serial: pl011: Add device tree support for RX DMA polling

Add equivalent attributes to those provided in the platform data
for use when RX DMA is enabled.
Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/pl011.txt

@@ -13,5 +13,10 @@ Optional properties:
 - dmas:			When present, may have one or two dma channels.
 			The first one must be named "rx", the second one
 			must be named "tx".
+- auto-poll:		Enables polling when using RX DMA.
+- poll-rate-ms:		Rate at which poll occurs when auto-poll is set,
+			default 100ms.
+- poll-timeout-ms:	Poll timeout when auto-poll is set, default
+			3000ms.
 
 See also bindings/arm/primecell.txt

drivers/tty/serial/amba-pl011.c

@@ -341,6 +341,7 @@ static void pl011_dma_probe_initcall(struct device *dev, struct uart_amba_port *
 		dmaengine_slave_config(chan, &rx_conf);
 		uap->dmarx.chan = chan;
 
+		uap->dmarx.auto_poll_rate = false;
 		if (plat && plat->dma_rx_poll_enable) {
 			/* Set poll rate if specified. */
 			if (plat->dma_rx_poll_rate) {
@@ -361,9 +362,24 @@ static void pl011_dma_probe_initcall(struct device *dev, struct uart_amba_port *
 					plat->dma_rx_poll_timeout;
 			else
 				uap->dmarx.poll_timeout = 3000;
-		} else
-			uap->dmarx.auto_poll_rate = false;
-
+		} else if (!plat && dev->of_node) {
+			uap->dmarx.auto_poll_rate = of_property_read_bool(
+						dev->of_node, "auto-poll");
+			if (uap->dmarx.auto_poll_rate) {
+				u32 x;
+
+				if (0 == of_property_read_u32(dev->of_node,
+						"poll-rate-ms", &x))
+					uap->dmarx.poll_rate = x;
+				else
+					uap->dmarx.poll_rate = 100;
+				if (0 == of_property_read_u32(dev->of_node,
+						"poll-timeout-ms", &x))
+					uap->dmarx.poll_timeout = x;
+				else
+					uap->dmarx.poll_timeout = 3000;
+			}
+		}
 		dev_info(uap->port.dev, "DMA channel RX %s\n",
 			 dma_chan_name(uap->dmarx.chan));
 	}