linux-kernel - Re: [PATCH linux v7 4/6] hwmon: occ: Add callbacks for parsing P8 OCC datastructures

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Date:   Mon, 13 Feb 2017 11:47:22 +1030
From:   Andrew Jeffery <andrew@...id.au>
To:     Joel Stanley <joel@....id.au>, eajames <eajames@...ux.vnet.ibm.com>
Cc:     Guenter Roeck <linux@...ck-us.net>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-doc@...r.kernel.org, jdelvare@...e.com, corbet@....net,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        "Edward A. James" <eajames@...ibm.com>
Subject: Re: [PATCH linux v7 4/6] hwmon: occ: Add callbacks for parsing P8
 OCC datastructures

On Fri, 2017-02-10 at 16:01 +1030, Joel Stanley wrote:
> > On Wed, Feb 8, 2017 at 9:40 AM,  <eajames@...ux.vnet.ibm.com> wrote:
> > > > From: "Edward A. James" <eajames@...ibm.com>
> > 
> > Add functions to parse the data structures that are specific to the OCC on
> > the POWER8 processor. These are the sensor data structures, including
> > temperature, frequency, power, and "caps."
> > 
> > > > Signed-off-by: Edward A. James <eajames@...ibm.com>
> > > > Signed-off-by: Andrew Jeffery <andrew@...id.au>
> > ---
> >  Documentation/hwmon/occ    |   9 ++
> >  drivers/hwmon/occ/occ_p8.c | 248 +++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/hwmon/occ/occ_p8.h |  30 ++++++
> >  3 files changed, 287 insertions(+)
> >  create mode 100644 drivers/hwmon/occ/occ_p8.c
> >  create mode 100644 drivers/hwmon/occ/occ_p8.h
> > 
> > diff --git a/drivers/hwmon/occ/occ_p8.c b/drivers/hwmon/occ/occ_p8.c
> > new file mode 100644
> > index 0000000..5c61fc4
> > --- /dev/null
> > +++ b/drivers/hwmon/occ/occ_p8.c
> > +void p8_parse_sensor(u8 *data, void *sensor, int sensor_type, int off,
> > +                    int snum)
> > +{
> > +       switch (sensor_type) {
> > +       case FREQ:
> > +       case TEMP:
> > +       {
> > +               struct p8_occ_sensor *os =
> > +                       &(((struct p8_occ_sensor *)sensor)[snum]);
> > +
> > +               os->sensor_id = be16_to_cpu(get_unaligned((u16 *)&data[off]));
> > +               os->value = be16_to_cpu(get_unaligned((u16 *)&data[off + 2]));
> > +       }
> > +               break;
> > +       case POWER:
> > +       {
> > +               struct p8_power_sensor *ps =
> > +                       &(((struct p8_power_sensor *)sensor)[snum]);
> > +
> > +               ps->sensor_id = be16_to_cpu(get_unaligned((u16 *)&data[off]));
> > +               ps->update_tag =
> > +                       be32_to_cpu(get_unaligned((u32 *)&data[off + 2]));
> 
> This might be more readable if you wrote a
> cast_get_unaliged_be32_to_cpu() macro.
> 
> > +               ps->accumulator =
> > +                       be32_to_cpu(get_unaligned((u32 *)&data[off + 6]));
> > +               ps->value = be16_to_cpu(get_unaligned((u16 *)&data[off + 10]));
> > +       }
> > +               break;
> > +       case CAPS:
> > +       {
> > +const u32 *p8_get_sensor_hwmon_configs()
> > +{
> > +       return p8_sensor_hwmon_configs;
> > +}
> > +EXPORT_SYMBOL(p8_get_sensor_hwmon_configs);
> > +
> > +struct occ *p8_occ_start(struct device *dev, void *bus,
> > +                        struct occ_bus_ops *bus_ops)
> > +{
> > +       return occ_start(dev, bus, bus_ops, &p8_ops, &p8_config);
> > +}
> > +EXPORT_SYMBOL(p8_occ_start);
> 
> We don't need to export these symbols; they're not used outside of the
> OCC module. The same goes for all of the exports you've made in this
> series.

Sorry, this was my doing in an attempt to get everything to build as
modules rather than just built-in. I should have studied
Documentation/kbuild/modules.txt a bit more.

> 
> I suggest we re-architect the drivers so we build all of the objects
> and link them into one module for each platform, instead of having an
> occ module and occ-p8/occ-p9 modules and i2c modules that all depend
> on each other. The Makefile could look like this:
> 
> obj-$(CONFIG_SENSORS_PPC_OCC_P8_I2C) += hwmon_occ_p8.o
> obj-$(CONFIG_SENSORS_PPC_OCC_P9) += hwmon_occ_p9.o
> 
> hwmon_occ_p8-$(CONFIG_SENSORS_PPC_OCC_P8_I2C) += occ_scom_i2c.o
> occ_p8.o p8_occ_i2c.o occ_sysfs.o occ.o
> hwmon_occ_p9-$(CONFIG_SENSORS_PPC_OCC_P9) += occ_p9.o occ_sysfs.o occ.o
> 
> And the Kbuild like this:
> 
> menuconfig SENSORS_PPC_OCC
>         bool "PPC On-Chip Controller"
> 
> if SENSORS_PPC_OCC
> 
> config SENSORS_PPC_OCC_P8_I2C
>         bool "POWER8 OCC hwmon support"
>         depends on I2C
> 
> config SENSORS_PPC_OCC_P9
>         bool "POWER9 OCC hwmon support"
> 
> endif

Given we can drop the exports that's a much more sensible idea.

Andrew
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