Re: [PATCH] arm/aspeed: rainier: Add i2c eeproms and muxes

[Joel Stanley]

On Mon, 28 Jun 2021 at 04:33, Andrew Jeffery <andrew@aj.id.au> wrote:
>
>
>
> On Fri, 25 Jun 2021, at 14:36, Joel Stanley wrote:
> > These are the devices documented by the Rainier device tree. With this
> > we can see the guest discovering the multiplexers and probing the eeprom
> > devices:
> >
> >  i2c i2c-2: Added multiplexed i2c bus 16
> >  i2c i2c-2: Added multiplexed i2c bus 17
> >  i2c i2c-2: Added multiplexed i2c bus 18
> >  i2c i2c-2: Added multiplexed i2c bus 19
> >  i2c-mux-gpio i2cmux: 4 port mux on 1e78a180.i2c-bus adapter
> >  at24 20-0050: 8192 byte 24c64 EEPROM, writable, 1 bytes/write
> >  i2c i2c-4: Added multiplexed i2c bus 20
> >  at24 21-0051: 8192 byte 24c64 EEPROM, writable, 1 bytes/write
> >  i2c i2c-4: Added multiplexed i2c bus 21
> >  at24 22-0052: 8192 byte 24c64 EEPROM, writable, 1 bytes/write
> >
> > Signed-off-by: Joel Stanley <joel@jms.id.au>
> > ---
> >  hw/arm/aspeed.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 56 insertions(+)
> >
> > diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
> > index 1301e8fdffb2..7ed22294c6eb 100644
> > --- a/hw/arm/aspeed.c
> > +++ b/hw/arm/aspeed.c
> > @@ -677,6 +677,10 @@ static void g220a_bmc_i2c_init(AspeedMachineState *bmc)
> >  static void rainier_bmc_i2c_init(AspeedMachineState *bmc)
> >  {
> >      AspeedSoCState *soc = &bmc->soc;
> > +    I2CSlave *i2c_mux;
> > +
> > +    smbus_eeprom_init_one(aspeed_i2c_get_bus(&soc->i2c, 0), 0x51,
> > +                          g_malloc0(32 * 1024));
> >
> >      /* The rainier expects a TMP275 but a TMP105 is compatible */
> >      i2c_slave_create_simple(aspeed_i2c_get_bus(&soc->i2c, 4), TYPE_TMP105,
> > @@ -685,11 +689,25 @@ static void rainier_bmc_i2c_init(AspeedMachineState 
> > *bmc)
> >                       0x49);
> >      i2c_slave_create_simple(aspeed_i2c_get_bus(&soc->i2c, 4), TYPE_TMP105,
> >                       0x4a);
> > +    i2c_mux = i2c_slave_create_simple(aspeed_i2c_get_bus(&soc->i2c, 4),
> > +                                      "pca9546", 0x70);
> > +    smbus_eeprom_init_one(pca954x_i2c_get_bus(i2c_mux, 0), 0x50,
> > +                          g_malloc0(64 * 1024));
>
> The EEPROMs described in the Rainier devicetree are Atmel AT2x devices and
> not SMBus EEPROMs. The SMBus EEPROM model uses SMBus block reads and
> writes which are not what the AT2x driver issues. If you try to read or
> write data under Linux from the EEPROMs in this patch you just get
> corrupt results. So as far as I can see the patch needs to be reworked.

That's fine, these are just there so the drivers can probe. As you can
see the devices have no data in them either, so it's nowhere near an
incomplete model.

If you want to extend the modelling to have the correct VPD data, and
allow writes where applicable, that would be welcome.

Cheers,

Joel