Re: [PATCH 10/11] hwmon: Add Altera A10-SR power supply alarms

From: Thor Thayer <tthayer@opensource.altera.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: <lee.jones@linaro.org>, <linus.walleij@linaro.org>,
	<gnurou@gmail.com>, <jdelvare@suse.com>, <robh+dt@kernel.org>,
	<pawel.moll@arm.com>, <mark.rutland@arm.com>,
	<ijc+devicetree@hellion.org.uk>, <dinguyen@opensource.altera.com>,
	<linux-gpio@vger.kernel.org>, <linux-hwmon@vger.kernel.org>,
	<devicetree@vger.kernel.org>
Subject: Re: [PATCH 10/11] hwmon: Add Altera A10-SR power supply alarms
Date: Mon, 25 Apr 2016 09:41:38 -0500	[thread overview]
Message-ID: <571E2CA2.3000900@opensource.altera.com> (raw)
In-Reply-To: <20160422222402.GA22294@roeck-us.net>

On 04/22/2016 05:24 PM, Guenter Roeck wrote:
> On Fri, Apr 22, 2016 at 10:33:38AM -0500, tthayer@opensource.altera.com wrote:
>> From: Thor Thayer <tthayer@opensource.altera.com>
>>
>> This patch adds the power supply alarms of the hwmon framework
>> to the Arria10 System Resource chip.
>>
>> Signed-off-by: Thor Thayer <tthayer@opensource.altera.com>
>> ---
>
> Please read and follow Documentation/hwmon/sysfs-interface
> as well as Documentation/hwmon/submitting-patches. At the very least,
> you are expected to document your driver, and you are expected to
> use standard attribute names.
>

OK. I misunderstood. The standard attribute names would be 
power[1-*]_alarm and the binding documentation the a10sr-hwmon portion 
for MFD doesn't cover this.

>>   drivers/hwmon/Kconfig              |    9 ++
>>   drivers/hwmon/Makefile             |    1 +
>>   drivers/hwmon/altera-a10sr-hwmon.c |  215 ++++++++++++++++++++++++++++++++++++
>>   3 files changed, 225 insertions(+)
>>   create mode 100644 drivers/hwmon/altera-a10sr-hwmon.c
>>
>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
>> index ff94007..af08846 100644
>> --- a/drivers/hwmon/Kconfig
>> +++ b/drivers/hwmon/Kconfig
>> @@ -248,6 +248,15 @@ config SENSORS_ADT7475
>>   	  This driver can also be build as a module.  If so, the module
>>   	  will be called adt7475.
>>
>> +config SENSORS_ALTERA_A10SR
>> +	bool "Altera Arria10 System Status"
>> +	depends on MFD_ALTERA_A10SR
>> +	help
>> +	  If you say yes here you get support for the power ready status
>> +	  for the Arria10's external power supplies on the Arria10 DevKit.
>> +	  These values are read over the SPI bus from the Arria10 System
>> +	  Resource chip.
>> +
>>   config SENSORS_ASC7621
>>   	tristate "Andigilog aSC7621"
>>   	depends on I2C
>> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
>> index 2ef5b7c..17d72a7 100644
>> --- a/drivers/hwmon/Makefile
>> +++ b/drivers/hwmon/Makefile
>> @@ -43,6 +43,7 @@ obj-$(CONFIG_SENSORS_ADT7411)	+= adt7411.o
>>   obj-$(CONFIG_SENSORS_ADT7462)	+= adt7462.o
>>   obj-$(CONFIG_SENSORS_ADT7470)	+= adt7470.o
>>   obj-$(CONFIG_SENSORS_ADT7475)	+= adt7475.o
>> +obj-$(CONFIG_SENSORS_ALTERA_A10SR) += altera-a10sr-hwmon.o
>>   obj-$(CONFIG_SENSORS_APPLESMC)	+= applesmc.o
>>   obj-$(CONFIG_SENSORS_ARM_SCPI)	+= scpi-hwmon.o
>>   obj-$(CONFIG_SENSORS_ASC7621)	+= asc7621.o
>> diff --git a/drivers/hwmon/altera-a10sr-hwmon.c b/drivers/hwmon/altera-a10sr-hwmon.c
>> new file mode 100644
>> index 0000000..1eecc6b
>> --- /dev/null
>> +++ b/drivers/hwmon/altera-a10sr-hwmon.c
>> @@ -0,0 +1,215 @@
>> +/*
>> + *  Copyright Altera Corporation (C) 2014-2016. All Rights Reserved
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope 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.  If not, see <http://www.gnu.org/licenses/>.
>> + *
>> + * HW Monitor driver for  Altera Arria10 MAX5 System Resource Chip
>> + * Adapted from DA9052
>> + */
>> +
>> +#include <linux/hwmon.h>
>> +#include <linux/hwmon-sysfs.h>
>> +#include <linux/mfd/altera-a10sr.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>
> Please list include files in alphabetic order.
>

OK. I thought this was in alphabetical order. I'll update this after 
figuring out where I was wrong.

>> +
>> +#define ALTR_A10SR_1V0_BIT_POS          ALTR_A10SR_PG1_1V0_SHIFT
>> +#define ALTR_A10SR_0V95_BIT_POS         ALTR_A10SR_PG1_0V95_SHIFT
>> +#define ALTR_A10SR_0V9_BIT_POS          ALTR_A10SR_PG1_0V9_SHIFT
>> +#define ALTR_A10SR_10V_BIT_POS          ALTR_A10SR_PG1_10V_SHIFT
>> +#define ALTR_A10SR_5V0_BIT_POS          ALTR_A10SR_PG1_5V0_SHIFT
>> +#define ALTR_A10SR_3V3_BIT_POS          ALTR_A10SR_PG1_3V3_SHIFT
>> +#define ALTR_A10SR_2V5_BIT_POS          ALTR_A10SR_PG1_2V5_SHIFT
>> +#define ALTR_A10SR_1V8_BIT_POS          ALTR_A10SR_PG1_1V8_SHIFT
>> +#define ALTR_A10SR_OP_FLAG_BIT_POS      ALTR_A10SR_PG1_OP_FLAG_SHIFT
>> +/* 2nd register needs an offset of 8 to get to 2nd register */
>> +#define ALTR_A10SR_FBC2MP_BIT_POS       (8 + ALTR_A10SR_PG2_FBC2MP_SHIFT)
>> +#define ALTR_A10SR_FAC2MP_BIT_POS       (8 + ALTR_A10SR_PG2_FAC2MP_SHIFT)
>> +#define ALTR_A10SR_FMCBVADJ_BIT_POS     (8 + ALTR_A10SR_PG2_FMCBVADJ_SHIFT)
>> +#define ALTR_A10SR_FMCAVADJ_BIT_POS     (8 + ALTR_A10SR_PG2_FMCAVADJ_SHIFT)
>> +#define ALTR_A10SR_HL_VDDQ_BIT_POS      (8 + ALTR_A10SR_PG2_HL_VDDQ_SHIFT)
>> +#define ALTR_A10SR_HL_VDD_BIT_POS       (8 + ALTR_A10SR_PG2_HL_VDD_SHIFT)
>> +#define ALTR_A10SR_HL_HPS_BIT_POS       (8 + ALTR_A10SR_PG2_HL_HPS_SHIFT)
>> +#define ALTR_A10SR_HPS_BIT_POS          (8 + ALTR_A10SR_PG2_HPS_SHIFT)
>> +/* 3rd register needs an offset of 16 to get to 3rd register */
>> +#define ALTR_A10SR_10V_FAIL_BIT_POS     (16 + ALTR_A10SR_PG3_10V_FAIL_SHIFT)
>> +#define ALTR_A10SR_FAM2C_BIT_POS        (16 + ALTR_A10SR_PG3_FAM2C_SHIFT)
>> +
>> +/**
>> + * struct altr_a10sr_hwmon - Altera Max5 HWMON device private data structure
>> + * @device: hwmon class.
>> + * @regmap: the regmap from the parent device.
>> + */
>> +struct altr_a10sr_hwmon {
>> +	struct device		*class_device;
>> +	struct regmap		*regmap;
>> +};
>> +
>> +static ssize_t altr_a10sr_read_status(struct device *dev,
>> +				      struct device_attribute *devattr,
>> +				      char *buf)
>> +{
>> +	struct altr_a10sr_hwmon *hwmon = dev_get_drvdata(dev);
>> +	int val, ret, index = to_sensor_dev_attr(devattr)->index;
>> +	int mask = ALTR_A10SR_REG_BIT_MASK(index);
>> +	unsigned char reg = ALTR_A10SR_PWR_GOOD1_REG +
>> +			    ALTR_A10SR_REG_OFFSET(index);
>> +
>> +	ret = regmap_read(hwmon->regmap, reg, &val);
>
> The pointer parameter to regmap_read() is unsigned int. I would suggest
> to use the same variable type to avoid surprises.
>
Understood. Thanks.

>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return sprintf(buf, "%d\n", !!(~val & mask));
>
> Are alarms all active low ?
>
Yes, They are actually Power Good signals (Good = high) so I'm inverting.

>> +}
>> +
>> +static ssize_t altr_a10sr_hwmon_show_name(struct device *dev,
>> +					  struct device_attribute *devattr,
>> +					  char *buf)
>> +{
>> +	return sprintf(buf, "altr_a10sr\n");
>> +}
>> +
>> +/* First Power Good Register Bits */
>> +static SENSOR_DEVICE_ATTR(1v0_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_1V0_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(0v95_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_0V95_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(0v9_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_0V9_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(5v0_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_5V0_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(3v3_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_3V3_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(2v5_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_2V5_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(1v8_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_1V8_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(opflag_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_OP_FLAG_BIT_POS);
>> +/* Second Power Good Register Bits */
>> +static SENSOR_DEVICE_ATTR(fbc2mp_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_FBC2MP_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(fac2mp_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_FAC2MP_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(fmcbvadj_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_FMCBVADJ_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(fmcavadj_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_FMCAVADJ_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(hl_vddq_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_HL_VDDQ_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(hl_vdd_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_HL_VDD_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(hlhps_vdd_alarm, S_IRUGO, altr_a10sr_read_status,
>> +			  NULL, ALTR_A10SR_HL_HPS_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(hps_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_HPS_BIT_POS);
>> +/* Third Power Good Register Bits */
>> +static SENSOR_DEVICE_ATTR(10v_alarm, S_IRUGO, altr_a10sr_read_status,
>> +			  NULL, ALTR_A10SR_10V_FAIL_BIT_POS);
>> +static SENSOR_DEVICE_ATTR(fam2c_alarm, S_IRUGO, altr_a10sr_read_status, NULL,
>> +			  ALTR_A10SR_FAM2C_BIT_POS);
>> +
>> +static DEVICE_ATTR(name, S_IRUGO, altr_a10sr_hwmon_show_name, NULL);
>> +
>> +static struct attribute *altr_a10sr_attr[] = {
>> +	&dev_attr_name.attr,
>> +	/* First Power Good Register */
>> +	&sensor_dev_attr_opflag_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_1v8_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_2v5_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_1v0_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_3v3_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_5v0_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_0v9_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_0v95_alarm.dev_attr.attr,
>> +	/* Second Power Good Register */
>> +	&sensor_dev_attr_hps_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_hlhps_vdd_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_hl_vdd_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_hl_vddq_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_fmcavadj_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_fmcbvadj_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_fac2mp_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_fbc2mp_alarm.dev_attr.attr,
>> +	/* Third Power Good Register */
>> +	&sensor_dev_attr_10v_alarm.dev_attr.attr,
>> +	&sensor_dev_attr_fam2c_alarm.dev_attr.attr,
>
> Ultimately, this doesn't really make much sense, even with standard attribute
> names. The ABI assumes that _input attrributes exist. Not sure if that could
> be solved by providing 'dummy' unreadable input attributes (permission 0);
> that might be worth a try. If you want to attach names to the attributes,
> you would need to provide label attributes. Specifically you would need
>
> 	inX_input (with permission 0) - not sure if that is even possible
> 	inX_alarm
> 	inX_label
>
Hmm. OK. I may need to rethink this.

>> +	NULL
>> +};
>> +
>> +static const struct attribute_group altr_a10sr_attr_group = {
>> +	.attrs = altr_a10sr_attr
>> +};
>> +
>> +static int altr_a10sr_hwmon_probe(struct platform_device *pdev)
>> +{
>> +	struct altr_a10sr_hwmon *hwmon;
>> +	int ret;
>> +	struct altr_a10sr *a10sr = dev_get_drvdata(pdev->dev.parent);
>> +
>
> What if someone creates a stand-alone devicetree property for this driver,
> and there is no parent (or parent driver data) ?
>
I agree if this was a commercially available part. However, this is a 
specific driver for a programmable logic device (PLD) that will always 
be part of an MFD parent. The PLD only supports the Altera Development Kit.

>> +	hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
>> +	if (!hwmon)
>> +		return -ENOMEM;
>> +
>> +	hwmon->regmap = a10sr->regmap;
>> +
>> +	platform_set_drvdata(pdev, hwmon);
>> +
>> +	ret = sysfs_create_group(&pdev->dev.kobj, &altr_a10sr_attr_group);
>> +	if (ret)
>> +		goto err_mem;
>> +
>> +	hwmon->class_device = hwmon_device_register(&pdev->dev);
>> +	if (IS_ERR(hwmon->class_device)) {
>> +		ret = PTR_ERR(hwmon->class_device);
>> +		goto err_sysfs;
>> +	}
>
> Please use devm_hwmon_device_register_with_groups().
>
Understood. Thanks.

Thanks for reviewing.

>> +
>> +	return 0;
>> +
>> +err_sysfs:
>> +	sysfs_remove_group(&pdev->dev.kobj, &altr_a10sr_attr_group);
>> +err_mem:
>> +	return ret;
>> +}
>> +
>> +static int altr_a10sr_hwmon_remove(struct platform_device *pdev)
>> +{
>> +	struct altr_a10sr_hwmon *hwmon = platform_get_drvdata(pdev);
>> +
>> +	hwmon_device_unregister(hwmon->class_device);
>> +	sysfs_remove_group(&pdev->dev.kobj, &altr_a10sr_attr_group);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id altr_a10sr_hwmon_of_match[] = {
>> +	{ .compatible = "altr,a10sr-hwmon" },
>> +	{ },
>> +};
>> +MODULE_DEVICE_TABLE(of, altr_a10sr_hwmon_of_match);
>> +
>> +static struct platform_driver altr_a10sr_hwmon_driver = {
>> +	.probe = altr_a10sr_hwmon_probe,
>> +	.remove = altr_a10sr_hwmon_remove,
>> +	.driver = {
>> +		.name = "altr_a10sr_hwmon",
>> +		.of_match_table = of_match_ptr(altr_a10sr_hwmon_of_match),
>> +	},
>> +};
>> +
>> +module_platform_driver(altr_a10sr_hwmon_driver);
>> +
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_AUTHOR("Thor Thayer <tthayer@opensource.altera.com>");
>> +MODULE_DESCRIPTION("HW Monitor driver for Altera Arria10 System Resource Chip");
>> --
>> 1.7.9.5
>>