Re: [PATCH v2] mtd: spi-nor: Add support for cy15x104q

[Vignesh Raghavendra <vigneshr@xxxxxx>]

On 09/03/20 2:10 pm, Sascha Hauer wrote:
> The Cypress cy15b104q and cy15v104q are 4Mbit serial SPI F-RAM devices.
> Add support for them to the spi-nor driver.
> 
> Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> ---
> 
> Changes since v1:
> - Instead of specifying 1024 sectors with a sector size of 512 specify
>   512 * 1024 sectos with a sector size of 1. The device has no idea of
>   sectors and is not erasable, so a sector size of 1 seems to better
>   reflect reality.
> 
>  drivers/mtd/spi-nor/spi-nor.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 4fc632ec18fe..a5c1d684364c 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -2335,6 +2335,9 @@ static const struct flash_info spi_nor_ids[] = {
>  
>  	{ "at45db081d", INFO(0x1f2500, 0, 64 * 1024, 16, SECT_4K) },
>  
> +	/* Cypress */
> +	{ "cy15x104q",  INFO6(0x042cc2, 0x7f7f7f, 512 * 1024, 1, SPI_NOR_NO_ERASE) },

This seems wrong

As the datasheet for the device says:

"Device ID
The CY15B104Q device can be interrogated for its manufacturer, product
identification, and die revision. The RDID opcode 9Fh allows
the user to read the manufacturer ID and product ID, both of which are
read-only bytes. The JEDEC-assigned manufacturer ID places
the Cypress (Ramtron) identifier in bank 7; therefore, there are six
bytes of the continuation code 7Fh followed by the single byte C2h.
There are two bytes of product ID, which includes a family code, a
density code, a sub code, and the product revision code."

I am not sure how are you reading 0x4 as the first byte. It should have
been 6 bytes of 0x7F followed by 0xc2 right?

Also 0x7F is continuation code and not actual device ID (See JEDEC
standard JEP106). You will have to extend spi_nor_read_id() function to
take care of continuation code and read more bytes in order to get the
actual Manuf/device ID

> +
>  	/* EON -- en25xxx */
>  	{ "en25f32",    INFO(0x1c3116, 0, 64 * 1024,   64, SECT_4K) },
>  	{ "en25p32",    INFO(0x1c2016, 0, 64 * 1024,   64, 0) },
> 

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