[PATCH 1/6] clk: pistachio: Fix 32bit integer overflows

[Govindraj Raja <govindraj.raja@xxxxxxxxxx>]

From: Zdenko Pulitika <zdenko.pulitika@xxxxxxxxxx>

This commit fixes 32bit integer overflows throughout the pll driver
(i.e. wherever the result of integer multiplication may exceed the
range of u32).

One of the functions affected by this problem is .recalc_rate. It
returns incorrect rate for some pll settings (not for all though)
which in turn results in the incorrect rate setup of pll's child
clocks.

Signed-off-by: Zdenko Pulitika <zdenko.pulitika@xxxxxxxxxx>
Signed-off-by: Govindraj Raja <govindraj.raja@xxxxxxxxxx>
---
 drivers/clk/pistachio/clk-pll.c | 26 ++++++++++++--------------
 drivers/clk/pistachio/clk.h     | 18 +++++++++++-------
 2 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/drivers/clk/pistachio/clk-pll.c b/drivers/clk/pistachio/clk-pll.c
index e17dada..68066ef 100644
--- a/drivers/clk/pistachio/clk-pll.c
+++ b/drivers/clk/pistachio/clk-pll.c
@@ -88,12 +88,10 @@ static inline void pll_lock(struct pistachio_clk_pll *pll)
 		cpu_relax();
 }
 
-static inline u32 do_div_round_closest(u64 dividend, u32 divisor)
+static inline u64 do_div_round_closest(u64 dividend, u64 divisor)
 {
 	dividend += divisor / 2;
-	do_div(dividend, divisor);
-
-	return dividend;
+	return div64_u64(dividend, divisor);
 }
 
 static inline struct pistachio_clk_pll *to_pistachio_pll(struct clk_hw *hw)
@@ -173,7 +171,7 @@ static int pll_gf40lp_frac_set_rate(struct clk_hw *hw, unsigned long rate,
 	struct pistachio_clk_pll *pll = to_pistachio_pll(hw);
 	struct pistachio_pll_rate_table *params;
 	int enabled = pll_gf40lp_frac_is_enabled(hw);
-	u32 val, vco, old_postdiv1, old_postdiv2;
+	u64 val, vco, old_postdiv1, old_postdiv2;
 	const char *name = __clk_get_name(hw->clk);
 
 	if (rate < MIN_OUTPUT_FRAC || rate > MAX_OUTPUT_FRAC)
@@ -183,17 +181,17 @@ static int pll_gf40lp_frac_set_rate(struct clk_hw *hw, unsigned long rate,
 	if (!params || !params->refdiv)
 		return -EINVAL;
 
-	vco = params->fref * params->fbdiv / params->refdiv;
+	vco = div64_u64(params->fref * params->fbdiv, params->refdiv);
 	if (vco < MIN_VCO_FRAC_FRAC || vco > MAX_VCO_FRAC_FRAC)
-		pr_warn("%s: VCO %u is out of range %lu..%lu\n", name, vco,
+		pr_warn("%s: VCO %llu is out of range %lu..%lu\n", name, vco,
 			MIN_VCO_FRAC_FRAC, MAX_VCO_FRAC_FRAC);
 
-	val = params->fref / params->refdiv;
+	val = div64_u64(params->fref, params->refdiv);
 	if (val < MIN_PFD)
-		pr_warn("%s: PFD %u is too low (min %lu)\n",
+		pr_warn("%s: PFD %llu is too low (min %lu)\n",
 			name, val, MIN_PFD);
 	if (val > vco / 16)
-		pr_warn("%s: PFD %u is too high (max %u)\n",
+		pr_warn("%s: PFD %llu is too high (max %llu)\n",
 			name, val, vco / 16);
 
 	val = pll_readl(pll, PLL_CTRL1);
@@ -237,8 +235,7 @@ static unsigned long pll_gf40lp_frac_recalc_rate(struct clk_hw *hw,
 						 unsigned long parent_rate)
 {
 	struct pistachio_clk_pll *pll = to_pistachio_pll(hw);
-	u32 val, prediv, fbdiv, frac, postdiv1, postdiv2;
-	u64 rate = parent_rate;
+	u64 val, prediv, fbdiv, frac, postdiv1, postdiv2, rate;
 
 	val = pll_readl(pll, PLL_CTRL1);
 	prediv = (val >> PLL_CTRL1_REFDIV_SHIFT) & PLL_CTRL1_REFDIV_MASK;
@@ -251,6 +248,7 @@ static unsigned long pll_gf40lp_frac_recalc_rate(struct clk_hw *hw,
 		PLL_FRAC_CTRL2_POSTDIV2_MASK;
 	frac = (val >> PLL_FRAC_CTRL2_FRAC_SHIFT) & PLL_FRAC_CTRL2_FRAC_MASK;
 
+	rate = parent_rate;
 	rate *= (fbdiv << 24) + frac;
 	rate = do_div_round_closest(rate, (prediv * postdiv1 * postdiv2) << 24);
 
@@ -325,12 +323,12 @@ static int pll_gf40lp_laint_set_rate(struct clk_hw *hw, unsigned long rate,
 	if (!params || !params->refdiv)
 		return -EINVAL;
 
-	vco = params->fref * params->fbdiv / params->refdiv;
+	vco = div_u64(params->fref * params->fbdiv, params->refdiv);
 	if (vco < MIN_VCO_LA || vco > MAX_VCO_LA)
 		pr_warn("%s: VCO %u is out of range %lu..%lu\n", name, vco,
 			MIN_VCO_LA, MAX_VCO_LA);
 
-	val = params->fref / params->refdiv;
+	val = div_u64(params->fref, params->refdiv);
 	if (val < MIN_PFD)
 		pr_warn("%s: PFD %u is too low (min %lu)\n",
 			name, val, MIN_PFD);
diff --git a/drivers/clk/pistachio/clk.h b/drivers/clk/pistachio/clk.h
index 52fabbc..6ea6f4b 100644
--- a/drivers/clk/pistachio/clk.h
+++ b/drivers/clk/pistachio/clk.h
@@ -94,14 +94,18 @@ struct pistachio_fixed_factor {
 		.parent		= _pname,			\
 	}
 
+/*
+ * in order to avoid u32 multiplication overflow, declare all
+ * members of this structure as u64
+ */
 struct pistachio_pll_rate_table {
-	unsigned long fref;
-	unsigned long fout;
-	unsigned int refdiv;
-	unsigned int fbdiv;
-	unsigned int postdiv1;
-	unsigned int postdiv2;
-	unsigned int frac;
+	unsigned long long fref;
+	unsigned long long fout;
+	unsigned long long refdiv;
+	unsigned long long fbdiv;
+	unsigned long long postdiv1;
+	unsigned long long postdiv2;
+	unsigned long long frac;
 };
 
 enum pistachio_pll_type {
-- 
1.9.1