Re: [PATCH v3 1/3] eeprom: at24: avoid adjusting offset for 24AA025E{48, 64}

[Bartosz Golaszewski <brgl@bgdev.pl>]

On Fri, Jun 28, 2024 at 4:17 PM <Andrei.Simion@microchip.com> wrote:
>
> On 28.06.2024 11:30, Bartosz Golaszewski wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >
> > On Fri, Jun 28, 2024 at 10:02 AM Andrei Simion
> > <andrei.simion@microchip.com> wrote:
> >>
> >> From: Claudiu Beznea <claudiu.beznea@microchip.com>
> >>
> >> The EEPROMs could be used only for MAC storage. In this case the
> >> EEPROM areas where MACs resides could be modeled as NVMEM cells
> >> (directly via DT bindings) such that the already available networking
> >> infrastructure to read properly the MAC addresses (via
> >> of_get_mac_address()). The previously available compatibles needs the
> >> offset adjustment probably for compatibility w/ old DT bindings.
> >> Add "microchip,24aa025e48", "microchip,24aa025e64" compatible for the
> >> usage w/ 24AA025E{48, 64} type of EEPROMs where "24aa025e48" stands
> >> for EUI-48 address and "24aa025e64" stands for EUI-64 address.
> >>
> >> Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
> >> [andrei.simion@microchip.com: Add extended macros to initialize the structure
> >> with explicit value to adjusting offset. Add extra description for the commit
> >> message.]
> >> Signed-off-by: Andrei Simion <andrei.simion@microchip.com>
> >> ---
> >> v2 -> v3:
> >> - add specific compatible names according with
> >> https://ww1.microchip.com/downloads/en/DeviceDoc/24AA02E48-24AA025E48-24AA02E64-24AA025E64-Data-Sheet-20002124H.pdf
> >> - add extended macros to initialize the structure with explicit value for adjoff
> >> - drop co-developed-by to maintain the commit history
> >>  (chronological order of modifications)
> >>
> >> v1 -> v2:
> >> - no change
> >> ---
> >>  drivers/misc/eeprom/at24.c | 28 +++++++++++++++++++++++-----
> >>  1 file changed, 23 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> >> index 4bd4f32bcdab..e2ac08f656cf 100644
> >> --- a/drivers/misc/eeprom/at24.c
> >> +++ b/drivers/misc/eeprom/at24.c
> >> @@ -121,20 +121,29 @@ struct at24_chip_data {
> >>         u32 byte_len;
> >>         u8 flags;
> >>         u8 bank_addr_shift;
> >> +       u8 adjoff;
> >>         void (*read_post)(unsigned int off, char *buf, size_t count);
> >>  };
> >>
> >> -#define AT24_CHIP_DATA(_name, _len, _flags)                            \
> >> +#define AT24_CHIP_DATA_AO(_name, _len, _flags, _ao)                    \
> >
> > Please, don't try to save space on a few letters, call it
> > AT24_CHIP_DATA_ADJOFF() for better readability.
> >
>
> I will change in next the version.
>
> >>         static const struct at24_chip_data _name = {                    \
> >>                 .byte_len = _len, .flags = _flags,                      \
> >> +               .adjoff = _ao                                           \
> >>         }
> >>
> >> -#define AT24_CHIP_DATA_CB(_name, _len, _flags, _read_post)             \
> >> +#define AT24_CHIP_DATA(_name, _len, _flags)                            \
> >> +       AT24_CHIP_DATA_AO(_name, _len, _flags, 0)
> >> +
> >> +#define AT24_CHIP_DATA_CB_AO(_name, _len, _flags, _ao, _read_post)     \
> >>         static const struct at24_chip_data _name = {                    \
> >>                 .byte_len = _len, .flags = _flags,                      \
> >> +               .adjoff = _ao,                                          \
> >>                 .read_post = _read_post,                                \
> >>         }
> >>
> >> +#define AT24_CHIP_DATA_CB(_name, _len, _flags, _read_post)             \
> >> +       AT24_CHIP_DATA_CB_AO(_name, _len, _flags, 0, _read_post)
> >> +
> >>  #define AT24_CHIP_DATA_BS(_name, _len, _flags, _bank_addr_shift)       \
> >>         static const struct at24_chip_data _name = {                    \
> >>                 .byte_len = _len, .flags = _flags,                      \
> >> @@ -170,9 +179,13 @@ AT24_CHIP_DATA(at24_data_24cs01, 16,
> >>  AT24_CHIP_DATA(at24_data_24c02, 2048 / 8, 0);
> >>  AT24_CHIP_DATA(at24_data_24cs02, 16,
> >>         AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
> >> -AT24_CHIP_DATA(at24_data_24mac402, 48 / 8,
> >> +AT24_CHIP_DATA_AO(at24_data_24mac402, 48 / 8,
> >> +       AT24_FLAG_MAC | AT24_FLAG_READONLY, 1);
> >
> > And this will not break existing users? I guess you refer to these
> > changes in your commit message but it's not very clear what you're
> > doing and why.
> >
>
> For those types of eeprom 24AA025E{48, 64} adjusting offset is not required (at24_get_offset_adj()).
> So, indeed, it is an entanglement in logic.
> To keep the implementation as it is:
> adjoff (which is a flag that indicates when to use the adjusting offset) needs to be 1 for old compatibles but for these new ones needs to be 0.
>
> I think that is enough not to break the existing users. What are your thoughts?
>

Wait... is the adjoff field effectively a boolean? Why u8?

Bart

> Best Regards,
> Andrei Simion
>
> >> +AT24_CHIP_DATA_AO(at24_data_24mac602, 64 / 8,
> >> +       AT24_FLAG_MAC | AT24_FLAG_READONLY, 1);
> >> +AT24_CHIP_DATA(at24_data_24aa025e48, 48 / 8,
> >>         AT24_FLAG_MAC | AT24_FLAG_READONLY);
> >> -AT24_CHIP_DATA(at24_data_24mac602, 64 / 8,
> >> +AT24_CHIP_DATA(at24_data_24aa025e64, 64 / 8,
> >>         AT24_FLAG_MAC | AT24_FLAG_READONLY);
> >>  /* spd is a 24c02 in memory DIMMs */
> >>  AT24_CHIP_DATA(at24_data_spd, 2048 / 8,
> >> @@ -218,6 +231,8 @@ static const struct i2c_device_id at24_ids[] = {
> >>         { "24cs02",     (kernel_ulong_t)&at24_data_24cs02 },
> >>         { "24mac402",   (kernel_ulong_t)&at24_data_24mac402 },
> >>         { "24mac602",   (kernel_ulong_t)&at24_data_24mac602 },
> >> +       { "24aa025e48", (kernel_ulong_t)&at24_data_24aa025e48 },
> >> +       { "24aa025e64", (kernel_ulong_t)&at24_data_24aa025e64 },
> >>         { "spd",        (kernel_ulong_t)&at24_data_spd },
> >>         { "24c02-vaio", (kernel_ulong_t)&at24_data_24c02_vaio },
> >>         { "24c04",      (kernel_ulong_t)&at24_data_24c04 },
> >> @@ -270,6 +285,8 @@ static const struct of_device_id __maybe_unused at24_of_match[] = {
> >>         { .compatible = "atmel,24c1024",        .data = &at24_data_24c1024 },
> >>         { .compatible = "atmel,24c1025",        .data = &at24_data_24c1025 },
> >>         { .compatible = "atmel,24c2048",        .data = &at24_data_24c2048 },
> >> +       { .compatible = "microchip,24aa025e48", .data = &at24_data_24aa025e48 },
> >> +       { .compatible = "microchip,24aa025e64", .data = &at24_data_24aa025e64 },
> >>         { /* END OF LIST */ },
> >>  };
> >>  MODULE_DEVICE_TABLE(of, at24_of_match);
> >> @@ -690,7 +707,8 @@ static int at24_probe(struct i2c_client *client)
> >>         at24->read_post = cdata->read_post;
> >>         at24->bank_addr_shift = cdata->bank_addr_shift;
> >>         at24->num_addresses = num_addresses;
> >> -       at24->offset_adj = at24_get_offset_adj(flags, byte_len);
> >> +       at24->offset_adj = cdata->adjoff ?
> >> +                               at24_get_offset_adj(flags, byte_len) : 0;
> >>         at24->client_regmaps[0] = regmap;
> >>
> >>         at24->vcc_reg = devm_regulator_get(dev, "vcc");
> >> --
> >> 2.34.1
> >>
> >
> > Bart