[U-Boot] [PATCHv4 1/4] Serial: p1011: new vendor init options

[John Rigby]

Two new options:

CONFIG_PL011_SERIAL_RLCR

Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
have separate receive and transmit line control registers.  Set
this variable to initialize the extra register.

CONFIG_PL011_SERIAL_FLUSH_ON_INIT

On some platforms (e.g. U8500) U-Boot is loaded by a second stage
boot loader that has already initialized the UART.  Define this
variable to flush the UART at init time.
empty fifo on init

Signed-off-by: John Rigby <john.rigby at linaro.org>
Signed-off-by: Rabin Vincent <rabin.vincent at stericsson.com>
---
v2: No changes
v3: Enable changes with new CONFIG_* options instead of platform.
Document new CONFIG_* options in README.
v4: Added delay before writing to RLCR.
Removed Rabin as author at his request.

 README                        |   12 ++++++++++++
 drivers/serial/serial_pl01x.c |   30 +++++++++++++++++++++++++++---
 drivers/serial/serial_pl01x.h |    4 ++++
 3 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/README b/README
index 4917e26..496a428 100644
--- a/README
+++ b/README
@@ -468,6 +468,18 @@ The following options need to be configured:
 		define this to a list of base addresses for each (supported)
 		port. See e.g. include/configs/versatile.h
 
+		CONFIG_PL011_SERIAL_RLCR
+
+		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
+		have separate receive and transmit line control registers.  Set
+		this variable to initialize the extra register.
+
+		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
+
+		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
+		boot loader that has already initialized the UART.  Define this
+		variable to flush the UART at init time.
+
 
 - Console Interface:
 		Depending on board, define exactly one serial port
diff --git a/drivers/serial/serial_pl01x.c b/drivers/serial/serial_pl01x.c
index 5dfcde8..7a064ff 100644
--- a/drivers/serial/serial_pl01x.c
+++ b/drivers/serial/serial_pl01x.c
@@ -111,6 +111,15 @@ int serial_init (void)
 	unsigned int divider;
 	unsigned int remainder;
 	unsigned int fraction;
+	unsigned int lcr;
+
+#ifdef CONFIG_PL011_SERIAL_FLUSH_ON_INIT
+	/* Empty RX fifo if necessary */
+	if (readl(&regs->pl011_cr) & UART_PL011_CR_UARTEN) {
+		while (!(readl(&regs->fr) & UART_PL01x_FR_RXFE))
+			readl(&regs->dr);
+	}
+#endif
 
 	/* First, disable everything */
 	writel(0, &regs->pl011_cr);
@@ -131,9 +140,24 @@ int serial_init (void)
 	writel(fraction, &regs->pl011_fbrd);
 
 	/* Set the UART to be 8 bits, 1 stop bit, no parity, fifo enabled */
-	writel(UART_PL011_LCRH_WLEN_8 | UART_PL011_LCRH_FEN,
-	       &regs->pl011_lcrh);
-
+	lcr = UART_PL011_LCRH_WLEN_8 | UART_PL011_LCRH_FEN;
+	writel(lcr, &regs->pl011_lcrh);
+
+#ifdef CONFIG_PL011_SERIAL_RLCR
+	{
+		int i;
+
+		/*
+		 * Program receive line control register after waiting
+		 * 10 bus cycles.  Delay be writing to readonly register
+		 * 10 times
+		 */
+		for (i = 0; i < 10; i++)
+			writel(lcr, &regs->fr);
+
+		writel(lcr, &regs->pl011_rlcr);
+	}
+#endif
 	/* Finally, enable the UART */
 	writel(UART_PL011_CR_UARTEN | UART_PL011_CR_TXE | UART_PL011_CR_RXE,
 	       &regs->pl011_cr);
diff --git a/drivers/serial/serial_pl01x.h b/drivers/serial/serial_pl01x.h
index b670c24..96ee381 100644
--- a/drivers/serial/serial_pl01x.h
+++ b/drivers/serial/serial_pl01x.h
@@ -43,7 +43,11 @@ struct pl01x_regs {
 	u32	pl010_lcrl;	/* 0x10 Line control register, low byte */
 	u32	pl010_cr;	/* 0x14 Control register */
 	u32	fr;		/* 0x18 Flag register (Read only) */
+#ifdef CONFIG_PL011_SERIAL_RLCR
+	u32	pl011_rlcr;	/* 0x1c Receive line control register */
+#else
 	u32	reserved;
+#endif
 	u32	ilpr;		/* 0x20 IrDA low-power counter register */
 	u32	pl011_ibrd;	/* 0x24 Integer baud rate register */
 	u32	pl011_fbrd;	/* 0x28 Fractional baud rate register */
-- 
1.7.1