[PATCH linux-next v4 1/5] mtd: spi-nor: notify (Q)SPI controller about protocol change

Cyrille Pitchen
2015-08-24T10:14:10Z

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 <cyrille.pitchen@atmel.com>
---
drivers/mtd/spi-nor/spi-nor.c | 21 +++++++++++++++++++++
include/linux/mtd/spi-nor.h | 13 +++++++++++++
2 files changed, 34 insertions(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 47df4b5eae2f..e2a6029dc056 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -163,6 +163,22 @@ static inline int write_disable(struct spi_nor *nor)
return nor->write_reg(nor, SPINOR_OP_WRDI, NULL, 0, 0);
}

+/*
+ * Let the spi-nor framework notify lower layers, especially the driver of the
+ * (Q)SPI controller, about the new protocol to be used. Indeed, once the
+ * spi-nor framework has sent manufacturer specific commands to a memory to
+ * enable its Quad SPI mode, it should immediately after tell the QSPI
+ * controller to use the very same Quad SPI protocol as expected by the memory.
+ */
+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;
@@ -944,6 +960,11 @@ static int micron_quad_enable(struct spi_nor *nor)
return ret;
}

+ /* switch protocol to Quad CMD 4-4-4 */
+ ret = spi_nor_set_protocol(nor, SPI_PROTO_4_4_4);
+ if (ret)
+ return ret;
+
ret = spi_nor_wait_till_ready(nor);
if (ret)
return ret;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index e5409524bb0a..1bf6f11310ef 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -87,6 +87,16 @@ enum read_mode {
SPI_NOR_QUAD,
};

+enum spi_protocol {
+ SPI_PROTO_1_1_1, /* SPI */
+ SPI_PROTO_1_1_2, /* Dual Output */
+ SPI_PROTO_1_1_4, /* Quad Output */
+ SPI_PROTO_1_2_2, /* Dual IO */
+ SPI_PROTO_1_4_4, /* Quad IO */
+ SPI_PROTO_2_2_2, /* Dual Command */
+ SPI_PROTO_4_4_4, /* Quad Command */
+};
+
/**
* struct spi_nor_xfer_cfg - Structure for defining a Serial Flash transfer
* @wren: command for "Write Enable", or 0x00 for not required
@@ -149,6 +159,7 @@ enum spi_nor_option_flags {
* read/write/erase/lock/unlock operations
* @read_xfer: [OPTIONAL] the read fundamental primitive
* @write_xfer: [OPTIONAL] the writefundamental primitive
+ * @set_protocol: [OPTIONAL] notify about protocol change
* @read_reg: [DRIVER-SPECIFIC] read out the register
* @write_reg: [DRIVER-SPECIFIC] write data to the register
* @read: [DRIVER-SPECIFIC] read data from the SPI NOR
@@ -185,6 +196,8 @@ struct spi_nor {
int (*write_reg)(struct spi_nor *nor, u8 opcode, u8 *buf, int len,
int write_enable);

+ int (*set_protocol)(struct spi_nor *nor, enum spi_protocol proto);
+
int (*read)(struct spi_nor *nor, loff_t from,
size_t len, size_t *retlen, u_char *read_buf);
void (*write)(struct spi_nor *nor, loff_t to,
--
1.8.2.2