Re: [PATCH 1/3] hwmon: (pmbus) Add driver for Delta DPS-920AB PSU

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On 5/24/21 5:21 AM, Robert Marko wrote:
On Fri, May 21, 2021 at 4:46 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:

On 5/21/21 4:56 AM, Robert Marko wrote:
On Fri, May 21, 2021 at 12:56 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:

On 5/21/21 1:36 AM, Robert Marko wrote:
On Wed, May 19, 2021 at 3:19 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:

On 5/19/21 5:38 AM, Robert Marko wrote:
On Fri, Apr 30, 2021 at 3:48 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:

On Fri, Apr 30, 2021 at 03:27:33PM +0200, Robert Marko wrote:
This adds support for the Delta DPS-920AB PSU.

Only missing feature is fan control which the PSU supports.

Signed-off-by: Robert Marko <robert.marko@xxxxxxxxxx>
---
     Documentation/hwmon/dps920ab.rst | 80 ++++++++++++++++++++++++++++++++
     Documentation/hwmon/index.rst    |  1 +
     drivers/hwmon/pmbus/Kconfig      |  9 ++++
     drivers/hwmon/pmbus/Makefile     |  1 +
     drivers/hwmon/pmbus/dps920ab.c   | 63 +++++++++++++++++++++++++
     5 files changed, 154 insertions(+)
     create mode 100644 Documentation/hwmon/dps920ab.rst
     create mode 100644 drivers/hwmon/pmbus/dps920ab.c

diff --git a/Documentation/hwmon/dps920ab.rst b/Documentation/hwmon/dps920ab.rst
new file mode 100644
index 000000000000..df0aef530c7e
--- /dev/null
+++ b/Documentation/hwmon/dps920ab.rst
@@ -0,0 +1,80 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver dps920ab
+========================
+
+Supported chips:
+
+  * Delta DPS920AB
+
+    Prefix: 'dps920ab'
+
+    Addresses scanned: -
+
+Authors:
+    Robert Marko <robert.marko@xxxxxxxxxx>
+
+
+Description
+-----------
+
+This driver implements support for Delta DPS920AB 920W 54V DC single output
+power supply with PMBus support.
+
+The driver is a client driver to the core PMBus driver.
+Please see Documentation/hwmon/pmbus.rst for details on PMBus client drivers.
+
+
+Usage Notes
+-----------
+
+This driver does not auto-detect devices. You will have to instantiate the
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
+details.
+
+
+Sysfs entries
+-------------
+
+======================= ======================================================
+curr1_label          "iin"
+curr1_input          Measured input current
+curr1_crit           Critical maximum current
+curr1_crit_alarm     Current critical high alarm
+
+curr2_label          "iout1"
+curr2_input          Measured output current
+curr2_crit           Critical maximum current
+curr2_crit_alarm     Current critical high alarm
+
+in1_label            "vin"
+in1_input            Measured input voltage
+in1_lcrit            Critical minimum input voltage
+in1_lcrit_alarm              Input voltage critical low alarm
+in1_crit             Critical maximum input voltage
+in1_crit_alarm               Input voltage critical high alarm
+
+in2_label            "vout1"
+in2_input            Measured output voltage
+in2_lcrit            Critical minimum output voltage
+in2_lcrit_alarm              Output voltage critical low alarm
+in2_crit             Critical maximum output voltage
+in2_crit_alarm               Output voltage critical high alarm
+
+power1_label         "pin"
+power1_input         Measured input power
+power1_alarm         Input power high alarm
+
+power2_label         "pout1"
+power2_input         Measured output power
+
+temp[1-2]_input              Measured temperature
+temp[1-2]_crit               Critical high temperature
+temp[1-2]_crit_alarm Chip temperature critical high alarm
+temp[1-2]_max                Maximum temperature
+temp[1-2]_max_alarm  Chip temperature high alarm
+
+fan1_alarm           Fan 1 warning.
+fan1_fault           Fan 1 fault.
+fan1_input           Fan 1 speed in RPM.
+======================= ======================================================
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 8d5a2df1ecb6..b24436f22052 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -54,6 +54,7 @@ Hardware Monitoring Kernel Drivers
        dell-smm-hwmon
        dme1737
        drivetemp
+   dps920ab
        ds1621
        ds620
        emc1403
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index 32d2fc850621..865ade0aa205 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -66,6 +66,15 @@ config SENSORS_IBM_CFFPS
            This driver can also be built as a module. If so, the module will
            be called ibm-cffps.

+config SENSORS_DPS920AB
+     tristate "Delta DPS920AB Power Supply"
+     help
+       If you say yes here you get hardware monitoring support for Delta
+       DPS920AB Power Supplies.
+
+       This driver can also be built as a module. If so, the module will
+       be called dps920ab.
+
     config SENSORS_INSPUR_IPSPS
          tristate "INSPUR Power System Power Supply"
          help
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 6a4ba0fdc1db..f59ba0123d68 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_IBM_CFFPS)      += ibm-cffps.o
+obj-$(CONFIG_SENSORS_DPS920AB)       += dps920ab.o
     obj-$(CONFIG_SENSORS_INSPUR_IPSPS) += inspur-ipsps.o
     obj-$(CONFIG_SENSORS_IR35221)        += ir35221.o
     obj-$(CONFIG_SENSORS_IR38064)        += ir38064.o
diff --git a/drivers/hwmon/pmbus/dps920ab.c b/drivers/hwmon/pmbus/dps920ab.c
new file mode 100644
index 000000000000..d579ed9f879c
--- /dev/null
+++ b/drivers/hwmon/pmbus/dps920ab.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for Delta DPS920AB PSU
+ *
+ * Copyright (C) 2021 Delta Networks, Inc.
+ * Copyright (C) 2021 Sartura Ltd.
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include "pmbus.h"
+
+static struct pmbus_driver_info dps920ab_info = {
+     .pages = 1,
+
+     .format[PSC_VOLTAGE_IN] = linear,
+     .format[PSC_VOLTAGE_OUT] = linear,
+     .format[PSC_CURRENT_IN] = linear,
+     .format[PSC_CURRENT_OUT] = linear,
+     .format[PSC_POWER] = linear,
+     .format[PSC_FAN] = linear,
+     .format[PSC_TEMPERATURE] = linear,
+
+     .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN  |
+     PMBUS_HAVE_VOUT  | PMBUS_HAVE_STATUS_VOUT   |
+     PMBUS_HAVE_IOUT  | PMBUS_HAVE_STATUS_IOUT   |
+     PMBUS_HAVE_TEMP  | PMBUS_HAVE_TEMP2         |
+     PMBUS_HAVE_PIN   | PMBUS_HAVE_POUT          |
+     PMBUS_HAVE_FAN12 | PMBUS_HAVE_STATUS_FAN12  |
+     PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_STATUS_TEMP,
+};
+
+static int dps920ab_probe(struct i2c_client *client)
+{
+     if (!i2c_check_functionality(client->adapter,
+                                  I2C_FUNC_SMBUS_BYTE_DATA |
+                                  I2C_FUNC_SMBUS_WORD_DATA))
+             return -ENODEV;

This check is done in pmbus_do_probe(), and repeating it here does not add
any value.

Ok, makes sense.

That makes me wonder: Is this driver needed in the first place, or could
it be added to drivers/hwmon/pmbus/pmbus.c ?

It could be added as a generic driver, but that creates properties in
the sysfs that this thing
does not support like 3 voltage readings, 3 fans, and so on.


Can you be more specific ? What additional unsupported attributes
are added, and why ? Are you saying the PSU reports registers as
existing which do not really exist ? If so, which registers are those ?

Sure, when core does probing and autodiscovery, then the following
sysfs attributes are created:

curr1_crit         fan3_fault       in3_min_alarm      temp1_max
curr1_crit_alarm   fan3_input       in3_rated_max      temp1_max_alarm
curr1_input        fan3_target      in3_rated_min      temp1_min
curr1_label        in1_crit         name               temp1_min_alarm
curr1_max          in1_crit_alarm   of_node            temp1_rated_max
curr1_max_alarm    in1_input        power              temp2_crit
curr1_rated_max    in1_label        power1_alarm       temp2_crit_alarm
curr2_crit         in1_lcrit        power1_input       temp2_input
curr2_crit_alarm   in1_lcrit_alarm  power1_label       temp2_lcrit
curr2_input        in1_max          power1_max         temp2_lcrit_alarm
curr2_label        in1_max_alarm    power1_rated_max   temp2_max
curr2_lcrit        in1_min          power2_cap         temp2_max_alarm
curr2_lcrit_alarm  in1_min_alarm    power2_cap_alarm   temp2_min
curr2_max          in1_rated_max    power2_crit        temp2_min_alarm
curr2_max_alarm    in1_rated_min    power2_crit_alarm  temp2_rated_max
curr2_rated_max    in2_input        power2_input       temp3_crit
device             in2_label        power2_label       temp3_crit_alarm
fan1_alarm         in3_crit         power2_max         temp3_input
fan1_fault         in3_crit_alarm   power2_max_alarm   temp3_lcrit
fan1_input         in3_input        power2_rated_max   temp3_lcrit_alarm
fan1_target        in3_label        subsystem          temp3_max
fan2_alarm         in3_lcrit        temp1_crit         temp3_max_alarm
fan2_fault         in3_lcrit_alarm  temp1_crit_alarm   temp3_min
fan2_input         in3_max          temp1_input        temp3_min_alarm
fan2_target        in3_max_alarm    temp1_lcrit        temp3_rated_max
fan3_alarm         in3_min          temp1_lcrit_alarm  uevent

The following return -1, or -500 so they are not supported.
* fan2
* in2

Weirdly, with the external driver both fan2 and in2 are enabled and work fine,
but when auto probing they are fan3 and in3.

temp3 actually seems to return a valid temperature despite it not being used in
the vendor driver that features were picked from.


Can you run "grep . *" in the hwmon directory so I can see actual values ?

Sure:

curr1_crit:-500
curr1_crit_alarm:0
curr1_input:195
curr1_label:iin
curr1_max:-500
curr1_max_alarm:0
curr1_rated_max:-500
curr2_crit:-500
curr2_crit_alarm:0
curr2_input:320
curr2_label:iout1
curr2_lcrit:-500
curr2_lcrit_alarm:0
curr2_max:18625
curr2_max_alarm:0
curr2_rated_max:16875
grep: device: Is a directory
fan1_alarm:0
fan1_fault:0
fan1_input:10000
fan1_target:0
fan2_alarm:1
fan2_fault:1
fan2_input:-1
fan2_target:-1
fan3_alarm:1
fan3_fault:1
fan3_input:-1
fan3_target:-1
in1_crit:-500
in1_crit_alarm:0
in1_input:245250
in1_label:vin
in1_lcrit:-500
in1_lcrit_alarm:0
in1_max:-500
in1_max_alarm:0
in1_min:-500
in1_min_alarm:0
in1_rated_max:-500
in1_rated_min:-500
in2_input:-500
in2_label:vcap
in3_crit:255996
in3_crit_alarm:0
in3_input:54511
in3_label:vout1
in3_lcrit:255996
in3_lcrit_alarm:0
in3_max:255996
in3_max_alarm:0
in3_min:255996
in3_min_alarm:0
in3_rated_max:56136
in3_rated_min:52863
name:dps920ab
grep: of_node: Is a directory
grep: power: Is a directory
power1_alarm:0
power1_input:33250000
power1_label:pin
power1_max:-500000
power1_rated_max:-500000
power2_cap:-500000
power2_cap_alarm:0
power2_crit:-500000
power2_crit_alarm:0
power2_input:17750000
power2_label:pout1
power2_max:-500000
power2_max_alarm:0
power2_rated_max:920000000
grep: subsystem: Is a directory
temp1_crit:-500
temp1_crit_alarm:0
temp1_input:23000
temp1_lcrit:-500
temp1_lcrit_alarm:0
temp1_max:-500
temp1_max_alarm:0
temp1_min:-500
temp1_min_alarm:0
temp1_rated_max:-500
temp2_crit:-500
temp2_crit_alarm:0
temp2_input:26000
temp2_lcrit:-500
temp2_lcrit_alarm:0
temp2_max:-500
temp2_max_alarm:0
temp2_min:-500
temp2_min_alarm:0
temp2_rated_max:-500
temp3_crit:-500
temp3_crit_alarm:0
temp3_input:30000
temp3_lcrit:-500
temp3_lcrit_alarm:0
temp3_max:-500
temp3_max_alarm:0
temp3_min:-500
temp3_min_alarm:0
temp3_rated_max:-500
uevent:OF_NAME=psu
uevent:OF_FULLNAME=/ap806/config-space@f0000000/i2c@511000/psu@5a
uevent:OF_COMPATIBLE_0=delta,dps920ab
uevent:OF_COMPATIBLE_N=1

Ok, good enough. It looks like the PSU reports values for pretty much everything,
including registers which don't exist. With that in mind, please check
the attributes generated by your driver - I suspect that some of the limit
attributes are not really supported (maybe none of them is supported).

Yeah, I also think that none of those limits are actually supported.
Does the core expose a way to not register those?


Have the read_word function return -ENXIO for unsupported registers
(and add a comment to the code explaining why you do that).
See drivers/hwmon/pmbus/fsp-3y.c for an example.

Guenter



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