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authorScott Telford <stelford@cadence.com>2016-09-22 16:58:16 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-09-27 12:54:41 +0200
commitc41251b17563234371a9b376ed4914efa4bc079b (patch)
tree7fa3e64e794043e6184232621af6a7272b46bacc /drivers/tty
parent212d249b6acbe00ac3617938433ce785c2d68e88 (diff)
serial: xuartps: Add some register initialisation to cdns_early_console_setup()
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@cadence.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/xilinx_uartps.c27
1 files changed, 26 insertions, 1 deletions
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 39f41bfd7c22..f37edaa5ac75 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;