[PATCH v4 2/7] mtd: spi-nor: Wait for NOR ready with poll_timeout_us()

[Paul Cercueil]

From: Tanmay Jagdale <tanmay@xxxxxxxxxxx>

Instead of polling for the spi_nor_ready() with a custom loop, use
poll_timeout_us(). The sleep period between two polls is set to 100 us
which I think should be fine.

This will make it simpler to support waiting for the SPI NOR in atomic
context later.

Signed-off-by: Tanmay Jagdale <tanmay@xxxxxxxxxxx>
Co-developed-by: Paul Cercueil <paul.cercueil@xxxxxxxxxxx>
Signed-off-by: Paul Cercueil <paul.cercueil@xxxxxxxxxxx>
---

Notes:
    v2: New patch
    
    v3: Set 'timeout_ms' parameter to u64 to prevent u32 overflow
    
    v4: Also update kernel doc for new 'timeout_ms' parameter

 drivers/mtd/spi-nor/core.c | 42 +++++++++++++++-----------------------
 1 file changed, 17 insertions(+), 25 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 8bc117b46e02..7f347141ea3f 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -12,6 +12,7 @@
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/errno.h>
+#include <linux/iopoll.h>
 #include <linux/math64.h>
 #include <linux/module.h>
 #include <linux/mtd/mtd.h>
@@ -32,13 +33,13 @@
  * For everything but full-chip erase; probably could be much smaller, but kept
  * around for safety for now
  */
-#define DEFAULT_READY_WAIT_JIFFIES		(40UL * HZ)
+#define DEFAULT_READY_TIMEOUT_MS		40000UL
 
 /*
  * For full-chip erase, calibrated to a 2MB flash (M25P16); should be scaled up
  * for larger flash
  */
-#define CHIP_ERASE_2MB_READY_WAIT_JIFFIES	(40UL * HZ)
+#define CHIP_ERASE_2MB_READY_TIMEOUT_MS		40000UL
 
 #define SPI_NOR_MAX_ADDR_NBYTES	4
 
@@ -707,34 +708,25 @@ static int spi_nor_ready(struct spi_nor *nor)
  * spi_nor_wait_till_ready_with_timeout() - Service routine to read the
  * Status Register until ready, or timeout occurs.
  * @nor:		pointer to "struct spi_nor".
- * @timeout_jiffies:	jiffies to wait until timeout.
+ * @timeout_ms:		timeout value in milliseconds.
  *
  * Return: 0 on success, -errno otherwise.
  */
-static int spi_nor_wait_till_ready_with_timeout(struct spi_nor *nor,
-						unsigned long timeout_jiffies)
+static int spi_nor_wait_till_ready_with_timeout(struct spi_nor *nor, u64 timeout_ms)
 {
-	unsigned long deadline;
-	int timeout = 0, ret;
+	int ret, status;
 
-	deadline = jiffies + timeout_jiffies;
-
-	while (!timeout) {
-		if (time_after_eq(jiffies, deadline))
-			timeout = 1;
-
-		ret = spi_nor_ready(nor);
-		if (ret < 0)
-			return ret;
-		if (ret)
-			return 0;
-
-		cond_resched();
+	ret = poll_timeout_us(status = spi_nor_ready(nor), status,
+			      100, timeout_ms * 1000, false);
+	if (ret < 0) {
+		dev_dbg(nor->dev, "flash operation timed out\n");
+		return ret;
 	}
 
-	dev_dbg(nor->dev, "flash operation timed out\n");
+	if (status < 0)
+		return status;
 
-	return -ETIMEDOUT;
+	return 0;
 }
 
 /**
@@ -747,7 +739,7 @@ static int spi_nor_wait_till_ready_with_timeout(struct spi_nor *nor,
 int spi_nor_wait_till_ready(struct spi_nor *nor)
 {
 	return spi_nor_wait_till_ready_with_timeout(nor,
-						    DEFAULT_READY_WAIT_JIFFIES);
+						    DEFAULT_READY_TIMEOUT_MS);
 }
 
 /**
@@ -1781,8 +1773,8 @@ static int spi_nor_erase_dice(struct spi_nor *nor, loff_t addr,
 	 * pull these from CFI/SFDP, but these values should be good
 	 * enough for now.
 	 */
-	timeout = max(CHIP_ERASE_2MB_READY_WAIT_JIFFIES,
-		      CHIP_ERASE_2MB_READY_WAIT_JIFFIES *
+	timeout = max(CHIP_ERASE_2MB_READY_TIMEOUT_MS,
+		      CHIP_ERASE_2MB_READY_TIMEOUT_MS *
 		      (unsigned long)(nor->mtd.size / SZ_2M));
 
 	do {
-- 
2.47.3