[U-Boot] [PATCH v10 03/27] mtd: add SPI-NOR core support

[Vignesh R]

On Wednesday 03 January 2018 03:02 PM, Jagan Teki wrote:
> On Wed, Jan 3, 2018 at 2:19 PM, Vignesh R <vigneshr at ti.com> wrote:
>>
>>
>> On Thursday 28 December 2017 11:42 AM, Jagan Teki wrote:
>> [...]
>>> +static const struct mtd_ops spi_nor_mtd_ops = {
>>> +     .read   = spi_nor_mread,
>>> +     .erase  = spi_nor_merase,
>>> +};
>>> +
>>
>> Wondering why spi_nor_mwrite is not hooked up here?
> 
> yes, because of sst we need to assign the write hook during scan, see spi-nor.c
> 
>>
>>> +U_BOOT_DRIVER(spinor_mtd) = {
>>> +     .name           = "spinor_mtd",
>>> +     .id             = UCLASS_MTD,
>>> +     .ops            = &spi_nor_mtd_ops,
>>> +     .probe          = spi_nor_mtd_probe,
>>> +};
>>> +
>>> +U_BOOT_DRIVER(spinor) = {
>>> +     .name   = "spinor",
>>> +     .id     = UCLASS_SPI_NOR,
>>> +};
>>> +
>>> +UCLASS_DRIVER(spinor) = {
>>> +     .id             = UCLASS_SPI_NOR,
>>> +     .name           = "spinor",
>>> +     .flags          = DM_UC_FLAG_SEQ_ALIAS,
>>> +     .per_device_auto_alloc_size = sizeof(struct spi_nor_uclass_priv),
>>> +};
>>
>> [...]
>>
>>> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
>>> new file mode 100644
>>> index 0000000..e1688e2
>>> --- /dev/null
>>> +++ b/include/linux/mtd/spi-nor.h
>>> @@ -0,0 +1,217 @@
>> [...]
>>> +struct spi_nor {
>>> +     struct udevice          *dev;
>>> +     const char              *name;
>>> +     u8                      init_done;
>>> +     u32                     page_size;
>>> +     u8                      addr_width;
>>> +     u8                      erase_opcode;
>>> +     u8                      read_opcode;
>>> +     u8                      read_dummy;
>>> +     u8                      program_opcode;
>>> +     u32                     max_write_size;
>>> +     u32                     flags;
>>> +     u8                      mode;
>>
>>> +     u8                      read_mode;
>>
>> Where is this field used? Shouldn't this field carry single/dual/quad
>> mode information?
> 
> I think it came up from previous versions, no real use as of now will
> check and update in next version

This field is very much needed to inform SPI NOR controllers where to
use 1-1-2 or 1-1-4 or 1-1-1 mode for reading data from flash. It should
be the SPI NOR framework providing this info and not expecting driver to
assume this or infer from DT.

-- 
Regards
Vignesh