dm: imx: serial: Support DTE mode when using driver model

The MXC UART IP can be run in DTE or DCE mode. This depends on the
board wiring and the pinmux used and hence is board specific. This
extends platform data with a new field to choose wheather DTE
mode shall be used.

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/serial/serial_mxc.c

@@ -76,6 +76,7 @@
 #define  UFCR_RXTL_SHF   0       /* Receiver trigger level shift */
 #define  UFCR_RFDIV      (7<<7)  /* Reference freq divider mask */
 #define  UFCR_RFDIV_SHF  7      /* Reference freq divider shift */
+#define  UFCR_DCEDTE	 (1<<6)  /* DTE mode select */
 #define  UFCR_TXTL_SHF   10      /* Transmitter trigger level shift */
 #define  USR1_PARITYERR  (1<<15) /* Parity error interrupt flag */
 #define  USR1_RTSS	 (1<<14) /* RTS pin status */
@@ -150,6 +151,7 @@ static void mxc_serial_setbrg(void)
 	__REG(UART_PHYS + UFCR) = (RFDIV << UFCR_RFDIV_SHF)
 		| (TXTL << UFCR_TXTL_SHF)
 		| (RXTL << UFCR_RXTL_SHF);
+	__REG(UART_PHYS + UFCR) |= UFCR_DCEDTE;
 	__REG(UART_PHYS + UBIR) = 0xf;
 	__REG(UART_PHYS + UBMR) = clk / (2 * gd->baudrate);
 
@@ -269,8 +271,13 @@ int mxc_serial_setbrg(struct udevice *dev, int baudrate)
 	struct mxc_serial_platdata *plat = dev->platdata;
 	struct mxc_uart *const uart = plat->reg;
 	u32 clk = imx_get_uartclk();
+	u32 tmp;
+
+	tmp = 4 << UFCR_RFDIV_SHF;
+	if (plat->use_dte)
+		tmp |= UFCR_DCEDTE;
+	writel(tmp, &uart->fcr);
 
-	writel(4 << 7, &uart->fcr); /* divide input clock by 2 */
 	writel(0xf, &uart->bir);
 	writel(clk / (2 * baudrate), &uart->bmr);
 

include/dm/platform_data/serial_mxc.h

@@ -9,6 +9,7 @@
 /* Information about a serial port */
 struct mxc_serial_platdata {
 	struct mxc_uart *reg;  /* address of registers in physical memory */
+	bool use_dte;
 };
 
 #endif