target: pass target to observers via const pointer

There are quite a lot of "getters" in target interface.
They do not change target structure, nevertheless the structure is
passed to these functions via a plain pointer.

The intention is to clarify the purpouse of these functions by passing
the `target` structure as a pointer to constant data.

Change-Id: Ida4a798da94938753b86a293a308d93b091d1bf3
Signed-off-by: Evgeniy Naydanov <evgeniy.naydanov@syntacore.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8092
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/target/target.c

@@ -244,7 +244,7 @@ static const struct nvp nvp_reset_modes[] = {
 	{ .name = NULL,      .value = -1 },
 };
 
-const char *debug_reason_name(struct target *t)
+const char *debug_reason_name(const struct target *t)
 {
 	const char *cp;
 
@@ -257,7 +257,7 @@ const char *debug_reason_name(struct target *t)
 	return cp;
 }
 
-const char *target_state_name(struct target *t)
+const char *target_state_name(const struct target *t)
 {
 	const char *cp;
 	cp = nvp_value2name(nvp_target_state, t->state)->name;
@@ -733,7 +733,7 @@ int target_examine(void)
 	return retval;
 }
 
-const char *target_type_name(struct target *target)
+const char *target_type_name(const struct target *target)
 {
 	return target->type->name;
 }
@@ -1398,7 +1398,7 @@ int target_get_gdb_reg_list_noread(struct target *target,
 	return target_get_gdb_reg_list(target, reg_list, reg_list_size, reg_class);
 }
 
-bool target_supports_gdb_connection(struct target *target)
+bool target_supports_gdb_connection(const struct target *target)
 {
 	/*
 	 * exclude all the targets that don't provide get_gdb_reg_list
@@ -4851,7 +4851,7 @@ static int target_jim_set_reg(Jim_Interp *interp, int argc,
 /**
  * Returns true only if the target has a handler for the specified event.
  */
-bool target_has_event_action(struct target *target, enum target_event event)
+bool target_has_event_action(const struct target *target, enum target_event event)
 {
 	struct target_event_action *teap;
 

src/target/target.h

@@ -222,19 +222,19 @@ struct gdb_fileio_info {
 };
 
 /** Returns a description of the endianness for the specified target. */
-static inline const char *target_endianness(struct target *target)
+static inline const char *target_endianness(const struct target *target)
 {
 	return (target->endianness == TARGET_ENDIAN_UNKNOWN) ? "unknown" :
 			(target->endianness == TARGET_BIG_ENDIAN) ? "big endian" : "little endian";
 }
 
 /** Returns the instance-specific name of the specified target. */
-static inline const char *target_name(struct target *target)
+static inline const char *target_name(const struct target *target)
 {
 	return target->cmd_name;
 }
 
-const char *debug_reason_name(struct target *t);
+const char *debug_reason_name(const struct target *t);
 
 enum target_event {
 
@@ -301,7 +301,7 @@ struct target_event_action {
 	struct target_event_action *next;
 };
 
-bool target_has_event_action(struct target *target, enum target_event event);
+bool target_has_event_action(const struct target *target, enum target_event event);
 
 struct target_event_callback {
 	int (*callback)(struct target *target, enum target_event event, void *priv);
@@ -421,7 +421,7 @@ struct target *get_target(const char *id);
  * This routine is a wrapper for the target->type->name field.
  * Note that this is not an instance-specific name for his target.
  */
-const char *target_type_name(struct target *target);
+const char *target_type_name(const struct target *target);
 
 /**
  * Examine the specified @a target, letting it perform any
@@ -432,7 +432,7 @@ const char *target_type_name(struct target *target);
 int target_examine_one(struct target *target);
 
 /** @returns @c true if target_set_examined() has been called. */
-static inline bool target_was_examined(struct target *target)
+static inline bool target_was_examined(const struct target *target)
 {
 	return target->examined;
 }
@@ -527,7 +527,7 @@ int target_get_gdb_reg_list_noread(struct target *target,
  *
  * Some target do not implement the necessary code required by GDB.
  */
-bool target_supports_gdb_connection(struct target *target);
+bool target_supports_gdb_connection(const struct target *target);
 
 /**
  * Step the target.
@@ -694,7 +694,7 @@ unsigned target_address_bits(struct target *target);
 unsigned int target_data_bits(struct target *target);
 
 /** Return the *name* of this targets current state */
-const char *target_state_name(struct target *target);
+const char *target_state_name(const struct target *target);
 
 /** Return the *name* of a target event enumeration value */
 const char *target_event_name(enum target_event event);