clk: sunxi-ng: div: Allow to set a maximum

Some dividers might have a maximum value that is lower than the width of
the register.

Add a field to _ccu_div to handle those case properly. If the field is set
to 0, the code will assume that the maximum value is the maximum one that
can be used with the field register width.

Otherwise, we'll use whatever value has been set.

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

1 files changed, 10 insertions, 6 deletions

diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
index e35ddd8..b61bdd8 100644
--- a/drivers/clk/sunxi-ng/ccu_nm.c
+++ b/drivers/clk/sunxi-ng/ccu_nm.c
@@ -61,11 +61,13 @@ 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;
 
-	rational_best_approximation(rate, *parent_rate,
-				    1 << nm->n.width, 1 << nm->m.width,
-				    &n, &m);
+	max_n = 1 << nm->n.width;
+	max_m = nm->m.max ?: 1 << nm->m.width;
+
+	rational_best_approximation(rate, *parent_rate, max_n, max_m, &n, &m);
 
 	return *parent_rate * n / m;
 }
@@ -75,6 +77,7 @@ static int ccu_nm_set_rate(struct clk_hw *hw, unsigned long rate,
 {
 	struct ccu_nm *nm = hw_to_ccu_nm(hw);
 	unsigned long flags;
+	unsigned long max_n, max_m;
 	unsigned long n, m;
 	u32 reg;
 
@@ -83,9 +86,10 @@ static int ccu_nm_set_rate(struct clk_hw *hw, unsigned long rate,
 	else
 		ccu_frac_helper_disable(&nm->common, &nm->frac);
 
-	rational_best_approximation(rate, parent_rate,
-				    1 << nm->n.width, 1 << nm->m.width,
-				    &n, &m);
+	max_n = 1 << nm->n.width;
+	max_m = nm->m.max ?: 1 << nm->m.width;
+
+	rational_best_approximation(rate, parent_rate, max_n, max_m, &n, &m);
 
 	spin_lock_irqsave(nm->common.lock, flags);