Re: [PATCH v3 1/2] hwmon: (pmbus) Add Delta AHE-50DC fan control module driver

[Zev Weiss <zev@bewilderbeest.net>]

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@bmc-oob:~# strings -n8 /lib/modules/4.1.51-deltapower/extra/fancontrol.ko | head
     fancontrol
     license=GPL
     description=FANCTRL Driver
     author=Ping Mao <pmao@linkedin.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@bmc-oob:~# cd /sys/bus/i2c/drivers/fancontrol/8-0030
     root@bmc-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@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@bewilderbeest.net>
>>>>+L:    linux-hwmon@vger.kernel.org
>>>>+S:    Maintained
>>>>+F:    drivers/hwmon/pmbus/delta-ahe50dc-fan.c
>>>>+
>>>> DELTA DPS920AB PSU DRIVER
>>>> M:    Robert Marko <robert.marko@sartura.hr>
>>>> L:    linux-hwmon@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@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.
>

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@bmc-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).


Zev