Date:   Fri, 10 Feb 2017 16:01:23 +1030
From:   Joel Stanley <joel@....id.au>
To:     eajames <eajames@...ux.vnet.ibm.com>
Cc:     Guenter Roeck <linux@...ck-us.net>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-doc@...r.kernel.org, jdelvare@...e.com, corbet@....net,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Andrew Jeffery <andrew@...id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        "Edward A. James" <eajames@...ibm.com>
Subject: Re: [PATCH linux v7 2/6] hwmon: occ: Add sysfs interface

On Wed, Feb 8, 2017 at 9:40 AM,  <eajames@...ux.vnet.ibm.com> wrote:
> From: "Edward A. James" <eajames@...ibm.com>
>
> Add a generic mechanism to expose the sensors provided by the OCC in
> sysfs.
>
> Signed-off-by: Edward A. James <eajames@...ibm.com>
> Signed-off-by: Andrew Jeffery <andrew@...id.au>
> ---
>  Documentation/hwmon/occ       |  62 +++++++++++
>  drivers/hwmon/occ/Makefile    |   2 +-
>  drivers/hwmon/occ/occ_sysfs.c | 251 ++++++++++++++++++++++++++++++++++++++++++
>  drivers/hwmon/occ/occ_sysfs.h |  30 +++++
>  4 files changed, 344 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/hwmon/occ/occ_sysfs.c
>  create mode 100644 drivers/hwmon/occ/occ_sysfs.h
>
> diff --git a/Documentation/hwmon/occ b/Documentation/hwmon/occ
> index 79d1642..d0bdf06 100644
> --- a/Documentation/hwmon/occ
> +++ b/Documentation/hwmon/occ
> @@ -25,6 +25,68 @@ Currently, all versions of the OCC support four types of sensor data: power,
>  temperature, frequency, and "caps," which indicate limits and thresholds used
>  internally on the OCC.
>
> +sysfs Entries
> +-------------
> +
> +The OCC driver uses the hwmon sysfs framework to provide data to userspace.
> +
> +The driver exports a number of sysfs files for each type of sensor. The
> +sensor-specific files vary depending on the processor type, though many of the
> +attributes are common for both the POWER8 and POWER9.
> +
> +The hwmon interface cannot define every type of sensor that may be used.
> +Therefore, the frequency sensor on the OCC uses the "input" type sensor defined
> +by the hwmon interface, rather than defining a new type of custom sensor.
> +
> +Below are detailed the names and meaning of each sensor file for both types of
> +processors. All sensors are read-only unless otherwise specified. <x> indicates
> +the hwmon index. sensor id indicates the unique internal OCC identifer. Please
> +see the POWER OCC specification for details on all these sensor values.
> +
> +frequency:
> +       all processors:
> +               in<x>_input - frequency value
> +               in<x>_label - sensor id
> +temperature:
> +       POWER8:
> +               temp<x>_input - temperature value
> +               temp<x>_label - sensor id
> +       POWER9 (in addition to above):
> +               temp<x>_type - FRU type
> +
> +power:
> +       POWER8:
> +               power<x>_input - power value
> +               power<x>_label - sensor id
> +               power<x>_average - accumulator
> +               power<x>_average_interval - update tag (number of samples in
> +                       accumulator)
> +       POWER9:
> +               power<x>_input - power value
> +               power<x>_label - sensor id
> +               power<x>_average_min - accumulator[0]
> +               power<x>_average_max - accumulator[1] (64 bits total)
> +               power<x>_average_interval - update tag
> +               power<x>_reset_history - (function_id | (apss_channel << 8)
> +
> +caps:
> +       POWER8:
> +               power<x>_cap - current powercap
> +               power<x>_cap_max - max powercap
> +               power<x>_cap_min - min powercap
> +               power<x>_max - normal powercap
> +               power<x>_alarm - user powercap, r/w
> +       POWER9:
> +               power<x>_cap_alarm - user powercap source
> +
> +The driver also provides two sysfs entries through hwmon to better
> +control the driver and monitor the master OCC. Though there may be multiple
> +OCCs present on the system, these two files are only present for the "master"
> +OCC.
> +       name - read the name of the driver
> +       update_interval - read or write the minimum interval for polling the
> +               OCC.
> +
>  BMC - Host Communications
>  -------------------------
>
> diff --git a/drivers/hwmon/occ/Makefile b/drivers/hwmon/occ/Makefile
> index 93cb52f..a6881f9 100644
> --- a/drivers/hwmon/occ/Makefile
> +++ b/drivers/hwmon/occ/Makefile
> @@ -1 +1 @@
> -obj-$(CONFIG_SENSORS_PPC_OCC) += occ.o
> +obj-$(CONFIG_SENSORS_PPC_OCC) += occ.o occ_sysfs.o
> diff --git a/drivers/hwmon/occ/occ_sysfs.c b/drivers/hwmon/occ/occ_sysfs.c
> new file mode 100644
> index 0000000..9598f78
> --- /dev/null
> +++ b/drivers/hwmon/occ/occ_sysfs.c
> @@ -0,0 +1,251 @@
> +/*
> + * occ_sysfs.c - OCC sysfs interface
> + *
> + * This file contains the methods and data structures for implementing the OCC
> + * hwmon sysfs entries.
> + *
> + * Copyright 2016 IBM Corp.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/init.h>
> +#include <linux/jiffies.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include "occ.h"
> +#include "occ_sysfs.h"
> +
> +#define OCC_HWMON_NAME_LENGTH  32
> +
> +struct occ_sysfs {
> +       struct device *dev;
> +       struct occ *occ;
> +
> +       char hwmon_name[OCC_HWMON_NAME_LENGTH + 1];
> +       const u32 *sensor_hwmon_configs;
> +       struct hwmon_channel_info **occ_sensors;
> +       struct hwmon_chip_info occ_info;
> +       u16 user_powercap;
> +};
> +
> +static int occ_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> +                         u32 attr, int channel, long *val)
> +{
> +       int rc;
> +       struct occ_sysfs *driver = dev_get_drvdata(dev);
> +       struct occ *occ = driver->occ;
> +
> +       switch (type) {
> +       case hwmon_in:
> +               rc = occ_get_sensor_field(occ, FREQ, channel, attr, val);
> +               break;
> +       case hwmon_temp:
> +               rc = occ_get_sensor_field(occ, TEMP, channel, attr, val);
> +               break;
> +       case hwmon_power:
> +               rc = occ_get_sensor_field(occ, POWER, channel, attr, val);
> +               break;
> +       default:
> +               rc = -EOPNOTSUPP;
> +       }
> +
> +       return rc;
> +}
> +
> +static int occ_hwmon_read_string(struct device *dev,
> +                                enum hwmon_sensor_types type, u32 attr,
> +                                int channel, char **str)
> +{
> +       int rc;
> +       unsigned long val = 0;
> +
> +       if (!((type == hwmon_in && attr == hwmon_in_label) ||
> +           (type == hwmon_temp && attr == hwmon_temp_label) ||
> +           (type == hwmon_power && attr == hwmon_power_label)))
> +               return -EOPNOTSUPP;
> +
> +       /* will fetch the "label", the sensor_id */
> +       rc = occ_hwmon_read(dev, type, attr, channel, &val);
> +       if (rc < 0)
> +               return rc;
> +
> +       rc = snprintf(*str, PAGE_SIZE - 1, "%lu", val);
> +       if (rc > 0)
> +               rc = 0;
> +
> +       return rc;
> +}
> +
> +static int occ_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
> +                          u32 attr, int channel, long val)
> +{
> +       int rc;
> +       struct occ_sysfs *driver = dev_get_drvdata(dev);
> +
> +       if (type == hwmon_power && attr == hwmon_power_alarm) {
> +               rc = occ_set_user_powercap(driver->occ, val);
> +               if (rc) {
> +                       dev_err(dev, "set user powercap failed:%d\n", rc);
> +                       return rc;
> +               }
> +
> +               driver->user_powercap = val;
> +
> +               return rc;
> +       }
> +
> +       return -EOPNOTSUPP;
> +}
> +
> +static umode_t occ_is_visible(const void *data, enum hwmon_sensor_types type,
> +                             u32 attr, int channel)
> +{
> +       const struct occ_sysfs *driver = data;
> +
> +       switch (type) {
> +       case hwmon_chip:
> +               if (attr == hwmon_chip_update_interval)
> +                       return 00644;

Perhaps 0644?

> +               break;
> +       case hwmon_in:
> +               if (BIT(attr) & driver->sensor_hwmon_configs[0])
> +                       return 00444;
> +               break;
> +       case hwmon_temp:
> +               if (BIT(attr) & driver->sensor_hwmon_configs[1])
> +                       return 00444;
> +               break;
> +       case hwmon_power:
> +               /* user power limit */
> +               if (attr == hwmon_power_alarm)
> +                       return 00644;
> +               else if ((BIT(attr) & driver->sensor_hwmon_configs[2]) ||
> +                        (BIT(attr) & driver->sensor_hwmon_configs[3]))
> +                       return 00444;
> +               break;
> +       default:
> +               return 0;
> +       }
> +
> +       return 0;
> +}
> +
> +static const struct hwmon_ops occ_hwmon_ops = {
> +       .is_visible = occ_is_visible,
> +       .read = occ_hwmon_read,
> +       .read_string = occ_hwmon_read_string,
> +       .write = occ_hwmon_write,
> +};
> +
> +static const enum hwmon_sensor_types occ_sensor_types[MAX_OCC_SENSOR_TYPE] = {
> +       hwmon_in,
> +       hwmon_temp,
> +       hwmon_power,
> +       hwmon_power
> +};
> +
> +struct occ_sysfs *occ_sysfs_start(struct device *dev, struct occ *occ,
> +                                 const u32 *sensor_hwmon_configs,
> +                                 const char *name)
> +{
> +       int rc, i, j, num_sensors, index = 0, id;
> +       char *brk;
> +       struct occ_blocks *resp = NULL;
> +       u32 *sensor_config;
> +       struct occ_sysfs *hwmon = devm_kzalloc(dev, sizeof(struct occ_sysfs),
> +                                              GFP_KERNEL);
> +       if (!hwmon)
> +               return ERR_PTR(-ENOMEM);
> +
> +       /* need space for null-termination */
> +       hwmon->occ_sensors =
> +               devm_kzalloc(dev, sizeof(struct hwmon_channel_info *) *
> +                            (MAX_OCC_SENSOR_TYPE + 1), GFP_KERNEL);
> +       if (!hwmon->occ_sensors)
> +               return ERR_PTR(-ENOMEM);
> +
> +       hwmon->occ = occ;
> +       hwmon->sensor_hwmon_configs = sensor_hwmon_configs;
> +       hwmon->occ_info.ops = &occ_hwmon_ops;
> +       hwmon->occ_info.info =
> +               (const struct hwmon_channel_info **)hwmon->occ_sensors;
> +
> +       occ_get_response_blocks(occ, &resp);
> +
> +       for (i = 0; i < MAX_OCC_SENSOR_TYPE; ++i)
> +               resp->sensor_block_id[i] = -1;
> +
> +       /* read sensor data from occ */
> +       rc = occ_update_device(occ);
> +       if (rc)
> +               return ERR_PTR(rc);
> +
> +       for (i = 0; i < MAX_OCC_SENSOR_TYPE; i++) {
> +               id = resp->sensor_block_id[i];
> +               if (id < 0)
> +                       continue;
> +
> +               num_sensors = resp->blocks[id].header.num_sensors;
> +               /* need null-termination */
> +               sensor_config = devm_kzalloc(dev,
> +                                            sizeof(u32) * (num_sensors + 1),
> +                                            GFP_KERNEL);
> +               if (!sensor_config)
> +                       return ERR_PTR(-ENOMEM);
> +
> +               for (j = 0; j < num_sensors; j++)
> +                       sensor_config[j] = sensor_hwmon_configs[i];
> +
> +               hwmon->occ_sensors[index] =
> +                       devm_kzalloc(dev, sizeof(struct hwmon_channel_info),
> +                                    GFP_KERNEL);
> +               if (!hwmon->occ_sensors[index])
> +                       return ERR_PTR(-ENOMEM);
> +
> +               hwmon->occ_sensors[index]->type = occ_sensor_types[i];
> +               hwmon->occ_sensors[index]->config = sensor_config;
> +               index++;
> +       }
> +
> +       /* search for bad chars */
> +       strncpy(hwmon->hwmon_name, name, OCC_HWMON_NAME_LENGTH);
> +       brk = strpbrk(hwmon->hwmon_name, "-* \t\n");
> +       while (brk) {
> +               *brk = '_';
> +               brk = strpbrk(brk,  "-* \t\n");
> +       }
> +
> +       hwmon->dev = devm_hwmon_device_register_with_info(dev,
> +                                                         hwmon->hwmon_name,
> +                                                         hwmon,
> +                                                         &hwmon->occ_info,
> +                                                         NULL);
> +       if (IS_ERR(hwmon->dev)) {
> +               dev_err(dev, "cannot register hwmon device %s: %ld\n",
> +                       hwmon->hwmon_name, PTR_ERR(hwmon->dev));
> +               return ERR_CAST(hwmon->dev);
> +       }
> +
> +       return hwmon;
> +}
> +EXPORT_SYMBOL(occ_sysfs_start);
> +
> +MODULE_AUTHOR("Eddie James <eajames@...ibm.com>");
> +MODULE_DESCRIPTION("OCC sysfs driver");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/hwmon/occ/occ_sysfs.h b/drivers/hwmon/occ/occ_sysfs.h
> new file mode 100644
> index 0000000..462f9d2
> --- /dev/null
> +++ b/drivers/hwmon/occ/occ_sysfs.h
> @@ -0,0 +1,30 @@
> +/*
> + * occ_sysfs.h - OCC sysfs interface
> + *
> + * This file contains the data structures and function prototypes for the OCC
> + * hwmon sysfs entries.
> + *
> + * Copyright 2016 IBM Corp.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef __OCC_SYSFS_H__
> +#define __OCC_SYSFS_H__
> +
> +struct occ;
> +struct device;
> +struct occ_sysfs;
> +
> +struct occ_sysfs *occ_sysfs_start(struct device *dev, struct occ *occ,
> +                                 const u32 *sensor_hwmon_configs,
> +                                 const char *name);
> +#endif /* __OCC_SYSFS_H__ */
> --
> 1.8.3.1
>

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