Add DT earlycon for omap_serial driver. This boot console is included
with CONFIG_SERIAL_EARLYCON=y, CONFIG_OF=y, CONFIG_SERIAL_OMAP=y, and
CONFIG_OF_EARLY_FLATTREE=y.
This boot console is enabled with the command line option "earlycon"
(without "=<name>...") when the DT 'stdout-path' property matches a
compatible uart.
Signed-off-by: Lokesh Vutla <lokeshvutla@xxxxxx>
---
drivers/tty/serial/omap-serial.c | 55 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 55 insertions(+)
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index a2a529994ba5..3bbc4b5b6245 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1234,6 +1234,61 @@ static int serial_omap_poll_get_char(struct uart_port *port)
#ifdef CONFIG_SERIAL_OMAP_CONSOLE
+#ifdef CONFIG_SERIAL_EARLYCON
+static unsigned int __init omap_serial_early_in(struct uart_port *port,
+ int offset)
+{
+ offset <<= port->regshift;
+ return readw(port->membase + offset);
+}
+
+static void __init omap_serial_early_out(struct uart_port *port, int offset,
+ int value)
+{
+ offset <<= port->regshift;
+ writew(value, port->membase + offset);
+}
+
+static void __init omap_serial_early_putc(struct uart_port *port, int c)
+{
+ unsigned int status;
+
+ for (;;) {
+ status = omap_serial_early_in(port, UART_LSR);
+ if ((status & BOTH_EMPTY) == BOTH_EMPTY)
+ break;
+ cpu_relax();
+ }
+ omap_serial_early_out(port, UART_TX, c);
+}
+
+static void __init early_omap_serial_write(struct console *console,
+ const char *s, unsigned int count)
+{
+ struct earlycon_device *device = console->data;
+ struct uart_port *port = &device->port;
+
+ uart_console_write(port, s, count, omap_serial_early_putc);
+}
+
+static int __init early_omap_serial_setup(struct earlycon_device *device,
+ const char *options)
+{
+ struct uart_port *port = &device->port;
+
+ if (!(device->port.membase || device->port.iobase))
+ return -ENODEV;
+
+ port->regshift = 2;
+ device->con->write = early_omap_serial_write;
+ return 0;
+}
+
+OF_EARLYCON_DECLARE(omapserial, "ti,omap2-uart", early_omap_serial_setup);
+OF_EARLYCON_DECLARE(omapserial, "ti,omap3-uart", early_omap_serial_setup);
+OF_EARLYCON_DECLARE(omapserial, "ti,omap4-uart", early_omap_serial_setup);
+#endif /* CONFIG_SERIAL_EARLYCON */
+
static struct uart_omap_port *serial_omap_console_ports[OMAP_MAX_HSUART_PORTS];
static struct uart_driver serial_omap_reg;
--
2.11.0
--
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