[PATCH v3 1/2] hwmon: (pmbus) Add Delta AHE-50DC fan control module driver
Guenter Roeck
linux at roeck-us.net
Wed Dec 8 06:44:01 AEDT 2021
On 12/7/21 11:22 AM, Zev Weiss wrote:
> On Tue, Dec 07, 2021 at 09:50:15AM PST, Guenter Roeck wrote:
>> On Mon, Dec 06, 2021 at 11:15:20PM -0800, Zev Weiss wrote:
>>> This device is an integrated module of the Delta AHE-50DC Open19 power
>>> shelf. For lack of proper documentation, this driver has been developed
>>> referencing an existing (GPL) driver that was included in a code release
>>> from LinkedIn [1]. It provides four fan speeds, four temperatures, and
>>> one voltage reading, as well as a handful of warning and fault
>>> indicators.
>>>
>>> [1] https://github.com/linkedin/o19-bmc-firmware/blob/master/meta-openbmc/meta-linkedin/meta-deltapower/recipes-kernel/fancontrol-mod/files/fancontrol.c
>>>
>>
>> Hmm, that reference isn't really accurate anymore. I think it would be
>> better to just say that the device was found to be PMBus compliant.
>
> Sure, will do.
>
>>
>>> Signed-off-by: Zev Weiss <zev at bewilderbeest.net>
>>> ---
>>> MAINTAINERS | 6 ++
>>> drivers/hwmon/pmbus/Kconfig | 12 ++++
>>> drivers/hwmon/pmbus/Makefile | 1 +
>>> drivers/hwmon/pmbus/delta-ahe50dc-fan.c | 84 +++++++++++++++++++++++++
>>> 4 files changed, 103 insertions(+)
>>> create mode 100644 drivers/hwmon/pmbus/delta-ahe50dc-fan.c
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 0ac052200ecb..8bb7ba52d2f5 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -5425,6 +5425,12 @@ W: https://linuxtv.org
>>> T: git git://linuxtv.org/media_tree.git
>>> F: drivers/media/platform/sti/delta
>>>
>>> +DELTA AHE-50DC FAN CONTROL MODULE DRIVER
>>> +M: Zev Weiss <zev at bewilderbeest.net>
>>> +L: linux-hwmon at vger.kernel.org
>>> +S: Maintained
>>> +F: drivers/hwmon/pmbus/delta-ahe50dc-fan.c
>>> +
>>> DELTA DPS920AB PSU DRIVER
>>> M: Robert Marko <robert.marko at sartura.hr>
>>> L: linux-hwmon at vger.kernel.org
>>> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
>>> index ffb609cee3a4..937e1c2c11e7 100644
>>> --- a/drivers/hwmon/pmbus/Kconfig
>>> +++ b/drivers/hwmon/pmbus/Kconfig
>>> @@ -66,6 +66,18 @@ config SENSORS_BPA_RS600
>>> This driver can also be built as a module. If so, the module will
>>> be called bpa-rs600.
>>>
>>> +config SENSORS_DELTA_AHE50DC_FAN
>>> + tristate "Delta AHE-50DC fan control module"
>>> + depends on I2C
>>> + select REGMAP_I2C
>
> And I realize I neglected to drop the depends & select lines here when moving this bit into the pmbus directory...
>
>>> + help
>>> + If you say yes here you get hardware monitoring support for
>>> + the integrated fan control module of the Delta AHE-50DC
>>> + Open19 power shelf.
>>> +
>>> + This driver can also be built as a module. If so, the module
>>> + will be called delta-ahe50dc-fan.
>>> +
>>> config SENSORS_FSP_3Y
>>> tristate "FSP/3Y-Power power supplies"
>>> help
>>> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
>>> index 0ed4d596a948..a56b2897288d 100644
>>> --- a/drivers/hwmon/pmbus/Makefile
>>> +++ b/drivers/hwmon/pmbus/Makefile
>>> @@ -9,6 +9,7 @@ obj-$(CONFIG_SENSORS_ADM1266) += adm1266.o
>>> obj-$(CONFIG_SENSORS_ADM1275) += adm1275.o
>>> obj-$(CONFIG_SENSORS_BEL_PFE) += bel-pfe.o
>>> obj-$(CONFIG_SENSORS_BPA_RS600) += bpa-rs600.o
>>> +obj-$(CONFIG_SENSORS_DELTA_AHE50DC_FAN) += delta-ahe50dc-fan.o
>>> obj-$(CONFIG_SENSORS_FSP_3Y) += fsp-3y.o
>>> obj-$(CONFIG_SENSORS_IBM_CFFPS) += ibm-cffps.o
>>> obj-$(CONFIG_SENSORS_DPS920AB) += dps920ab.o
>>> diff --git a/drivers/hwmon/pmbus/delta-ahe50dc-fan.c b/drivers/hwmon/pmbus/delta-ahe50dc-fan.c
>>> new file mode 100644
>>> index 000000000000..07b1e7c5f5f5
>>> --- /dev/null
>>> +++ b/drivers/hwmon/pmbus/delta-ahe50dc-fan.c
>>> @@ -0,0 +1,84 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Delta AHE-50DC power shelf fan control module driver
>>> + *
>>> + * Copyright 2021 Zev Weiss <zev at bewilderbeest.net>
>>> + */
>>> +
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/i2c.h>
>>> +#include <linux/pmbus.h>
>>
>> Alphabetic include file order please.
>
> Ack, will fix.
>
>>
>>> +
>>> +#include "pmbus.h"
>>> +
>>> +#define AHE50DC_PMBUS_READ_TEMP4 0xd0
>>> +
>>> +static int ahe50dc_fan_read_word_data(struct i2c_client *client, int page, int phase, int reg)
>>> +{
>>> + /* temp1 in (virtual) page 1 is remapped to mfr-specific temp4 */
>>> + if (page == 1) {
>>> + if (reg == PMBUS_READ_TEMPERATURE_1)
>>> + return i2c_smbus_read_word_data(client, AHE50DC_PMBUS_READ_TEMP4);
>>> + return -EOPNOTSUPP;
>>> + }
>>> + return -ENODATA;
>>> +}
>>> +
>>> +static struct pmbus_driver_info ahe50dc_fan_info = {
>>> + .pages = 2,
>>> + .format[PSC_FAN] = direct,
>>> + .format[PSC_TEMPERATURE] = direct,
>>> + .format[PSC_VOLTAGE_IN] = direct,
>>> + .m[PSC_FAN] = 1,
>>> + .b[PSC_FAN] = 0,
>>> + .R[PSC_FAN] = 0,
>>> + .m[PSC_TEMPERATURE] = 1,
>>> + .b[PSC_TEMPERATURE] = 0,
>>> + .R[PSC_TEMPERATURE] = 1,
>>> + .m[PSC_VOLTAGE_IN] = 1,
>>> + .b[PSC_VOLTAGE_IN] = 0,
>>> + .R[PSC_VOLTAGE_IN] = 3,
>>
>> How did you determine the exponents ? The referenced driver
>> doesn't seem to make a difference between voltage and temperature
>> exponents (nor fan speed, which is a bit odd).
>
> Lacking documentation, the honest answer here is that I just sort of eyeballed it. However, after doing so, I dug through the code dump a bit more and found some userspace unit-conversion bits that appear to confirm what I arrived at:
>
> https://github.com/linkedin/o19-bmc-firmware/blob/master/meta-openbmc/meta-linkedin/meta-deltapower/recipes-deltapower/platform-lib/files/powershelf/powershelf_fan.c
>
> (Lines 107, and 153/161/169/177.)
>
Brr. Well, why use a standard API/ABI if one can invent a non-standard one.
Can you check this with real hardware, by any chance ?
>>
>>> + .func[0] = PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_TEMP3 |
>>> + PMBUS_HAVE_VIN | PMBUS_HAVE_FAN12 | PMBUS_HAVE_FAN34 |
>>> + PMBUS_HAVE_STATUS_FAN12 | PMBUS_HAVE_STATUS_FAN34 | PMBUS_PAGE_VIRTUAL,
>>> + .func[1] = PMBUS_HAVE_TEMP | PMBUS_PAGE_VIRTUAL,
>>> + .read_word_data = ahe50dc_fan_read_word_data,
>>> +};
>>> +
>>> +static struct pmbus_platform_data ahe50dc_fan_data = {
>>> + .flags = PMBUS_NO_CAPABILITY,
>>> +};
>>
>> Is that necessary ? It should only be used if trying to read CAPABILITY
>> reports bad data.
>
> Unfortunately it does seem to be needed -- CAPABILITY returns 0xff, but despite having bit 7 set the device mangles all subsequent transactions by returning bad PEC bytes if we enable I2C_CLIENT_PEC. Actually, none of the fields in that CAPABILITY value seem to accurately reflect the device's observed behavior; I'm pretty sure 0xff is just what it returns when it doesn't support something (I think the bad PECs it sends are all 0xff too).
>
> I'll add an explanatory comment in v4.
>
>
Please do.
Thanks,
Guenter
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