SAML21 minor stuff

TODO

@@ -1080,7 +1080,7 @@ o USB (drivers/usbdev, drivers/usbhost)
                channels.
 
                This works okay until you add a hub and try connect multiple
-               devices.  A typical device will require 3-4 pipe and, hence,
+               devices.  A typical device will require 3-4 pipes and, hence,
                4-5 channels.  This effectively prevents using a hub with the
                STM32 devices.  This also applies to the EFM32 which uses the
                same IP.

arch/arm/src/samdl/sam_dmac.c

@@ -803,9 +803,10 @@ void weak_function up_dmainitialize(void)
   putreg32((uint32_t)g_base_desc, SAM_DMAC_BASEADDR);
   putreg32((uint32_t)g_writeback_desc, SAM_DMAC_WRBADDR);
 
-  /* Enable the DMA controller */
+  /* Enable the DMA controller and all priority levels */
 
-  putreg16(DMAC_CTRL_DMAENABLE, SAM_DMAC_CTRL);
+  putreg16(DMAC_CTRL_DMAENABLE | DMAC_CTRL_LVLEN0 | DMAC_CTRL_LVLEN1 |
+           DMAC_CTRL_LVLEN2, SAM_DMAC_CTRL);
 
   /* Enable the IRQ at the NVIC (still disabled at the DMA controller) */
 

configs/saml21-xplained/README.txt

@@ -32,6 +32,8 @@ STATUS/ISSUES
     configuration is working well with the serial console provided by
     SERCOM4 as 115200 8N1.
 
+  - 2015-6-14: Added a DMAC driver.  There is no way to verify it at present.
+
 Modules
 =======