Merge tag 'renesas-drivers-for-v6.5-tag2' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-devel into soc/drivers

Renesas driver updates for v6.5 (take two)

  - Convert the R-Mobile SYSC driver to readl_poll_timeout_atomic().

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

Link: https://lore.kernel.org/r/cover.1686304612.git.geert+renesas@glider.be
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: arndb

drivers/soc/renesas/rmobile-sysc.c

@@ -12,15 +12,15 @@
 #include <linux/clk/renesas.h>
 #include <linux/console.h>
 #include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/pm.h>
 #include <linux/pm_clock.h>
 #include <linux/pm_domain.h>
 #include <linux/slab.h>
 
-#include <asm/io.h>
-
 /* SYSC */
 #define SPDCR		0x08	/* SYS Power Down Control Register */
 #define SWUCR		0x14	/* SYS Wakeup Control Register */
@@ -47,6 +47,7 @@ static int rmobile_pd_power_down(struct generic_pm_domain *genpd)
 {
 	struct rmobile_pm_domain *rmobile_pd = to_rmobile_pd(genpd);
 	unsigned int mask = BIT(rmobile_pd->bit_shift);
+	u32 val;
 
 	if (rmobile_pd->suspend) {
 		int ret = rmobile_pd->suspend();
@@ -56,14 +57,10 @@ static int rmobile_pd_power_down(struct generic_pm_domain *genpd)
 	}
 
 	if (readl(rmobile_pd->base + PSTR) & mask) {
-		unsigned int retry_count;
 		writel(mask, rmobile_pd->base + SPDCR);
 
-		for (retry_count = PSTR_RETRIES; retry_count; retry_count--) {
-			if (!(readl(rmobile_pd->base + SPDCR) & mask))
-				break;
-			cpu_relax();
-		}
+		readl_poll_timeout_atomic(rmobile_pd->base + SPDCR, val,
+					  !(val & mask), 0, PSTR_RETRIES);
 	}
 
 	pr_debug("%s: Power off, 0x%08x -> PSTR = 0x%08x\n", genpd->name, mask,
@@ -74,25 +71,17 @@ static int rmobile_pd_power_down(struct generic_pm_domain *genpd)
 
 static int __rmobile_pd_power_up(struct rmobile_pm_domain *rmobile_pd)
 {
-	unsigned int mask = BIT(rmobile_pd->bit_shift);
-	unsigned int retry_count;
+	unsigned int val, mask = BIT(rmobile_pd->bit_shift);
 	int ret = 0;
 
 	if (readl(rmobile_pd->base + PSTR) & mask)
 		return ret;
 
 	writel(mask, rmobile_pd->base + SWUCR);
 
-	for (retry_count = 2 * PSTR_RETRIES; retry_count; retry_count--) {
-		if (!(readl(rmobile_pd->base + SWUCR) & mask))
-			break;
-		if (retry_count > PSTR_RETRIES)
-			udelay(PSTR_DELAY_US);
-		else
-			cpu_relax();
-	}
-	if (!retry_count)
-		ret = -EIO;
+	ret = readl_poll_timeout_atomic(rmobile_pd->base + SWUCR, val,
+					(val & mask), PSTR_DELAY_US,
+					PSTR_RETRIES * PSTR_DELAY_US);
 
 	pr_debug("%s: Power on, 0x%08x -> PSTR = 0x%08x\n",
 		 rmobile_pd->genpd.name, mask,

include/linux/iopoll.h

@@ -53,6 +53,7 @@
 		} \
 		if (__sleep_us) \
 			usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
+		cpu_relax(); \
 	} \
 	(cond) ? 0 : -ETIMEDOUT; \
 })
@@ -73,28 +74,41 @@
  * 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.
  */
 #define read_poll_timeout_atomic(op, val, cond, delay_us, timeout_us, \
 					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; \
 })