[console] Allow usage to be defined independently for each console

Add the concept of a "console usage", such as "standard output" or
"debug messages".  Allow usages to be associated with each console
independently.  For example, to send debugging output via the serial
port, while preventing it from appearing on the local console:

  #define CONSOLE_SERIAL CONSOLE_USAGE_ALL
  #define CONSOLE_PCBIOS ( CONSOLE_USAGE_ALL & ~CONSOLE_USAGE_DEBUG )

If no usages are explicitly specified, then a default set of usages
will be applied.  For example:

  #define CONSOLE_SERIAL

will have the same affect as

  #define CONSOLE_SERIAL CONSOLE_USAGE_ALL

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/i386/core/video_subr.c

@@ -11,6 +11,14 @@
 #include <ipxe/console.h>
 #include <ipxe/init.h>
 #include "vga.h"
+#include <config/console.h>
+
+/* Set default console usage if applicable */
+#if ! ( defined ( CONSOLE_DIRECT_VGA ) && \
+	CONSOLE_EXPLICIT ( CONSOLE_DIRECT_VGA ) )
+#undef CONSOLE_DIRECT_VGA
+#define CONSOLE_DIRECT_VGA CONSOLE_USAGE_ALL
+#endif
 
 struct console_driver vga_console __console_driver;
 
@@ -97,6 +105,7 @@ static void vga_putc(int byte)
 struct console_driver vga_console __console_driver = {
 	.putchar = vga_putc,
 	.disabled = 1,
+	.usage = CONSOLE_DIRECT_VGA,
 };
 
 struct init_fn video_init_fn __init_fn ( INIT_EARLY ) = {

src/arch/i386/firmware/pcbios/bios_console.c

@@ -23,6 +23,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <ipxe/console.h>
 #include <ipxe/ansiesc.h>
 #include <ipxe/keymap.h>
+#include <config/console.h>
 
 #define ATTR_BOLD		0x08
 
@@ -48,6 +49,12 @@ FILE_LICENCE ( GPL2_OR_LATER );
 
 #define ATTR_DEFAULT		ATTR_FCOL_WHITE
 
+/* Set default console usage if applicable */
+#if ! ( defined ( CONSOLE_PCBIOS ) && CONSOLE_EXPLICIT ( CONSOLE_PCBIOS ) )
+#undef CONSOLE_PCBIOS
+#define CONSOLE_PCBIOS CONSOLE_USAGE_ALL
+#endif
+
 /** Current character attribute */
 static unsigned int bios_attr = ATTR_DEFAULT;
 
@@ -319,4 +326,5 @@ struct console_driver bios_console __console_driver = {
 	.putchar = bios_putchar,
 	.getchar = bios_getchar,
 	.iskey = bios_iskey,
+	.usage = CONSOLE_PCBIOS,
 };

src/arch/i386/interface/vmware/vmconsole.c

@@ -29,10 +29,17 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <ipxe/lineconsole.h>
 #include <ipxe/init.h>
 #include <ipxe/guestrpc.h>
+#include <config/console.h>
 
 /** VMware logfile console buffer size */
 #define VMCONSOLE_BUFSIZE 128
 
+/* Set default console usage if applicable */
+#if ! ( defined ( CONSOLE_VMWARE ) && CONSOLE_EXPLICIT ( CONSOLE_VMWARE ) )
+#undef CONSOLE_VMWARE
+#define CONSOLE_VMWARE CONSOLE_USAGE_ALL
+#endif
+
 /** VMware logfile console GuestRPC channel */
 static int vmconsole_channel;
 
@@ -87,6 +94,7 @@ static void vmconsole_putchar ( int character ) {
 struct console_driver vmconsole __console_driver = {
 	.putchar = vmconsole_putchar,
 	.disabled = 1,
+	.usage = CONSOLE_VMWARE,
 };
 
 /**