[PATCH AUTOSEL 4.19 077/206] clk: stratix10: use do_div() for 64-bit calculation

[Sasha Levin]

From: Dinh Nguyen <dinguyen@xxxxxxxxxx>

[ Upstream commit cc26ed7be46c5f5fa45f3df8161ed7ca3c4d318c ]

do_div() macro to perform u64 division and guards against overflow if
the result is too large for the unsigned long return type.

Signed-off-by: Dinh Nguyen <dinguyen@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200114160726.19771-1-dinguyen@xxxxxxxxxx
Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/clk/socfpga/clk-pll-s10.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/socfpga/clk-pll-s10.c b/drivers/clk/socfpga/clk-pll-s10.c
index c4d0b6f6abf2e..fc2e2839fe570 100644
--- a/drivers/clk/socfpga/clk-pll-s10.c
+++ b/drivers/clk/socfpga/clk-pll-s10.c
@@ -38,7 +38,9 @@ static unsigned long clk_pll_recalc_rate(struct clk_hw *hwclk,
 	/* read VCO1 reg for numerator and denominator */
 	reg = readl(socfpgaclk->hw.reg);
 	refdiv = (reg & SOCFPGA_PLL_REFDIV_MASK) >> SOCFPGA_PLL_REFDIV_SHIFT;
-	vco_freq = (unsigned long long)parent_rate / refdiv;
+
+	vco_freq = parent_rate;
+	do_div(vco_freq, refdiv);
 
 	/* Read mdiv and fdiv from the fdbck register */
 	reg = readl(socfpgaclk->hw.reg + 0x4);
-- 
2.25.1