On Fri, Sep 12, 2014 at 10:36:07AM -0700, David E. Box wrote: > This patch implements an I2C bus sharing mechanism between the host and > platform > hardware on select Intel BayTrail SoC platforms using the XPower AXP288 PMIC. > > On these platforms access to the PMIC must be shared with platform hardware. > The > hardware unit assumes full control of the I2C bus and the host must request > access through a special semaphore. Hardware control of the bus also makes it > necessary to disable runtime pm to avoid interfering with hardware > transactions.
Is this because we need to access the PMIC from host as well? I mean from some PMIC driver (which driver btw)? Otherwise it would be best to just detect _SEM and return -ENODEV. > > Signed-off-by: David E. Box <david.e....@linux.intel.com> > --- > drivers/i2c/busses/Kconfig | 10 +++ > drivers/i2c/busses/Makefile | 1 + > drivers/i2c/busses/i2c-designware-core.h | 14 ++++ > drivers/i2c/busses/i2c-designware-platdrv.c | 78 +++++++++++++++++++-- > drivers/i2c/busses/i2c-shared-controller.c | 101 > ++++++++++++++++++++++++++++ > 5 files changed, 200 insertions(+), 4 deletions(-) > create mode 100644 drivers/i2c/busses/i2c-shared-controller.c > > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig > index 2ac87fa..672ef23 100644 > --- a/drivers/i2c/busses/Kconfig > +++ b/drivers/i2c/busses/Kconfig > @@ -441,6 +441,16 @@ config I2C_DESIGNWARE_PCI > This driver can also be built as a module. If so, the module > will be called i2c-designware-pci. > > +config I2C_SHARED_CONTROLLER > + tristate "Intel Baytrail PMIC shared I2C bus support" > + depends on ACPI > + select IOSF_MBI > + select I2C_DESIGNWARE_CORE > + help > + This driver enables shared access to the PMIC I2C bus on select Intel > + BayTrail platforms using the XPower AXP288 PMIC. This driver is > + required for host access to the PMIC on these platforms. Can't we detect this runtime in the i2c-designware-platdrv.c code so that you look (in the ACPI part of the driver) for _SEM and in that case change the xfer function behaviour a bit to return -EBUSY or whatever? Without this horrible #ifdeffery. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
