From: Tobias Klauser <tklauser@distanz.ch>
Date: Wed, 22 Mar 2017 12:50:13 +0000 (+0100)
Subject: serial: altera_uart: add earlycon support
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4d9d7d896d77e70e6868cfe681e7fcd58dc9526d;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

serial: altera_uart: add earlycon support

Nios2 currently uses its own early printk implementation, rather than
using unified earlycon support to show boot messages on altera_uart.

Add earlycon support to altera_uart so that other archs may use it.
Also, this (together with the corresponding patch for altera_jtaguart)
will allow the early printk implementation in arch/nios2 to be removed
in a future patch.

Cc: Ley Foon Tan <lftan@altera.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 896f5eb78da0..5c8850f7a2a0 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1392,6 +1392,7 @@ config SERIAL_ALTERA_UART_CONSOLE
 	bool "Altera UART console support"
 	depends on SERIAL_ALTERA_UART=y
 	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
 	help
 	  Enable a Altera UART port to be the system console.
 
diff --git a/drivers/tty/serial/altera_uart.c b/drivers/tty/serial/altera_uart.c
index 820a74208696..46d3438a0d27 100644
--- a/drivers/tty/serial/altera_uart.c
+++ b/drivers/tty/serial/altera_uart.c
@@ -489,6 +489,38 @@ console_initcall(altera_uart_console_init);
 
 #define	ALTERA_UART_CONSOLE	(&altera_uart_console)
 
+static void altera_uart_earlycon_write(struct console *co, const char *s,
+				       unsigned int count)
+{
+	struct earlycon_device *dev = co->data;
+
+	uart_console_write(&dev->port, s, count, altera_uart_console_putc);
+}
+
+static int __init altera_uart_earlycon_setup(struct earlycon_device *dev,
+					     const char *options)
+{
+	struct uart_port *port = &dev->port;
+
+	if (!port->membase)
+		return -ENODEV;
+
+	/* Enable RX interrupts now */
+	writel(ALTERA_UART_CONTROL_RRDY_MSK,
+	       port->membase + ALTERA_UART_CONTROL_REG);
+
+	if (dev->baud) {
+		unsigned int baudclk = port->uartclk / dev->baud;
+
+		writel(baudclk, port->membase + ALTERA_UART_DIVISOR_REG);
+	}
+
+	dev->con->write = altera_uart_earlycon_write;
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(uart, "altr,uart-1.0", altera_uart_earlycon_setup);
+
 #else
 
 #define	ALTERA_UART_CONSOLE	NULL