[U-Boot] [PATCH 1/4] mtd: spi: spi-nor-core: Add Microchip SFDP parser

[Vignesh Raghavendra]

On 09-Oct-19 9:20 PM, Tudor.Ambarus at microchip.com wrote:
> Hi, Vignesh,
> 
> On 10/09/2019 03:04 PM, Vignesh Raghavendra wrote:
>> External E-Mail
>>
>>
>> Hi Tudor,
>>
>> On 01/10/19 2:29 PM, Tudor.Ambarus at microchip.com wrote:
>>> From: Tudor Ambarus <tudor.ambarus at microchip.com>
>>>
>>> JESD216 allow vendors to define their own SFDP tables.
>>>
>>> Add Microchip SFDP parser. The vendor table is allocated using
>>> resource-managed kmalloc - the table will be freed on driver detach.
>>> It will be accessible by getting the UCLASS_SPI_FLASH's private data.
>>>
>>> The Michrochip's SFDP table is particularly of interest because contains
>>> pre-programmed globally unique EUI-48 and EUI-64 identifiers.
>>>
>>> Signed-off-by: Tudor Ambarus <tudor.ambarus at microchip.com>
>>> ---
>>>  drivers/mtd/spi/spi-nor-core.c | 35 +++++++++++++++++++++++++++++++++++
>>>  include/linux/mtd/spi-nor.h    |  2 ++
>>>  2 files changed, 37 insertions(+)
>>>
>>> diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
>>> index 1acff745d1a2..bade7d8a9f79 100644
>>> --- a/drivers/mtd/spi/spi-nor-core.c
>>> +++ b/drivers/mtd/spi/spi-nor-core.c
>>> @@ -1417,6 +1417,7 @@ struct sfdp_parameter_header {
>>>  
>>>  #define SFDP_BFPT_ID		0xff00	/* Basic Flash Parameter Table */
>>>  #define SFDP_SECTOR_MAP_ID	0xff81	/* Sector Map Table */
>>> +#define SFDP_MICROCHIP_ID	0x01bf	/* Manufacturer specific Table */
>>>  
>> Is this ID unique enough such that no other vendor will use the same? I
>> recall that MSB byte should be assigned to Vendor and 0x01 does not seem
>> to be Microchip specific? Or did I miss something?
>>
> 
> It is unique.
> 
> Quoting form JESD216 rev D, section "6.3.3 Definition of Parameter ID Field":
> "The original JESD216 specification used only a one byte ID field to identify
> the parameter table owner.
>  JESD216 revision A expanded the ID field to two bytes, MSB and LSB, because a
> single byte is
>  insufficient to uniquely identify all manufacturers ( vendors). The original
> single byte parameter ID is
>  now referred to as the parameter ID LSB."
> 
> In the Microchip's case, 01h is the Parameter ID MSB (respects the 01h-7fh
> interval) and bfh is the Parameter ID LSB (has odd parity, which is correct).
> Now I'm looking in the JEP106AZ standard (Standard Manufacturer’s
> Identification Code): 01h MSB indicates the bank number (one), and bfh LSB
> indicates the Manufacturer Identification code (which is bfh for SST).
> 

Ah, thanks for the explanation! I was confused with bank number
initially. Was also confused by the fact that there is an entry for
Microchip Technology in JEP106AZ that reads 29. May be rename the macro
to indicate SFDP_SST_ID?

Regards
Vignesh