Re: I2C adapters protocol deviation

[Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>]

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> So what we really have is a single slave i2c host sort of. At least
> we could model it like that. The host could be told which address to
> listen to (and which single i2c write to do to init the pmic) through
> devicetree and then all the differences would be hidden in the host
> driver, ie we would check the slave-address and if it is not the single
> one we support, we just return the appropriate error for a device not
> acking, and everything should work as a regular i2c host which
> only supports i2c_smbus_read_byte and i2c_smbus_write_byte.

I'd think we need a new message flag like I2C_M_PUSHPULL which says that
this message has only the direction bit instead of the address and needs
a parity bit afterwards. In addition to that, we need a new
functionality flag I2C_FUNC_PUSHPULL which means the host driver can
handle those messages. So, the PMIC driver could query support for
I2C_FUNC_SMBUS_BYTE | I2C_FUNC_PUSHPULL and if successful send messages
using smbus functions with the new flag set.

Not sure about the I2C-to-PushPull switch: Is it 100% host configuration
or does it also depend on the one slave attached? Are there some
datasheets available?


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