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

[Tudor.Ambarus at microchip.com]

On 10/09/2019 07:25 PM, Vignesh Raghavendra wrote:
> External E-Mail
> 
> 
> 
> 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?

Ok, will do so. Thanks!