I have a simple DSolve[ ] of a Piecewise function

DSolve[{gg''[x]==sol3},{gg[x]},x]

where sol3 is a piecewise function. But , when I try to enter boundary conditions like

DSolve[{gg[x]==sol3, gg[.9]=0 }, gg[x],x]

returns an error. The piecewise contains polynomial equations.

sol0 = Piecewise[{{1, 0 <= x < 1}, {-2, 1 <= x < 2}, {1, 2 <= x < 3}}]

sol00p = Plot[{sol0}, {x, -.1, 3.3}, Filling -> Axis, Exclusions -> None]

sol1 = Integrate[sol0, x]

sol10p = Plot[{sol1}, {x, -.1, 4.3}, Filling -> Axis, Exclusions -> None]

sol2=DSolve[{y''[x]=sol1},y[x],x]

Now what my interest is the DSolve of the piecewise equation from 2 degree to first degree. I need to add boundary conditions. But I get an error. For example, when trying y'[.2]=0,y[3]=0.