Subject: Re: [PATCH v4] powerpc/powernv: hwmon driver for power, fan rpm, voltage and temperature

From: Guenter Roeck <[email-masked]>
Date: Fri, 04 Jul 2014 19:25:36 -0700

On 07/04/2014 04:02 AM, Neelesh Gupta wrote:
> This patch adds basic kernel support for reading power values, fan
> speed rpm, voltage and temperature data on powernv platforms which will
> be exported to user space through sysfs interface.
>

Hi Neelesh,

Copying devicetree mailing list. Please copy it on the next (hopefully final)
revision; devicetree maintainers at least need a chance to comment.
[ Yes, I understand this is a shipping product, but still ... ]

I am ok with the code except for a couple of minor nitpicks (see below).

Thanks,
Guenter

> Test results:
> -------------
> [root@tul163p1 ~]# sensors
> ibmpowernv-isa-0000
> Adapter: ISA adapter
> fan1:        5567 RPM  (min =    0 RPM)
> fan2:        5232 RPM  (min =    0 RPM)
> fan3:        5532 RPM  (min =    0 RPM)
> fan4:        4945 RPM  (min =    0 RPM)
> fan5:           0 RPM  (min =    0 RPM)
> fan6:           0 RPM  (min =    0 RPM)
> fan7:        7392 RPM  (min =    0 RPM)
> fan8:        7936 RPM  (min =    0 RPM)
> temp1:        +39.0°C  (high =  +0.0°C)
> power1:      191.00 W
>
> [root@tul163p1 ~]# ls /sys/devices/platform/
> alarmtimer  ibmpowernv.0  power  rtc-generic  serial8250  uevent
> [root@tul163p1 ~]# ls /sys/devices/platform/ibmpowernv.0/hwmon/hwmon0/
> device	    fan2_min	fan4_min    fan6_min	fan8_min   power
> fan1_fault  fan3_fault	fan5_fault  fan7_fault	in1_fault  power1_input
> fan1_input  fan3_input	fan5_input  fan7_input	in2_fault  subsystem
> fan1_min    fan3_min	fan5_min    fan7_min	in3_fault  temp1_input
> fan2_fault  fan4_fault	fan6_fault  fan8_fault	in4_fault  temp1_max
> fan2_input  fan4_input	fan6_input  fan8_input	name	   uevent
> [root@tul163p1 ~]#
> [root@tul163p1 ~]# ls /sys/class/hwmon/hwmon0/
> device	    fan2_min	fan4_min    fan6_min	fan8_min   power
> fan1_fault  fan3_fault	fan5_fault  fan7_fault	in1_fault  power1_input
> fan1_input  fan3_input	fan5_input  fan7_input	in2_fault  subsystem
> fan1_min    fan3_min	fan5_min    fan7_min	in3_fault  temp1_input
> fan2_fault  fan4_fault	fan6_fault  fan8_fault	in4_fault  temp1_max
> fan2_input  fan4_input	fan6_input  fan8_input	name	   uevent
> [root@tul163p1 ~]#
>
> Signed-off-by: Neelesh Gupta <[email-masked]>
> ---
>
> Changes in v4
> =============
> - Replaced pr_err() with dev_err() for loggin print messages.
> - Using kstrtou32() function for converting string to u32 instead of sscanf().
>
> Changes in v3
> =============
> - Fixed an endianness bug leading the driver to break on LE.
> - Fixed a bug that when one of the 'attribute_group' not populated, following
>    groups attributes were dropped.
> - Rewrite the get_sensor_index_attr() function to handle all the error scenarios
>    like 'sscanf' etc.
> - Fixed all the errors/warnings related to coding style/whitespace.
> - Added 'Documentation' files.
> - Addressed remaining review comments on V2.
>
> Changes in v2
> =============
> - Generic use of devm_* functions in hwmon like using devm_kzalloc() for dynamic
>    memory request, avoiding the need to explicit free of memory.
>    Adding 'struct attribute_group' as member of platform data structure to be
>    populated and then passed to devm_hwmon_device_register_with_groups().
>
>    Note: Having an array of pointers of 'attribute_group' and each group
>    corresponds to 'enum sensors' type. Not completely sure, if it's ideal or
>    could have just one group populated with attributes of sensor types?
>
> - 'ibmpowernv' is not hot-pluggable device so moving 'platform_driver' callback
>    function (probe) as part of __init code.
> - Fixed issues related to coding style.
> - Other general comments in v1.
>
>   .../devicetree/bindings/hwmon/ibmpowernv.txt       |   27 +
>   Documentation/hwmon/ibmpowernv                     |   41 ++
>   drivers/hwmon/Kconfig                              |   11 +
>   drivers/hwmon/Makefile                             |    1
>   drivers/hwmon/ibmpowernv.c                         |  362 ++++++++++++++++++++
>   5 files changed, 442 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/hwmon/ibmpowernv.txt
>   create mode 100644 Documentation/hwmon/ibmpowernv
>   create mode 100644 drivers/hwmon/ibmpowernv.c
>
> diff --git a/Documentation/devicetree/bindings/hwmon/ibmpowernv.txt b/Documentation/devicetree/bindings/hwmon/ibmpowernv.txt
> new file mode 100644
> index 0000000..e3bd1eb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/ibmpowernv.txt
> @@ -0,0 +1,27 @@
> +IBM POWERNV platform sensors
> +----------------------------
> +
> +Required node properties:
> +- compatible: must be one of
> +		"ibm,opal-sensor-cooling-fan"
> +		"ibm,opal-sensor-amb-temp"
> +		"ibm,opal-sensor-power-supply"
> +		"ibm,opal-sensor-power"
> +- sensor-id: an opaque id provided by the firmware to the kernel, identifies a
> +	     given sensor and its attribute data
> +
> +Example sensors node:
> +
> +cooling-fan#8-data {
> +	sensor-id = <0x7052107>;
> +	phandle = <0x10000028>;
> +	linux,phandle = <0x10000028>;
> +	compatible = "ibm,opal-sensor-cooling-fan";

phandle and linux-phandle are neither documented nor used. Either document or drop.

> +};
> +
> +amb-temp#1-thrs {
> +	sensor-id = <0x5096000>;
> +	phandle = <0x10000017>;
> +	linux,phandle = <0x10000017>;
> +	compatible = "ibm,opal-sensor-amb-temp";
> +};
> diff --git a/Documentation/hwmon/ibmpowernv b/Documentation/hwmon/ibmpowernv
> new file mode 100644
> index 0000000..644245a
> --- /dev/null
> +++ b/Documentation/hwmon/ibmpowernv
> @@ -0,0 +1,41 @@
> +Kernel Driver IBMPOWENV
> +=======================
> +
> +Supported systems:
> +  * Any recent IBM P servers based on POWERNV platform
> +
> +Author: Neelesh Gupta
> +
> +Description
> +-----------
> +
> +This driver implements reading the platform sensors data like temperature/fan/
> +voltage/power for 'POWERNV' platform.
> +
> +The driver uses the platform device infrastructure. It probes the device tree
> +for sensor devices during the __init phase and registers them with the 'hwmon'.
> +'hwmon' populates the 'sysfs' tree having attribute files, each for a given
> +sensor type and its attribute data.
> +
> +All the nodes in the DT appear under "/ibm,opal/sensors" and each valid node in
> +the DT maps to an attribute file in 'sysfs'. The node exports unique 'sensor-id'
> +which the driver uses to make an OPAL call to the firmware.
> +
> +Usage notes
> +-----------
> +The driver is built statically with the kernel by enabling the config
> +CONFIG_SENSORS_IBMPOWERNV. It can also be built as module 'ibmpowernv'.
> +
> +Sysfs attributes
> +----------------
> +
> +fanX_input		Measured RPM value.
> +fanX_min		Threshold RPM for alert generation.
> +fanX_fault		0: No fail condition
> +			1: Failing fan
> +tempX_input		Measured ambient temperature.
> +tempX_max		Threshold ambient temperature for alert generation.
> +inX_input		Measured power supply voltage
> +inX_fault		0: No fail condition.
> +			1: Failing power supply.
> +power1_input		System power consumption (microWatt)
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 02d3d85..29c3fcb 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -554,6 +554,17 @@ config SENSORS_IBMPEX
>   	  This driver can also be built as a module.  If so, the module
>   	  will be called ibmpex.
>
> +config SENSORS_IBMPOWERNV
> +	tristate "IBM POWERNV platform sensors"
> +	depends on PPC_POWERNV
> +	default y
> +	help
> +	  If you say yes here you get support for the temperature/fan/power
> +	  sensors on your PowerNV platform.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called ibmpowernv.
> +
>   config SENSORS_IIO_HWMON
>   	tristate "Hwmon driver that uses channels specified via iio maps"
>   	depends on IIO
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 3dc0f02..fc4ed26 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -71,6 +71,7 @@ obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
>   obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o
>   obj-$(CONFIG_SENSORS_IBMAEM)	+= ibmaem.o
>   obj-$(CONFIG_SENSORS_IBMPEX)	+= ibmpex.o
> +obj-$(CONFIG_SENSORS_IBMPOWERNV)+= ibmpowernv.o
>   obj-$(CONFIG_SENSORS_IIO_HWMON) += iio_hwmon.o
>   obj-$(CONFIG_SENSORS_INA209)	+= ina209.o
>   obj-$(CONFIG_SENSORS_INA2XX)	+= ina2xx.o
> diff --git a/drivers/hwmon/ibmpowernv.c b/drivers/hwmon/ibmpowernv.c
> new file mode 100644
> index 0000000..44dcd99
> --- /dev/null
> +++ b/drivers/hwmon/ibmpowernv.c
> @@ -0,0 +1,362 @@
> +/*
> + * IBM PowerNV platform sensors for temperature/fan/voltage/power
> + * Copyright (C) 2014 IBM
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.
> + */
> +
> +#define DRVNAME		"ibmpowernv"
> +#define pr_fmt(fmt)	DRVNAME ": " fmt
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/of.h>
> +#include <linux/slab.h>
> +
> +#include <linux/platform_device.h>
> +#include <asm/opal.h>
> +#include <linux/err.h>
> +
> +#define MAX_ATTR_LEN	32
> +
> +/* Sensor suffix name from DT */
> +#define DT_FAULT_ATTR_SUFFIX		"faulted"
> +#define DT_DATA_ATTR_SUFFIX		"data"
> +#define DT_THRESHOLD_ATTR_SUFFIX	"thrs"
> +
> +/*
> + * Enumerates all the types of sensors in the POWERNV platform and does index
> + * into 'struct sensor_group'
> + */
> +enum sensors {
> +	FAN,
> +	AMBIENT_TEMP,
> +	POWER_SUPPLY,
> +	POWER_INPUT,
> +	MAX_SENSOR_TYPE,
> +};
> +
> +static struct sensor_group {
> +	const char *name;
> +	const char *compatible;
> +	struct attribute_group group;
> +	u32 attr_count;
> +} sensor_groups[] = {
> +	{"fan", "ibm,opal-sensor-cooling-fan"},
> +	{"temp", "ibm,opal-sensor-amb-temp"},
> +	{"in", "ibm,opal-sensor-power-supply"},
> +	{"power", "ibm,opal-sensor-power"}
> +};
> +
> +struct sensor_data {
> +	u32 id; /* An opaque id of the firmware for each sensor */
> +	enum sensors type;
> +	char name[MAX_ATTR_LEN];
> +	struct device_attribute dev_attr;
> +};
> +
> +struct platform_data {
> +	const struct attribute_group *attr_groups[MAX_SENSOR_TYPE + 1];
> +	u32 sensors_count; /* Total count of sensors from each group */
> +};
> +
> +/* Platform device representing all the ibmpowernv sensors */
> +static struct platform_device *pdevice;
> +
> +static ssize_t show_sensor(struct device *dev, struct device_attribute *devattr,
> +			   char *buf)
> +{
> +	struct sensor_data *sdata = container_of(devattr, struct sensor_data,
> +						 dev_attr);
> +	ssize_t ret;
> +	u32 x;
> +
> +	ret = opal_get_sensor_data(sdata->id, &x);
> +	if (ret)
> +		return ret;
> +
> +	/* Convert temperature to milli-degrees */
> +	if (sdata->type == AMBIENT_TEMP)
> +		x *= 1000;
> +	/* Convert power to micro-watts */
> +	else if (sdata->type == POWER_INPUT)
> +		x *= 1000000;
> +
> +	return sprintf(buf, "%u\n", x);
> +}
> +
> +static int __init get_sensor_index_attr(const char *name, u32 *index,
> +					char *attr)
> +{
> +	char *hash_pos = strchr(name, '#');
> +	char buf[8] = { 0 };
> +	char *dash_pos;
> +	u32 copy_len;
> +
> +	if (!hash_pos)
> +		return -EINVAL;
> +
> +	dash_pos = strchr(hash_pos, '-');
> +	if (!dash_pos)
> +		return -EINVAL;
> +
> +	copy_len = dash_pos - hash_pos - 1;
> +	if (copy_len >= sizeof(buf))
> +		return -EINVAL;
> +
> +	strncpy(buf, hash_pos + 1, copy_len);
> +
> +	if (kstrtou32(buf, 10, index))
> +		return -EINVAL;
> +
smatch isn't going to like that. Please use

	int err;
	...
	err = kstrtou32(buf, 10, index));
	if (err)
		return err;

> +	strncpy(attr, dash_pos + 1, MAX_ATTR_LEN);
> +
> +	return 0;
> +}
> +
> +/*
> + * This function translates the DT node name into the 'hwmon' attribute name.
> + * IBMPOWERNV device node appear like cooling-fan#2-data, amb-temp#1-thrs etc.
> + * which need to be mapped as fan2_input, temp1_max respectively before
> + * populating them inside hwmon device class.
> + */
> +static int __init create_hwmon_attr_name(struct device *dev, enum sensors type,
> +					 const char *node_name,
> +					 char *hwmon_attr_name)
> +{
> +	char attr_suffix[MAX_ATTR_LEN];
> +	char *attr_name;
> +	u32 index;
> +	int err;
> +
> +	err = get_sensor_index_attr(node_name, &index, attr_suffix);
> +	if (err) {
> +		dev_err(dev, "Sensor device node name '%s' is invalid\n",
> +			node_name);
> +		return err;
> +	}
> +
> +	if (!strcmp(attr_suffix, DT_FAULT_ATTR_SUFFIX)) {
> +		attr_name = "fault";
> +	} else if (!strcmp(attr_suffix, DT_DATA_ATTR_SUFFIX)) {
> +		attr_name = "input";
> +	} else if (!strcmp(attr_suffix, DT_THRESHOLD_ATTR_SUFFIX)) {
> +		if (type == AMBIENT_TEMP)
> +			attr_name = "max";
> +		else if (type == FAN)
> +			attr_name = "min";
> +		else
> +			return -ENOENT;
> +	} else {
> +		return -ENOENT;
> +	}
> +
> +	snprintf(hwmon_attr_name, MAX_ATTR_LEN, "%s%d_%s",
> +		 sensor_groups[type].name, index, attr_name);
> +	return 0;
> +}
> +
> +static int __init populate_attr_groups(struct platform_device *pdev)
> +{
> +	struct platform_data *pdata = platform_get_drvdata(pdev);
> +	const struct attribute_group **pgroups = pdata->attr_groups;
> +	struct device_node *opal, *np;
> +	enum sensors type;
> +
> +	opal = of_find_node_by_path("/ibm,opal/sensors");
> +	if (!opal) {
> +		dev_err(&pdev->dev, "Opal node 'sensors' not found\n");
> +		return -ENODEV;
> +	}
> +
> +	for_each_child_of_node(opal, np) {
> +		if (np->name == NULL)
> +			continue;
> +
> +		for (type = 0; type < MAX_SENSOR_TYPE; type++)
> +			if (of_device_is_compatible(np,
> +					sensor_groups[type].compatible)) {
> +				sensor_groups[type].attr_count++;
> +				break;
> +			}
> +	}
> +
> +	of_node_put(opal);
> +
> +	for (type = 0; type < MAX_SENSOR_TYPE; type++) {
> +		sensor_groups[type].group.attrs = devm_kzalloc(&pdev->dev,
> +					sizeof(struct attribute *) *
> +					(sensor_groups[type].attr_count + 1),
> +					GFP_KERNEL);
> +		if (!sensor_groups[type].group.attrs)
> +			return -ENOMEM;
> +
> +		pgroups[type] = &sensor_groups[type].group;
> +		pdata->sensors_count += sensor_groups[type].attr_count;
> +		sensor_groups[type].attr_count = 0;
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * Iterate through the device tree for each child of 'sensors' node, create
> + * a sysfs attribute file, the file is named by translating the DT node name
> + * to the name required by the higher 'hwmon' driver like fan1_input, temp1_max
> + * etc..
> + */
> +static int __init create_device_attrs(struct platform_device *pdev)
> +{
> +	struct platform_data *pdata = platform_get_drvdata(pdev);
> +	const struct attribute_group **pgroups = pdata->attr_groups;
> +	struct device_node *opal, *np;
> +	struct sensor_data *sdata;
> +	const __be32 *sensor_id;
> +	enum sensors type;
> +	u32 count = 0;
> +	int err = 0;
> +
> +	opal = of_find_node_by_path("/ibm,opal/sensors");
> +	sdata = devm_kzalloc(&pdev->dev, pdata->sensors_count * sizeof(*sdata),
> +			     GFP_KERNEL);
> +	if (!sdata) {
> +		err = -ENOMEM;
> +		goto exit_put_node;
> +	}
> +
> +	for_each_child_of_node(opal, np) {
> +		if (np->name == NULL)
> +			continue;
> +
> +		for (type = 0; type < MAX_SENSOR_TYPE; type++)
> +			if (of_device_is_compatible(np,
> +					sensor_groups[type].compatible))
> +				break;
> +
> +		if (type == MAX_SENSOR_TYPE)
> +			continue;
> +
> +		sensor_id = of_get_property(np, "sensor-id", NULL);
> +		if (!sensor_id) {
> +			dev_info(&pdev->dev,
> +				 "'sensor-id' missing in the node '%s'\n",
> +				 np->name);
> +			continue;
> +		}
> +
> +		sdata[count].id = be32_to_cpup(sensor_id);
> +		sdata[count].type = type;
> +		err = create_hwmon_attr_name(&pdev->dev, type, np->name,
> +					     sdata[count].name);
> +		if (err)
> +			goto exit_put_node;
> +
> +		sysfs_attr_init(&sdata[count].dev_attr.attr);
> +		sdata[count].dev_attr.attr.name = sdata[count].name;
> +		sdata[count].dev_attr.attr.mode = S_IRUGO;
> +		sdata[count].dev_attr.show = show_sensor;
> +
> +		pgroups[type]->attrs[sensor_groups[type].attr_count++] =
> +				&sdata[count++].dev_attr.attr;
> +	}
> +
> +exit_put_node:
> +	of_node_put(opal);
> +	return err;
> +}
> +
> +static int __init ibmpowernv_probe(struct platform_device *pdev)
> +{
> +	struct platform_data *pdata;
> +	struct device *hwmon_dev;
> +	int err;
> +
> +	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
> +	if (!pdata)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, pdata);
> +	pdata->sensors_count = 0;
> +	err = populate_attr_groups(pdev);
> +	if (err)
> +		return err;
> +
> +	/* Create sysfs attribute data for each sensor found in the DT */
> +	err = create_device_attrs(pdev);
> +	if (err)
> +		return err;
> +
> +	/* Finally, register with hwmon */
> +	hwmon_dev = devm_hwmon_device_register_with_groups(&pdev->dev, DRVNAME,
> +							   pdata,
> +							   pdata->attr_groups);
> +
> +	return PTR_ERR_OR_ZERO(hwmon_dev);
> +}
> +
> +static struct platform_driver ibmpowernv_driver = {
> +	.driver = {
> +		.owner = THIS_MODULE,
> +		.name = DRVNAME,
> +	},
> +};
> +
> +static int __init ibmpowernv_init(void)
> +{
> +	int err;
> +
> +	pdevice = platform_device_alloc(DRVNAME, 0);
> +	if (!pdevice) {
> +		pr_err("Device allocation failed\n");
> +		err = -ENOMEM;
> +		goto exit;
> +	}
> +
> +	err = platform_device_add(pdevice);
> +	if (err) {
> +		pr_err("Device addition failed (%d)\n", err);
> +		goto exit_device_put;
> +	}
> +
> +	err = platform_driver_probe(&ibmpowernv_driver, ibmpowernv_probe);
> +	if (err) {
> +		pr_err("Platfrom driver probe failed\n");
> +		goto exit_device_del;
> +	}
> +
> +	return 0;
> +
> +exit_device_del:
> +	platform_device_del(pdevice);
> +exit_device_put:
> +	platform_device_put(pdevice);
> +exit:
> +	return err;
> +}
> +
> +static void __exit ibmpowernv_exit(void)
> +{
> +	platform_driver_unregister(&ibmpowernv_driver);
> +	platform_device_unregister(pdevice);
> +}
> +
> +MODULE_AUTHOR("Neelesh Gupta <[email-masked]>");
> +MODULE_DESCRIPTION("IBM POWERNV platform sensors");
> +MODULE_LICENSE("GPL");
> +
> +module_init(ibmpowernv_init);
> +module_exit(ibmpowernv_exit);
>
>
>