clk: renesas: Updates for v6.5 (take two)

- Convert the Renesas clock drivers to readl_poll_timeout_atomic().
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Merge tag 'renesas-clk-for-v6.5-tag2' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers into clk-renesas

Pull more Renesas clk driver updates from Geert Uytterhoeven:

 - Convert the Renesas clock drivers to readl_poll_timeout_atomic()

* tag 'renesas-clk-for-v6.5-tag2' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers:
  clk: renesas: rzg2l: Convert to readl_poll_timeout_atomic()
  clk: renesas: mstp: Convert to readl_poll_timeout_atomic()
  clk: renesas: cpg-mssr: Convert to readl_poll_timeout_atomic()
  iopoll: Do not use timekeeping in read_poll_timeout_atomic()
  iopoll: Call cpu_relax() in busy loops

drivers/clk/renesas/clk-mstp.c

@@ -14,6 +14,7 @@
 #include <linux/clk/renesas.h>
 #include <linux/device.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/pm_clock.h>
@@ -78,8 +79,8 @@ static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
 	struct mstp_clock_group *group = clock->group;
 	u32 bitmask = BIT(clock->bit_index);
 	unsigned long flags;
-	unsigned int i;
 	u32 value;
+	int ret;
 
 	spin_lock_irqsave(&group->lock, flags);
 
@@ -101,19 +102,14 @@ static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
 	if (!enable || !group->mstpsr)
 		return 0;
 
-	for (i = 1000; i > 0; --i) {
-		if (!(cpg_mstp_read(group, group->mstpsr) & bitmask))
-			break;
-		cpu_relax();
-	}
-
-	if (!i) {
+	/* group->width_8bit is always false if group->mstpsr is present */
+	ret = readl_poll_timeout_atomic(group->mstpsr, value,
+					!(value & bitmask), 0, 10);
+	if (ret)
 		pr_err("%s: failed to enable %p[%d]\n", __func__,
 		       group->smstpcr, clock->bit_index);
-		return -ETIMEDOUT;
-	}
 
-	return 0;
+	return ret;
 }
 
 static int cpg_mstp_clock_enable(struct clk_hw *hw)

drivers/clk/renesas/renesas-cpg-mssr.c

@@ -17,6 +17,7 @@
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
@@ -196,8 +197,8 @@ static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
 	struct device *dev = priv->dev;
 	u32 bitmask = BIT(bit);
 	unsigned long flags;
-	unsigned int i;
 	u32 value;
+	int error;
 
 	dev_dbg(dev, "MSTP %u%02u/%pC %s\n", reg, bit, hw->clk,
 		enable ? "ON" : "OFF");
@@ -228,19 +229,13 @@ static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
 	if (!enable || priv->reg_layout == CLK_REG_LAYOUT_RZ_A)
 		return 0;
 
-	for (i = 1000; i > 0; --i) {
-		if (!(readl(priv->base + priv->status_regs[reg]) & bitmask))
-			break;
-		cpu_relax();
-	}
-
-	if (!i) {
+	error = readl_poll_timeout_atomic(priv->base + priv->status_regs[reg],
+					  value, !(value & bitmask), 0, 10);
+	if (error)
 		dev_err(dev, "Failed to enable SMSTP %p[%d]\n",
 			priv->base + priv->control_regs[reg], bit);
-		return -ETIMEDOUT;
-	}
 
-	return 0;
+	return error;
 }
 
 static int cpg_mstp_clock_enable(struct clk_hw *hw)
@@ -896,8 +891,9 @@ static int cpg_mssr_suspend_noirq(struct device *dev)
 static int cpg_mssr_resume_noirq(struct device *dev)
 {
 	struct cpg_mssr_priv *priv = dev_get_drvdata(dev);
-	unsigned int reg, i;
+	unsigned int reg;
 	u32 mask, oldval, newval;
+	int error;
 
 	/* This is the best we can do to check for the presence of PSCI */
 	if (!psci_ops.cpu_suspend)
@@ -935,14 +931,9 @@ static int cpg_mssr_resume_noirq(struct device *dev)
 		if (!mask)
 			continue;
 
-		for (i = 1000; i > 0; --i) {
-			oldval = readl(priv->base + priv->status_regs[reg]);
-			if (!(oldval & mask))
-				break;
-			cpu_relax();
-		}
-
-		if (!i)
+		error = readl_poll_timeout_atomic(priv->base + priv->status_regs[reg],
+						oldval, !(oldval & mask), 0, 10);
+		if (error)
 			dev_warn(dev, "Failed to enable SMSTP%u[0x%x]\n", reg,
 				 oldval & mask);
 	}

drivers/clk/renesas/rzg2l-cpg.c

@@ -903,9 +903,9 @@ static int rzg2l_mod_clock_endisable(struct clk_hw *hw, bool enable)
 	unsigned int reg = clock->off;
 	struct device *dev = priv->dev;
 	unsigned long flags;
-	unsigned int i;
 	u32 bitmask = BIT(clock->bit);
 	u32 value;
+	int error;
 
 	if (!clock->off) {
 		dev_dbg(dev, "%pC does not support ON/OFF\n",  hw->clk);
@@ -930,19 +930,13 @@ static int rzg2l_mod_clock_endisable(struct clk_hw *hw, bool enable)
 	if (!priv->info->has_clk_mon_regs)
 		return 0;
 
-	for (i = 1000; i > 0; --i) {
-		if (((readl(priv->base + CLK_MON_R(reg))) & bitmask))
-			break;
-		cpu_relax();
-	}
-
-	if (!i) {
+	error = readl_poll_timeout_atomic(priv->base + CLK_MON_R(reg), value,
+					  value & bitmask, 0, 10);
+	if (error)
 		dev_err(dev, "Failed to enable CLK_ON %p\n",
 			priv->base + CLK_ON_R(reg));
-		return -ETIMEDOUT;
-	}
 
-	return 0;
+	return error;
 }
 
 static int rzg2l_mod_clock_enable(struct clk_hw *hw)

include/linux/iopoll.h

@@ -53,6 +53,7 @@
 		} \
 		if (__sleep_us) \
 			usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
+		cpu_relax(); \
 	} \
 	(cond) ? 0 : -ETIMEDOUT; \
 })
@@ -73,6 +74,10 @@
  * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
  * case, the last read value at @args is stored in @val.
  *
+ * This macro does not rely on timekeeping.  Hence it is safe to call even when
+ * timekeeping is suspended, at the expense of an underestimation of wall clock
+ * time, which is rather minimal with a non-zero delay_us.
+ *
  * When available, you'll probably want to use one of the specialized
  * macros defined below rather than this macro directly.
  */
@@ -80,21 +85,30 @@
 					delay_before_read, args...) \
 ({ \
 	u64 __timeout_us = (timeout_us); \
+	s64 __left_ns = __timeout_us * NSEC_PER_USEC; \
 	unsigned long __delay_us = (delay_us); \
-	ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \
-	if (delay_before_read && __delay_us) \
+	u64 __delay_ns = __delay_us * NSEC_PER_USEC; \
+	if (delay_before_read && __delay_us) { \
 		udelay(__delay_us); \
+		if (__timeout_us) \
+			__left_ns -= __delay_ns; \
+	} \
 	for (;;) { \
 		(val) = op(args); \
 		if (cond) \
 			break; \
-		if (__timeout_us && \
-		    ktime_compare(ktime_get(), __timeout) > 0) { \
+		if (__timeout_us && __left_ns < 0) { \
 			(val) = op(args); \
 			break; \
 		} \
-		if (__delay_us) \
+		if (__delay_us) { \
 			udelay(__delay_us); \
+			if (__timeout_us) \
+				__left_ns -= __delay_ns; \
+		} \
+		cpu_relax(); \
+		if (__timeout_us) \
+			__left_ns--; \
 	} \
 	(cond) ? 0 : -ETIMEDOUT; \
 })