serial: lpuart: Enable RX and TX FIFO

Enable the RX and TX FIFO in LPUART driver to avoid the input lost
during U-Boot boot up.

Signed-off-by: Ye Li <ye.li@nxp.com>
Acked-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
Cc: Stefano Babic <sbabic@denx.de>

diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c
index c14a8105c92759971f96369c31583aefb557dd23..b28f7cf68d201d5e75b0e232adc90896f205bba8 100644 (file)
--- a/drivers/serial/serial_lpuart.c
+++ b/drivers/serial/serial_lpuart.c
@@ -40,6 +40,12 @@
 #define CTRL_TE                (1 << 19)
 #define CTRL_RE                (1 << 18)
 
+#define FIFO_RXFLUSH           BIT(14)
+#define FIFO_TXFLUSH           BIT(15)
+#define FIFO_TXSIZE_MASK       0x70
+#define FIFO_TXSIZE_OFF        4
+#define FIFO_RXSIZE_MASK       0x7
+#define FIFO_RXSIZE_OFF        0
 #define FIFO_TXFE              0x80
 #ifdef CONFIG_ARCH_IMX8
 #define FIFO_RXFE              0x08
@@ -47,7 +53,7 @@
 #define FIFO_RXFE              0x40
 #endif
 
-#define WATER_TXWATER_OFF      1
+#define WATER_TXWATER_OFF      0
 #define WATER_RXWATER_OFF      16
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -318,15 +324,28 @@ static int _lpuart32_serial_tstc(struct lpuart_serial_platdata *plat)
 static int _lpuart32_serial_init(struct lpuart_serial_platdata *plat)
 {
        struct lpuart_fsl_reg32 *base = (struct lpuart_fsl_reg32 *)plat->reg;
-       u32 ctrl;
+       u32 val, tx_fifo_size;
 
-       lpuart_read32(plat->flags, &base->ctrl, &ctrl);
-       ctrl &= ~CTRL_RE;
-       ctrl &= ~CTRL_TE;
-       lpuart_write32(plat->flags, &base->ctrl, ctrl);
+       lpuart_read32(plat->flags, &base->ctrl, &val);
+       val &= ~CTRL_RE;
+       val &= ~CTRL_TE;
+       lpuart_write32(plat->flags, &base->ctrl, val);
 
        lpuart_write32(plat->flags, &base->modir, 0);
-       lpuart_write32(plat->flags, &base->fifo, ~(FIFO_TXFE | FIFO_RXFE));
+
+       lpuart_read32(plat->flags, &base->fifo, &val);
+       tx_fifo_size = (val & FIFO_TXSIZE_MASK) >> FIFO_TXSIZE_OFF;
+       /* Set the TX water to half of FIFO size */
+       if (tx_fifo_size > 1)
+               tx_fifo_size = tx_fifo_size >> 1;
+
+       /* Set RX water to 0, to be triggered by any receive data */
+       lpuart_write32(plat->flags, &base->water,
+                      (tx_fifo_size << WATER_TXWATER_OFF));
+
+       /* Enable TX and RX FIFO */
+       val |= (FIFO_TXFE | FIFO_RXFE | FIFO_TXFLUSH | FIFO_RXFLUSH);
+       lpuart_write32(plat->flags, &base->fifo, val);
 
        lpuart_write32(plat->flags, &base->match, 0);