1 files changed, 71 insertions, 76 deletions

diff --git a/drivers/clk/samsung/clk-pll.c b/drivers/clk/samsung/clk-pll.c
index ac70ad785d8e..5873a9354b50 100644
--- a/drivers/clk/samsung/clk-pll.c
+++ b/drivers/clk/samsung/clk-pll.c
@@ -8,14 +8,17 @@
 
 #include <linux/errno.h>
 #include <linux/hrtimer.h>
+#include <linux/iopoll.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
+#include <linux/timekeeping.h>
 #include <linux/clk-provider.h>
 #include <linux/io.h>
 #include "clk.h"
 #include "clk-pll.h"
 
-#define PLL_TIMEOUT_MS		10
+#define PLL_TIMEOUT_US		20000U
+#define PLL_TIMEOUT_LOOPS	1000000U
 
 struct samsung_clk_pll {
 	struct clk_hw		hw;
@@ -63,6 +66,53 @@ static long samsung_pll_round_rate(struct clk_hw *hw,
 	return rate_table[i - 1].rate;
 }
 
+static bool pll_early_timeout = true;
+
+static int __init samsung_pll_disable_early_timeout(void)
+{
+	pll_early_timeout = false;
+	return 0;
+}
+arch_initcall(samsung_pll_disable_early_timeout);
+
+/* Wait until the PLL is locked */
+static int samsung_pll_lock_wait(struct samsung_clk_pll *pll,
+				 unsigned int reg_mask)
+{
+	int i, ret;
+	u32 val;
+
+	/*
+	 * This function might be called when the timekeeping API can't be used
+	 * to detect timeouts. One situation is when the clocksource is not yet
+	 * initialized, another when the timekeeping is suspended. udelay() also
+	 * cannot be used when the clocksource is not running on arm64, since
+	 * the current timer is used as cycle counter. So a simple busy loop
+	 * is used here in that special cases. The limit of iterations has been
+	 * derived from experimental measurements of various PLLs on multiple
+	 * Exynos SoC variants. Single register read time was usually in range
+	 * 0.4...1.5 us, never less than 0.4 us.
+	 */
+	if (pll_early_timeout || timekeeping_suspended) {
+		i = PLL_TIMEOUT_LOOPS;
+		while (i-- > 0) {
+			if (readl_relaxed(pll->con_reg) & reg_mask)
+				return 0;
+
+			cpu_relax();
+		}
+		ret = -ETIMEDOUT;
+	} else {
+		ret = readl_relaxed_poll_timeout_atomic(pll->con_reg, val,
+					val & reg_mask, 0, PLL_TIMEOUT_US);
+	}
+
+	if (ret < 0)
+		pr_err("Could not lock PLL %s\n", clk_hw_get_name(&pll->hw));
+
+	return ret;
+}
+
 static int samsung_pll3xxx_enable(struct clk_hw *hw)
 {
 	struct samsung_clk_pll *pll = to_clk_pll(hw);
@@ -72,13 +122,7 @@ static int samsung_pll3xxx_enable(struct clk_hw *hw)
 	tmp |= BIT(pll->enable_offs);
 	writel_relaxed(tmp, pll->con_reg);
 
-	/* wait lock time */
-	do {
-		cpu_relax();
-		tmp = readl_relaxed(pll->con_reg);
-	} while (!(tmp & BIT(pll->lock_offs)));
-
-	return 0;
+	return samsung_pll_lock_wait(pll, BIT(pll->lock_offs));
 }
 
 static void samsung_pll3xxx_disable(struct clk_hw *hw)
@@ -240,13 +284,10 @@ static int samsung_pll35xx_set_rate(struct clk_hw *hw, unsigned long drate,
 			(rate->sdiv << PLL35XX_SDIV_SHIFT);
 	writel_relaxed(tmp, pll->con_reg);
 
-	/* Wait until the PLL is locked if it is enabled. */
-	if (tmp & BIT(pll->enable_offs)) {
-		do {
-			cpu_relax();
-			tmp = readl_relaxed(pll->con_reg);
-		} while (!(tmp & BIT(pll->lock_offs)));
-	}
+	/* Wait for PLL lock if the PLL is enabled */
+	if (tmp & BIT(pll->enable_offs))
+		return samsung_pll_lock_wait(pll, BIT(pll->lock_offs));
+
 	return 0;
 }
 
@@ -318,7 +359,7 @@ static int samsung_pll36xx_set_rate(struct clk_hw *hw, unsigned long drate,
 					unsigned long parent_rate)
 {
 	struct samsung_clk_pll *pll = to_clk_pll(hw);
-	u32 tmp, pll_con0, pll_con1;
+	u32 pll_con0, pll_con1;
 	const struct samsung_pll_rate_table *rate;
 
 	rate = samsung_get_pll_settings(pll, drate);
@@ -356,13 +397,8 @@ static int samsung_pll36xx_set_rate(struct clk_hw *hw, unsigned long drate,
 	pll_con1 |= rate->kdiv << PLL36XX_KDIV_SHIFT;
 	writel_relaxed(pll_con1, pll->con_reg + 4);
 
-	/* wait_lock_time */
-	if (pll_con0 & BIT(pll->enable_offs)) {
-		do {
-			cpu_relax();
-			tmp = readl_relaxed(pll->con_reg);
-		} while (!(tmp & BIT(pll->lock_offs)));
-	}
+	if (pll_con0 & BIT(pll->enable_offs))
+		return samsung_pll_lock_wait(pll, BIT(pll->lock_offs));
 
 	return 0;
 }
@@ -437,7 +473,6 @@ static int samsung_pll45xx_set_rate(struct clk_hw *hw, unsigned long drate,
 	struct samsung_clk_pll *pll = to_clk_pll(hw);
 	const struct samsung_pll_rate_table *rate;
 	u32 con0, con1;
-	ktime_t start;
 
 	/* Get required rate settings from table */
 	rate = samsung_get_pll_settings(pll, drate);
@@ -488,21 +523,8 @@ static int samsung_pll45xx_set_rate(struct clk_hw *hw, unsigned long drate,
 	writel_relaxed(con1, pll->con_reg + 0x4);
 	writel_relaxed(con0, pll->con_reg);
 
-	/* Wait for locking. */
-	start = ktime_get();
-	while (!(readl_relaxed(pll->con_reg) & PLL45XX_LOCKED)) {
-		ktime_t delta = ktime_sub(ktime_get(), start);
-
-		if (ktime_to_ms(delta) > PLL_TIMEOUT_MS) {
-			pr_err("%s: could not lock PLL %s\n",
-					__func__, clk_hw_get_name(hw));
-			return -EFAULT;
-		}
-
-		cpu_relax();
-	}
-
-	return 0;
+	/* Wait for PLL lock */
+	return samsung_pll_lock_wait(pll, PLL45XX_LOCKED);
 }
 
 static const struct clk_ops samsung_pll45xx_clk_ops = {
@@ -588,7 +610,6 @@ static int samsung_pll46xx_set_rate(struct clk_hw *hw, unsigned long drate,
 	struct samsung_clk_pll *pll = to_clk_pll(hw);
 	const struct samsung_pll_rate_table *rate;
 	u32 con0, con1, lock;
-	ktime_t start;
 
 	/* Get required rate settings from table */
 	rate = samsung_get_pll_settings(pll, drate);
@@ -647,21 +668,8 @@ static int samsung_pll46xx_set_rate(struct clk_hw *hw, unsigned long drate,
 	writel_relaxed(con0, pll->con_reg);
 	writel_relaxed(con1, pll->con_reg + 0x4);
 
-	/* Wait for locking. */
-	start = ktime_get();
-	while (!(readl_relaxed(pll->con_reg) & PLL46XX_LOCKED)) {
-		ktime_t delta = ktime_sub(ktime_get(), start);
-
-		if (ktime_to_ms(delta) > PLL_TIMEOUT_MS) {
-			pr_err("%s: could not lock PLL %s\n",
-					__func__, clk_hw_get_name(hw));
-			return -EFAULT;
-		}
-
-		cpu_relax();
-	}
-
-	return 0;
+	/* Wait for PLL lock */
+	return samsung_pll_lock_wait(pll, PLL46XX_LOCKED);
 }
 
 static const struct clk_ops samsung_pll46xx_clk_ops = {
@@ -1035,14 +1043,9 @@ static int samsung_pll2550xx_set_rate(struct clk_hw *hw, unsigned long drate,
 			(rate->sdiv << PLL2550XX_S_SHIFT);
 	writel_relaxed(tmp, pll->con_reg);
 
-	/* wait_lock_time */
-	do {
-		cpu_relax();
-		tmp = readl_relaxed(pll->con_reg);
-	} while (!(tmp & (PLL2550XX_LOCK_STAT_MASK
-			<< PLL2550XX_LOCK_STAT_SHIFT)));
-
-	return 0;
+	/* Wait for PLL lock */
+	return samsung_pll_lock_wait(pll,
+			PLL2550XX_LOCK_STAT_MASK << PLL2550XX_LOCK_STAT_SHIFT);
 }
 
 static const struct clk_ops samsung_pll2550xx_clk_ops = {
@@ -1132,13 +1135,9 @@ static int samsung_pll2650x_set_rate(struct clk_hw *hw, unsigned long drate,
 	con1 |= ((rate->kdiv & PLL2650X_K_MASK) << PLL2650X_K_SHIFT);
 	writel_relaxed(con1, pll->con_reg + 4);
 
-	do {
-		cpu_relax();
-		con0 = readl_relaxed(pll->con_reg);
-	} while (!(con0 & (PLL2650X_LOCK_STAT_MASK
-			<< PLL2650X_LOCK_STAT_SHIFT)));
-
-	return 0;
+	/* Wait for PLL lock */
+	return samsung_pll_lock_wait(pll,
+			PLL2650X_LOCK_STAT_MASK << PLL2650X_LOCK_STAT_SHIFT);
 }
 
 static const struct clk_ops samsung_pll2650x_clk_ops = {
@@ -1196,7 +1195,7 @@ static int samsung_pll2650xx_set_rate(struct clk_hw *hw, unsigned long drate,
 					unsigned long parent_rate)
 {
 	struct samsung_clk_pll *pll = to_clk_pll(hw);
-	u32 tmp, pll_con0, pll_con2;
+	u32 pll_con0, pll_con2;
 	const struct samsung_pll_rate_table *rate;
 
 	rate = samsung_get_pll_settings(pll, drate);
@@ -1229,11 +1228,7 @@ static int samsung_pll2650xx_set_rate(struct clk_hw *hw, unsigned long drate,
 	writel_relaxed(pll_con0, pll->con_reg);
 	writel_relaxed(pll_con2, pll->con_reg + 8);
 
-	do {
-		tmp = readl_relaxed(pll->con_reg);
-	} while (!(tmp & (0x1 << PLL2650XX_PLL_LOCKTIME_SHIFT)));
-
-	return 0;
+	return samsung_pll_lock_wait(pll, 0x1 << PLL2650XX_PLL_LOCKTIME_SHIFT);
 }
 
 static const struct clk_ops samsung_pll2650xx_clk_ops = {