisi_sas/hisi_sas_main.ko] undefined!
    ERROR: "dma_pool_free" [drivers/scsi/hisi_sas/hisi_sas_main.ko] undefined!
    ERROR: "dma_pool_alloc" [drivers/scsi/hisi_sas/hisi_sas_main.ko] undefined!
    ERROR: "dma_pool_create" [drivers/scsi/hisi_sas/hisi_sas_main.ko] undefined!
    ERROR: "dma_pool_alloc" [drivers/mailbox/bcm-pdc-mailbox.ko] undefined!
    ERROR: "dma_pool_free" [drivers/mailbox/bcm-pdc-mailbox.ko] undefined!
    ERROR: "dma_pool_create" [drivers/mailbox/bcm-pdc-mailbox.ko] undefined!
    ERROR: "dma_pool_destroy" [drivers/mailbox/bcm-pdc-mailbox.ko] undefined!

Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
---
 include/linux/dmapool.h | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/include/linux/dmapool.h b/include/linux/dmapool.h
index 53ba737505df31c7..adeb5e56c3ad73a8 100644
--- a/include/linux/dmapool.h
+++ b/include/linux/dmapool.h
@@ -16,6 +16,7 @@
 
 struct device;
 
+#ifdef CONFIG_HAS_DMA
 struct dma_pool *dma_pool_create(const char *name, struct device *dev, 
 			size_t size, size_t align, size_t allocation);
 
@@ -23,6 +24,17 @@ void dma_pool_destroy(struct dma_pool *pool);
 
 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 		     dma_addr_t *handle);
+void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t addr);
+#else /* !CONFIG_HAS_DMA */
+static inline struct dma_pool *dma_pool_create(const char *name,
+	struct device *dev, size_t size, size_t align, size_t allocation)
+{ return NULL; }
+static inline void dma_pool_destroy(struct dma_pool *pool) { }
+static inline void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
+				   dma_addr_t *handle) { return NULL; }
+static inline void dma_pool_free(struct dma_pool *pool, void *vaddr,
+				 dma_addr_t addr) { }
+#endif /* !CONFIG_HAS_DMA */
 
 static inline void *dma_pool_zalloc(struct dma_pool *pool, gfp_t mem_flags,
 				    dma_addr_t *handle)
@@ -30,14 +42,19 @@ static inline void *dma_pool_zalloc(struct dma_pool *pool, gfp_t mem_flags,
 	return dma_pool_alloc(pool, mem_flags | __GFP_ZERO, handle);
 }
 
-void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t addr);
-
 /*
  * Managed DMA pool
  */
+#ifdef CONFIG_HAS_DMA
 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 				  size_t size, size_t align, size_t allocation);
 void dmam_pool_destroy(struct dma_pool *pool);
+#else /* !CONFIG_HAS_DMA */
+static inline struct dma_pool *dmam_pool_create(const char *name,
+	struct device *dev, size_t size, size_t align, size_t allocation)
+{ return NULL; }
+static inline void dmam_pool_destroy(struct dma_pool *pool) { }
+#endif /* !CONFIG_HAS_DMA */
 
 #endif
 
-- 
2.7.4