mtd: spi-nor: fsl-quadspi: reset the module in the probe

The uboot may run the QuadSpi controler with command:
    #sf probe

So we should reset the module in the probe.
This patch also clear the pending interrupts which arised by the uboot
code.
Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/spi-nor/fsl-quadspi.c

@@ -716,6 +716,11 @@ static int fsl_qspi_nor_setup(struct fsl_qspi *q)
 	if (ret)
 		return ret;
 
+	/* Reset the module */
+	writel(QUADSPI_MCR_SWRSTSD_MASK | QUADSPI_MCR_SWRSTHD_MASK,
+		base + QUADSPI_MCR);
+	udelay(1);
+
 	/* Init the LUT table. */
 	fsl_qspi_init_lut(q);
 
@@ -733,6 +738,9 @@ static int fsl_qspi_nor_setup(struct fsl_qspi *q)
 	writel(QUADSPI_MCR_RESERVED_MASK | QUADSPI_MCR_END_CFG_MASK,
 			base + QUADSPI_MCR);
 
+	/* clear all interrupt status */
+	writel(0xffffffff, q->iobase + QUADSPI_FR);
+
 	/* enable the interrupt */
 	writel(QUADSPI_RSER_TFIE, q->iobase + QUADSPI_RSER);