Re: [PATCH v3 4/4] i2c: Add multi-instantiate pseudo driver

John Garry
2018-08-07T12:46:18Z

On 07/08/2018 09:05, Hans de Goede wrote:
> On systems with ACPI instantiated i2c-clients, normally there is 1 fw_node
> per i2c-device and that fw-node contains 1 I2cSerialBus resource for that 1
> i2c-device.
>
> But in some rare cases the manufacturer has decided to describe multiple
> i2c-devices in a single ACPI fwnode with multiple I2cSerialBus resources.
>
> An earlier attempt to fix this in the i2c-core resulted in a lot of extra
> code to support this corner-case.
>
> This commit introduces a new i2c-multi-instantiate driver which fixes this
> in a different way. This new driver can be built as a module which will
> only loaded on affected systems.
>
> This driver will instantiate a new i2c-client per I2cSerialBus resource,
> using the driver_data from the acpi_device_id it is binding to to tell it
> which chip-type (and optional irq-resource) to use when instantiating.
>
> Note this driver depends on a platform device being instantiated for the
> ACPI fwnode, see the i2c_multi_instantiate_ids list of ACPI device-ids in
> drivers/acpi/scan.c: acpi_device_enumeration_by_parent().
>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> MAINTAINERS | 6 +
> drivers/platform/x86/Kconfig | 11 ++
> drivers/platform/x86/Makefile | 1 +
> drivers/platform/x86/i2c-multi-instantiate.c | 131 +++++++++++++++++++
> 4 files changed, 149 insertions(+)
> create mode 100644 drivers/platform/x86/i2c-multi-instantiate.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9b377508f24f..09e16d76cab7 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6657,6 +6657,12 @@ F: drivers/i2c/i2c-mux.c
> F: drivers/i2c/muxes/
> F: include/linux/i2c-mux.h
>
> +I2C MULTI INSTANTIATE DRIVER
> +M: Hans de Goede <hdegoede@redhat.com>
> +L: linux-i2c@vger.kernel.org
> +S: Maintained
> +F: drivers/drivers/platform/x86/i2c-multi-instantiate.c

This path looks incorrect

> +
> I2C MV64XXX MARVELL AND ALLWINNER DRIVER
> M: Gregory CLEMENT <gregory.clement@bootlin.com>
> L: linux-i2c@vger.kernel.org
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 85a93453237c..8256629f58f7 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -1219,6 +1219,17 @@ config INTEL_CHTDC_TI_PWRBTN
> To compile this driver as a module, choose M here: the module
> will be called intel_chtdc_ti_pwrbtn.
>
> +config I2C_MULTI_INSTANTIATE
> + tristate "I2C multi instantiate pseudo device driver"
> + depends on I2C && ACPI
> + help
> + Some ACPI bases systems list multiple i2c-devices in a single ACPI

I guess that this should be "Some ACPI-based systems"

> + firmware-node. This driver will instantiate separate i2c-clients
> + for each device in the firmware-node.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called i2c-multi-instantiate.
> +

Thanks,
John