[PATCH v2 1/5] mtd: spi-nor: notify (Q)SPI controller about protocol change

Once the Quad SPI mode has been enabled on a Micron flash memory, this
device expects ALL the following commands to use the SPI 4-4-4 protocol.
The (Q)SPI controller needs to be notified about the protocol change so it
can adapt and keep on dialoging with the Micron memory.

Signed-off-by: Cyrille Pitchen <redacted>
---
 drivers/mtd/spi-nor/spi-nor.c | 17 +++++++++++++++++
 include/linux/mtd/spi-nor.h   | 13 +++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index d78831b4422b..93627d4e6be8 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c

@@ -163,6 +163,18 @@ static inline int write_disable(struct spi_nor *nor)
 	return nor->write_reg(nor, SPINOR_OP_WRDI, NULL, 0, 0);
 }

+/*
+ * Notify the (Q)SPI controller about the new protocol to be used.

+ */
+static inline int spi_nor_set_protocol(struct spi_nor *nor,
+				       enum spi_protocol proto)
+{
+	if (nor->set_protocol)
+		return nor->set_protocol(nor, proto);
+
+	return 0;
+}
+
 static inline struct spi_nor *mtd_to_spi_nor(struct mtd_info *mtd)
 {
 	return mtd->priv;