usb: musb: use a Kconfig choice to pick the right DMA method

The logic to allow only one DMA driver in MUSB is currently
flawed, because it also allows picking no DMA driver at all
and also not selecting PIO mode.

Using a choice statement makes this foolproof for now and
also simplifies the Makefile.

Unfortunately, we will have to revisit this when we start
supporting multiple ARM platforms in a single kernel binary,
because at that point we will actually need to select
multiple DMA drivers and pick the right one at run-time.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Felipe Balbi <balbi@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/Kconfig

@@ -65,46 +65,57 @@ config USB_MUSB_UX500
 
 endchoice
 
-config MUSB_PIO_ONLY
-	bool 'Disable DMA (always use PIO)'
-	depends on USB_MUSB_HDRC
-	default USB_MUSB_TUSB6010 || USB_MUSB_DA8XX || USB_MUSB_AM35X
+choice
+	prompt 'MUSB DMA mode'
+	default USB_UX500_DMA if USB_MUSB_UX500
+	default USB_INVENTRA_DMA if USB_MUSB_OMAP2PLUS || USB_MUSB_BLACKFIN
+	default USB_TI_CPPI_DMA if USB_MUSB_DAVINCI
+	default USB_TUSB_OMAP_DMA if USB_MUSB_TUSB6010
+	default MUSB_PIO_ONLY if USB_MUSB_TUSB6010 || USB_MUSB_DA8XX || USB_MUSB_AM35X
 	help
-	  All data is copied between memory and FIFO by the CPU.
-	  DMA controllers are ignored.
-
-	  Do not select 'n' here unless DMA support for your SOC or board
-	  is unavailable (or unstable).  When DMA is enabled at compile time,
-	  you can still disable it at run time using the "use_dma=n" module
-	  parameter.
+	  Unfortunately, only one option can be enabled here. Ideally one
+	  should be able to build all these drivers into one kernel to
+	  allow using DMA on multiplatform kernels.
 
 config USB_UX500_DMA
-	bool
-	depends on USB_MUSB_HDRC && !MUSB_PIO_ONLY
-	default USB_MUSB_UX500
+	bool 'ST Ericsson U8500 and U5500'
+	depends on USB_MUSB_HDRC
+	depends on USB_MUSB_UX500
 	help
 	  Enable DMA transfers on UX500 platforms.
 
 config USB_INVENTRA_DMA
-	bool
-	depends on USB_MUSB_HDRC && !MUSB_PIO_ONLY
-	default USB_MUSB_OMAP2PLUS || USB_MUSB_BLACKFIN
+	bool 'Inventra'
+	depends on USB_MUSB_HDRC
+	depends on USB_MUSB_OMAP2PLUS || USB_MUSB_BLACKFIN
 	help
 	  Enable DMA transfers using Mentor's engine.
 
 config USB_TI_CPPI_DMA
-	bool
-	depends on USB_MUSB_HDRC && !MUSB_PIO_ONLY
-	default USB_MUSB_DAVINCI
+	bool 'TI CPPI (Davinci)'
+	depends on USB_MUSB_HDRC
+	depends on USB_MUSB_DAVINCI
 	help
 	  Enable DMA transfers when TI CPPI DMA is available.
 
 config USB_TUSB_OMAP_DMA
-	bool
-	depends on USB_MUSB_HDRC && !MUSB_PIO_ONLY
+	bool 'TUSB 6010'
+	depends on USB_MUSB_HDRC
 	depends on USB_MUSB_TUSB6010
 	depends on ARCH_OMAP
-	default y
 	help
 	  Enable DMA transfers on TUSB 6010 when OMAP DMA is available.
 
+config MUSB_PIO_ONLY
+	bool 'Disable DMA (always use PIO)'
+	depends on USB_MUSB_HDRC
+	help
+	  All data is copied between memory and FIFO by the CPU.
+	  DMA controllers are ignored.
+
+	  Do not choose this unless DMA support for your SOC or board
+	  is unavailable (or unstable).  When DMA is enabled at compile time,
+	  you can still disable it at run time using the "use_dma=n" module
+	  parameter.
+
+endchoice

drivers/usb/musb/Makefile

@@ -24,25 +24,7 @@ obj-$(CONFIG_USB_MUSB_UX500)			+= ux500.o
 # PIO only, or DMA (several potential schemes).
 # though PIO is always there to back up DMA, and for ep0
 
-ifneq ($(CONFIG_MUSB_PIO_ONLY),y)
-
-  ifeq ($(CONFIG_USB_INVENTRA_DMA),y)
-    musb_hdrc-y			+= musbhsdma.o
-
-  else
-    ifeq ($(CONFIG_USB_TI_CPPI_DMA),y)
-      musb_hdrc-y		+= cppi_dma.o
-
-    else
-      ifeq ($(CONFIG_USB_TUSB_OMAP_DMA),y)
-	musb_hdrc-y		+= tusb6010_omap.o
-
-      else
-        ifeq ($(CONFIG_USB_UX500_DMA),y)
-	  musb_hdrc-y		+= ux500_dma.o
-
-        endif
-      endif
-    endif
-  endif
-endif
+musb_hdrc-$(CONFIG_USB_INVENTRA_DMA)		+= musbhsdma.o
+musb_hdrc-$(CONFIG_USB_TI_CPPI_DMA)		+= cppi_dma.o
+musb_hdrc-$(CONFIG_USB_TUSB_OMAP_DMA)		+= tusb6010_omap.o
+musb_hdrc-$(CONFIG_USB_UX500_DMA)		+= ux500_dma.o