clk: sunxi-ng: Remove the use of rational computations

While the rational library works great, it doesn't really allow us to add
more constraints, like the minimum.

Remove that in order to be able to deal with the constraints we'll need.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>

1 files changed, 41 insertions, 13 deletions

diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
index b61bdd8c7a7f..c6d652289320 100644
--- a/drivers/clk/sunxi-ng/ccu_nm.c
+++ b/drivers/clk/sunxi-ng/ccu_nm.c
@@ -9,12 +9,42 @@
  */
 
 #include <linux/clk-provider.h>
-#include <linux/rational.h>
 
 #include "ccu_frac.h"
 #include "ccu_gate.h"
 #include "ccu_nm.h"
 
+struct _ccu_nm {
+	unsigned long	n, max_n;
+	unsigned long	m, max_m;
+};
+
+static void ccu_nm_find_best(unsigned long parent, unsigned long rate,
+			     struct _ccu_nm *nm)
+{
+	unsigned long best_rate = 0;
+	unsigned long best_n = 0, best_m = 0;
+	unsigned long _n, _m;
+
+	for (_n = 1; _n <= nm->max_n; _n++) {
+		for (_m = 1; _n <= nm->max_m; _m++) {
+			unsigned long tmp_rate = parent * _n  / _m;
+
+			if (tmp_rate > rate)
+				continue;
+
+			if ((rate - tmp_rate) < (rate - best_rate)) {
+				best_rate = tmp_rate;
+				best_n = _n;
+				best_m = _m;
+			}
+		}
+	}
+
+	nm->n = best_n;
+	nm->m = best_m;
+}
+
 static void ccu_nm_disable(struct clk_hw *hw)
 {
 	struct ccu_nm *nm = hw_to_ccu_nm(hw);
@@ -61,24 +91,22 @@ static long ccu_nm_round_rate(struct clk_hw *hw, unsigned long rate,
 			      unsigned long *parent_rate)
 {
 	struct ccu_nm *nm = hw_to_ccu_nm(hw);
-	unsigned long max_n, max_m;
-	unsigned long n, m;
+	struct _ccu_nm _nm;
 
-	max_n = 1 << nm->n.width;
-	max_m = nm->m.max ?: 1 << nm->m.width;
+	_nm.max_n = 1 << nm->n.width;
+	_nm.max_m = nm->m.max ?: 1 << nm->m.width;
 
-	rational_best_approximation(rate, *parent_rate, max_n, max_m, &n, &m);
+	ccu_nm_find_best(*parent_rate, rate, &_nm);
 
-	return *parent_rate * n / m;
+	return *parent_rate * _nm.n / _nm.m;
 }
 
 static int ccu_nm_set_rate(struct clk_hw *hw, unsigned long rate,
 			   unsigned long parent_rate)
 {
 	struct ccu_nm *nm = hw_to_ccu_nm(hw);
+	struct _ccu_nm _nm;
 	unsigned long flags;
-	unsigned long max_n, max_m;
-	unsigned long n, m;
 	u32 reg;
 
 	if (ccu_frac_helper_has_rate(&nm->common, &nm->frac, rate))
@@ -86,10 +114,10 @@ static int ccu_nm_set_rate(struct clk_hw *hw, unsigned long rate,
 	else
 		ccu_frac_helper_disable(&nm->common, &nm->frac);
 
-	max_n = 1 << nm->n.width;
-	max_m = nm->m.max ?: 1 << nm->m.width;
+	_nm.max_n = 1 << nm->n.width;
+	_nm.max_m = nm->m.max ?: 1 << nm->m.width;
 
-	rational_best_approximation(rate, parent_rate, max_n, max_m, &n, &m);
+	ccu_nm_find_best(parent_rate, rate, &_nm);
 
 	spin_lock_irqsave(nm->common.lock, flags);
 
@@ -97,7 +125,7 @@ static int ccu_nm_set_rate(struct clk_hw *hw, unsigned long rate,
 	reg &= ~GENMASK(nm->n.width + nm->n.shift - 1, nm->n.shift);
 	reg &= ~GENMASK(nm->m.width + nm->m.shift - 1, nm->m.shift);
 
-	writel(reg | ((m - 1) << nm->m.shift) | ((n - 1) << nm->n.shift),
+	writel(reg | ((_nm.m - 1) << nm->m.shift) | ((_nm.n - 1) << nm->n.shift),
 	       nm->common.base + nm->common.reg);
 
 	spin_unlock_irqrestore(nm->common.lock, flags);