tty/serial: at91: fix bad offset for UART timeout register

With SAMA5D2, the UART has hw timeout but the offset of the register to
define this value is not the same as the one for USART.
When using the new UART, the value of this register was 0 so we never
get timeout irqs. It involves that when using DMA, we were stuck until
the execution of the dma callback which happens when a buffer is full
(so after receiving 2048 bytes).

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/atmel_serial.c

@@ -159,6 +159,7 @@ struct atmel_uart_port {
 	u32			rts_high;
 	u32			rts_low;
 	bool			ms_irq_enabled;
+	u32			rtor;	/* address of receiver timeout register if it exists */
 	bool			has_hw_timer;
 	struct timer_list	uart_timer;
 
@@ -1718,12 +1719,16 @@ static void atmel_get_ip_name(struct uart_port *port)
 
 	atmel_port->has_hw_timer = false;
 
-	if (name == usart || name == new_uart) {
-		dev_dbg(port->dev, "Usart or uart with hw timer\n");
+	if (name == new_uart) {
+		dev_dbg(port->dev, "Uart with hw timer");
 		atmel_port->has_hw_timer = true;
+		atmel_port->rtor = ATMEL_UA_RTOR;
+	} else if (name == usart) {
+		dev_dbg(port->dev, "Usart\n");
+		atmel_port->has_hw_timer = true;
+		atmel_port->rtor = ATMEL_US_RTOR;
 	} else if (name == dbgu_uart) {
 		dev_dbg(port->dev, "Dbgu or uart without hw timer\n");
-		atmel_port->has_hw_timer = false;
 	} else {
 		/* fallback for older SoCs: use version field */
 		version = atmel_uart_readl(port, ATMEL_US_VERSION);
@@ -1732,11 +1737,11 @@ static void atmel_get_ip_name(struct uart_port *port)
 		case 0x10213:
 			dev_dbg(port->dev, "This version is usart\n");
 			atmel_port->has_hw_timer = true;
+			atmel_port->rtor = ATMEL_US_RTOR;
 			break;
 		case 0x203:
 		case 0x10202:
 			dev_dbg(port->dev, "This version is uart\n");
-			atmel_port->has_hw_timer = false;
 			break;
 		default:
 			dev_err(port->dev, "Not supported ip name nor version, set to uart\n");
@@ -1841,7 +1846,8 @@ static int atmel_startup(struct uart_port *port)
 					jiffies + uart_poll_timeout(port));
 		/* set USART timeout */
 		} else {
-			atmel_uart_writel(port, ATMEL_US_RTOR, PDC_RX_TIMEOUT);
+			atmel_uart_writel(port, atmel_port->rtor,
+					  PDC_RX_TIMEOUT);
 			atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_STTTO);
 
 			atmel_uart_writel(port, ATMEL_US_IER,
@@ -1856,7 +1862,8 @@ static int atmel_startup(struct uart_port *port)
 					jiffies + uart_poll_timeout(port));
 		/* set USART timeout */
 		} else {
-			atmel_uart_writel(port, ATMEL_US_RTOR, PDC_RX_TIMEOUT);
+			atmel_uart_writel(port, atmel_port->rtor,
+					  PDC_RX_TIMEOUT);
 			atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_STTTO);
 
 			atmel_uart_writel(port, ATMEL_US_IER,