serial: earlycon: add DT support

This adds the infrastructure to generic earlycon for earlycon setup
using DT. The actual setup is not enabled until a following commit to
add the FDT parsing.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Grant Likely <grant.likely@linaro.org>

1 files changed, 28 insertions, 0 deletions

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index c92e83088adb..5131b5ee6164 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -15,6 +15,8 @@
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/serial_core.h>
+#include <linux/sizes.h>
+#include <linux/mod_devicetable.h>
 
 #ifdef CONFIG_FIX_EARLYCON_MEM
 #include <asm/fixmap.h>
@@ -32,6 +34,9 @@ static struct earlycon_device early_console_dev = {
         .con = &early_con,
 };
 
+static const struct of_device_id __earlycon_of_table_sentinel
+        __used __section(__earlycon_of_table_end);
+
 static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
 {
         void __iomem *base;
@@ -142,3 +147,26 @@ int __init setup_earlycon(char *buf, const char *match,
         register_console(early_console_dev.con);
         return 0;
 }
+
+int __init of_setup_earlycon(unsigned long addr,
+                             int (*setup)(struct earlycon_device *, const char *))
+{
+        int err;
+        struct uart_port *port = &early_console_dev.port;
+
+        port->iotype = UPIO_MEM;
+        port->mapbase = addr;
+        port->uartclk = BASE_BAUD * 16;
+        port->membase = earlycon_map(addr, SZ_4K);
+
+        early_console_dev.con->data = &early_console_dev;
+        err = setup(&early_console_dev, NULL);
+        if (err < 0)
+                return err;
+        if (!early_console_dev.con->write)
+                return -ENODEV;
+
+
+        register_console(early_console_dev.con);
+        return 0;
+}