On 1/11/2018 5:22 AM, Arnd Bergmann wrote:
On Thu, Jan 11, 2018 at 12:45 AM, Jae Hyun Yoo
<jae.hyun....@linux.intel.com> wrote:
On 1/10/2018 4:29 AM, Arnd Bergmann wrote:

On Tue, Jan 9, 2018 at 11:31 PM, Jae Hyun Yoo
<jae.hyun....@linux.intel.com> wrote:

This commit adds driver implementation for a generic PECI hwmon.

Signed-off-by: Jae Hyun Yoo <jae.hyun....@linux.intel.com>


+static int xfer_peci_msg(int cmd, void *pmsg)
+{
+       int rc;
+
+       mutex_lock(&peci_hwmon_lock);
+       rc = peci_ioctl(NULL, cmd, (unsigned long)pmsg);
+       mutex_unlock(&peci_hwmon_lock);
+
+       return rc;
+}


I said earlier that peci_ioctl() looked unused, that was obviously
wrong, but what you have here
is not a proper way to abstract a bus.

Maybe this can be done more like an i2c bus: make the peci controller
a bus device
and register all known target/index pairs as devices with the peci bus
type, and have
them probed from DT. The driver can then bind to each of those
individually.
Not sure if that is getting to granular at that point, I'd have to
understand better
how it is expected to get used, and what the variances are between
implementations.


Thanks for sharing your opinion. In fact, this was also suggested by openbmc
community so I should consider of redesigning it. I'm currently thinking
about adding a new PECI device class as an abstract layer and any BMC
chipset specific driver could be attached to the PECI class driver. Then,
each CPU client could be registered as an individual device as you
suggested. Will consider your suggestion.

Another idea might be to pretend that PECI was I2C. We already have a few
drivers for hardware that is not I2C but whose software interface looks
similar enough that it just works. No idea if that is the case for PECI, but
xfer_peci_msg might be close enough to i2c_xfer to make it work. If you
are able to do that, then the PECI controller would just register itself
as an i2c controller and it can be accessed using /dev/i2c from user space
or a high-level i2c_driver.

       Arnd


Thanks for the good idea. It looks like one of possible options. I'll check this idea as well. :)

Thanks,
Jae
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