mm: Add NO_DMA dummies for DMA pool API

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@linux-m68k.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

include/linux/dmapool.h

@@ -16,6 +16,8 @@
 
 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);
 
@@ -23,13 +25,6 @@ void dma_pool_destroy(struct dma_pool *pool);
 
 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 		     dma_addr_t *handle);
-
-static inline void *dma_pool_zalloc(struct dma_pool *pool, gfp_t mem_flags,
-				    dma_addr_t *handle)
-{
-	return dma_pool_alloc(pool, mem_flags | __GFP_ZERO, handle);
-}
-
 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t addr);
 
 /*
@@ -39,5 +34,26 @@ 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 *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) { }
+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 */
+
+static inline void *dma_pool_zalloc(struct dma_pool *pool, gfp_t mem_flags,
+				    dma_addr_t *handle)
+{
+	return dma_pool_alloc(pool, mem_flags | __GFP_ZERO, handle);
+}
+
 #endif