variable number of dependent nested loops

Given two integers n and d, I would like to construct a list of all nonnegative tuples of length d that sum up to n, including all permutations. This is similar to the integer partitioning problem, but the solution is much simpler. For example for d==3:

[
    [n-i-j, j, i]
    for i in range(n+1)
    for j in range(n-i+1)
]

This can be extended to more dimensions quite easily, e.g., d==5:

[
    [n-i-j-k-l, l, k, j, i]
    for i in range(n+1)
    for j in range(n-i+1)
    for k in range(n-i-j+1)
    for l in range(n-i-j-l+1)
]

I would now like to make d, i.e., the number of nested loops, a variable, but I'm not sure how to nest the loops then.

Any hints?