On Fri, Apr 21, 2023 at 01:18:27PM +0300, Tomi Valkeinen wrote: > From: Luca Ceresoli <luca@xxxxxxxxxxxxxxxx> > > An ATR is a device that looks similar to an i2c-mux: it has an I2C > slave "upstream" port and N master "downstream" ports, and forwards > transactions from upstream to the appropriate downstream port. But it > is different in that the forwarded transaction has a different slave > address. The address used on the upstream bus is called the "alias" > and is (potentially) different from the physical slave address of the > downstream chip. > > Add a helper file (just like i2c-mux.c for a mux or switch) to allow > implementing ATR features in a device driver. The helper takes care or > adapter creation/destruction and translates addresses at each transaction. > > Signed-off-by: Luca Ceresoli <luca@xxxxxxxxxxxxxxxx> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > --- > .../devicetree/bindings/i2c/i2c-atr.yaml | 34 + > Documentation/i2c/i2c-address-translators.rst | 96 +++ > Documentation/i2c/index.rst | 1 + > MAINTAINERS | 8 + > drivers/i2c/Kconfig | 9 + > drivers/i2c/Makefile | 1 + > drivers/i2c/i2c-atr.c | 684 ++++++++++++++++++ > include/linux/i2c-atr.h | 116 +++ > 8 files changed, 949 insertions(+) > create mode 100644 Documentation/devicetree/bindings/i2c/i2c-atr.yaml > create mode 100644 Documentation/i2c/i2c-address-translators.rst > create mode 100644 drivers/i2c/i2c-atr.c > create mode 100644 include/linux/i2c-atr.h > > diff --git a/Documentation/devicetree/bindings/i2c/i2c-atr.yaml b/Documentation/devicetree/bindings/i2c/i2c-atr.yaml > new file mode 100644 > index 000000000000..d7f73d98110d > --- /dev/null > +++ b/Documentation/devicetree/bindings/i2c/i2c-atr.yaml > @@ -0,0 +1,34 @@ > +# SPDX-License-Identifier: GPL-2.0 Dual license. > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/i2c/i2c-atr.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Common i2c address translator properties. Drop hard stop. > + > +maintainers: > + - Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> > + > +description: > + An I2C Address Translator (ATR) is a device with an I2C slave parent > + ("upstream") port and N I2C master child ("downstream") ports, and > + forwards transactions from upstream to the appropriate downstream port > + with a modified slave address. The address used on the parent bus is > + called the "alias" and is (potentially) different from the physical > + slave address of the child bus. Address translation is done by the > + hardware. > + > +properties: > + i2c-alias-pool: > + $ref: /schemas/types.yaml#/definitions/uint16-array We do support some flags in the upper 16-bits of I2C addresses. Any of those possibly needed here? > + description: > + I2C alias pool is a pool of I2C addresses on the main I2C bus that can be > + used to access the remote peripherals on the serializer's I2C bus. The > + addresses must be available, not used by any other peripheral. Each > + remote peripheral is assigned an alias from the pool, and transactions to > + that address will be forwarded to the remote peripheral, with the address > + translated to the remote peripheral's real address. This property is not > + needed if there are no I2C addressable remote peripherals. > + > +additionalProperties: true > +...
