Add initialisation of control register and baud rate to
cdns_early_console_setup(), required when running kernel standalone
without a boot loader. Baud rate is only initialised when specified in
earlycon command-line option, otherwise it is assumed this has been
set by a boot loader. Updated Documentation/kernel-parameters.txt
accordingly.
Signed-off-by: Scott Telford <stelford@xxxxxxxxxxx>
---
Documentation/kernel-parameters.txt | 11 ++++++-----
drivers/tty/serial/xilinx_uartps.c | 27 ++++++++++++++++++++++++++-
2 files changed, 32 insertions(+), 6 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a4f4d69..70b51f8 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1045,11 +1045,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
determined by the stdout-path property in device
tree's chosen node.
- cdns,<addr>
- Start an early, polled-mode console on a cadence serial
- port at the specified address. The cadence serial port
- must already be setup and configured. Options are not
- yet supported.
+ cdns,<addr>[,options]
+ Start an early, polled-mode console on a Cadence
+ (xuartps) serial port at the specified address. Only
+ supported option is baud rate. If baud rate is not
+ specified, the serial port must already be setup and
+ configured.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index e13006d..5119af6 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1165,9 +1165,34 @@ static void __init cdns_early_write(struct console *con, const char *s,
static int __init cdns_early_console_setup(struct earlycon_device *device,
const char *opt)
{
- if (!device->port.membase)
+ struct uart_port *port = &device->port;
+
+ if (!port->membase)
return -ENODEV;
+ /* initialise control register */
+ writel(CDNS_UART_CR_TX_EN|CDNS_UART_CR_TXRST|CDNS_UART_CR_RXRST,
+ port->membase + CDNS_UART_CR);
+
+ /* only set baud if specified on command line - otherwise
+ * assume it has been initialized by a boot loader.
+ */
+ if (device->baud) {
+ u32 cd = 0, bdiv = 0;
+ u32 mr;
+ int div8;
+
+ cdns_uart_calc_baud_divs(port->uartclk, device->baud,
+ &bdiv, &cd, &div8);
+ mr = CDNS_UART_MR_PARITY_NONE;
+ if (div8)
+ mr |= CDNS_UART_MR_CLKSEL;
+
+ writel(mr, port->membase + CDNS_UART_MR);
+ writel(cd, port->membase + CDNS_UART_BAUDGEN);
+ writel(bdiv, port->membase + CDNS_UART_BAUDDIV);
+ }
+
device->con->write = cdns_early_write;
return 0;
--
2.2.2
--
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