clk: at91: Fix division by zero in PLL recalc_rate()

BugLink: https://bugs.launchpad.net/bugs/1836802
commit 0f5cb0e6225cae2f029944cb8c74617aab6ddd49 upstream.

Commit a982e45dc150 ("clk: at91: PLL recalc_rate() now using cached MUL
and DIV values") removed a check that prevents a division by zero. This
now causes a stacktrace when booting the kernel on a at91 platform if
the PLL DIV register contains zero. This commit reintroduces this check.

Fixes: a982e45dc150 ("clk: at91: PLL recalc_rate() now using cached...")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ronald Wahl <rwahl@gmx.de>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/clk/at91/clk-pll.c b/drivers/clk/at91/clk-pll.c
index 72b6091eb7b944f50b6a2e3d9ceafa8077a851d2..dc7fbc796cb652156cbec8f1483a462948955e40 100644 (file)
--- a/drivers/clk/at91/clk-pll.c
+++ b/drivers/clk/at91/clk-pll.c
@@ -133,6 +133,9 @@ static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
 {
        struct clk_pll *pll = to_clk_pll(hw);
 
+       if (!pll->div || !pll->mul)
+               return 0;
+
        return (parent_rate / pll->div) * (pll->mul + 1);
 }