Introduce a compile time option to select a default programmer

Heavily influenced by a discussion with (and based on code from) Peter Stuge.
Please read the comment in the Makefile before using this option.

Corresponding to flashrom svn r1607.
Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Peter Stuge <peter@stuge.se>

Makefile

@@ -39,6 +39,18 @@ CFLAGS  ?= -Os -Wall -Wshadow
 EXPORTDIR ?= .
 AR      ?= ar
 RANLIB  ?= ranlib
+# The following parameter changes the default programmer that will be used if there is no -p/--programmer
+# argument given when running flashrom. The predefined setting does not enable any default so that every
+# user has to declare the programmer he wants to use on every run. The rationale for this to be not set
+# (to e.g. the internal programmer) is that forgetting to specify this when working with another programmer
+# easily puts the system attached to the default programmer at risk (e.g. you want to flash coreboot to another
+# system attached to an external programmer while the default programmer is set to the internal programmer, and
+# you forget to use the -p parameter. This would (try to) overwrite the existing firmware of the computer
+# running flashrom). Please do not enable this without thinking about the possible consequences. Possible
+# values are those specified in enum programmer in programmer.h (which depend on other CONFIG_* options
+# evaluated below, namely those that enable/disable the various programmers).
+# Compilation will fail for unspecified values.
+CONFIG_DEFAULT_PROGRAMMER ?= PROGRAMMER_INVALID
 
 # If your compiler spits out excessive warnings, run make WARNERROR=no
 # You shouldn't have to change this flag.
@@ -399,6 +411,8 @@ endif
 ###############################################################################
 # Programmer drivers and programmer support infrastructure.
 
+FEATURE_CFLAGS += -D'CONFIG_DEFAULT_PROGRAMMER=$(CONFIG_DEFAULT_PROGRAMMER)'
+
 ifeq ($(CONFIG_INTERNAL), yes)
 FEATURE_CFLAGS += -D'CONFIG_INTERNAL=1'
 PROGRAMMER_OBJS += processor_enable.o chipset_enable.o board_enable.o cbtable.o dmi.o internal.o

cli_classic.c

@@ -402,12 +402,18 @@ int main(int argc, char *argv[])
 	}
 
 	if (prog == PROGRAMMER_INVALID) {
+		if (CONFIG_DEFAULT_PROGRAMMER != PROGRAMMER_INVALID) {
+			prog = CONFIG_DEFAULT_PROGRAMMER;
+			msg_pinfo("Using default programmer \"%s\".\n",
+				  programmer_table[CONFIG_DEFAULT_PROGRAMMER].name);
+		} else {
 			msg_perr("Please select a programmer with the --programmer parameter.\n"
 				 "Valid choices are:\n");
 			list_programmers_linebreak(0, 80, 0);
 			ret = 1;
 			goto out;
 		}
+	}
 
 	/* FIXME: Delay calibration should happen in programmer code. */
 	myusec_calibrate_delay();