mtd: spinand: add spi nand mtd resume handler

[<patrice.chotard@foss.st.com>]

From: Christophe Kerello <christophe.kerello@foss.st.com>

After power up, all SPI NAND's blocks are locked. Only read operations
are allowed, write and erase operations are forbidden.
The SPI NAND framework unlocks all the blocks during its initialization.

During a standby low power, the memory is powered down, losing its
configuration.
During the resume, the QSPI driver state is restored but the SPI NAND
framework does not reconfigured the memory.

This patch adds spi nand mtd PM handlers for resume ops.
SPI NAND resume op re-initializes SPI NAND flash to its probed state.

Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
---
 drivers/mtd/nand/spi/core.c | 56 +++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 17f63f95f4a2..6abaf874eb3f 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -1074,6 +1074,61 @@ static int spinand_detect(struct spinand_device *spinand)
 	return 0;
 }
 
+static void spinand_mtd_resume(struct mtd_info *mtd)
+{
+	struct spinand_device *spinand = mtd_to_spinand(mtd);
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	struct device *dev = &spinand->spimem->spi->dev;
+	int ret, i;
+
+	ret = spinand_reset_op(spinand);
+	if (ret)
+		return;
+
+	ret = spinand_init_quad_enable(spinand);
+	if (ret) {
+		dev_err(dev,
+			"Failed to initialize the quad part (err = %d)\n",
+			ret);
+		return;
+	}
+
+	ret = spinand_upd_cfg(spinand, CFG_OTP_ENABLE, 0);
+	if (ret) {
+		dev_err(dev,
+			"Failed to updtae the OTP (err = %d)\n",
+			ret);
+		return;
+	}
+
+	ret = spinand_manufacturer_init(spinand);
+	if (ret) {
+		dev_err(dev,
+			"Failed to initialize the SPI NAND chip (err = %d)\n",
+			ret);
+		return;
+	}
+
+	/* After power up, all blocks are locked, so unlock them here. */
+	for (i = 0; i < nand->memorg.ntargets; i++) {
+		ret = spinand_select_target(spinand, i);
+		if (ret) {
+			dev_err(dev,
+				"Failed to select the target (err = %d)\n",
+				ret);
+			return;
+		}
+
+		ret = spinand_lock_block(spinand, BL_ALL_UNLOCKED);
+		if (ret) {
+			dev_err(dev,
+				"Failed to unlock block (err = %d)\n",
+				ret);
+			return;
+		}
+	}
+}
+
 static int spinand_init(struct spinand_device *spinand)
 {
 	struct device *dev = &spinand->spimem->spi->dev;
@@ -1167,6 +1222,7 @@ static int spinand_init(struct spinand_device *spinand)
 	mtd->_block_isreserved = spinand_mtd_block_isreserved;
 	mtd->_erase = spinand_mtd_erase;
 	mtd->_max_bad_blocks = nanddev_mtd_max_bad_blocks;
+	mtd->_resume = spinand_mtd_resume;
 
 	if (nand->ecc.engine) {
 		ret = mtd_ooblayout_count_freebytes(mtd);
-- 
2.17.1