Use const in PROGRAMMER function arguments where appropriate

In order to get meaningful const properties for the PROGRAMMER, AVRPART and
AVRMEM arguments, some code needed to be moved around, otherwise a network of
"tainted" assignments risked rendering nothing const:

 - Change void (*enable)(PROGRAMMER *pgm) to void (*enable)(PROGRAMMER *pgm,
   const AVRPART *p); this allows changes in the PROGRAMMER structure after
   the part is known. For example, use TPI, UPDI, PDI functions in that
   programmer appropriate to the part. This used to be done later in the
   process, eg, in the initialize() function, which "taints" all other
   programmer functions wrt const and sometimes requires other finessing with
   flags etc. Much clearer with the modified enable() interface.

 - Move TPI initpgm-type code from initialize() to enable() --- note that
   initpgm() does not have the info at the time when it is called whether or
   not TPI is required

 - buspirate.c: move pgm->flag to PDATA(pgm)->flag (so legitimate
   modification of the flag does not change PROGRAMMER structure)

 - Move AVRPART_INIT_SMC and AVRPART_WRITE bits from the flags field in
   AVRPART to jtagmkII.c's private data flags32 fiels as FLAGS32_INIT_SMC and
   FLAGS32_WRITE bits

 - Move the xbeeResetPin component to private data in stk500.c as this is
   needed by xbee when it saddles on the stk500 code (previously, the flags
   component of the part was re-dedicated to this)

 - Change the way the "chained" private data are used in jtag3.c whilst
   keeping the PROGRAMMER structure read-only otherwise

 - In stk500v2.c move the STK600 pgm update from stk500v2_initialize() to
   stk500v2_enable() so the former keeps the PROGRAMMER structure read-only
   (for const assertion).

 - In usbasp change the code from changing PROGRAMMER functions late to
   dispatching to TPI or regular SPI protocol functions at runtime; reason
   being the decision whether to use TPI protocol is done at run-time
   depending on the capability of the attached programmer

Also fixes Issue #1071, the treatment of default eecr value.

src/par.c

@@ -73,8 +73,7 @@ static struct ppipins_t ppipins[] = {
 
 #define NPINS (sizeof(ppipins)/sizeof(struct ppipins_t))
 
-static int par_setpin_internal(PROGRAMMER * pgm, int pin, int value)
-{
+static int par_setpin_internal(const PROGRAMMER *pgm, int pin, int value) {
   int inverted;
 
   inverted = pin & PIN_INVERSE;
@@ -102,13 +101,11 @@ static int par_setpin_internal(PROGRAMMER * pgm, int pin, int value)
   return 0;
 }
 
-static int par_setpin(PROGRAMMER * pgm, int pinfunc, int value)
-{
+static int par_setpin(const PROGRAMMER * pgm, int pinfunc, int value) {
   return par_setpin_internal(pgm, pgm->pinno[pinfunc], value);
 }
 
-static void par_setmany(PROGRAMMER * pgm, int pinfunc, int value)
-{
+static void par_setmany(const PROGRAMMER *pgm, int pinfunc, int value) {
   int pin, mask;
   int pinset = pgm->pinno[pinfunc];
 
@@ -121,8 +118,7 @@ static void par_setmany(PROGRAMMER * pgm, int pinfunc, int value)
   }
 }
 
-static int par_getpin(PROGRAMMER * pgm, int pinfunc)
-{
+static int par_getpin(const PROGRAMMER * pgm, int pinfunc) {
   int value;
   int inverted;
   int pin = pgm->pinno[pinfunc];
@@ -150,8 +146,7 @@ static int par_getpin(PROGRAMMER * pgm, int pinfunc)
 }
 
 
-static int par_highpulsepin(PROGRAMMER * pgm, int pinfunc)
-{
+static int par_highpulsepin(const PROGRAMMER *pgm, int pinfunc) {
   int inverted;
   int pin = pgm->pinno[pinfunc];
 
@@ -190,8 +185,7 @@ static int par_highpulsepin(PROGRAMMER * pgm, int pinfunc)
 /*
  * apply power to the AVR processor
  */
-static void par_powerup(PROGRAMMER * pgm)
-{
+static void par_powerup(const PROGRAMMER *pgm) {
   par_setmany(pgm, PPI_AVR_VCC, 1);	/* power up */
   usleep(100000);
 }
@@ -200,18 +194,15 @@ static void par_powerup(PROGRAMMER * pgm)
 /*
  * remove power from the AVR processor
  */
-static void par_powerdown(PROGRAMMER * pgm)
-{
+static void par_powerdown(const PROGRAMMER *pgm) {
   par_setmany(pgm, PPI_AVR_VCC, 0);	/* power down */
 }
 
-static void par_disable(PROGRAMMER * pgm)
-{
+static void par_disable(const PROGRAMMER *pgm) {
   par_setmany(pgm, PPI_AVR_BUFF, 1); /* turn off */
 }
 
-static void par_enable(PROGRAMMER * pgm)
-{
+static void par_enable(PROGRAMMER *pgm, const AVRPART *p) {
   /*
    * Prepare to start talking to the connected device - pull reset low
    * first, delay a few milliseconds, then enable the buffer.  This
@@ -232,8 +223,7 @@ static void par_enable(PROGRAMMER * pgm)
   par_setmany(pgm, PPI_AVR_BUFF, 0);
 }
 
-static int par_open(PROGRAMMER * pgm, char * port)
-{
+static int par_open(PROGRAMMER *pgm, const char *port) {
   int rc;
 
   if (bitbang_check_prerequisites(pgm) < 0)
@@ -267,8 +257,7 @@ static int par_open(PROGRAMMER * pgm, char * port)
 }
 
 
-static void par_close(PROGRAMMER * pgm)
-{
+static void par_close(PROGRAMMER *pgm) {
 
   /*
    * Restore pin values before closing,
@@ -331,40 +320,41 @@ static void par_close(PROGRAMMER * pgm)
 /*
  * parse the -E string
  */
-static int par_parseexitspecs(PROGRAMMER * pgm, char *s)
-{
-  char *cp;
+static int par_parseexitspecs(PROGRAMMER *pgm, const char *sp) {
+  char *cp, *s, *str = cfg_strdup("par_parseexitspecs()", sp);
 
-  while ((cp = strtok(s, ","))) {
-    if (strcmp(cp, "reset") == 0) {
+  s = str;
+  while((cp = strtok(s, ","))) {
+    if(strcmp(cp, "reset") == 0)
       pgm->exit_reset = EXIT_RESET_ENABLED;
-    }
-    else if (strcmp(cp, "noreset") == 0) {
+
+    else if(strcmp(cp, "noreset") == 0)
       pgm->exit_reset = EXIT_RESET_DISABLED;
-    }
-    else if (strcmp(cp, "vcc") == 0) {
+
+    else if(strcmp(cp, "vcc") == 0)
       pgm->exit_vcc = EXIT_VCC_ENABLED;
-    }
-    else if (strcmp(cp, "novcc") == 0) {
+
+    else if(strcmp(cp, "novcc") == 0)
       pgm->exit_vcc = EXIT_VCC_DISABLED;
-    }
-    else if (strcmp(cp, "d_high") == 0) {
+
+    else if(strcmp(cp, "d_high") == 0)
       pgm->exit_datahigh = EXIT_DATAHIGH_ENABLED;
-    }
-    else if (strcmp(cp, "d_low") == 0) {
+
+    else if(strcmp(cp, "d_low") == 0)
       pgm->exit_datahigh = EXIT_DATAHIGH_DISABLED;
-    }
+
     else {
+      free(str);
       return -1;
     }
-    s = 0; /* strtok() should be called with the actual string only once */
+    s = NULL; // Only call strtok() once with the actual string
   }
 
+  free(str);
   return 0;
 }
 
-void par_initpgm(PROGRAMMER * pgm)
-{
+void par_initpgm(PROGRAMMER *pgm) {
   strcpy(pgm->type, "PPI");
 
   pgm_fill_old_pins(pgm); // TODO to be removed if old pin data no longer needed
@@ -400,10 +390,8 @@ void par_initpgm(PROGRAMMER * pgm)
 
 #else  /* !HAVE_PARPORT */
 
-void par_initpgm(PROGRAMMER * pgm)
-{
-  avrdude_message(MSG_INFO, "%s: parallel port access not available in this configuration\n",
-                  progname);
+void par_initpgm(PROGRAMMER *pgm) {
+  avrdude_message(MSG_INFO, "%s: parallel port access not available in this configuration\n", progname);
 }
 
 #endif /* HAVE_PARPORT */