Message-ID: <Ya/inWEDpNmk62Fu@hatter.bewilderbeest.net>
Date:   Tue, 7 Dec 2021 14:39:25 -0800
From:   Zev Weiss <zev@...ilderbeest.net>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     linux-hwmon@...r.kernel.org, Jean Delvare <jdelvare@...e.com>,
        openbmc@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] hwmon: (pmbus) Add Delta AHE-50DC fan control
 module driver

On Tue, Dec 07, 2021 at 01:53:44PM PST, Zev Weiss wrote:
>On Tue, Dec 07, 2021 at 11:44:01AM PST, Guenter Roeck wrote:
>>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.
>>>
>>
>>Makes me wonder: How do you know that the referenced driver is for 
>>Delta AHE-50DC ?
>
>We'd been waiting for the source code for the software it ships with 
>for a while, and were finally provided with that repo; everything I've 
>observed from the factory software is consistent with the code in that 
>driver.  A sampling:
>
>    # no modinfo command available, but...
>    root@...-oob:~# strings -n8 /lib/modules/4.1.51-deltapower/extra/fancontrol.ko | head
>    fancontrol
>    license=GPL
>    description=FANCTRL Driver
>    author=Ping Mao <pmao@...kedin.com>
>    alias=i2c:fancontrol
>    depends=i2c_dev_sysfs
>    vermagic=4.1.51-deltapower mod_unload ARMv5 p2v8
>    fancontrol
>    status_word
>    bit 2:  Temparature Warning
>    root@...-oob:~# cd /sys/bus/i2c/drivers/fancontrol/8-0030
>    root@...-oob:/sys/bus/i2c/drivers/fancontrol/8-0030# grep . fan* temp* vin
>    fan1_2_status:0
>    fan1_speed:7860
>    fan2_speed:7860
>    fan3_4_status:0
>    fan3_speed:7680
>    fan4_speed:7560
>    temperature1:292
>    temperature2:278
>    temperature3:286
>    temperature4:302
>    vin:12251
>
>
>>>>
>>>>>Signed-off-by: Zev Weiss <zev@...ilderbeest.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@...ilderbeest.net>
>>>>>+L:    linux-hwmon@...r.kernel.org
>>>>>+S:    Maintained
>>>>>+F:    drivers/hwmon/pmbus/delta-ahe50dc-fan.c
>>>>>+
>>>>> DELTA DPS920AB PSU DRIVER
>>>>> M:    Robert Marko <robert.marko@...tura.hr>
>>>>> L:    linux-hwmon@...r.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@...ilderbeest.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.
>>
>
>It's...not the only bit of gratuitous wheel-reinvention we've come
>across in this particular system.
>
>>Can you check this with real hardware, by any chance ?
>>
>
>If you mean running that code on it, yes -- here's the userspace 
>utility that invokes that library routine:
>
>    root@...-oob:~# fan-util.sh
>    fan1 speed: 7860 RPM
>    fan2 speed: 7860 RPM
>    fan3 speed: 7620 RPM
>    fan4 speed: 7560 RPM
>    temperature1: 29.20 C
>    temperature2: 27.80 C
>    temperature3: 28.50 C
>    temperature4: 30.20 C
>    vin_undervolt_fault: no
>    overtemperature_warning: no
>    fan_fault: no
>    fan_warning: no
>    fan_status: ok
>
>That fan-util.sh script being this:
>
>https://github.com/linkedin/o19-bmc-firmware/blob/master/meta-openbmc/meta-linkedin/meta-deltapower/recipes-deltapower/liutils/files/fan-util.sh
>
>which invokes this:
>
>https://github.com/linkedin/o19-bmc-firmware/blob/master/meta-openbmc/meta-linkedin/meta-deltapower/recipes-deltapower/liutils/files/fan-ctrl/fan-util.c
>
>(which calls into the routine in powershelf_fan.c linked above).
>

...though I think I accidentally glossed over some additional steps in 
beteween there; looks like there's actually another daemon involved that 
does the read from the sysfs files and the unit normalization and then 
drops the resulting data into a file that fan-util.c then reads:

https://github.com/linkedin/o19-bmc-firmware/blob/master/meta-openbmc/meta-linkedin/meta-deltapower/recipes-core/health-mon/files/healthmon.c

Anyway, the upshot is that I'm fairly confident that the code there is 
in fact what's running on the device as shipped from the factory, and I 
think the coefficients I determined for the pmbus driver should handle 
it appropriately.  (It produces readings that align with what the 
factory software gives and are generally sane-looking.)


Zev

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