Re: [lm-sensors] [PATCH v2 03/13] hwmon: Versatile Express hwmon driver

[Guenter Roeck <linux@roeck-us.net>]

On Tue, Sep 18, 2012 at 03:17:45PM +0100, Pawel Moll wrote:
> hwmon framework driver for Versatile Express sensors, providing
> information about board level voltage (only when regulator driver
> is not configured), currents, temperature and power/energy usage.
> Labels for the values can be defined as DT properties.
> 
> Signed-off-by: Pawel Moll <pawel.moll@arm.com>
> ---
>  drivers/hwmon/Kconfig    |    8 ++
>  drivers/hwmon/Makefile   |    1 +
>  drivers/hwmon/vexpress.c |  330 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 339 insertions(+)
>  create mode 100644 drivers/hwmon/vexpress.c
> 
> Hi Jean, Guenter,
> 
> Would you be able to merge this in time for 3.7? (if it looks fine, that is)
> 
> Regards
> 
> Pawel
> 
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index b0a2e4c..7359a07 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1187,6 +1187,14 @@ config SENSORS_TWL4030_MADC
>  	This driver can also be built as a module. If so it will be called
>  	twl4030-madc-hwmon.
>  
> +config SENSORS_VEXPRESS
> +	tristate "Versatile Express"
> +	depends on VEXPRESS_CONFIG
> +	help
> +	  This driver provides support for hardware sensors available on
> +	  the ARM Ltd's Versatile Express platform. It can provide wide
> +	  range of information like temperature, power, energy.
> +
>  config SENSORS_VIA_CPUTEMP
>  	tristate "VIA CPU temperature sensor"
>  	depends on X86
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 7aa9811..e719a7d 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -120,6 +120,7 @@ obj-$(CONFIG_SENSORS_TMP102)	+= tmp102.o
>  obj-$(CONFIG_SENSORS_TMP401)	+= tmp401.o
>  obj-$(CONFIG_SENSORS_TMP421)	+= tmp421.o
>  obj-$(CONFIG_SENSORS_TWL4030_MADC)+= twl4030-madc-hwmon.o
> +obj-$(CONFIG_SENSORS_VEXPRESS)	+= vexpress.o
>  obj-$(CONFIG_SENSORS_VIA_CPUTEMP)+= via-cputemp.o
>  obj-$(CONFIG_SENSORS_VIA686A)	+= via686a.o
>  obj-$(CONFIG_SENSORS_VT1211)	+= vt1211.o
> diff --git a/drivers/hwmon/vexpress.c b/drivers/hwmon/vexpress.c
> new file mode 100644
> index 0000000..fe80c63
> --- /dev/null
> +++ b/drivers/hwmon/vexpress.c
> @@ -0,0 +1,330 @@
> +/*
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * 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.
> + *
> + * Copyright (C) 2012 ARM Limited
> + */
> +
> +#define DRVNAME "vexpress-hwmon"
> +#define pr_fmt(fmt) DRVNAME ": " fmt
> +
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/vexpress.h>
> +
> +static struct device *vexpress_hwmon_dev;
> +static int vexpress_hwmon_dev_refcount;
> +static DEFINE_SPINLOCK(vexpress_hwmon_dev_lock);
> +
> +static ssize_t vexpress_hwmon_name_show(struct device *dev,
> +		struct device_attribute *dev_attr, char *buffer)
> +{
> +	return sprintf(buffer, "%s\n", DRVNAME);
> +}
> +
> +static struct device_attribute vexpress_hwmon_name_attr > +		__ATTR(name, 0444, vexpress_hwmon_name_show, NULL);
> +
> +struct vexpress_hwmon_attrs {
> +	struct vexpress_config_func *func;
> +	const char *label;
> +	struct device_attribute label_attr;
> +	char label_name[16];
> +	struct device_attribute input_attr;
> +	char input_name[16];
> +	u32 divisor;
> +};
> +
> +static ssize_t vexpress_hwmon_label_show(struct device *dev,
> +		struct device_attribute *dev_attr, char *buffer)
> +{
> +	struct vexpress_hwmon_attrs *attrs = container_of(dev_attr,
> +			struct vexpress_hwmon_attrs, label_attr);
> +
> +	return snprintf(buffer, PAGE_SIZE, "%s\n", attrs->label);
> +}
> +
> +static ssize_t vexpress_hwmon_u32_show(struct device *dev,
> +		struct device_attribute *dev_attr, char *buffer)
> +{
> +	struct vexpress_hwmon_attrs *attrs = container_of(dev_attr,
> +			struct vexpress_hwmon_attrs, input_attr);
> +	int err;
> +	u32 value;
> +
> +	err = vexpress_config_read(attrs->func, 0, &value);
> +	if (err)
> +		return err;
> +
> +	return snprintf(buffer, PAGE_SIZE, "%u\n", value / attrs->divisor);
> +}
> +
> +static ssize_t vexpress_hwmon_u64_show(struct device *dev,
> +		struct device_attribute *dev_attr, char *buffer)
> +{
> +	struct vexpress_hwmon_attrs *attrs = container_of(dev_attr,
> +			struct vexpress_hwmon_attrs, input_attr);
> +	int err;
> +	u32 value_hi, value_lo;
> +
> +	err = vexpress_config_read(attrs->func, 0, &value_lo);
> +	if (err)
> +		return err;
> +
> +	err = vexpress_config_read(attrs->func, 1, &value_hi);
> +	if (err)
> +		return err;
> +
> +	return snprintf(buffer, PAGE_SIZE, "%llu\n",
> +			div_u64(((u64)value_hi << 32) | value_lo,
> +			attrs->divisor));
> +}
> +
> +static struct device *vexpress_hwmon_dev_get(void)
> +{
> +	struct device *result;
> +
> +	spin_lock(&vexpress_hwmon_dev_lock);
> +
> +	if (vexpress_hwmon_dev) {
> +		result = vexpress_hwmon_dev;
> +	} else {
> +		int err;
> +
> +		result = hwmon_device_register(NULL);
> +		if (IS_ERR(result))
> +			goto out;
> +
> +		err = device_create_file(result, &vexpress_hwmon_name_attr);
> +		if (err) {
> +			result = ERR_PTR(err);
> +			hwmon_device_unregister(result);
> +			goto out;
> +		}
> +
> +		vexpress_hwmon_dev = result;
> +	}
> +
> +	vexpress_hwmon_dev_refcount++;
> +
> +out:
> +	spin_unlock(&vexpress_hwmon_dev_lock);
> +
> +	return result;
> +}
> +
> +static void vexpress_hwmon_dev_put(void)
> +{
> +	spin_lock(&vexpress_hwmon_dev_lock);
> +
> +	if (--vexpress_hwmon_dev_refcount = 0) {
> +		hwmon_device_unregister(vexpress_hwmon_dev);
> +		vexpress_hwmon_dev = NULL;
> +	}
> +
> +	WARN_ON(vexpress_hwmon_dev_refcount < 0);
> +
> +	spin_unlock(&vexpress_hwmon_dev_lock);
> +}
> +
This is a highly unusual means to register a hwmon driver (and you are leaking
the name attribute on remove as far as I can see).

> +struct vexpress_hwmon_func {
> +	const char *name;
> +	bool wide;
> +	u32 divisor;
> +	atomic_t index;
> +};
> +
> +#if !defined(CONFIG_REGULATOR_VEXPRESS)
> +static struct vexpress_hwmon_func vexpress_hwmon_volt = {
> +	.name = "in",
> +	.divisor = 1000,
> +};
> +#endif
> +
> +static struct vexpress_hwmon_func vexpress_hwmon_amp = {
> +	.name = "curr",
> +	.divisor = 1000,
> +};
> +
> +static struct vexpress_hwmon_func vexpress_hwmon_temp = {
> +	.name = "temp",
> +	.divisor = 1000,
> +};
> +
> +static struct vexpress_hwmon_func vexpress_hwmon_power = {
> +	.name = "power",
> +	.divisor = 1,
> +};
> +
> +static struct vexpress_hwmon_func vexpress_hwmon_energy = {
> +	.name = "energy",
> +	.wide = true,
> +	.divisor = 1,
> +};
> +
> +static struct of_device_id vexpress_hwmon_of_match[] = {
> +#if !defined(CONFIG_REGULATOR_VEXPRESS)
> +	{
> +		.compatible = "arm,vexpress-volt",
> +		.data = &vexpress_hwmon_volt,
> +	},
> +#endif
> +	{
> +		.compatible = "arm,vexpress-amp",
> +		.data = &vexpress_hwmon_amp,
> +	}, {
> +		.compatible = "arm,vexpress-temp",
> +		.data = &vexpress_hwmon_temp,
> +	}, {
> +		.compatible = "arm,vexpress-power",
> +		.data = &vexpress_hwmon_power,
> +	}, {
> +		.compatible = "arm,vexpress-energy",
> +		.data = &vexpress_hwmon_energy,
> +	},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, vexpress_hwmon_of_match);
> +
> +static int vexpress_hwmon_probe(struct platform_device *pdev)
> +{
> +	int err;
> +	const struct of_device_id *match;
> +	struct vexpress_hwmon_func *hwmon_func;
> +	struct device *hwmon_dev;
> +	struct vexpress_hwmon_attrs *attrs;
> +	const char *attr_name;
> +	int attr_index;
> +
> +	match = of_match_device(vexpress_hwmon_of_match, &pdev->dev);
> +	if (!match) {
> +		err = -EINVAL;
> +		goto error_match_device;
> +	}
> +	hwmon_func = match->data;
> +
> +	hwmon_dev = vexpress_hwmon_dev_get();
> +	if (IS_ERR(hwmon_dev)) {
> +		err = PTR_ERR(hwmon_dev);
> +		goto error_hwmon_dev_get;
> +	}
> +
> +	attrs = devm_kzalloc(&pdev->dev, sizeof(*attrs), GFP_KERNEL);
> +	if (!attrs) {
> +		err = -ENOMEM;
> +		goto error_kzalloc;
> +	}
> +
> +	attrs->func = vexpress_config_func_get_by_dev(&pdev->dev);
> +	if (!attrs->func) {
> +		err = -ENXIO;
> +		goto error_get_func;
> +	}
> +
> +	err = sysfs_create_link(&pdev->dev.kobj, &hwmon_dev->kobj, "hwmon");
> +	if (err)
> +		goto error_create_link;
> +
> +	attr_index = atomic_inc_return(&hwmon_func->index);
> +	attr_name = hwmon_func->name;
> +
> +	snprintf(attrs->input_name, sizeof(attrs->input_name),
> +			"%s%d_input", attr_name, attr_index);
> +	attrs->input_attr.attr.name = attrs->input_name;
> +	attrs->input_attr.attr.mode = 0444;
> +	if (hwmon_func->wide)
> +		attrs->input_attr.show = vexpress_hwmon_u64_show;
> +	else
> +		attrs->input_attr.show = vexpress_hwmon_u32_show;
> +	sysfs_attr_init(&attrs->input_attr.attr);
> +	err = device_create_file(hwmon_dev, &attrs->input_attr);
> +	if (err)
> +		goto error_create_input;
> +
and a highly unusual way of, as much as I understand of it, bypass the hwmon
infrastructure as much as possible.

I don't even understand what you are trying to do, much less why you don't
just use the existing infrastructure, and I don't have time to try to figure
it out. Maybe Jean has time to review this driver, but not me.

So, no, for my part I don't think it would be a good idea to rush this driver
into 3.7.

Really, I would suggest to submit a standard hwmon driver (there are lots of
examples out there).

Guenter

> +	attrs->label = of_get_property(pdev->dev.of_node, "label", NULL);
> +	if (attrs->label) {
> +		snprintf(attrs->label_name, sizeof(attrs->label_name),
> +				"%s%d_label", attr_name, attr_index);
> +		attrs->label_attr.attr.name = attrs->label_name;
> +		attrs->label_attr.attr.mode = 0444;
> +		attrs->label_attr.show = vexpress_hwmon_label_show;
> +		sysfs_attr_init(&attrs->label_attr.attr);
> +		err = device_create_file(hwmon_dev, &attrs->label_attr);
> +		if (err)
> +			goto error_create_label;
> +	}
> +
> +	attrs->divisor = hwmon_func->divisor;
> +
> +	platform_set_drvdata(pdev, attrs);
> +
> +	return 0;
> +
> +error_create_label:
> +	device_remove_file(hwmon_dev, &attrs->input_attr);
> +error_create_input:
> +	sysfs_remove_link(&pdev->dev.kobj, "hwmon");
> +error_create_link:
> +	vexpress_config_func_put(attrs->func);
> +error_get_func:
> +error_kzalloc:
> +	vexpress_hwmon_dev_put();
> +error_hwmon_dev_get:
> +error_match_device:
> +	return err;
> +}
> +
> +static int __devexit vexpress_hwmon_remove(struct platform_device *pdev)
> +{
> +	struct vexpress_hwmon_attrs *attrs = platform_get_drvdata(pdev);
> +	const struct of_device_id *match > +		of_match_device(vexpress_hwmon_of_match, &pdev->dev);
> +	struct vexpress_hwmon_func *hwmon_func = match->data;
> +
> +	if (attrs->label)
> +		device_remove_file(vexpress_hwmon_dev, &attrs->label_attr);
> +	device_remove_file(vexpress_hwmon_dev, &attrs->input_attr);
> +	atomic_dec(&hwmon_func->index);
> +	sysfs_remove_link(&pdev->dev.kobj, "hwmon");
> +	vexpress_config_func_put(attrs->func);
> +	vexpress_hwmon_dev_put();
> +
> +	return 0;
> +}
> +
> +static struct platform_driver vexpress_hwmon_driver = {
> +	.probe = vexpress_hwmon_probe,
> +	.remove = __devexit_p(vexpress_hwmon_remove),
> +	.driver	= {
> +		.name = DRVNAME,
> +		.owner = THIS_MODULE,
> +		.of_match_table = vexpress_hwmon_of_match,
> +	},
> +};
> +
> +static int __init vexpress_hwmon_init(void)
> +{
> +	return platform_driver_register(&vexpress_hwmon_driver);
> +}
> +
> +static void __exit vexpress_hwmon_exit(void)
> +{
> +	platform_driver_unregister(&vexpress_hwmon_driver);
> +}
> +
> +MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
> +MODULE_DESCRIPTION("Versatile Express hwmon");
> +MODULE_LICENSE("GPL");
> +
> +module_init(vexpress_hwmon_init);
> +module_exit(vexpress_hwmon_exit);
> -- 
> 1.7.9.5
> 
> 
> 

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