dma-mapping updates for 4.17:

- provide proper stubs for architectures not supporting dma (Geert)
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Merge tag 'dma-mapping-4.17' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping updates from Christoph Hellwig:
 "Very light this round as the interesting dma mapping changes went
  through the x86 tree.

  This just provides proper stubs for architectures not supporting dma
  (Geert Uytterhoeven)"

* tag 'dma-mapping-4.17' of git://git.infradead.org/users/hch/dma-mapping:
  usb: gadget: Add NO_DMA dummies for DMA mapping API
  scsi: Add NO_DMA dummies for SCSI DMA mapping API
  mm: Add NO_DMA dummies for DMA pool API
  dma-coherent: Add NO_DMA dummies for managed DMA API
  dma-mapping: Convert NO_DMA get_dma_ops() into a real dummy

include/linux/dma-mapping.h

@@ -212,14 +212,14 @@ static inline void set_dma_ops(struct device *dev,
 }
 #else
 /*
- * Define the dma api to allow compilation but not linking of
+ * Define the dma api to allow compilation of dma dependent code.
- * dma dependent code.  Code that depends on the dma-mapping
+ * Code that depends on the dma-mapping API needs to set 'depends on HAS_DMA'
- * API needs to set 'depends on HAS_DMA' in its Kconfig
+ * in its Kconfig, unless it already depends on <something> || COMPILE_TEST,
+ * where <something> guarantuees the availability of the dma-mapping API.
  */
-extern const struct dma_map_ops bad_dma_ops;
 static inline const struct dma_map_ops *get_dma_ops(struct device *dev)
 {
-	return &bad_dma_ops;
+	return NULL;
 }
 #endif
 
@@ -772,10 +772,19 @@ static inline void dma_deconfigure(struct device *dev) {}
 /*
  * Managed DMA API
  */
+#ifdef CONFIG_HAS_DMA
 extern void *dmam_alloc_coherent(struct device *dev, size_t size,
 				 dma_addr_t *dma_handle, gfp_t gfp);
 extern void dmam_free_coherent(struct device *dev, size_t size, void *vaddr,
 			       dma_addr_t dma_handle);
+#else /* !CONFIG_HAS_DMA */
+static inline void *dmam_alloc_coherent(struct device *dev, size_t size,
+					dma_addr_t *dma_handle, gfp_t gfp)
+{ return NULL; }
+static inline void dmam_free_coherent(struct device *dev, size_t size,
+				      void *vaddr, dma_addr_t dma_handle) { }
+#endif /* !CONFIG_HAS_DMA */
+
 extern void *dmam_alloc_attrs(struct device *dev, size_t size,
 			      dma_addr_t *dma_handle, gfp_t gfp,
 			      unsigned long attrs);

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
 

include/linux/usb/gadget.h

@@ -806,6 +806,7 @@ int usb_otg_descriptor_init(struct usb_gadget *gadget,
 
 /* utility to simplify map/unmap of usb_requests to/from DMA */
 
+#ifdef	CONFIG_HAS_DMA
 extern int usb_gadget_map_request_by_dev(struct device *dev,
 		struct usb_request *req, int is_in);
 extern int usb_gadget_map_request(struct usb_gadget *gadget,
@@ -815,6 +816,17 @@ extern void usb_gadget_unmap_request_by_dev(struct device *dev,
 		struct usb_request *req, int is_in);
 extern void usb_gadget_unmap_request(struct usb_gadget *gadget,
 		struct usb_request *req, int is_in);
+#else /* !CONFIG_HAS_DMA */
+static inline int usb_gadget_map_request_by_dev(struct device *dev,
+		struct usb_request *req, int is_in) { return -ENOSYS; }
+static inline int usb_gadget_map_request(struct usb_gadget *gadget,
+		struct usb_request *req, int is_in) { return -ENOSYS; }
+
+static inline void usb_gadget_unmap_request_by_dev(struct device *dev,
+		struct usb_request *req, int is_in) { }
+static inline void usb_gadget_unmap_request(struct usb_gadget *gadget,
+		struct usb_request *req, int is_in) { }
+#endif /* !CONFIG_HAS_DMA */
 
 /*-------------------------------------------------------------------------*/
 

include/scsi/scsi_cmnd.h

@@ -174,8 +174,13 @@ extern void scsi_kunmap_atomic_sg(void *virt);
 
 extern int scsi_init_io(struct scsi_cmnd *cmd);
 
+#ifdef CONFIG_SCSI_DMA
 extern int scsi_dma_map(struct scsi_cmnd *cmd);
 extern void scsi_dma_unmap(struct scsi_cmnd *cmd);
+#else /* !CONFIG_SCSI_DMA */
+static inline int scsi_dma_map(struct scsi_cmnd *cmd) { return -ENOSYS; }
+static inline void scsi_dma_unmap(struct scsi_cmnd *cmd) { }
+#endif /* !CONFIG_SCSI_DMA */
 
 static inline unsigned scsi_sg_count(struct scsi_cmnd *cmd)
 {