console: Set Linux console parameter automatically

Linux specifies the linux,stdout-path property in the /chosen node
in the devicetree. Unfortunately this is ignored in most cases.
For cases in which barebox uses this property for its own use we
translate this into a Linux boot arg with:

- the console name provided by the serial driver
- the the instance from the 'serial' alias
- the baudrate from the actual baudrate.

So with this it's for devicetee enabled boards no longer necessary
to manually assign a console= parameter. Should a user not want
to use the automatically assigned parameter it should do:

global.linux.bootargs.console=

in the environment.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

common/console.c

@@ -31,6 +31,8 @@
 #include <kfifo.h>
 #include <module.h>
 #include <poller.h>
+#include <magicvar.h>
+#include <globalvar.h>
 #include <linux/list.h>
 #include <linux/stringify.h>
 #include <debug_ll.h>
@@ -140,6 +142,26 @@ static void console_init_early(void)
 	initialized = CONSOLE_INITIALIZED_BUFFER;
 }
 
+static void console_set_stdoutpath(struct console_device *cdev)
+{
+	int id;
+	char *str;
+
+	if (!cdev->linux_console_name)
+		return;
+
+	id = of_alias_get_id(cdev->dev->device_node, "serial");
+	if (id < 0)
+		return;
+
+	str = asprintf("console=%s%d,%dn8", cdev->linux_console_name,
+			id, cdev->baudrate);
+
+	globalvar_add_simple("linux.bootargs.console", str);
+
+	free(str);
+}
+
 int console_register(struct console_device *newcdev)
 {
 	struct device_d *dev = &newcdev->class_dev;
@@ -169,8 +191,10 @@ int console_register(struct console_device *newcdev)
 		activate = 1;
 	}
 
-	if (newcdev->dev && of_device_is_stdout_path(newcdev->dev))
+	if (newcdev->dev && of_device_is_stdout_path(newcdev->dev)) {
 		activate = 1;
+		console_set_stdoutpath(newcdev);
+	}
 
 	list_add_tail(&newcdev->list, &console_list);
 
@@ -357,3 +381,6 @@ int ctrlc (void)
 }
 EXPORT_SYMBOL(ctrlc);
 #endif /* ARCH_HAS_CTRC */
+
+BAREBOX_MAGICVAR_NAMED(global_linux_bootargs_console, global.linux.bootargs.console,
+		"console= argument for Linux from the linux,stdout-path property in /chosen node");

defaultenv-2/base/bin/init

@@ -8,6 +8,7 @@ global autoboot_timeout
 global boot.default
 global allow_color
 global linux.bootargs.base
+global linux.bootargs.console
 #linux.bootargs.dyn.* will be cleared at the beginning of boot
 global linux.bootargs.dyn.ip
 global linux.bootargs.dyn.root

drivers/serial/serial_imx.c

@@ -336,6 +336,7 @@ static int imx_serial_probe(struct device_d *dev)
 	cdev->getc = imx_serial_getc;
 	cdev->flush = imx_serial_flush;
 	cdev->setbrg = imx_serial_setbaudrate;
+	cdev->linux_console_name = "ttymxc";
 
 	imx_serial_init_port(cdev);
 

drivers/serial/serial_ns16550.c

@@ -57,6 +57,7 @@ static inline struct ns16550_priv *to_ns16550_priv(struct console_device *cdev)
 
 struct ns16550_drvdata {
 	void (*init_port)(struct console_device *cdev);
+	const char *linux_console_name;
 };
 
 /**
@@ -251,6 +252,7 @@ static struct ns16550_drvdata ns16550_drvdata = {
 
 static __maybe_unused struct ns16550_drvdata omap_drvdata = {
 	.init_port = ns16550_omap_init_port,
+	.linux_console_name = "ttyO",
 };
 
 /**
@@ -312,6 +314,7 @@ static int ns16550_probe(struct device_d *dev)
 	cdev->putc = ns16550_putc;
 	cdev->getc = ns16550_getc;
 	cdev->setbrg = ns16550_setbaudrate;
+	cdev->linux_console_name = devtype->linux_console_name;
 
 	devtype->init_port(cdev);
 

include/console.h

@@ -49,6 +49,8 @@ struct console_device {
 	unsigned char f_active;
 
 	unsigned int baudrate;
+
+	const char *linux_console_name;
 };
 
 int console_register(struct console_device *cdev);