Re: [PATCH 2/2] tty/serial: at91: add a fallback option to determine uart/usart property

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On 14/10/2013 15:59, Jean-Christophe PLAGNIOL-VILLARD :
On 10:43 Thu 10 Oct     , Nicolas Ferre wrote:
On older SoC, the "name" field is not filled in the register map.
Fix the way to figure out if the serial port is an uart or an usart for these
older products (with corresponding properties).

Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
---
  drivers/tty/serial/atmel_serial.c | 19 ++++++++++++++++++-
  include/linux/atmel_serial.h      |  1 +
  2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 6b0f75e..c7d99af 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -99,6 +99,7 @@ static void atmel_stop_rx(struct uart_port *port);
  #define UART_PUT_RTOR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_RTOR)
  #define UART_PUT_TTGR(port, v)	__raw_writel(v, (port)->membase + ATMEL_US_TTGR)
  #define UART_GET_IP_NAME(port)	__raw_readl((port)->membase + ATMEL_US_NAME)
+#define UART_GET_IP_VERSION(port) __raw_readl((port)->membase + ATMEL_US_VERSION)

   /* PDC registers */
  #define UART_PUT_PTCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
@@ -1503,6 +1504,7 @@ static void atmel_get_ip_name(struct uart_port *port)
  {
  	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
  	int name = UART_GET_IP_NAME(port);
+	u32 version;
  	int usart, uart;
  	/* usart and uart ascii */
  	usart = 0x55534152;
@@ -1517,7 +1519,22 @@ static void atmel_get_ip_name(struct uart_port *port)
  		dev_dbg(port->dev, "This is uart\n");
  		atmel_port->is_usart = false;
  	} else {
-		dev_err(port->dev, "Not supported ip name, set to uart\n");
+		/* fallback for older SoCs: use version field */
+		version = UART_GET_IP_VERSION(port);
+		switch (version) {
+		case 0x302:
+		case 0x10213:
+			dev_dbg(port->dev, "This version is usart\n");
+			atmel_port->is_usart = true;
+			break;
+		case 0x203:
+		case 0x10202:
+			dev_dbg(port->dev, "This version is uart\n");
+			atmel_port->is_usart = false;
+			break;
+		default:
+			dev_err(port->dev, "Not supported ip name nor version, set to uart\n");

it's not really an error a dev_warn is more oppropriate

As we are already in -rc5 and that these fixes are critical for at91 platforms, I will not re-spin another patch just for this.

Moreover, I have the feeling that if we end up in this case, it means that we are in big troubles because the usart/uart included in the product triggering this log is not known (I recall that newer products do not have to hit these lines of code).

With these 2 reasons, I prefer to keep my patch like it is.

Greg, can you consider taking these two patches as regression fixes for 3.12 (with Tested-by tag from Thomas)?

Thanks, bye,

+		}
  	}
  }

diff --git a/include/linux/atmel_serial.h b/include/linux/atmel_serial.h
index be201ca..00beddf 100644
--- a/include/linux/atmel_serial.h
+++ b/include/linux/atmel_serial.h
@@ -125,5 +125,6 @@
  #define ATMEL_US_IF		0x4c			/* IrDA Filter Register */

  #define ATMEL_US_NAME		0xf0			/* Ip Name */
+#define ATMEL_US_VERSION	0xfc			/* Ip Version */

  #endif
--
1.8.2.2





--
Nicolas Ferre
--
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