serial: earlycon: Refactor parse_options into serial core

Prepare to support console-defined matching; refactor the command
line parameter string processing from parse_options() into a
new core function, uart_parse_earlycon(), which decodes command line
parameters of the form:
   earlycon=<name>,io|mmio|mmio32,<addr>,<options>
   console=<name>,io|mmio|mmio32,<addr>,<options>
   earlycon=<name>,0x<addr>,<options>
   console=<name>,0x<addr>,<options>

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 63d29473c703..8379e3fa0162 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1809,6 +1809,52 @@ uart_get_console(struct uart_port *ports, int nr, struct console *co)
 }
 
 /**
+ *      uart_parse_earlycon - Parse earlycon options
+ *      @p:       ptr to 2nd field (ie., just beyond '<name>,')
+ *      @iotype:  ptr for decoded iotype (out)
+ *      @addr:    ptr for decoded mapbase/iobase (out)
+ *      @options: ptr for <options> field; NULL if not present (out)
+ *
+ *      Decodes earlycon kernel command line parameters of the form
+ *         earlycon=<name>,io|mmio|mmio32,<addr>,<options>
+ *         console=<name>,io|mmio|mmio32,<addr>,<options>
+ *
+ *      The optional form
+ *         earlycon=<name>,0x<addr>,<options>
+ *         console=<name>,0x<addr>,<options>
+ *      is also accepted; the returned @iotype will be UPIO_MEM.
+ *
+ *      Returns 0 on success or -EINVAL on failure
+ */
+int uart_parse_earlycon(char *p, unsigned char *iotype, unsigned long *addr,
+                        char **options)
+{
+        if (strncmp(p, "mmio,", 5) == 0) {
+                *iotype = UPIO_MEM;
+                p += 5;
+        } else if (strncmp(p, "mmio32,", 7) == 0) {
+                *iotype = UPIO_MEM32;
+                p += 7;
+        } else if (strncmp(p, "io,", 3) == 0) {
+                *iotype = UPIO_PORT;
+                p += 3;
+        } else if (strncmp(p, "0x", 2) == 0) {
+                *iotype = UPIO_MEM;
+        } else {
+                return -EINVAL;
+        }
+
+        *addr = simple_strtoul(p, NULL, 0);
+        p = strchr(p, ',');
+        if (p)
+                p++;
+
+        *options = p;
+        return 0;
+}
+EXPORT_SYMBOL_GPL(uart_parse_earlycon);
+
+/**
  *      uart_parse_options - Parse serial port baud/parity/bits/flow control.
  *      @options: pointer to option string
  *      @baud: pointer to an 'int' variable for the baud rate.