[RFC PATCH v6 4/4] mtd: spi-nor: add spi_nor_init() function

From: Cyrille Pitchen
Date: Sun Apr 16 2017 - 17:43:15 EST


This patch extracts some chunks from spi_nor_scan() and moves them into
a new spi_nor_init() function.

Indeed, spi_nor_init() regroups all the required SPI flash commands to be
sent to the SPI flash memory before performing any runtime operations
(Fast Read, Page Program, Sector Erase, ...). Hence spi_nor_init():
1) removes the flash protection if applicable for certain vendors.
2) sets the Quad Enable bit, if needed, before using Quad SPI protocols.
3) makes the memory enter its (stateful) 4-byte address mode, if needed,
for SPI flash memory > 128Mbits not supporting the 4-byte address
instruction set.

spi_nor_scan() now ends by calling spi_nor_init() once the probe phase has
completed. Further patches could also use spi_nor_init() to implement the
mtd->_resume() handler for the spi-nor framework.

Signed-off-by: Kamal Dasu <kdasu.kdev@xxxxxxxxx>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
---
drivers/mtd/spi-nor/spi-nor.c | 71 ++++++++++++++++++++++++++++---------------
include/linux/mtd/spi-nor.h | 8 +++++
2 files changed, 55 insertions(+), 24 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 2377fe54f8b9..523fd9d85f57 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -255,6 +255,8 @@ static void spi_nor_set_4byte_opcodes(struct spi_nor *nor,
nor->read_opcode = spi_nor_convert_3to4_read(nor->read_opcode);
nor->program_opcode = spi_nor_convert_3to4_program(nor->program_opcode);
nor->erase_opcode = spi_nor_convert_3to4_erase(nor->erase_opcode);
+
+ nor->flags |= SNOR_F_4B_OPCODES;
}

/* Enable/disable 4-byte addressing mode. */
@@ -1836,6 +1838,45 @@ static int spi_nor_setup(struct spi_nor *nor, const struct flash_info *info,
return 0;
}

+static int spi_nor_init(struct spi_nor *nor)
+{
+ const struct flash_info *info = nor->info;
+ struct device *dev = nor->dev;
+ int ret;
+
+ /*
+ * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
+ * with the software protection bits set
+ */
+
+ if (JEDEC_MFR(info) == SNOR_MFR_ATMEL ||
+ JEDEC_MFR(info) == SNOR_MFR_INTEL ||
+ JEDEC_MFR(info) == SNOR_MFR_SST ||
+ info->flags & SPI_NOR_HAS_LOCK) {
+ write_enable(nor);
+ write_sr(nor, 0);
+ spi_nor_wait_till_ready(nor);
+ }
+
+ /* Set the Quad Enable bit, if needed. */
+ if (nor->flash_quad_enable) {
+ ret = nor->flash_quad_enable(nor);
+ if (ret) {
+ dev_err(dev, "quad mode not supported\n");
+ return ret;
+ }
+ }
+
+ /*
+ * For SPI flash memories above 128Mib, enter the 4-byte address mode
+ * only if the 4-byte address instruction set is not supported.
+ */
+ if (nor->addr_width == 4 && !(nor->flags & SNOR_F_4B_OPCODES))
+ set_4byte(nor, info, 1);
+
+ return 0;
+}
+
int spi_nor_scan(struct spi_nor *nor, const char *name,
const struct spi_nor_hwcaps *hwcaps)
{
@@ -1903,20 +1944,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
if (ret)
return ret;

- /*
- * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
- * with the software protection bits set
- */
-
- if (JEDEC_MFR(info) == SNOR_MFR_ATMEL ||
- JEDEC_MFR(info) == SNOR_MFR_INTEL ||
- JEDEC_MFR(info) == SNOR_MFR_SST ||
- info->flags & SPI_NOR_HAS_LOCK) {
- write_enable(nor);
- write_sr(nor, 0);
- spi_nor_wait_till_ready(nor);
- }
-
if (!mtd->name)
mtd->name = dev_name(dev);
mtd->priv = nor;
@@ -1987,14 +2014,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
if (ret)
return ret;

- if (nor->flash_quad_enable) {
- ret = nor->flash_quad_enable(nor);
- if (ret) {
- dev_err(dev, "quad mode not supported\n");
- return ret;
- }
- }
-
if (info->addr_width)
nor->addr_width = info->addr_width;
else if (mtd->size > 0x1000000) {
@@ -2003,8 +2022,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
if (JEDEC_MFR(info) == SNOR_MFR_SPANSION ||
info->flags & SPI_NOR_4B_OPCODES)
spi_nor_set_4byte_opcodes(nor, info);
- else
- set_4byte(nor, info, 1);
} else {
nor->addr_width = 3;
}
@@ -2021,6 +2038,12 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
return ret;
}

+ /* Send all the required SPI flash commands to initialize the memory. */
+ nor->info = info;
+ ret = spi_nor_init(nor);
+ if (ret)
+ return ret;
+
dev_info(dev, "%s (%lld Kbytes)\n", info->name,
(long long)mtd->size >> 10);

diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index e0c58d9d9286..618ecac9337a 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -214,9 +214,16 @@ enum spi_nor_option_flags {
SNOR_F_NO_OP_CHIP_ERASE = BIT(2),
SNOR_F_S3AN_ADDR_DEFAULT = BIT(3),
SNOR_F_READY_XSR_RDY = BIT(4),
+ SNOR_F_4B_OPCODES = BIT(5),
};

/**
+ * struct flash_info - Forward declaration of a structure used internally by
+ * spi_nor_scan() and spi_nor_init().
+ */
+struct flash_info;
+
+/**
* struct spi_nor - Structure for defining a the SPI NOR layer
* @mtd: point to a mtd_info structure
* @lock: the lock for the read/write/erase/lock/unlock operations
@@ -255,6 +262,7 @@ struct spi_nor {
struct mtd_info mtd;
struct mutex lock;
struct device *dev;
+ const struct flash_info *info;
u32 page_size;
u8 addr_width;
u8 erase_opcode;
--
2.9.3