clk: fractional-divider: allow overriding of approximation

Fractional dividers may have special requirements concerning numerator
and denominator selection that differ from just getting the best
approximation.

For example on Rockchip socs the denominator must be at least 20 times
larger than the numerator to generate precise clock frequencies.

Therefore add the ability to provide custom approximation functions.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index c59c62571e4f..1fc113fbf955 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -565,6 +565,9 @@ struct clk_fractional_divider {
 	u8		nwidth;
 	u32		nmask;
 	u8		flags;
+	void		(*approximation)(struct clk_hw *hw,
+				unsigned long rate, unsigned long *parent_rate,
+				unsigned long *m, unsigned long *n);
 	spinlock_t	*lock;
 };