tegra: Update the UART Tx data path and added new system DMA API.

-Using workqueues instead of tasklets for Tx DMA.
-Waiting for the FIFO to drain after the DMA is done, as it is apparently
needed by the HW.
- Added new DMA API to check if the req is already queued. Using
  tegra_dma_is_empty might not be correct as one DMA chanel can be serviced
  by multiple clients.

With this change, i can browse the BT sometimes. It takes some retires to
enable the BT.

Also during the operation of the BT, i still see the messages like
"out-of-order packet arrived"

Don't know if this is an issue with ther UART or the BT protocol.

Change-Id: I1502ad8178c3c95b4128c564c9f3c1d957195d46

2 files changed, 25 insertions, 9 deletions

diff --git a/arch/arm/mach-tegra/dma.c b/arch/arm/mach-tegra/dma.c
index 4f337d06c5a7..bbd3691240ea 100644
--- a/arch/arm/mach-tegra/dma.c
+++ b/arch/arm/mach-tegra/dma.c
@@ -212,23 +212,40 @@ int tegra_dma_dequeue_req(int channel, struct tegra_dma_req *_req)
 }
 EXPORT_SYMBOL(tegra_dma_dequeue_req);
 
-int tegra_dma_is_empty(int channel)
+bool tegra_dma_is_empty(int channel)
 {
 	unsigned long irq_flags;
 	struct tegra_dma_channel *ch = &dma_channels[channel];
-	int is_empty;
+	bool is_empty;
 
 	spin_lock_irqsave(&ch->lock, irq_flags);
 	if (list_empty(&ch->list))
-		is_empty = 1;
+		is_empty = true;
 	else
-		is_empty = 0;
+		is_empty = false;
 	spin_unlock_irqrestore(&ch->lock, irq_flags);
-
 	return is_empty;
 }
 EXPORT_SYMBOL(tegra_dma_is_empty);
 
+bool tegra_dma_is_req_inflight(int channel, struct tegra_dma_req *_req)
+{
+	unsigned long irq_flags;
+	struct tegra_dma_channel *ch = &dma_channels[channel];
+	struct tegra_dma_req *req;
+
+	spin_lock_irqsave(&ch->lock, irq_flags);
+	list_for_each_entry (req, &ch->list, list) {
+		if (req == _req) {
+			spin_unlock_irqrestore(&ch->lock, irq_flags);
+			return true;
+		}
+	}
+	spin_unlock_irqrestore(&ch->lock, irq_flags);
+	return false;
+}
+EXPORT_SYMBOL(tegra_dma_is_req_inflight);
+
 int tegra_dma_enqueue_req(int channel, struct tegra_dma_req *req)
 {
 	unsigned long irq_flags;
diff --git a/arch/arm/mach-tegra/include/mach/dma.h b/arch/arm/mach-tegra/include/mach/dma.h
index c39be865bafc..508e2fcf8409 100644
--- a/arch/arm/mach-tegra/include/mach/dma.h
+++ b/arch/arm/mach-tegra/include/mach/dma.h
@@ -101,12 +101,11 @@ struct tegra_dma_req {
 int tegra_dma_enqueue_req(int channel, struct tegra_dma_req *req);
 int tegra_dma_dequeue_req(int channel, struct tegra_dma_req *req);
 void tegra_dma_dequeue(int channel);
-
-/*  Returns 1 if there are DMA is empty.
- */
-int tegra_dma_is_empty(int channel);
 void tegra_dma_flush(int channel);
 
+bool tegra_dma_is_req_inflight(int channel, struct tegra_dma_req *req);
+bool tegra_dma_is_empty(int channel);
+
 int tegra_dma_allocate_channel(int mode);
 void tegra_dma_free_channel(int channel);