USB: musb: sanitize clearing TXCSR DMA bits (take 2)

The MUSB code clears TXCSR_DMAMODE incorrectly in several
places, either asserting that TXCSR_DMAENAB is clear (when
sometimes it isn't) or clearing both bits together.  Recent
versions of the programmer's guide require DMAENAB to be
cleared first, although some older ones didn't.

Fix this and while at it:

 - In musb_gadget::txstate(), stop clearing the AUTOSET
   and DMAMODE bits for the CPPI case since they never
   get set anyway (the former bit is reserved on DaVinci);
   but do clear the DMAENAB bit on the DMA error path.

 - In musb_host::musb_ep_program(), remove the duplicate
   DMA controller specific code code clearing the TXCSR
   previous state, add the code to clear TXCSR DMA bits
   on the Inventra DMA error path, to replace such code
   (executed late) on the PIO path.

 - In musbhsdma::dma_channel_abort()/dma_controller_irq(),
   add/use the 'offset' variable to avoid MUSB_EP_OFFSET()
   invocations on every RXCSR/TXCSR access.

[dbrownell@users.sourceforge.net: don't introduce CamelCase,
shrink diff]

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 22 insertions, 11 deletions

diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index c7ebd0867fcc..f79440cdfe7e 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -165,9 +165,15 @@ static void nuke(struct musb_ep *ep, const int status)
 	if (is_dma_capable() && ep->dma) {
 		struct dma_controller	*c = ep->musb->dma_controller;
 		int value;
+
 		if (ep->is_in) {
+			/*
+			 * The programming guide says that we must not clear
+			 * the DMAMODE bit before DMAENAB, so we only
+			 * clear it in the second write...
+			 */
 			musb_writew(epio, MUSB_TXCSR,
-					0 | MUSB_TXCSR_FLUSHFIFO);
+				    MUSB_TXCSR_DMAMODE | MUSB_TXCSR_FLUSHFIFO);
 			musb_writew(epio, MUSB_TXCSR,
 					0 | MUSB_TXCSR_FLUSHFIFO);
 		} else {
@@ -230,7 +236,7 @@ static inline int max_ep_writesize(struct musb *musb, struct musb_ep *ep)
 		  |	IN token(s) are recd from Host.
 		  |		-> DMA interrupt on completion
 		  |		   calls TxAvail.
-		  |		      -> stop DMA, ~DmaEenab,
+		  |		      -> stop DMA, ~DMAENAB,
 		  |		      -> set TxPktRdy for last short pkt or zlp
 		  |		      -> Complete Request
 		  |		      -> Continue next request (call txstate)
@@ -315,9 +321,17 @@ static void txstate(struct musb *musb, struct musb_request *req)
 					request->dma, request_size);
 			if (use_dma) {
 				if (musb_ep->dma->desired_mode == 0) {
-					/* ASSERT: DMAENAB is clear */
-					csr &= ~(MUSB_TXCSR_AUTOSET |
-							MUSB_TXCSR_DMAMODE);
+					/*
+					 * We must not clear the DMAMODE bit
+					 * before the DMAENAB bit -- and the
+					 * latter doesn't always get cleared
+					 * before we get here...
+					 */
+					csr &= ~(MUSB_TXCSR_AUTOSET
+						| MUSB_TXCSR_DMAENAB);
+					musb_writew(epio, MUSB_TXCSR, csr
+						| MUSB_TXCSR_P_WZC_BITS);
+					csr &= ~MUSB_TXCSR_DMAMODE;
 					csr |= (MUSB_TXCSR_DMAENAB |
 							MUSB_TXCSR_MODE);
 					/* against programming guide */
@@ -334,10 +348,7 @@ static void txstate(struct musb *musb, struct musb_request *req)
 
 #elif defined(CONFIG_USB_TI_CPPI_DMA)
 		/* program endpoint CSR first, then setup DMA */
-		csr &= ~(MUSB_TXCSR_AUTOSET
-				| MUSB_TXCSR_DMAMODE
-				| MUSB_TXCSR_P_UNDERRUN
-				| MUSB_TXCSR_TXPKTRDY);
+		csr &= ~(MUSB_TXCSR_P_UNDERRUN | MUSB_TXCSR_TXPKTRDY);
 		csr |= MUSB_TXCSR_MODE | MUSB_TXCSR_DMAENAB;
 		musb_writew(epio, MUSB_TXCSR,
 			(MUSB_TXCSR_P_WZC_BITS & ~MUSB_TXCSR_P_UNDERRUN)
@@ -364,8 +375,8 @@ static void txstate(struct musb *musb, struct musb_request *req)
 		if (!use_dma) {
 			c->channel_release(musb_ep->dma);
 			musb_ep->dma = NULL;
-			/* ASSERT: DMAENAB clear */
-			csr &= ~(MUSB_TXCSR_DMAMODE | MUSB_TXCSR_MODE);
+			csr &= ~MUSB_TXCSR_DMAENAB;
+			musb_writew(epio, MUSB_TXCSR, csr);
 			/* invariant: prequest->buf is non-null */
 		}
 #elif defined(CONFIG_USB_TUSB_OMAP_DMA)