From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: From: Marek Vasut To: linux-clk@vger.kernel.org Cc: Marek Vasut , Stephen Boyd , Alexey Firago , Michael Turquette , Laurent Pinchart , linux-renesas-soc@vger.kernel.org Subject: [PATCH 1/8] clk: vc5: Prevent division by zero on unconfigured outputs Date: Thu, 29 Jun 2017 12:18:44 +0200 Message-Id: <20170629101851.23972-1-marek.vasut@gmail.com> List-ID: From: Marek Vasut In case the initial values of the FOD registers are not configured in the OTP or by the bootloader, it is possible that the FOD registers will contain zeroes. The code in vc5_fod_recalc_rate() immediately feeds the FOD divider value obtained from the FOD registers into the div64_u64() and if the FOD divider value is zero, triggers division by zero exception. Check if the FOD divider value is zero and return the frequency of the FOD output as 0 Hz if it is so. This prevents the division by zero exception. Signed-off-by: Marek Vasut Cc: Stephen Boyd Cc: Alexey Firago Cc: Michael Turquette Cc: Laurent Pinchart Cc: linux-renesas-soc@vger.kernel.org --- drivers/clk/clk-versaclock5.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/clk/clk-versaclock5.c b/drivers/clk/clk-versaclock5.c index ea7d552a2f2b..60bf4afb51bd 100644 --- a/drivers/clk/clk-versaclock5.c +++ b/drivers/clk/clk-versaclock5.c @@ -426,6 +426,10 @@ static unsigned long vc5_fod_recalc_rate(struct clk_hw *hw, div_frc = (od_frc[0] << 22) | (od_frc[1] << 14) | (od_frc[2] << 6) | (od_frc[3] >> 2); + /* Avoid division by zero if the output is not configured. */ + if ((div_int == 0) && (div_frc == 0)) + return 0; + /* The PLL divider has 12 integer bits and 30 fractional bits */ return div64_u64((u64)f_in << 24ULL, ((u64)div_int << 24ULL) + div_frc); } -- 2.11.0