Re: [PATCH v2 1/3] hwmon: (pmbus) Add driver for Delta DPS-920AB PSU

[Robert Marko <robert.marko@sartura.hr>]

On Fri, May 28, 2021 at 3:28 PM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 5/28/21 3:38 AM, 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@sartura.hr>
> > ---
> > Changes in v2:
> > * Check for Manufacturer and Model
> > * Restrict word read/write to supported only
> > * Update documentation to reflect driver changes
> > * Add basic debugfs entries
> >
> >   Documentation/hwmon/dps920ab.rst |  73 ++++++++++
> >   Documentation/hwmon/index.rst    |   1 +
> >   drivers/hwmon/pmbus/Kconfig      |   9 ++
> >   drivers/hwmon/pmbus/Makefile     |   1 +
> >   drivers/hwmon/pmbus/dps920ab.c   | 229 +++++++++++++++++++++++++++++++
> >   5 files changed, 313 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..c33b4cdc0a60
> > --- /dev/null
> > +++ b/Documentation/hwmon/dps920ab.rst
> > @@ -0,0 +1,73 @@
> > +.. SPDX-License-Identifier: GPL-2.0-or-later
> > +
> > +Kernel driver dps920ab
> > +========================
> > +
> > +Supported chips:
> > +
> > +  * Delta DPS920AB
> > +
> > +    Prefix: 'dps920ab'
> > +
> > +    Addresses scanned: -
> > +
> > +Authors:
> > +    Robert Marko <robert.marko@sartura.hr>
> > +
> > +
> > +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_alarm          Input current high alarm
> > +
> > +curr2_label          "iout1"
> > +curr2_input          Measured output current
> > +curr2_max            Maximum output current
> > +curr2_rated_max              Maximum rated output current
> > +
> > +in1_label            "vin"
> > +in1_input            Measured input voltage
> > +in1_alarm            Input voltage alarm
> > +
> > +in2_label            "vout1"
> > +in2_input            Measured output voltage
> > +in2_rated_min                Minimum rated output voltage
> > +in2_rated_max                Maximum rated output voltage
> > +in2_alarm            Output voltage alarm
> > +
> > +power1_label         "pin"
> > +power1_input         Measured input power
> > +power1_alarm         Input power high alarm
> > +
> > +power2_label         "pout1"
> > +power2_input         Measured output power
> > +power2_rated_max     Maximum rated output power
> > +
> > +temp[1-3]_input              Measured temperature
> > +temp[1-3]_alarm              Temperature 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..de084a42dec3
> > --- /dev/null
> > +++ b/drivers/hwmon/pmbus/dps920ab.c
> > @@ -0,0 +1,229 @@
> > +// 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/debugfs.h>
> > +#include <linux/i2c.h>
> > +#include <linux/module.h>
> > +#include <linux/of_device.h>
> > +#include "pmbus.h"
> > +
> > +struct dps920ab_data {
> > +     struct i2c_client *client;
> > +     struct dentry *debugfs_dir;
> > +};
> > +
> > +static int dps920ab_read_word_data(struct i2c_client *client, int page, int phase, int reg)
> > +{
> > +     int ret;
> > +
> > +     /*
> > +      * This masks commands which are not supported.
> > +      * PSU advertises that all features are supported,
> > +      * in reality that unfortunately is not true.
> > +      * So enable only those that the datasheet confirms.
> > +      */
> > +     switch (reg) {
> > +     case PMBUS_FAN_COMMAND_1:
> > +     case PMBUS_IOUT_OC_WARN_LIMIT:
> > +     case PMBUS_STATUS_WORD:
> > +     case PMBUS_READ_VIN:
> > +     case PMBUS_READ_IIN:
> > +     case PMBUS_READ_VOUT:
> > +     case PMBUS_READ_IOUT:
> > +     case PMBUS_READ_TEMPERATURE_1:
> > +     case PMBUS_READ_TEMPERATURE_2:
> > +     case PMBUS_READ_TEMPERATURE_3:
> > +     case PMBUS_READ_FAN_SPEED_1:
> > +     case PMBUS_READ_POUT:
> > +     case PMBUS_READ_PIN:
> > +     case PMBUS_MFR_VOUT_MIN:
> > +     case PMBUS_MFR_VOUT_MAX:
> > +     case PMBUS_MFR_IOUT_MAX:
> > +     case PMBUS_MFR_POUT_MAX:
> > +             break;
> > +     default:
> > +             return -ENXIO;
> > +     }
> > +
> > +     ret = pmbus_set_page(client, page, phase);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     return i2c_smbus_read_word_data(client, reg);
>
> I find the code a bit confusing. I think it would be better to move the action code
> into the case statement.

Agree, makes sense.
>
> > +}
> > +
> > +static int dps920ab_write_word_data(struct i2c_client *client, int page, int reg,
> > +                                 u16 word)
> > +{
> > +     int ret;
> > +
> > +     /*
> > +      * This masks commands which are not supported.
> > +      * PSU only has one R/W register and that is
> > +      * for the fan.
> > +      */
> > +     switch (reg) {
> > +     case PMBUS_FAN_COMMAND_1:
> > +             break;
> > +     default:
> > +             ret = -ENODATA;
> > +     }
> > +
>
> Does this work ? It is the wrong error message for a failed write;
> it should probably return -EACCES.

It appears to work fine, I was looking at other drivers, and all of them
use -ENODATA for unsupported word registers.
>
> > +     ret = pmbus_set_page(client, page, 0xff);
> > +     if (ret < 0)
> > +             return ret;
> > +
> There is only one page, so what would this be for ?
>
> > +     return i2c_smbus_write_word_data(client, reg, word);
>
> Same as avove; I think it would be better to handle the
> access code in the case statement.

Agreed, will do.
>
> > +}
> > +
> > +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_PIN |
> > +             PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT | PMBUS_HAVE_POUT |
> > +             PMBUS_HAVE_TEMP  | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_TEMP3 |
> > +             PMBUS_HAVE_FAN12 | PMBUS_HAVE_STATUS_FAN12 |
> > +             PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_STATUS_IOUT |
> > +             PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_STATUS_TEMP,
> > +     .read_word_data = dps920ab_read_word_data,
> > +     .write_word_data = dps920ab_write_word_data,
> > +};
> > +
> > +static int dps920ab_mfr_id_show(struct seq_file *s, void *data)
> > +{
> > +     struct dps920ab_data *priv = s->private;
> > +     u8 buf[I2C_SMBUS_BLOCK_MAX + 1];
> > +     int ret;
> > +
> > +     ret = i2c_smbus_read_block_data(priv->client, PMBUS_MFR_ID, buf);
> > +     if (ret < 0)
> > +             return ret;
> > +
>         buf[ret] = '\0';
>
> missing here. With that, the two functions are effectively the same
> and can be merged into one with the register as additional parameter.
> Also, you might consider storing this information in struct dps920ab_data.
> After all, it is unlikely to change, so reading it over and over again
> has no real value.

Ok, makes sense.

>
> > +     seq_printf(s, "%s\n", buf);
> > +
> > +     return 0;
> > +}
> > +
> > +DEFINE_SHOW_ATTRIBUTE(dps920ab_mfr_id);
> > +
> > +static int dps920ab_mfr_model_show(struct seq_file *s, void *data)
> > +{
> > +     struct dps920ab_data *priv = s->private;
> > +     u8 buf[I2C_SMBUS_BLOCK_MAX + 1];
> > +     int ret;
> > +
> > +     ret = i2c_smbus_read_block_data(priv->client, PMBUS_MFR_MODEL, buf);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     buf[ret] = '\0';
> > +
> > +     seq_printf(s, "%s\n", buf);
> > +
> > +     return 0;
> > +}
> > +
> > +DEFINE_SHOW_ATTRIBUTE(dps920ab_mfr_model);
> > +
> > +static void dps920ab_init_debugfs(struct dps920ab_data *data)
> > +{
> > +     struct dentry *root;
> > +
> > +     root = pmbus_get_debugfs_dir(data->client);
> > +     if (!root)
> > +             return;
> > +
> > +     data->debugfs_dir = debugfs_create_dir(data->client->name, root);
> > +     if (!data->debugfs_dir)
> > +             return;
> > +
> > +     debugfs_create_file("mfr_id",
> > +                         0400,
> > +                         data->debugfs_dir,
> > +                         data,
> > +                         &dps920ab_mfr_id_fops);
> > +
> > +     debugfs_create_file("mfr_model",
> > +                         0400,
> > +                         data->debugfs_dir,
> > +                         data,
> > +                         &dps920ab_mfr_model_fops);
> > +}
> > +
> > +static int dps920ab_probe(struct i2c_client *client)
> > +{
> > +     u8 buf[I2C_SMBUS_BLOCK_MAX + 1];
> > +     struct dps920ab_data *data;
> > +     int ret;
> > +
> > +     ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, buf);
> > +     if (ret < 0) {
> > +             dev_err(&client->dev, "Failed to read Manufacturer ID\n");
> > +             return ret;
> > +     }
> > +     if (ret != 5 || strncmp(buf, "DELTA", 5)) {
>
> Does this return 5 or 6 ? Just asking, because other supplies from Delta
> return 6.

This was weird for me as well, but it actually returns 5, I think only
the brick q54sj108a2
does that as well.

I will send out a v3 today.

Regards,
Robert
>
> > +             buf[ret] = '\0';
> > +             dev_err(&client->dev, "Unsupported Manufacturer ID '%s'\n", buf);
> > +             return -ENODEV;
> > +     }
> > +
> > +     ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, buf);
> > +     if (ret < 0) {
> > +             dev_err(&client->dev, "Failed to read Manufacturer Model\n");
> > +             return ret;
> > +     }
> > +     if (ret != 11 || strncmp(buf, "DPS-920AB", 9)) {
> > +             buf[ret] = '\0';
> > +             dev_err(&client->dev, "Unsupported Manufacturer Model '%s'\n", buf);
> > +             return -ENODEV;
> > +     }
> > +
> > +     ret = pmbus_do_probe(client, &dps920ab_info);
> > +     if (ret)
> > +             return ret;
> > +
> > +     data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
> > +     if (!data)
> > +             return -ENOMEM;
> > +
> > +     data->client = client;
> > +
> > +     dps920ab_init_debugfs(data);
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct of_device_id __maybe_unused dps920ab_of_match[] = {
> > +     { .compatible = "delta,dps920ab", },
> > +     {}
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, dps920ab_of_match);
> > +
> > +static struct i2c_driver dps920ab_driver = {
> > +     .driver = {
> > +                .name = "dps920ab",
> > +                .of_match_table = of_match_ptr(dps920ab_of_match),
> > +     },
> > +     .probe_new = dps920ab_probe,
> > +};
> > +
> > +module_i2c_driver(dps920ab_driver);
> > +
> > +MODULE_AUTHOR("Robert Marko <robert.marko@sartura.hr>");
> > +MODULE_DESCRIPTION("PMBus driver for Delta DPS920AB PSU");
> > +MODULE_LICENSE("GPL");
> >
>


-- 
Robert Marko
Staff Embedded Linux Engineer
Sartura Ltd.
Lendavska ulica 16a
10000 Zagreb, Croatia
Email: robert.marko@sartura.hr
Web: www.sartura.hr