On Wednesday 11 June 2014 10:39:40 Boris BREZILLON wrote: > The P2WI controller looks like an SMBus controller which only supports byte > data transfers. But, it differs from standard SMBus protocol on several > aspects: > - it supports only one slave device, and thus drop the address field > - it adds a parity bit every 8bits of data > - only one read access is required to read a byte (instead of a write > followed by a read access in standard SMBus protocol) > - there's no Ack bit after each byte transfer > > This means this bus cannot be used to interface with standard SMBus > devices (the only known device to support this interface is the AXP221 > PMIC). > However the P2WI protocol is close enough to SMBus to be integrated in > the I2C subsystem (see this thread [1] for detailed reasons that led to > integrating this driver in the I2C subsystem). > > [1] http://www.spinics.net/lists/linux-i2c/msg15066.html > > Signed-off-by: Boris BREZILLON <boris.brezillon@xxxxxxxxxxxxxxxxxx> > Acked-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> Acked-by: Arnd Bergmann <arnd@xxxxxxxx> > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig > index c94db1c..a6023fe 100644 > --- a/drivers/i2c/busses/Kconfig > +++ b/drivers/i2c/busses/Kconfig > @@ -771,6 +771,18 @@ config I2C_STU300 > This driver can also be built as a module. If so, the module > will be called i2c-stu300. > > +config I2C_SUN6I_P2WI > + tristate "Allwinner sun6i internal P2WI controller" > + depends on MACH_SUN6I && RESET_CONTROLLER One very minor comment: I wonder if we should make this depends on RESET_CONTROLLER depends on MACH_SUN6I || COMPILE_TEST instead so we have better build coverage. I haven't tested if building on other architectures works, or if there are additional dependencies. No need to change this if there are no other comments. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
