linux-kernel - [PATCH] clk: sophgo: Use div64 for fpll rate calculation

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Date: Sat, 13 Apr 2024 08:53:33 +0800
From: Inochi Amaoto <inochiama@...look.com>
To: Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Chen Wang <unicorn_wang@...look.com>,
	Inochi Amaoto <inochiama@...look.com>
Cc: linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	kernel test robot <lkp@...el.com>
Subject: [PATCH] clk: sophgo: Use div64 for fpll rate calculation

The CV1800 SoC needs to use 64-bit division for fpll rate
calculation, which will cause problem on 32-bit system.
Use div64 series function to avoid this problem.

Fixes: 80fd61ec4612 ("clk: sophgo: Add clock support for CV1800 SoC")
Signed-off-by: Inochi Amaoto <inochiama@...look.com>
Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404122344.d5pb2N1I-lkp@intel.com/
---
 drivers/clk/sophgo/clk-cv18xx-pll.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/sophgo/clk-cv18xx-pll.c b/drivers/clk/sophgo/clk-cv18xx-pll.c
index c546dad1791c..65aba3b95cf7 100644
--- a/drivers/clk/sophgo/clk-cv18xx-pll.c
+++ b/drivers/clk/sophgo/clk-cv18xx-pll.c
@@ -6,6 +6,7 @@
 #include <linux/clk-provider.h>
 #include <linux/io.h>
 #include <linux/limits.h>
+#include <linux/math64.h>
 #include <linux/spinlock.h>

 #include "clk-cv18xx-pll.h"
@@ -202,18 +203,18 @@ static unsigned long fpll_calc_rate(unsigned long parent_rate,
 {
 	u64 dividend = parent_rate * div_sel;
 	u64 factor = ssc_syn_set * pre_div_sel * post_div_sel;
+	u64 remainder;
 	unsigned long rate;

 	dividend <<= PLL_SYN_FACTOR_DOT_POS - 1;
-	rate = dividend / factor;
-	dividend %= factor;
+	rate = div64_u64_rem(dividend, factor, &remainder);

 	if (is_full_parent) {
-		dividend <<= 1;
+		remainder <<= 1;
 		rate <<= 1;
 	}

-	rate += DIV64_U64_ROUND_CLOSEST(dividend, factor);
+	rate += DIV64_U64_ROUND_CLOSEST(remainder, factor);

 	return rate;
 }
--
2.44.0