target: Add new methods for read/write individual regs.

src/include/target.h

@@ -62,6 +62,8 @@ size_t target_regs_size(target *t);
 const char *target_tdesc(target *t);
 void target_regs_read(target *t, void *data);
 void target_regs_write(target *t, const void *data);
+ssize_t target_reg_read(target *t, int reg, void *data, size_t max);
+ssize_t target_reg_write(target *t, int reg, const void *data, size_t size);
 
 /* Halt/resume functions */
 enum target_halt_reason {

src/target/target.c

@@ -337,6 +337,16 @@ int target_mem_write(target *t, target_addr dest, const void *src, size_t len)
 }
 
 /* Register access functions */
+ssize_t target_reg_read(target *t, int reg, void *data, size_t max)
+{
+	return t->reg_read(t, reg, data, max);
+}
+
+ssize_t target_reg_write(target *t, int reg, const void *data, size_t size)
+{
+	return t->reg_write(t, reg, data, size);
+}
+
 void target_regs_read(target *t, void *data) { t->regs_read(t, data); }
 void target_regs_write(target *t, const void *data) { t->regs_write(t, data); }
 

src/target/target_internal.h

@@ -92,6 +92,8 @@ struct target_s {
 	const char *tdesc;
 	void (*regs_read)(target *t, void *data);
 	void (*regs_write)(target *t, const void *data);
+	ssize_t (*reg_read)(target *t, int reg, void *data, size_t max);
+	ssize_t (*reg_write)(target *t, int reg, const void *data, size_t size);
 
 	/* Halt/resume functions */
 	void (*reset)(target *t);