2011-06-28 14:27:27

by Ashish Jangam

[permalink] [raw]
Subject: [PATCH 6/11] HWMON: DA9052 hwmon driver v1

The DA9052 PMIC provides an Analogue to Digital Converter with 10 bits
resolution and 10 channels.

This patch montiors the DA9052 PMIC's ADC channels mostly for battery parameters
like battery temperature, junction temperature, battery current etc.

Signed-off-by: David Dajun Chen <[email protected]>
Signed-off-by: Ashish Jangam <[email protected]>
---
Documentation/hwmon/da9052 | 58 ++++++++
drivers/hwmon/Kconfig | 10 ++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/da9052-hwmon.c | 332 ++++++++++++++++++++++++++++++++++++++++++
4 files changed, 401 insertions(+), 0 deletions(-)
create mode 100755 Documentation/hwmon/da9052
create mode 100755 drivers/hwmon/da9052-hwmon.c
diff --git a/Documentation/hwmon/da9052 b/Documentation/hwmon/da9052
new file mode 100755
index 0000000..0b7930f
--- /dev/null
+++ b/Documentation/hwmon/da9052
@@ -0,0 +1,58 @@
+Kernel driver da9052-hwmon
+==========================
+
+Supported chips:
+ * Dialog Semiconductors DA9052 PMICs
+ Prefix: 'da9052'
+ Datasheet: Kindly visit http://www.dialog-semiconductor.com and request for the
+ official datasheet.
+
+Authors: David Dajun Chen <[email protected]>
+
+Description
+-----------
+
+The DA9052 provides an Analogue to Digital Converter (ADC) with 10 bits
+resolution and track and hold circuitry combined with an analogue input
+multiplexer. The analogue input multiplexer will allow conversion of up to 10
+different inputs. The track and hold circuit ensures stable input voltages at
+the input of the ADC during the conversion.
+
+The ADC is used to measure the following inputs:
+Channel 0: VDDOUT - measurement of the system voltage
+Channel 1: ICH - internal battery charger current measurement
+Channel 2: TBAT - output from the battery NTC
+Channel 3: VBAT - measurement of the battery voltage
+Channel 4: ADC_IN4 - high impedance input (0 - 2.5V)
+Channel 5: ADC_IN5 - high impedance input (0 - 2.5V)
+Channel 6: ADC_IN6 - high impedance input (0 - 2.5V)
+Channel 7: XY - TSI interface to measure the X and Y voltage of the touch
+screen resistive potentiometers
+Channel 8: Internal Tjunc. - sense (internal temp. sensor)
+Channel 9: VBBAT - measurement of the backup battery voltage
+
+By using sysfs attributes we can measure the system voltage VDDOUT, the battery
+charging current ICH, battery temperature TBAT, battery junction temperature
+TJUNC, battery voltage VBAT and the back up battery voltage VBBAT.
+
+Voltage Monitoring
+------------------
+
+Voltages are sampled by a 10 bit ADC. Voltages in millivolts are 1.465
+times the ADC value.
+
+Temperature Monitoring
+----------------------
+
+Temperatures are sampled by a 10 bit ADC. Junction and battery temperatures
+are monitored by the ADC channels.
+
+The junction temperature is calculated:
+ Degrees celsius = 1.708 * (TJUNC_RES - T_OFFSET) - 108.8
+The junction temperature attribute is supported by the driver.
+
+The battery temperature is calculated:
+ Degree Celcius = 1 / (t1 + 1/298)- 273
+where t1 = (1/B)* ln(( ADCval * 2.5)/(R25*ITBAT*255))
+Default values of R25, B, ITBAT are 10e3, 3380 and 50e-6 respectively.
+
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 3236a45..da5ff6d 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -303,6 +303,16 @@ config SENSORS_DS1621
This driver can also be built as a module. If so, the module
will be called ds1621.

+config SENSORS_DA9052_ADC
+ tristate "Dialog DA9052 HWMON"
+ depends on PMIC_DA9052
+ help
+ Say y here to support the ADC found on
+ Dialog Semiconductor DA9052 PMIC.
+
+ This driver can also be built as module. If so, the module
+ will be called da9052-hwmon.
+
config SENSORS_I5K_AMB
tristate "FB-DIMM AMB temperature sensor on Intel 5000 series chipsets"
depends on PCI && EXPERIMENTAL
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index f7c0c28..88b81ca 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_SENSORS_ASC7621) += asc7621.o
obj-$(CONFIG_SENSORS_ATXP1) += atxp1.o
obj-$(CONFIG_SENSORS_CORETEMP) += coretemp.o
obj-$(CONFIG_SENSORS_PKGTEMP) += pkgtemp.o
+obj-$(CONFIG_SENSORS_DA9052_ADC) += da9052-hwmon.o
obj-$(CONFIG_SENSORS_DME1737) += dme1737.o
obj-$(CONFIG_SENSORS_DS620) += ds620.o
obj-$(CONFIG_SENSORS_DS1621) += ds1621.o
diff --git a/drivers/hwmon/da9052-hwmon.c b/drivers/hwmon/da9052-hwmon.c
new file mode 100755
index 0000000..e470e9d
--- /dev/null
+++ b/drivers/hwmon/da9052-hwmon.c
@@ -0,0 +1,332 @@
+/*
+ * HWMON Driver for Dialog DA9052
+ *
+ * Copyright(c) 2011 Dialog Semiconductor Ltd.
+ *
+ * Author: David Dajun Chen <[email protected]>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/da9052/da9052.h>
+#include <linux/mfd/da9052/reg.h>
+
+struct da9052_hwmon {
+ struct da9052 *da9052;
+ struct device *class_device;
+ struct mutex hwmon_lock;
+};
+
+static const char * const input_names[] = {
+ [DA9052_ADC_VDDOUT] = "VDDOUT",
+ [DA9052_ADC_ICH] = "CHARGING CURRENT",
+ [DA9052_ADC_TBAT] = "BATTERY TEMP",
+ [DA9052_ADC_VBAT] = "BATTERY VOLTAGE",
+ [DA9052_ADC_IN4] = "ADC IN4",
+ [DA9052_ADC_IN5] = "ADC IN5",
+ [DA9052_ADC_IN6] = "ADC IN6",
+ [DA9052_ADC_TJUNC] = "BATTERY JUNCTION TEMP",
+ [DA9052_ADC_VBBAT] = "BACK-UP BATTERY VOLTAGE",
+};
+
+static int da9052_enable_vddout_channel(struct da9052 *da9052)
+{
+ int ret;
+
+ ret = da9052_reg_read(da9052, DA9052_ADC_CONT_REG);
+ if (ret < 0)
+ return ret;
+
+ ret |= DA9052_ADCCONT_AUTOVDDEN;
+
+ return da9052_reg_write(da9052, DA9052_ADC_CONT_REG, ret);
+}
+
+static int da9052_disable_vddout_channel(struct da9052 *da9052)
+{
+ int ret;
+
+ ret = da9052_reg_read(da9052, DA9052_ADC_CONT_REG);
+ if (ret < 0)
+ return ret;
+
+ ret &= ~DA9052_ADCCONT_AUTOVDDEN;
+
+ return da9052_reg_write(da9052, DA9052_ADC_CONT_REG, ret);
+}
+
+static ssize_t da9052_read_vddout(struct device *dev,
+ struct device_attribute *devattr, char *buf)
+{
+ struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+ int ret, vdd = -1;
+
+ mutex_lock(&hwmon->hwmon_lock);
+
+ ret = da9052_enable_vddout_channel(hwmon->da9052);
+ if (ret < 0)
+ goto hwmon_err;
+
+ ret = da9052_reg_read(hwmon->da9052, DA9052_VDD_RES_REG);
+ if (ret < 0)
+ pr_err("failed to read VDD_RES_REG\n");
+ else
+ vdd = ret;
+
+ ret = da9052_disable_vddout_channel(hwmon->da9052);
+ if (ret < 0)
+ goto hwmon_err;
+
+ if (vdd >= 0) {
+ mutex_unlock(&hwmon->hwmon_lock);
+ return sprintf(buf, "%d\n", vdd);
+ }
+
+hwmon_err:
+ mutex_unlock(&hwmon->hwmon_lock);
+ return ret;
+}
+
+static ssize_t da9052_read_ich(struct device *dev,
+ struct device_attribute *devattr, char *buf)
+{
+ struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+ int ret;
+
+ ret = da9052_reg_read(hwmon->da9052, DA9052_ICHG_AV_REG);
+ if (ret < 0)
+ return ret;
+
+ /* Equivalent to 3.9mA/bit in register ICHG_AV */
+ return sprintf(buf, "%d\n", DIV_ROUND_CLOSEST(ret * 39, 10));
+}
+
+static ssize_t da9052_read_tbat(struct device *dev,
+ struct device_attribute *devattr, char *buf)
+{
+ struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+
+ return sprintf(buf, "%d\n", da9052_adc_temperature_read(hwmon->da9052));
+}
+
+static ssize_t da9052_read_vbat(struct device *dev,
+ struct device_attribute *devattr, char *buf)
+{
+ struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+ int ret;
+
+ ret = da9052_adc_manual_read(hwmon->da9052, DA9052_ADC_VBAT);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n", ret);
+}
+
+static ssize_t da9052_read_misc_channel(struct device *dev,
+ struct device_attribute *devattr,
+ char *buf)
+{
+ struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+ int channel = to_sensor_dev_attr(devattr)->index;
+ int ret;
+
+ ret = da9052_adc_manual_read(hwmon->da9052, channel);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n", ret);
+}
+
+static ssize_t da9052_read_tjunc(struct device *dev,
+ struct device_attribute *devattr, char *buf)
+{
+ struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+ int tjunc, toffset;
+
+ tjunc = da9052_reg_read(hwmon->da9052, DA9052_TJUNC_RES_REG);
+ if (tjunc < 0)
+ return tjunc;
+
+ toffset = da9052_reg_read(hwmon->da9052, DA9052_T_OFFSET_REG);
+ if (toffset < 0)
+ return toffset;
+
+ /* Degrees celsius = 1.708 * (TJUNC_RES - T_OFFSET) - 108.8 */
+ return sprintf(buf, "%d\n", 1708 * (tjunc - toffset) - 108800);
+}
+
+static ssize_t da9052_read_vbbat(struct device *dev,
+ struct device_attribute *devattr, char *buf)
+{
+ struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+ int ret;
+
+ ret = da9052_adc_manual_read(hwmon->da9052, DA9052_ADC_VBBAT);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n", ret);
+}
+
+static ssize_t da9052_hwmon_show_name(struct device *dev,
+ struct device_attribute *devattr,
+ char *buf)
+{
+ return sprintf(buf, "da9052-hwmon\n");
+}
+
+static ssize_t show_label(struct device *dev,
+ struct device_attribute *devattr, char *buf)
+{
+ return sprintf(buf, "%s\n",
+ input_names[to_sensor_dev_attr(devattr)->index]);
+}
+
+static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, da9052_read_vddout, NULL,
+ DA9052_ADC_ICH);
+static SENSOR_DEVICE_ATTR(in0_label, S_IRUGO, show_label, NULL,
+ DA9052_ADC_ICH);
+static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, da9052_read_vbat, NULL,
+ DA9052_ADC_VBAT);
+static SENSOR_DEVICE_ATTR(in3_label, S_IRUGO, show_label, NULL,
+ DA9052_ADC_VBAT);
+static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, da9052_read_misc_channel, NULL,
+ DA9052_ADC_IN4);
+static SENSOR_DEVICE_ATTR(in4_label, S_IRUGO, show_label, NULL,
+ DA9052_ADC_IN4);
+static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, da9052_read_misc_channel, NULL,
+ DA9052_ADC_IN5);
+static SENSOR_DEVICE_ATTR(in5_label, S_IRUGO, show_label, NULL,
+ DA9052_ADC_IN5);
+static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, da9052_read_misc_channel, NULL,
+ DA9052_ADC_IN6);
+static SENSOR_DEVICE_ATTR(in6_label, S_IRUGO, show_label, NULL,
+ DA9052_ADC_IN6);
+static SENSOR_DEVICE_ATTR(in9_input, S_IRUGO, da9052_read_vbbat, NULL,
+ DA9052_ADC_VBBAT);
+static SENSOR_DEVICE_ATTR(in9_label, S_IRUGO, show_label, NULL,
+ DA9052_ADC_VBBAT);
+
+static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, da9052_read_ich, NULL,
+ DA9052_ADC_ICH);
+static SENSOR_DEVICE_ATTR(curr1_label, S_IRUGO, show_label, NULL,
+ DA9052_ADC_ICH);
+
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, da9052_read_tbat, NULL,
+ DA9052_ADC_TBAT);
+static SENSOR_DEVICE_ATTR(temp1_label, S_IRUGO, show_label, NULL,
+ DA9052_ADC_TBAT);
+static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, da9052_read_tjunc, NULL,
+ DA9052_ADC_TJUNC);
+static SENSOR_DEVICE_ATTR(temp2_label, S_IRUGO, show_label, NULL,
+ DA9052_ADC_TJUNC);
+
+static DEVICE_ATTR(name, S_IRUGO, da9052_hwmon_show_name, NULL);
+
+static struct attribute *da9052_attr[] = {
+ &dev_attr_name.attr,
+ &sensor_dev_attr_in0_input.dev_attr.attr,
+ &sensor_dev_attr_in0_label.dev_attr.attr,
+ &sensor_dev_attr_in3_input.dev_attr.attr,
+ &sensor_dev_attr_in3_label.dev_attr.attr,
+ &sensor_dev_attr_in4_input.dev_attr.attr,
+ &sensor_dev_attr_in4_label.dev_attr.attr,
+ &sensor_dev_attr_in5_input.dev_attr.attr,
+ &sensor_dev_attr_in5_label.dev_attr.attr,
+ &sensor_dev_attr_in6_input.dev_attr.attr,
+ &sensor_dev_attr_in6_label.dev_attr.attr,
+ &sensor_dev_attr_in9_input.dev_attr.attr,
+ &sensor_dev_attr_in9_label.dev_attr.attr,
+ &sensor_dev_attr_curr1_input.dev_attr.attr,
+ &sensor_dev_attr_curr1_label.dev_attr.attr,
+ &sensor_dev_attr_temp1_input.dev_attr.attr,
+ &sensor_dev_attr_temp1_label.dev_attr.attr,
+ &sensor_dev_attr_temp2_input.dev_attr.attr,
+ &sensor_dev_attr_temp2_label.dev_attr.attr,
+ NULL
+};
+
+static const struct attribute_group da9052_attr_group = {.attrs = da9052_attr};
+
+static int __init da9052_hwmon_probe(struct platform_device *pdev)
+{
+ struct da9052_hwmon *hwmon;
+ int ret;
+
+ hwmon = kzalloc(sizeof(struct da9052_hwmon), GFP_KERNEL);
+ if (!hwmon)
+ return -ENOMEM;
+
+ mutex_init(&hwmon->hwmon_lock);
+ hwmon->da9052 = dev_get_drvdata(pdev->dev.parent);
+
+ platform_set_drvdata(pdev, hwmon);
+
+ ret = sysfs_create_group(&pdev->dev.kobj, &da9052_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;
+ }
+
+ return 0;
+
+err_sysfs:
+ sysfs_remove_group(&pdev->dev.kobj, &da9052_attr_group);
+err_mem:
+ kfree(hwmon);
+ return ret;
+}
+
+static int __devexit da9052_hwmon_remove(struct platform_device *pdev)
+{
+ struct da9052_hwmon *hwmon = platform_get_drvdata(pdev);
+
+ hwmon_device_unregister(hwmon->class_device);
+ sysfs_remove_group(&pdev->dev.kobj, &da9052_attr_group);
+ kfree(hwmon);
+
+ return 0;
+}
+
+static struct platform_driver da9052_hwmon_driver = {
+ .probe = da9052_hwmon_probe,
+ .remove = __devexit_p(da9052_hwmon_remove),
+ .driver = {
+ .name = "da9052-hwmon",
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init da9052_hwmon_init(void)
+{
+ return platform_driver_register(&da9052_hwmon_driver);
+}
+module_init(da9052_hwmon_init);
+
+static void __exit da9052_hwmon_exit(void)
+{
+ platform_driver_unregister(&da9052_hwmon_driver);
+}
+module_exit(da9052_hwmon_exit);
+
+MODULE_AUTHOR("David Dajun Chen <[email protected]>");
+MODULE_DESCRIPTION("DA9052 HWMON driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:da9052-hwmon");


2011-06-28 17:37:55

by Guenter Roeck

[permalink] [raw]
Subject: Re: [PATCH 6/11] HWMON: DA9052 hwmon driver v1

On Tue, 2011-06-28 at 10:24 -0400, ashishj3 wrote:
> The DA9052 PMIC provides an Analogue to Digital Converter with 10 bits
> resolution and 10 channels.
>
> This patch montiors the DA9052 PMIC's ADC channels mostly for battery parameters
> like battery temperature, junction temperature, battery current etc.
>
> Signed-off-by: David Dajun Chen <[email protected]>
> Signed-off-by: Ashish Jangam <[email protected]>

[ ... ]

> +static ssize_t da9052_read_vddout(struct device *dev,
> + struct device_attribute *devattr, char *buf)
> +{
> + struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
> + int ret, vdd = -1;
> +
> + mutex_lock(&hwmon->hwmon_lock);
> +
> + ret = da9052_enable_vddout_channel(hwmon->da9052);
> + if (ret < 0)
> + goto hwmon_err;
> +
> + ret = da9052_reg_read(hwmon->da9052, DA9052_VDD_RES_REG);
> + if (ret < 0)
> + pr_err("failed to read VDD_RES_REG\n");
> + else
> + vdd = ret;
> +
> + ret = da9052_disable_vddout_channel(hwmon->da9052);
> + if (ret < 0)
> + goto hwmon_err;
> +
> + if (vdd >= 0) {
> + mutex_unlock(&hwmon->hwmon_lock);
> + return sprintf(buf, "%d\n", vdd);
> + }
> +
> +hwmon_err:
> + mutex_unlock(&hwmon->hwmon_lock);
> + return ret;
> +}

This function still produces a bad result if the call to
da9052_reg_read() fails and the call to da9052_disable_vddout_channel()
doesn't.

I would suggest to replace pr_err() with "goto hwmon_err". If you do
that, you don't need to initialize vdd, you don't need the else case for
its assignment, and you don't need "if (vdd >= 0)" either.

Guenter

2011-06-29 11:47:05

by Ashish Jangam

[permalink] [raw]
Subject: Re: [PATCH 6/11] HWMON: DA9052 hwmon driver v1

On Tue, 2011-06-28 at 23:05 +0530, Guenter Roeck wrote:
> On Tue, 2011-06-28 at 10:24 -0400, ashish jangam wrote:
> > +static ssize_t da9052_read_vddout(struct device *dev,
> > + struct device_attribute *devattr, char *buf)
> > +{
> > + struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
> > + int ret, vdd = -1;
> > +
> > + mutex_lock(&hwmon->hwmon_lock);
> > +
> > + ret = da9052_enable_vddout_channel(hwmon->da9052);
> > + if (ret < 0)
> > + goto hwmon_err;
> > +
> > + ret = da9052_reg_read(hwmon->da9052, DA9052_VDD_RES_REG);
> > + if (ret < 0)
> > + pr_err("failed to read VDD_RES_REG\n");
> > + else
> > + vdd = ret;
> > +
> > + ret = da9052_disable_vddout_channel(hwmon->da9052);
> > + if (ret < 0)
> > + goto hwmon_err;
> > +
> > + if (vdd >= 0) {
> > + mutex_unlock(&hwmon->hwmon_lock);
> > + return sprintf(buf, "%d\n", vdd);
> > + }
> > +
> > +hwmon_err:
> > + mutex_unlock(&hwmon->hwmon_lock);
> > + return ret;
> > +}
>
> This function still produces a bad result if the call to
> da9052_reg_read() fails and the call to da9052_disable_vddout_channel()
> doesn't.
Thanks much for comments and patience. When vddout channel is enabled
and then read from this channel fails then, in this case should vddout
channel get disabled? Is this correct understanding.
>
> I would suggest to replace pr_err() with "goto hwmon_err". If you do
> that, you don't need to initialize vdd, you don't need the else case for
> its assignment, and you don't need "if (vdd >= 0)" either.
Will take care of this. Thanks...Ashish
>
> Guenter
>
>
>

2011-06-29 14:28:07

by Guenter Roeck

[permalink] [raw]
Subject: Re: [PATCH 6/11] HWMON: DA9052 hwmon driver v1

On Wed, Jun 29, 2011 at 07:44:08AM -0400, Ashish Jangam wrote:
> On Tue, 2011-06-28 at 23:05 +0530, Guenter Roeck wrote:
> > On Tue, 2011-06-28 at 10:24 -0400, ashish jangam wrote:
> > > +static ssize_t da9052_read_vddout(struct device *dev,
> > > + struct device_attribute *devattr, char *buf)
> > > +{
> > > + struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
> > > + int ret, vdd = -1;
> > > +
> > > + mutex_lock(&hwmon->hwmon_lock);
> > > +
> > > + ret = da9052_enable_vddout_channel(hwmon->da9052);
> > > + if (ret < 0)
> > > + goto hwmon_err;
> > > +
> > > + ret = da9052_reg_read(hwmon->da9052, DA9052_VDD_RES_REG);
> > > + if (ret < 0)
> > > + pr_err("failed to read VDD_RES_REG\n");
> > > + else
> > > + vdd = ret;
> > > +
> > > + ret = da9052_disable_vddout_channel(hwmon->da9052);
> > > + if (ret < 0)
> > > + goto hwmon_err;
> > > +
> > > + if (vdd >= 0) {
> > > + mutex_unlock(&hwmon->hwmon_lock);
> > > + return sprintf(buf, "%d\n", vdd);
> > > + }
> > > +
> > > +hwmon_err:
> > > + mutex_unlock(&hwmon->hwmon_lock);
> > > + return ret;
> > > +}
> >
> > This function still produces a bad result if the call to
> > da9052_reg_read() fails and the call to da9052_disable_vddout_channel()
> > doesn't.
> Thanks much for comments and patience. When vddout channel is enabled
> and then read from this channel fails then, in this case should vddout
> channel get disabled? Is this correct understanding.

Hmm, yes, you are right there. You should try to disable it. But you would have
to do that such that you don't override the original error. One possibility would
be to add an unconditional call to da9052_disable_vddout_channel() into the error
path.

ret = da9052_reg_read(hwmon->da9052, DA9052_VDD_RES_REG);
if (ret < 0)
goto hwmon_err_release;

...
hwmon_err_release:
da9052_disable_vddout_channel(hwmon->da9052);
hwmon_err:
...

Guenter