I am trying to list files by their directory an do something with files and go to next directory

this is the folder tree

root
   div1
      subdiv1
         up1
           d1s1u1_1.file
           d1s1u1_2.file
         up2
           d1s1u2_1.file
           d1s1u2_2.file
      subdiv2
         up1
           d1s2u1_1.file
           d1s2u1_2.file
         up2
           d1s2u2_1.file
           d1s2u2_2.file
   div2
      subdiv1
         up1
           d2s1u1_1.file
           d2s1u1_2.file
         up2
           d2s1u2_1.file
           d2s1u2_2.file
      subdiv2
         up1
           d2s2u1_1.file
           d2s2u1_2.file
         up2
           d2s2u2_1.file
           d2s2u2_2.file

   div3
      subdiv1
         up1
           d3s1u1_1.file
           d3s1u1_2.file
         up2
           d3s1u2_1.file
           d3s1u2_2.file
      subdiv2
         up1
           d3s2u1_1.file
           d3s2u1_2.file
         up2
           d3s2u2_1.file
           d3s2u2_2.file

how do I list files under up1 of div1 do something to the listed files and go to up2 and do the same thing for rest of the divs