Where does the dust on Mars come from?

The movie “The Martian” begins with the hero being separated from his crew by a dust storm and then being left behind, presumed dead, alone on Mars. In fact, because of its very thin atmosphere, a storm on Mars would feel like a light breeze on Earth and would definitely not have the force to knock over a spaceship. But Martian storms could certainly produce problems, because they would darken the sky, and this would make generating energy from sunlight no longer possible.

But where does the...