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>

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 34e5ac33c63b4636c8aa9549aeddb8d91f47bb2c..3b612bec274532c4200943cfdb7ef380a5a21275 100644 (file)
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -32,6 +32,7 @@
 #include <linux/bug.h>
 #include <linux/mtd/spinand.h>
 #include <linux/printk.h>
+#include <linux/delay.h>
 #endif
 
 struct spinand_plat {
@@ -362,21 +363,41 @@ 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)
+/**
+ * spinand_wait() - Poll memory device status
+ * @spinand: the spinand device
+ * @initial_delay_us: delay in us before starting to poll
+ * @poll_delay_us: time to sleep between reads in us
+ * @s: the pointer to variable to store the value of REG_STATUS
+ *
+ * This function polls a status register (REG_STATUS) and returns when
+ * the STATUS_READY bit is 0 or when the timeout has expired.
+ *
+ * Return: 0 on success, a negative error code otherwise.
+ */
+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);
 
        /*
@@ -418,7 +439,10 @@ 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)
@@ -466,7 +490,10 @@ 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;
 
@@ -498,9 +525,12 @@ 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;
 }
@@ -702,7 +732,10 @@ 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 163269313f66b1e7126438ca3679bedb16a5aae1..ba6c2ba149da94ae2f5ab8d31e285eb4e00de1a1 100644 (file)
--- 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