[PATCH v4 04/10] mtd: spinand: simulate behavior of linux's function spinand_wait()

[Mikhail Kshevetskiy]

also call schedule() to allow periodic actions

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy at iopsys.eu>
---
 drivers/mtd/nand/spi/core.c | 35 ++++++++++++++++++++++++++++-------
 include/linux/mtd/spinand.h | 22 ++++++++++++++++++++++
 2 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 4741d3e087c..bc16d9888d5 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -31,6 +31,7 @@
 #include <linux/bug.h>
 #include <linux/mtd/spinand.h>
 #include <linux/printk.h>
+#include <linux/delay.h>
 #endif
 
 /* SPI NAND index visible in MTD names */
@@ -357,21 +358,29 @@ static int spinand_erase_op(struct spinand_device *spinand,
 	return spi_mem_exec_op(spinand->slave, &op);
 }
 
-static int spinand_wait(struct spinand_device *spinand, u8 *s)
+static int spinand_wait(struct spinand_device *spinand,
+			unsigned long initial_delay_us,
+			unsigned long poll_delay_us,
+			u8 *s)
 {
 	unsigned long start, stop;
 	u8 status;
 	int ret;
 
+	udelay(initial_delay_us);
 	start = get_timer(0);
-	stop = 400;
+	stop = SPINAND_WAITRDY_TIMEOUT_MS;
 	do {
+		schedule();
+
 		ret = spinand_read_status(spinand, &status);
 		if (ret)
 			return ret;
 
 		if (!(status & STATUS_BUSY))
 			goto out;
+
+		udelay(poll_delay_us);
 	} while (get_timer(start) < stop);
 
 	/*
@@ -413,7 +422,10 @@ static int spinand_reset_op(struct spinand_device *spinand)
 	if (ret)
 		return ret;
 
-	return spinand_wait(spinand, NULL);
+	return spinand_wait(spinand,
+			    SPINAND_RESET_INITIAL_DELAY_US,
+			    SPINAND_RESET_POLL_DELAY_US,
+			    NULL);
 }
 
 static int spinand_lock_block(struct spinand_device *spinand, u8 lock)
@@ -461,7 +473,10 @@ static int spinand_read_page(struct spinand_device *spinand,
 	if (ret)
 		return ret;
 
-	ret = spinand_wait(spinand, &status);
+	ret = spinand_wait(spinand,
+			   SPINAND_READ_INITIAL_DELAY_US,
+			   SPINAND_READ_POLL_DELAY_US,
+			   &status);
 	if (ret < 0)
 		return ret;
 
@@ -493,9 +508,12 @@ static int spinand_write_page(struct spinand_device *spinand,
 	if (ret)
 		return ret;
 
-	ret = spinand_wait(spinand, &status);
+	ret = spinand_wait(spinand,
+			   SPINAND_WRITE_INITIAL_DELAY_US,
+			   SPINAND_WRITE_POLL_DELAY_US,
+			   &status);
 	if (!ret && (status & STATUS_PROG_FAILED))
-		ret = -EIO;
+		return -EIO;
 
 	return ret;
 }
@@ -697,7 +715,10 @@ static int spinand_erase(struct nand_device *nand, const struct nand_pos *pos)
 	if (ret)
 		return ret;
 
-	ret = spinand_wait(spinand, &status);
+	ret = spinand_wait(spinand,
+			   SPINAND_ERASE_INITIAL_DELAY_US,
+			   SPINAND_ERASE_POLL_DELAY_US,
+			   &status);
 	if (!ret && (status & STATUS_ERASE_FAILED))
 		ret = -EIO;
 
diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
index 5934b7604cc..b701d25f73d 100644
--- a/include/linux/mtd/spinand.h
+++ b/include/linux/mtd/spinand.h
@@ -176,6 +176,28 @@ struct spinand_op;
 struct spinand_device;
 
 #define SPINAND_MAX_ID_LEN	4
+/*
+ * For erase, write and read operation, we got the following timings :
+ * tBERS (erase) 1ms to 4ms
+ * tPROG 300us to 400us
+ * tREAD 25us to 100us
+ * In order to minimize latency, the min value is divided by 4 for the
+ * initial delay, and dividing by 20 for the poll delay.
+ * For reset, 5us/10us/500us if the device is respectively
+ * reading/programming/erasing when the RESET occurs. Since we always
+ * issue a RESET when the device is IDLE, 5us is selected for both initial
+ * and poll delay.
+ */
+#define SPINAND_READ_INITIAL_DELAY_US	6
+#define SPINAND_READ_POLL_DELAY_US	5
+#define SPINAND_RESET_INITIAL_DELAY_US	5
+#define SPINAND_RESET_POLL_DELAY_US	5
+#define SPINAND_WRITE_INITIAL_DELAY_US	75
+#define SPINAND_WRITE_POLL_DELAY_US	15
+#define SPINAND_ERASE_INITIAL_DELAY_US	250
+#define SPINAND_ERASE_POLL_DELAY_US	50
+
+#define SPINAND_WAITRDY_TIMEOUT_MS	400
 
 /**
  * struct spinand_id - SPI NAND id structure
-- 
2.39.2