[PATCH v5 02/12] clk: sunxi-ng: Use u64 for calculation of nkmp rate
From: Jernej Skrabec <hidden>
Date: 2018-02-14 20:09:43
Also in:
dri-devel, linux-clk, linux-devicetree, lkml
Subsystem:
arm/allwinner sunxi soc support, common clk framework, the rest · Maintainers:
Chen-Yu Tsai, Jernej Skrabec, Samuel Holland, Michael Turquette, Stephen Boyd, Linus Torvalds
When parent rate is 24MHz and multiplier N >= 180, intermediate clock rate doesn't fit in 32 bit variable anymore. Because of that, introduce function for calculating clock rate which uses 64 bit variable for intermediate result. Acked-by: Maxime Ripard <redacted> Signed-off-by: Jernej Skrabec <redacted> --- drivers/clk/sunxi-ng/ccu_nkmp.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/drivers/clk/sunxi-ng/ccu_nkmp.c b/drivers/clk/sunxi-ng/ccu_nkmp.c
index a99068a08315..c3f6fe7be565 100644
--- a/drivers/clk/sunxi-ng/ccu_nkmp.c
+++ b/drivers/clk/sunxi-ng/ccu_nkmp.c@@ -20,6 +20,18 @@ struct _ccu_nkmp { unsigned long p, min_p, max_p; }; +static unsigned long ccu_nkmp_calc_rate(unsigned long parent, + unsigned long n, unsigned long k, + unsigned long m, unsigned long p) +{ + u64 rate = parent; + + rate *= n * k; + do_div(rate, m * p); + + return rate; +} + static void ccu_nkmp_find_best(unsigned long parent, unsigned long rate, struct _ccu_nkmp *nkmp) {
@@ -33,7 +45,9 @@ static void ccu_nkmp_find_best(unsigned long parent, unsigned long rate, for (_p = nkmp->min_p; _p <= nkmp->max_p; _p <<= 1) { unsigned long tmp_rate; - tmp_rate = parent * _n * _k / (_m * _p); + tmp_rate = ccu_nkmp_calc_rate(parent, + _n, _k, + _m, _p); if (tmp_rate > rate) continue;
@@ -107,7 +121,7 @@ static unsigned long ccu_nkmp_recalc_rate(struct clk_hw *hw, p = reg >> nkmp->p.shift; p &= (1 << nkmp->p.width) - 1; - return (parent_rate * n * k >> p) / m; + return ccu_nkmp_calc_rate(parent_rate, n, k, m, 1 << p); } static long ccu_nkmp_round_rate(struct clk_hw *hw, unsigned long rate,
@@ -127,7 +141,8 @@ static long ccu_nkmp_round_rate(struct clk_hw *hw, unsigned long rate, ccu_nkmp_find_best(*parent_rate, rate, &_nkmp); - return *parent_rate * _nkmp.n * _nkmp.k / (_nkmp.m * _nkmp.p); + return ccu_nkmp_calc_rate(*parent_rate, _nkmp.n, _nkmp.k, + _nkmp.m, _nkmp.p); } static int ccu_nkmp_set_rate(struct clk_hw *hw, unsigned long rate,
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2.16.1