Date:	Wed, 13 Apr 2011 15:06:33 +0200
From:	Jean Delvare <khali@...ux-fr.org>
To:	Andreas Herrmann <herrmann.der.user@...glemail.com>
Cc:	Guenter Roeck <guenter.roeck@...csson.com>,
	Thomas Renninger <trenn@...e.de>, lm-sensors@...sensors.org,
	linux-kernel@...r.kernel.org, Clemens Ladisch <clemens@...isch.de>
Subject: Re: [PATCH v4] hwmon: Add driver for AMD family 15h processor power
 information

Hi Andreas,

On Fri, 8 Apr 2011 15:54:07 +0200, Andreas Herrmann wrote:
> From: Andreas Herrmann <andreas.herrmann3@....com>
> 
> This CPU family provides NB register values to gather following
> TDP information
> 
> * ProcessorPwrWatts: Specifies in Watts the maximum amount of power
>   the processor can support.
> * CurrPwrWatts: Specifies in Watts the current amount of power being
>   consumed by the processor.
> 
> This driver provides
> 
> * power1_max (ProcessorPwrWatts)

Still questionable whether power1_crit would be more appropriate...

> * power1_input (CurrPwrWatts)
> 
> Changes from v2:
>  - fix format strings
>  - removed paranoid checks for existense of functions 3 and 5
>  - changed return type of function f15h_power_is_internal_node0
>  - use power1_max instead of power1_cap
>  - use dev_warn instead of WARN_ON
>  - rebased against 2.6.39-rc2
>  - added Documentation/hwmon/f15h_power
> 
> Changes from v3:
>  - read static power information only once (during driver initialization)
>  - made use of attribute groups
>  - renamed f15h_power to fam15h_power
> 
> Signed-off-by: Andreas Herrmann <andreas.herrmann3@....com>
> ---
>  Documentation/hwmon/fam15h_power |   37 ++++++
>  drivers/hwmon/Kconfig            |   10 ++
>  drivers/hwmon/Makefile           |    1 +
>  drivers/hwmon/fam15h_power.c     |  229 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 277 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/hwmon/fam15h_power
>  create mode 100644 drivers/hwmon/fam15h_power.c
> 
> At this stage I consider the _max attribute as the right one for
> reporting ProcessorPwrWatts.
> 
> Hopefully I've addressed all your coments.
> Please apply.

It seems I have some more comments, but these are very small things you
should have no problem addressing quickly:

> diff --git a/Documentation/hwmon/fam15h_power b/Documentation/hwmon/fam15h_power
> new file mode 100644
> index 0000000..2f4d291
> --- /dev/null
> +++ b/Documentation/hwmon/fam15h_power
> @@ -0,0 +1,37 @@
> +Kernel driver fam15h_power
> +==========================
> +
> +Supported chips:
> +* AMD Family 15h Processors
> +
> +  Prefix: 'fam15h_power'
> +  Addresses scanned: PCI space
> +  Datasheets:
> +  BIOS and Kernel Developer's Guide (BKDG) For AMD Family 15h Processors
> +    (not yet published)
> +
> +Author: Andreas Herrmann <andreas.herrmann3@....com>
> +
> +Description
> +-----------
> +
> +This driver permits reading of registers providing power information
> +of AMD Family 15h processors.
> +
> +For AMD Family 15h processors the following power values can be
> +calculated using different processor northbridge function registers:
> +
> +* BasePwrWatts: Specifies in watts the maximum amount of power
> +  consumed by the processor for NB and logic external to the core.
> +* ProcessorPwrWatts: Specifies in watts the maximum amount of power
> +  the processor can support.
> +* CurrPwrWatts: Specifies in watts the current amount of power being
> +  consumed by the processor.
> +
> +This driver provides ProcessorPwrWatts and CurrPwrWatts:
> +* power1_max (ProcessorPwrWatts)
> +* power1_input (CurrPwrWatts)
> +
> +On multi-node processors the calculated value is for the entire
> +package and not for a single node. Thus the driver creates sysfs
> +attributes only for internal node0 of a multi-node processor.
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 060ef63..fb3e334 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -249,6 +249,16 @@ config SENSORS_K10TEMP
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called k10temp.
>  
> +config SENSORS_FAM15H_POWER
> +	tristate "AMD Family 15h processor power"
> +	depends on X86 && PCI
> +	help
> +	  If you say yes here you get support for processor power
> +	  information of your AMD family 15h CPU.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called fam15h_power.
> +
>  config SENSORS_ASB100
>  	tristate "Asus ASB100 Bach"
>  	depends on X86 && I2C && EXPERIMENTAL
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 967d0ea..236d3f9 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -49,6 +49,7 @@ obj-$(CONFIG_SENSORS_EMC2103)	+= emc2103.o
>  obj-$(CONFIG_SENSORS_F71805F)	+= f71805f.o
>  obj-$(CONFIG_SENSORS_F71882FG)	+= f71882fg.o
>  obj-$(CONFIG_SENSORS_F75375S)	+= f75375s.o
> +obj-$(CONFIG_SENSORS_FAM15H_POWER) += fam15h_power.o
>  obj-$(CONFIG_SENSORS_FSCHMD)	+= fschmd.o
>  obj-$(CONFIG_SENSORS_G760A)	+= g760a.o
>  obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
> diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
> new file mode 100644
> index 0000000..cb6eb99
> --- /dev/null
> +++ b/drivers/hwmon/fam15h_power.c
> @@ -0,0 +1,229 @@
> +/*
> + * fam15h_power.c - AMD Family 15h processor power monitoring
> + *
> + * Copyright (c) 2011 Advanced Micro Devices, Inc.
> + * Author: Andreas Herrmann <andreas.herrmann3@....com>
> + *
> + *
> + * This driver is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This driver 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 driver; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/bitops.h>
> +#include <asm/processor.h>
> +
> +MODULE_DESCRIPTION("AMD Family 15h CPU processor power monitor");
> +MODULE_AUTHOR("Andreas Herrmann <andreas.herrmann3@....com>");
> +MODULE_LICENSE("GPL");
> +
> +/* D18F3 */
> +#define REG_NORTHBRIDGE_CAP		0xe8
> +
> +/* D18F4 */
> +#define REG_PROCESSOR_TDP		0x1b8
> +
> +/* D18F5 */
> +#define REG_TDP_RUNNING_AVERAGE		0xe0
> +#define REG_TDP_LIMIT3			0xe8
> +
> +struct fam15h_power_data {
> +	struct device *hwmon_dev;
> +	unsigned int tdp_to_watt;
> +	unsigned int base_tdp;
> +	unsigned int processor_pwr_watts;

watt vs. watts is inconsistent, isn't it?

> +};
> +
> +static ssize_t show_power(struct device *dev,
> +			  struct device_attribute *attr, char *buf)
> +{
> +	u32 val, tdp_limit, running_avg_range;
> +	s32 running_avg_capture;
> +	u64 curr_pwr_watts;
> +	struct pci_dev *f4 = to_pci_dev(dev);
> +	struct fam15h_power_data *data = pci_get_drvdata(f4);

dev_get_drvdata(dev) would be more efficient.

> +
> +	pci_bus_read_config_dword(f4->bus, PCI_DEVFN(PCI_SLOT(f4->devfn), 5),
> +				  REG_TDP_RUNNING_AVERAGE, &val);
> +	running_avg_capture = (val >> 4) & 0x3fffff;
> +	running_avg_capture = sign_extend32(running_avg_capture, 22);
> +	running_avg_range = val & 0xf;
> +
> +	pci_bus_read_config_dword(f4->bus, PCI_DEVFN(PCI_SLOT(f4->devfn), 5),
> +				  REG_TDP_LIMIT3, &val);
> +
> +	tdp_limit = val >> 16;
> +	curr_pwr_watts = tdp_limit  + data->base_tdp -

Doubled space.

> +		(s32)(running_avg_capture >> (running_avg_range + 1));
> +	curr_pwr_watts *= data->tdp_to_watt;
> +
> +	/*
> +	 * Convert to microWatt
> +	 *
> +	 * power is in Watt provided as fixed point integer with
> +	 * scaling factor 1/(2^16).  For conversion we use
> +	 * (10^6)/(2^16) = 15625/(2^10)
> +	 */
> +	curr_pwr_watts = (curr_pwr_watts * 15625) >> 10;
> +	return sprintf(buf, "%u\n", (unsigned int) curr_pwr_watts);
> +}
> +static DEVICE_ATTR(power1_input, S_IRUGO, show_power, NULL);
> +
> +static ssize_t show_power_max(struct device *dev,
> +			     struct device_attribute *attr, char *buf)
> +{
> +	struct pci_dev *f4 = to_pci_dev(dev);
> +	struct fam15h_power_data *data = pci_get_drvdata(f4);

dev_get_drvdata(dev) would be more efficient (you don't even need f4
then.)

> +	return sprintf(buf, "%u\n", data->processor_pwr_watts);
> +}
> +static DEVICE_ATTR(power1_max, S_IRUGO, show_power_max, NULL);
> +
> +static ssize_t show_name(struct device *dev,
> +			 struct device_attribute *attr, char *buf)
> +{
> +	return sprintf(buf, "fam15h_power\n");
> +}
> +static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
> +
> +static struct attribute *fam15h_power_attrs[] = {
> +	&dev_attr_power1_input.attr,
> +	&dev_attr_power1_max.attr,
> +	&dev_attr_name.attr,
> +	NULL
> +};
> +
> +static struct attribute_group fam15h_power_attr_group = {

Can be made const.

> +	.attrs	= fam15h_power_attrs,
> +};
> +
> +static bool __devinit fam15h_power_is_internal_node0(struct pci_dev *f4)
> +{
> +	u32 val;
> +
> +	pci_bus_read_config_dword(f4->bus, PCI_DEVFN(PCI_SLOT(f4->devfn), 3),
> +				  REG_NORTHBRIDGE_CAP, &val);
> +	if ((val & BIT(29)) && ((val >> 30) & 3))
> +		return false;
> +
> +	return true;
> +}
> +
> +static void __devinit fam15h_power_init_data(struct pci_dev *f4,
> +					     struct fam15h_power_data *data)
> +{
> +	u32 val;
> +	u64 tmp;
> +
> +	pci_read_config_dword(f4, REG_PROCESSOR_TDP, &val);
> +	data->base_tdp = val >> 16;
> +	tmp = val & 0xffff;
> +
> +	pci_bus_read_config_dword(f4->bus, PCI_DEVFN(PCI_SLOT(f4->devfn), 5),
> +				  REG_TDP_LIMIT3, &val);
> +
> +	data->tdp_to_watt = ((val & 0x3ff) << 6) | ((val >> 10) & 0x3f);
> +	tmp *= data->tdp_to_watt;
> +
> +	/* result not allowed to be >= 256W */
> +	if ((tmp>>16) >= 256)

Please add spaces around ">>" for consistency.

> +		dev_warn(&f4->dev, "Bogus value for ProcessorPwrWatts "
> +			 "(processor_pwr_watts>=%u)\n",
> +			 (unsigned int) (tmp >> 16));
> +
> +	/* convert to microWatt */
> +	data->processor_pwr_watts = (tmp * 15625) >> 10;
> +}
> +
> +static int __devinit fam15h_power_probe(struct pci_dev *pdev,
> +					const struct pci_device_id *id)
> +{
> +	struct fam15h_power_data *data;
> +	struct device *dev;
> +	int err;
> +
> +	if (!fam15h_power_is_internal_node0(pdev)) {
> +		err = -ENODEV;
> +		goto exit;
> +	}
> +
> +	data = kzalloc(sizeof(struct fam15h_power_data), GFP_KERNEL);
> +	if (!data) {
> +		err = -ENOMEM;
> +		goto exit;
> +	}
> +	fam15h_power_init_data(pdev, data);
> +
> +	dev = &pdev->dev;
> +	err = sysfs_create_group(&dev->kobj, &fam15h_power_attr_group);
> +	if (err)
> +		goto exit_free_data;
> +
> +	data->hwmon_dev = hwmon_device_register(&pdev->dev);
> +	if (IS_ERR(data->hwmon_dev)) {
> +		err = PTR_ERR(data->hwmon_dev);
> +		goto exit_remove_group;
> +	}
> +	pci_set_drvdata(pdev, data);

This is racy. pci_set_drvdata() should be called before creating the
sysfs attributes, because the sysfs callbacks need it.

> +
> +	return 0;
> +
> +exit_remove_group:
> +	sysfs_remove_group(&dev->kobj, &fam15h_power_attr_group);
> +exit_free_data:
> +	kfree(data);
> +exit:
> +	return err;
> +}
> +
> +static void __devexit fam15h_power_remove(struct pci_dev *pdev)
> +{
> +	struct device *dev;
> +	struct fam15h_power_data *data = pci_get_drvdata(pdev);
> +
> +	dev = &pdev->dev;
> +	hwmon_device_unregister(data->hwmon_dev);
> +	sysfs_remove_group(&dev->kobj, &fam15h_power_attr_group);
> +	pci_set_drvdata(pdev, NULL);
> +	kfree(data);
> +}
> +
> +static DEFINE_PCI_DEVICE_TABLE(fam15h_power_id_table) = {
> +	{ PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(pci, fam15h_power_id_table);
> +
> +static struct pci_driver fam15h_power_driver = {
> +	.name = "fam15h_power",
> +	.id_table = fam15h_power_id_table,
> +	.probe = fam15h_power_probe,
> +	.remove = __devexit_p(fam15h_power_remove),
> +};
> +
> +static int __init fam15h_power_init(void)
> +{
> +	return pci_register_driver(&fam15h_power_driver);
> +}
> +
> +static void __exit fam15h_power_exit(void)
> +{
> +	pci_unregister_driver(&fam15h_power_driver);
> +}
> +
> +module_init(fam15h_power_init)
> +module_exit(fam15h_power_exit)

Thanks,
-- 
Jean Delvare
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