mtd: spinand: Extend spinand_wait() to match Linux kernel implementation

This aligns spinand_wait() with the linux kernel. Instead of calling into
spi_mem_poll_status() which is not implemented in U-Boot, we code the
polling logic and make sure that schedule() is called periodically.

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>

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