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SubjectRe: [PATCH v7 1/2] mtd: spi-nor: add spi_nor_init() function
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Hi Kamal,

Le 02/08/2017 à 00:41, Kamal Dasu a écrit :
> This patch extracts some chunks from spi_nor_init_params and 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@gmail.com>
> ---
> drivers/mtd/spi-nor/spi-nor.c | 62 ++++++++++++++++++++++++++++++-------------
> include/linux/mtd/spi-nor.h | 9 +++++++
> 2 files changed, 52 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 1413828..10033ed 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -1784,7 +1784,6 @@ static int spi_nor_setup(struct spi_nor *nor, const struct flash_info *info,
> const struct spi_nor_hwcaps *hwcaps)
> {
> u32 ignored_mask, shared_mask;
> - bool enable_quad_io;
> int err;
>
> /*
> @@ -1829,20 +1828,42 @@ static int spi_nor_setup(struct spi_nor *nor, const struct flash_info *info,
> return err;
> }
>
> - /* Enable Quad I/O if needed. */
> - enable_quad_io = (spi_nor_get_protocol_width(nor->read_proto) == 4 ||
> - spi_nor_get_protocol_width(nor->write_proto) == 4);
> - if (enable_quad_io && params->quad_enable) {
> - err = params->quad_enable(nor);
> + return 0;
> +}
> +
> +static int spi_nor_init(struct spi_nor *nor)
> +{
> + int err;
> +
> + /*
> + * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
> + * with the software protection bits set
> + */
> + if (JEDEC_MFR(nor->info) == SNOR_MFR_ATMEL ||
> + JEDEC_MFR(nor->info) == SNOR_MFR_INTEL ||
> + JEDEC_MFR(nor->info) == SNOR_MFR_SST ||
> + nor->info->flags & SPI_NOR_HAS_LOCK) {
> + write_enable(nor);
> + write_sr(nor, 0);
> + spi_nor_wait_till_ready(nor);
> + }
> +
> + if (nor->quad_enable) {
> + err = nor->quad_enable(nor);
> if (err) {
> dev_err(nor->dev, "quad mode not supported\n");
> return err;
> }
> }
>
> + if ((JEDEC_MFR(nor->info) != SNOR_MFR_SPANSION) &&
> + !(nor->info->flags & SPI_NOR_4B_OPCODES))
> + set_4byte(nor, nor->info, 1);
> +

I've forgotten to test whether nor->addr_width == 4: if not, set_4byte()
should not be called.

> return 0;
> }
>
> +
> int spi_nor_scan(struct spi_nor *nor, const char *name,
> const struct spi_nor_hwcaps *hwcaps)
> {
> @@ -1853,6 +1874,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
> struct device_node *np = spi_nor_get_flash_node(nor);
> int ret;
> int i;
> + bool enable_quad_io;
>
> ret = spi_nor_check(nor);
> if (ret)
> @@ -1915,15 +1937,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
> * with the software protection bits set
> */
>
The comment above is attached to the chunk below. Since you've moved
both the chunk and its comment into the spi_nor_init() function, remove
the comment from spi_nor_scan() too.

> - 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;
> @@ -2002,8 +2015,6 @@ 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;
> }
> @@ -2020,8 +2031,21 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
> return ret;
> }
>
> - dev_info(dev, "%s (%lld Kbytes)\n", info->name,
> - (long long)mtd->size >> 10);
> + /* Send all the required SPI flash commands to initialize device */
> + nor->info = info;
> + /* Enable Quad I/O if needed. */
> + enable_quad_io = (spi_nor_get_protocol_width(nor->read_proto) == 4 ||
> + spi_nor_get_protocol_width(nor->write_proto) == 4);
> + if (enable_quad_io && params.quad_enable)
> + nor->quad_enable = params.quad_enable;

I would just leave this chunk in spi_nor_setup() now executing
+ nor->quad_enable = params.quad_enable;
instead of calling
- err = params->quad_enable(nor);

2 reasons:
- to avoid spi_nor_scan() growing too much as it is already a little bit
too long, IMHO.
- The read & write protocols are selected in spi_nor_setup() and the
need to call params->quad_enable() is a direct consequence of those choices.

> +
> + ret = spi_nor_init(nor);
> + if (ret)
> + return ret;
> +
> + dev_info(dev, "%s (%lld Kbytes), %dByte addr, %s\n", info->name,
> + (long long)mtd->size >> 10, nor->addr_width,
> + (nor->quad_enable ? "quad io enabled" : "quad io disabled"));
>

The "quad io enabled" / "quad io disabled" are not really meaningful for
regular users, this is more a debug output.
Besides, the "quad io disabled" string would be displayed for all non
Quad SPI memories which doesn't make sense.
Also nor->quad_enable will be NULL for Micron memory since those
memories have no special procedure to enable Quad I/O. So printing "quad
io disabled" in that case would be wrong too.

Moreover, the "%dByte addr" string is debug output too and except for
very few particular cases, the memory size already tell us the actual
number of address bytes:
- <= 128Mib <-> 3 byte address
- > 128Mib <-> 4 byte address

So leave the dev_info() string as is, please.


> dev_dbg(dev,
> "mtd .name = %s, .size = 0x%llx (%lldMiB), "
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index 55faa2f..db127b8 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -220,11 +220,17 @@ enum spi_nor_option_flags {
> SNOR_F_READY_XSR_RDY = BIT(4),
> };
>
> +/* struct flash_info - Forward declaration of a structure used internally by
> + * spi_nor_scan()
> + */

The kernel doc format is:
/**
* strcut flash_info - Forward declaration ...
*
*/

Best regards,

Cyrille

> +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
> * @dev: point to a spi device, or a spi nor controller device.
> + * @info: spi-nor part JDEC MFR id and other info
> * @page_size: the page size of the SPI NOR
> * @addr_width: number of address bytes
> * @erase_opcode: the opcode for erasing a sector
> @@ -251,6 +257,7 @@ enum spi_nor_option_flags {
> * @flash_lock: [FLASH-SPECIFIC] lock a region of the SPI NOR
> * @flash_unlock: [FLASH-SPECIFIC] unlock a region of the SPI NOR
> * @flash_is_locked: [FLASH-SPECIFIC] check if a region of the SPI NOR is
> + * @quad_enable: [FLASH-SPECIFIC] enables SPI NOR quad mode
> * completely locked
> * @priv: the private data
> */
> @@ -258,6 +265,7 @@ 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;
> @@ -285,6 +293,7 @@ struct spi_nor {
> int (*flash_lock)(struct spi_nor *nor, loff_t ofs, uint64_t len);
> int (*flash_unlock)(struct spi_nor *nor, loff_t ofs, uint64_t len);
> int (*flash_is_locked)(struct spi_nor *nor, loff_t ofs, uint64_t len);
> + int (*quad_enable)(struct spi_nor *nor);
>
> void *priv;
> };
>

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