Re: [PATCH v3 05/10] serial: mps2-uart: add support for early console
From: Andy Shevchenko <hidden>
Date: 2016-02-16 10:36:15
Also in:
linux-api, linux-arm-kernel, linux-serial, lkml
On Tue, Feb 16, 2016 at 12:08 PM, Vladimir Murzin [off-list ref] wrote:
This adds support early console for MPS2 UART which can be enabled via earlycon=mps2,0x40004000
quoted hunk ↗ jump to hunk
--- a/drivers/tty/serial/mps2-uart.c +++ b/drivers/tty/serial/mps2-uart.c@@ -435,6 +435,36 @@ static struct console mps2_uart_console = { #define MPS2_SERIAL_CONSOLE (&mps2_uart_console) +static void mps2_early_putchar(struct uart_port *port, int ch) +{ + + while (readb(port->membase + UARTn_STATE) & UARTn_STATE_TX_FULL) + cpu_relax();
Infinite busy loop?
+
+ writeb((unsigned char)ch, port->membase + UARTn_DATA);
+}
+
+
+static void mps2_early_write(struct console *con, const char *s, unsigned n)
+{
+ struct earlycon_device *dev = con->data;
+
+ uart_console_write(&dev->port, s, n, mps2_early_putchar);
+}
+
+static int __init mps2_early_console_setup(struct earlycon_device *device,
+ const char *opt)
+{
+ if (!device->port.membase)
+ return -ENODEV;
+
+ device->con->write = mps2_early_write;
+
+ return 0;
+}
+EARLYCON_DECLARE(mps2, mps2_early_console_setup);
+OF_EARLYCON_DECLARE(mps2, "arm,mps2-uart", mps2_early_console_setup);IIRC Peter Hurley mentioned you don't need to put both anymore, OF_ one is enough. -- With Best Regards, Andy Shevchenko