Motivated by a series by Alain Volmat which implements SMBus Host Notify support as a slave backend (already upstream), I wondered how I could actually test it. Then, I picked up my old idea of a "custom remote device" and implemented it as another slave backend. This is the outcome and it works quite well on my Renesas Lager board where I connected two I2C busses where both I2C controllers are master and slave. One slave is the testunit, one slave is the HostNotify listener. As mentioned elsewhere, support for SMBus Alert and I2C_M_RECV_LEN are already planned. But I guess you can do much more. Ideas and comments welcome! Happy hacking, Wolfram Wolfram Sang (1): i2c: add slave testunit driver Documentation/i2c/slave-testunit-backend.rst | 66 +++++++ drivers/i2c/Kconfig | 8 + drivers/i2c/Makefile | 1 + drivers/i2c/i2c-slave-testunit.c | 175 +++++++++++++++++++ 4 files changed, 250 insertions(+) create mode 100644 Documentation/i2c/slave-testunit-backend.rst create mode 100644 drivers/i2c/i2c-slave-testunit.c -- 2.20.1