[RFC 05/12] clk: qcom: fix 16 bit alpha support calculation

[Abhishek Sahu]

The alpha value calculation function has been written for
40 bit alpha which is not coming properly for 16 bit alpha.

Signed-off-by: Abhishek Sahu <absahu@xxxxxxxxxxxxxx>
---
 drivers/clk/qcom/clk-alpha-pll.c | 58 +++++++++++++++++++++++-----------------
 1 file changed, 34 insertions(+), 24 deletions(-)

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index ef24c80..3a7ec42 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -45,8 +45,11 @@
  * Even though 40 bits are present, use only 32 for ease of calculation.
  */
 #define ALPHA_REG_BITWIDTH	40
+#define ALPHA_REG_16BIT_WIDTH	16
 #define ALPHA_BITWIDTH		32
-#define ALPHA_16BIT_MASK	0xffff
+
+#define pll_alpha_width(pll)  (pll->flags & SUPPORTS_16BIT_ALPHA ?	\
+			       ALPHA_REG_16BIT_WIDTH : ALPHA_REG_BITWIDTH)
 
 #define pll_mode(pll)		(pll->base + pll->offsets[ALPHA_PLL_MODE])
 #define pll_l(pll)		(pll->base + pll->offsets[ALPHA_PLL_L_VAL])
@@ -316,13 +319,16 @@ static void clk_alpha_pll_disable(struct clk_hw *hw)
 	regmap_update_bits(pll->clkr.regmap, pll_mode(pll), mask, 0);
 }
 
-static unsigned long alpha_pll_calc_rate(u64 prate, u32 l, u32 a)
+static unsigned long
+alpha_pll_calc_rate(u64 prate, u32 l, u32 a, u32 alpha_width)
 {
-	return (prate * l) + ((prate * a) >> ALPHA_BITWIDTH);
+	return (prate * l) + ((prate * a) >>
+		(alpha_width > ALPHA_BITWIDTH ? ALPHA_BITWIDTH : alpha_width));
 }
 
 static unsigned long
-alpha_pll_round_rate(unsigned long rate, unsigned long prate, u32 *l, u64 *a)
+alpha_pll_round_rate(unsigned long rate, unsigned long prate, u32 *l, u64 *a,
+		     u32 alpha_width)
 {
 	u64 remainder;
 	u64 quotient;
@@ -337,14 +343,16 @@ static unsigned long alpha_pll_calc_rate(u64 prate, u32 l, u32 a)
 	}
 
 	/* Upper ALPHA_BITWIDTH bits of Alpha */
-	quotient = remainder << ALPHA_BITWIDTH;
+	quotient = remainder << (alpha_width > ALPHA_BITWIDTH ?
+				 ALPHA_BITWIDTH : alpha_width);
+
 	remainder = do_div(quotient, prate);
 
 	if (remainder)
 		quotient++;
 
 	*a = quotient;
-	return alpha_pll_calc_rate(prate, *l, *a);
+	return alpha_pll_calc_rate(prate, *l, *a, alpha_width);
 }
 
 static const struct pll_vco *
@@ -363,26 +371,26 @@ static unsigned long alpha_pll_calc_rate(u64 prate, u32 l, u32 a)
 static unsigned long
 clk_alpha_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 {
-	u32 l, low, high, ctl;
-	u64 a = 0, prate = parent_rate;
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
+	u32 l, low, high, ctl, alpha_width = pll_alpha_width(pll);
+	u64 a = 0, prate = parent_rate;
 
 	regmap_read(pll->clkr.regmap, pll_l(pll), &l);
 
 	regmap_read(pll->clkr.regmap, pll_user_ctl(pll), &ctl);
 	if (ctl & PLL_ALPHA_EN) {
 		regmap_read(pll->clkr.regmap, pll_alpha(pll), &low);
-		if (pll->flags & SUPPORTS_16BIT_ALPHA) {
-			a = low & ALPHA_16BIT_MASK;
-		} else {
+		if (alpha_width > ALPHA_BITWIDTH) {
 			regmap_read(pll->clkr.regmap, pll_alpha_u(pll),
 				    &high);
-			a = (u64)high << 32 | low;
-			a >>= ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH;
+			a = (u64)high << ALPHA_BITWIDTH | low;
+			a >>= alpha_width - ALPHA_BITWIDTH;
+		} else {
+			a = low;
 		}
 	}
 
-	return alpha_pll_calc_rate(prate, l, a);
+	return alpha_pll_calc_rate(prate, l, a, alpha_width);
 }
 
 static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
@@ -390,10 +398,10 @@ static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 {
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
 	const struct pll_vco *vco;
-	u32 l;
+	u32 l, alpha_width = pll_alpha_width(pll);
 	u64 a;
 
-	rate = alpha_pll_round_rate(rate, prate, &l, &a);
+	rate = alpha_pll_round_rate(rate, prate, &l, &a, alpha_width);
 	vco = alpha_pll_find_vco(pll, rate);
 	if (!vco) {
 		pr_err("alpha pll not in a valid vco range\n");
@@ -402,14 +410,16 @@ static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 
 	regmap_write(pll->clkr.regmap, pll_l(pll), l);
 
-	if (pll->flags & SUPPORTS_16BIT_ALPHA) {
-		regmap_write(pll->clkr.regmap, pll_alpha(pll),
-			     a & ALPHA_16BIT_MASK);
-	} else {
-		a <<= (ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH);
-		regmap_write(pll->clkr.regmap, pll_alpha_u(pll), a >> 32);
+	if (alpha_width > ALPHA_BITWIDTH) {
+		a <<= (alpha_width - ALPHA_BITWIDTH);
+		regmap_update_bits(pll->clkr.regmap, pll_alpha_u(pll),
+				   GENMASK(0, alpha_width - ALPHA_BITWIDTH - 1),
+				   a >> ALPHA_BITWIDTH);
 	}
 
+	regmap_update_bits(pll->clkr.regmap, pll_alpha(pll),
+			   GENMASK(0, alpha_width - 1), a);
+
 	regmap_update_bits(pll->clkr.regmap, pll_user_ctl(pll),
 			   PLL_VCO_MASK << PLL_VCO_SHIFT,
 			   vco->val << PLL_VCO_SHIFT);
@@ -424,11 +434,11 @@ static long clk_alpha_pll_round_rate(struct clk_hw *hw, unsigned long rate,
 				     unsigned long *prate)
 {
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
-	u32 l;
+	u32 l, alpha_width = pll_alpha_width(pll);
 	u64 a;
 	unsigned long min_freq, max_freq;
 
-	rate = alpha_pll_round_rate(rate, *prate, &l, &a);
+	rate = alpha_pll_round_rate(rate, *prate, &l, &a, alpha_width);
 	if (alpha_pll_find_vco(pll, rate))
 		return rate;
 
-- 
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