loop: mov a,dpl
add a,#1
da a
mov dpl,a
mov a,dph
addc a,#0
da a
mov dph,a
sjmp loop

This will make the dptr count from 0000 to 9999 like crazy in BCD, but I doubt it will do you one spot of good, because there are some "details" missing from your question:
a) WHAT will be the input for your counter
b) HOW do you want to display the result