[PATCH 3/5] clk: sunxi-ng: nm: Support constraints on n/m ratio and parent rate

[Frank Oltmanns <frank@oltmanns.dev>]

The Allwinner A64 manual lists the following constraint for the
PLL-VIDEO0 clock: 8 <= N/M <= 25

The PLL-MIPI clock is implemented as ccu_nm. Therefore, add support for
this constraint.

Signed-off-by: Frank Oltmanns <frank@oltmanns.dev>
---
 drivers/clk/sunxi-ng/ccu_nm.c | 21 +++++++++++++++++++--
 drivers/clk/sunxi-ng/ccu_nm.h | 34 ++++++++++++++++++++++++++++++++--
 2 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
index ffac3deb89d6..cfc6981e398b 100644
--- a/drivers/clk/sunxi-ng/ccu_nm.c
+++ b/drivers/clk/sunxi-ng/ccu_nm.c
@@ -27,6 +27,19 @@ static unsigned long ccu_nm_calc_rate(unsigned long parent,
 	return rate;
 }
 
+static bool ccu_nm_is_valid_rate(struct ccu_common *common, unsigned long n, unsigned long m)
+{
+	struct ccu_nm *nm = container_of(common, struct ccu_nm, common);
+
+	if (nm->max_nm_ratio && (n > nm->max_nm_ratio * m))
+		return false;
+
+	if (nm->min_nm_ratio && (n < nm->min_nm_ratio * m))
+		return false;
+
+	return true;
+}
+
 static unsigned long ccu_nm_find_best(struct ccu_common *common, unsigned long parent,
 				      unsigned long rate, struct _ccu_nm *nm)
 {
@@ -36,8 +49,12 @@ static unsigned long ccu_nm_find_best(struct ccu_common *common, unsigned long p
 
 	for (_n = nm->min_n; _n <= nm->max_n; _n++) {
 		for (_m = nm->min_m; _m <= nm->max_m; _m++) {
-			unsigned long tmp_rate = ccu_nm_calc_rate(parent,
-								  _n, _m);
+			unsigned long tmp_rate;
+
+			if (!ccu_nm_is_valid_rate(common, _n, _m))
+				continue;
+
+			tmp_rate = ccu_nm_calc_rate(parent, _n, _m);
 
 			if (ccu_is_better_rate(common, rate, tmp_rate, best_rate)) {
 				best_rate = tmp_rate;
diff --git a/drivers/clk/sunxi-ng/ccu_nm.h b/drivers/clk/sunxi-ng/ccu_nm.h
index 93c11693574f..0075df6d9697 100644
--- a/drivers/clk/sunxi-ng/ccu_nm.h
+++ b/drivers/clk/sunxi-ng/ccu_nm.h
@@ -31,6 +31,8 @@ struct ccu_nm {
 	unsigned int		fixed_post_div;
 	unsigned int		min_rate;
 	unsigned int		max_rate;
+	unsigned long		min_nm_ratio; /* minimum value for m/n */
+	unsigned long		max_nm_ratio; /* maximum value for m/n */
 
 	struct ccu_common	common;
 };
@@ -108,7 +110,8 @@ struct ccu_nm {
 		},							\
 	}
 
-#define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT(_struct, _name,	\
+#define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT_NM_RATIO(		\
+						 _struct, _name,	\
 						 _parent, _reg,		\
 						 _min_rate, _max_rate,	\
 						 _nshift, _nwidth,	\
@@ -117,7 +120,9 @@ struct ccu_nm {
 						 _frac_rate_0,		\
 						 _frac_rate_1,		\
 						 _gate, _lock, _flags,	\
-						 _features)		\
+						 _features,		\
+						 _min_nm_ratio,		\
+						 _max_nm_ratio)		\
 	struct ccu_nm _struct = {					\
 		.enable		= _gate,				\
 		.lock		= _lock,				\
@@ -128,6 +133,8 @@ struct ccu_nm {
 						  _frac_rate_1),	\
 		.min_rate	= _min_rate,				\
 		.max_rate	= _max_rate,				\
+		.min_nm_ratio	= _min_nm_ratio,			\
+		.max_nm_ratio	= _max_nm_ratio,			\
 		.common		= {					\
 			.reg		= _reg,				\
 			.features	= _features,			\
@@ -138,6 +145,29 @@ struct ccu_nm {
 		},							\
 	}
 
+#define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT(_struct, _name,	\
+						 _parent, _reg,		\
+						 _min_rate, _max_rate,	\
+						 _nshift, _nwidth,	\
+						 _mshift, _mwidth,	\
+						 _frac_en, _frac_sel,	\
+						 _frac_rate_0,		\
+						 _frac_rate_1,		\
+						 _gate, _lock, _flags,	\
+						 _features)		\
+	SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT_NM_RATIO(		\
+						_struct, _name,		\
+						_parent, _reg,		\
+						_min_rate, _max_rate,	\
+						_nshift, _nwidth,	\
+						_mshift, _mwidth,	\
+						_frac_en, _frac_sel,	\
+						_frac_rate_0,		\
+						_frac_rate_1,		\
+						_gate, _lock, _flags,	\
+						_features,		\
+						0, 0)
+
 #define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX(_struct, _name,	\
 						 _parent, _reg,		\
 						 _min_rate, _max_rate,	\

-- 
2.43.0