Re: [PATCH v7 08/12] mfd: intel-peci-client: Add PECI client MFD driver

[Jae Hyun Yoo]

Hi Lee,

On 7/27/2018 1:26 AM, Lee Jones wrote:
> On Mon, 23 Jul 2018, Jae Hyun Yoo wrote:
>
> > This commit adds PECI client MFD driver.
> >
> > Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@xxxxxxxxxxxxxxx>
> > Cc: Lee Jones <lee.jones@xxxxxxxxxx>
> > Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> > Cc: Andrew Jeffery <andrew@xxxxxxxx>
> > Cc: James Feist <james.feist@xxxxxxxxxxxxxxx>
> > Cc: Jason M Biils <jason.m.bills@xxxxxxxxxxxxxxx>
> > Cc: Joel Stanley <joel@xxxxxxxxx>
> > Cc: Vernon Mauery <vernon.mauery@xxxxxxxxxxxxxxx>
> > ---
> >   drivers/mfd/Kconfig                   |  14 ++
> >   drivers/mfd/Makefile                  |   1 +
> >   drivers/mfd/intel-peci-client.c       | 182 ++++++++++++++++++++++++++
> >   include/linux/mfd/intel-peci-client.h |  81 ++++++++++++
> >   4 files changed, 278 insertions(+)
> >   create mode 100644 drivers/mfd/intel-peci-client.c
> >   create mode 100644 include/linux/mfd/intel-peci-client.h
> >
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index f3fa516011ec..e38b591479d4 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -595,6 +595,20 @@ config MFD_INTEL_MSIC
> >   	  Passage) chip. This chip embeds audio, battery, GPIO, etc.
> >   	  devices used in Intel Medfield platforms.
> >   
> > +config MFD_INTEL_PECI_CLIENT
> > +	bool "Intel PECI client"
> > +	depends on (PECI || COMPILE_TEST)
> > +	select MFD_CORE
> > +	help
> > +	  If you say yes to this option, support will be included for the
> > +	  multi-funtional Intel PECI (Platform Environment Control Interface)
> > +	  client. PECI is a one-wire bus interface that provides a communication
> > +	  channel from PECI clients in Intel processors and chipset components
> > +	  to external monitoring or control devices.
> > +
> > +	  Additional drivers must be enabled in order to use the functionality
> > +	  of the device.
> > +
> >   config MFD_IPAQ_MICRO
> >   	bool "Atmel Micro ASIC (iPAQ h3100/h3600/h3700) Support"
> >   	depends on SA1100_H3100 || SA1100_H3600
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index 2852a6042ecf..29e2cacc58bd 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -203,6 +203,7 @@ obj-$(CONFIG_MFD_INTEL_LPSS)	+= intel-lpss.o
> >   obj-$(CONFIG_MFD_INTEL_LPSS_PCI)	+= intel-lpss-pci.o
> >   obj-$(CONFIG_MFD_INTEL_LPSS_ACPI)	+= intel-lpss-acpi.o
> >   obj-$(CONFIG_MFD_INTEL_MSIC)	+= intel_msic.o
> > +obj-$(CONFIG_MFD_INTEL_PECI_CLIENT)	+= intel-peci-client.o
> >   obj-$(CONFIG_MFD_PALMAS)	+= palmas.o
> >   obj-$(CONFIG_MFD_VIPERBOARD)    += viperboard.o
> >   obj-$(CONFIG_MFD_RC5T583)	+= rc5t583.o rc5t583-irq.o
> > diff --git a/drivers/mfd/intel-peci-client.c b/drivers/mfd/intel-peci-client.c
> > new file mode 100644
> > index 000000000000..d7702cf1ea50
> > --- /dev/null
> > +++ b/drivers/mfd/intel-peci-client.c
> > @@ -0,0 +1,182 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +// Copyright (c) 2018 Intel Corporation
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/mfd/core.h>
> > +#include <linux/mfd/intel-peci-client.h>
> > +#include <linux/module.h>
> > +#include <linux/peci.h>
> > +#include <linux/of_device.h>
> > +
> > +enum cpu_gens {
> > +	CPU_GEN_HSX = 0, /* Haswell Xeon */
> > +	CPU_GEN_BRX,     /* Broadwell Xeon */
> > +	CPU_GEN_SKX,     /* Skylake Xeon */
> > +};
> > +
> > +static struct mfd_cell peci_functions[] = {
> > +	{
> > +		.name = "peci-cputemp",
> > +		.of_compatible = "intel,peci-cputemp",
> > +	},
> > +	{
> > +		.name = "peci-dimmtemp",
> > +		.of_compatible = "intel,peci-dimmtemp",
> > +	},
> > +};
>
> The more I look at this driver, the less I think it fits into MFD.
>
> What's stopping you from registering these devices directly from DT?

Because DT doesn't allow 2 nodes at the same address so Rob suggested
MFD for this case.

Thanks,

Jae