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

From: John Garry
Date: Tue Aug 07 2018 - 08:46:34 EST


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@xxxxxxxxxx>
---
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@xxxxxxxxxx>
+L: linux-i2c@xxxxxxxxxxxxxxx
+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@xxxxxxxxxxx>
L: linux-i2c@xxxxxxxxxxxxxxx
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