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Message-ID: <22dcfea4-00a2-3de8-8313-35d8d1350493@roeck-us.net>
Date: Wed, 29 May 2019 05:40:31 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Andrey Smirnov <andrew.smirnov@...il.com>, linux-pm@...r.kernel.org
Cc: Chris Healy <cphealy@...il.com>,
Lucas Stach <l.stach@...gutronix.de>,
Fabio Estevam <fabio.estevam@....com>,
Sebastian Reichel <sre@...nel.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] power: supply: Add HWMON compatibility layer
On 5/29/19 12:11 AM, Andrey Smirnov wrote:
> Add code implementing HWMON adapter/compatibility layer to allow
> expositing various sensors present on power supply devices via HWMON
> subsystem. This is done in order to allow userspace to use single
> ABI/library(libsensors) to access/manipulate all of the sensors of the
> system.
>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
> Cc: Chris Healy <cphealy@...il.com>
> Cc: Lucas Stach <l.stach@...gutronix.de>
> Cc: Fabio Estevam <fabio.estevam@....com>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Sebastian Reichel <sre@...nel.org>
> Cc: linux-kernel@...r.kernel.org
> Cc: linux-pm@...r.kernel.org
> ---
> drivers/power/supply/Kconfig | 14 +
> drivers/power/supply/Makefile | 1 +
> drivers/power/supply/power_supply_hwmon.c | 329 ++++++++++++++++++++++
> include/linux/power_supply.h | 11 +
> 4 files changed, 355 insertions(+)
> create mode 100644 drivers/power/supply/power_supply_hwmon.c
>
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index 26dacdab03cc..1f2252cb95fd 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -14,6 +14,20 @@ config POWER_SUPPLY_DEBUG
> Say Y here to enable debugging messages for power supply class
> and drivers.
>
> +config POWER_SUPPLY_HWMON
> + bool
> + prompt "Expose power supply sensors as hwmon device"
> + depends on HWMON=y || HWMON=POWER_SUPPLY
> + default y
Not sure if you want to enable that by default.
> + help
> + This options enables API that allows sensors found on a
> + power supply device (current, voltage, temperature) to be
> + exposed as a hwmon device.
> +
> + Say 'Y' here if you want power supplies to
> + have hwmon sysfs interface too.
> +
> +
> config PDA_POWER
> tristate "Generic PDA/phone power driver"
> depends on !S390
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
> index f208273f9686..c47e88ba16b9 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -6,6 +6,7 @@ power_supply-$(CONFIG_SYSFS) += power_supply_sysfs.o
> power_supply-$(CONFIG_LEDS_TRIGGERS) += power_supply_leds.o
>
> obj-$(CONFIG_POWER_SUPPLY) += power_supply.o
> +obj-$(CONFIG_POWER_SUPPLY_HWMON) += power_supply_hwmon.o
> obj-$(CONFIG_GENERIC_ADC_BATTERY) += generic-adc-battery.o
>
> obj-$(CONFIG_PDA_POWER) += pda_power.o
> diff --git a/drivers/power/supply/power_supply_hwmon.c b/drivers/power/supply/power_supply_hwmon.c
> new file mode 100644
> index 000000000000..dca7f79fae6e
> --- /dev/null
> +++ b/drivers/power/supply/power_supply_hwmon.c
> @@ -0,0 +1,329 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * power_supply_hwmon.c - power supply hwmon support.
> + */
> +
> +#include <linux/hwmon.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +#include <linux/power_supply.h>
> +
Alphabetic order ?
> +struct power_supply_hwmon {
> + struct power_supply *psy;
> + unsigned long *props;
> +};
> +
> +static int power_supply_hwmon_in_to_property(u32 attr)
> +{
> + switch (attr) {
> + case hwmon_in_average:
> + return POWER_SUPPLY_PROP_VOLTAGE_AVG;
> + case hwmon_in_min:
> + return POWER_SUPPLY_PROP_VOLTAGE_MIN;
> + case hwmon_in_max:
> + return POWER_SUPPLY_PROP_VOLTAGE_MAX;
> + case hwmon_in_input:
> + return POWER_SUPPLY_PROP_VOLTAGE_NOW;
> + default:
> + break;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int power_supply_hwmon_curr_to_property(u32 attr)
> +{
> + switch (attr) {
> + case hwmon_curr_average:
> + return POWER_SUPPLY_PROP_CURRENT_AVG;
> + case hwmon_curr_max:
> + return POWER_SUPPLY_PROP_CURRENT_MAX;
> + case hwmon_curr_input:
> + return POWER_SUPPLY_PROP_CURRENT_NOW;
> + default:
> + break;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int power_supply_hwmon_temp_to_property(u32 attr, int channel)
> +{
> + if (channel) {
> + switch (attr) {
> + case hwmon_temp_input:
> + return POWER_SUPPLY_PROP_TEMP_AMBIENT;
> + case hwmon_temp_min_alarm:
> + return POWER_SUPPLY_PROP_TEMP_AMBIENT_ALERT_MIN;
> + case hwmon_temp_max_alarm:
> + return POWER_SUPPLY_PROP_TEMP_AMBIENT_ALERT_MAX;
> + default:
> + break;
> + }
> + } else {
> + switch (attr) {
> + case hwmon_temp_input:
> + return POWER_SUPPLY_PROP_TEMP;
> + case hwmon_temp_max:
> + return POWER_SUPPLY_PROP_TEMP_MAX;
> + case hwmon_temp_min:
> + return POWER_SUPPLY_PROP_TEMP_MIN;
> + case hwmon_temp_min_alarm:
> + return POWER_SUPPLY_PROP_TEMP_ALERT_MIN;
> + case hwmon_temp_max_alarm:
> + return POWER_SUPPLY_PROP_TEMP_ALERT_MAX;
> + default:
> + break;
> + }
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int
> +power_supply_hwmon_to_property(enum hwmon_sensor_types type,
> + u32 attr, int channel)
> +{
> + switch (type) {
> + case hwmon_in:
> + return power_supply_hwmon_in_to_property(attr);
> + case hwmon_curr:
> + return power_supply_hwmon_curr_to_property(attr);
> + case hwmon_temp:
> + return power_supply_hwmon_temp_to_property(attr, channel);
> + default:
> + break;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static bool power_supply_hwmon_is_a_label(enum hwmon_sensor_types type,
> + u32 attr)
> +{
> + return type == hwmon_temp && attr == hwmon_temp_label;
> +}
> +
> +static umode_t power_supply_hwmon_is_visible(const void *data,
> + enum hwmon_sensor_types type,
> + u32 attr, int channel)
> +{
> + const struct power_supply_hwmon *psyhw = data;
> + int prop, is_writable;
> +
> + if (power_supply_hwmon_is_a_label(type, attr))
> + return 0444;
> +
> + prop = power_supply_hwmon_to_property(type, attr, channel);
> + if (prop < 0 || !test_bit(prop, psyhw->props))
> + return 0;
> +
> + is_writable = power_supply_property_is_writeable(psyhw->psy, prop);
> +
> + return (is_writable <= 0) ? 0444 : 0644;
I a a bit concerned that this can result in writeable voltage/current/temp
values (not just for limits), which would be very undesirable. It might be
better to add another check to ensure that this does not happen.
> +}
> +
> +static int power_supply_hwmon_read_string(struct device *dev,
> + enum hwmon_sensor_types type,
> + u32 attr, int channel,
> + const char **str)
> +{
> + *str = channel ? "temp" : "temp ambient";
> + return 0;
> +}
> +
> +static int
> +power_supply_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, long *val)
> +{
> + struct power_supply_hwmon *psyhw = dev_get_drvdata(dev);
> + struct power_supply *psy = psyhw->psy;
> + union power_supply_propval pspval;
> + int ret, prop;
> +
> + prop = power_supply_hwmon_to_property(type, attr, channel);
> + if (prop < 0)
> + return prop;
> +
> + ret = power_supply_get_property(psy, prop, &pspval);
> + if (ret)
> + return ret;
> +
> + switch (type) {
> + /*
> + * Both voltage and current is reported in units of
> + * microvolts/microamps, so we need to adjust it to
> + * milliamps(volts)
> + */
> + case hwmon_curr:
> + case hwmon_in:
> + pspval.intval /= 1000;
DIV_ROUND_CLOSEST() ?
> + break;
> + /*
> + * Temp needs to be converted from 1/10 C to milli-C
> + */
> + case hwmon_temp:
> + pspval.intval *= 100;
intval is an int, so theoretically this could result in an overflow.
> + break;
> + default:
Wouldn't this be an error ?
Personally I prefer direct value assignments. I don't see value in
updating pspval.intval first only to assign it to *val later.
> + break;
> + }
> +
> + *val = pspval.intval;
> +
> + return 0;
> +}
> +
> +static int
> +power_supply_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, long val)
> +{
> + struct power_supply_hwmon *psyhw = dev_get_drvdata(dev);
> + struct power_supply *psy = psyhw->psy;
> + union power_supply_propval pspval;
> + int prop;
> +
> + prop = power_supply_hwmon_to_property(type, attr, channel);
> + if (prop < 0)
> + return prop;
> +
> + pspval.intval = val;
> +
> + switch (type) {
> + /*
> + * Both voltage and current is reported in units of
> + * microvolts/microamps, so we need to adjust it to
> + * milliamps(volts)
> + */
> + case hwmon_curr:
> + case hwmon_in:
> + pspval.intval *= 1000;
Range checks ? This can result in an overflow.
> + break;
> + /*
> + * Temp needs to be converted from 1/10 C to milli-C
> + */
> + case hwmon_temp:
> + pspval.intval /= 100;
> + break;
> + default:
> + break;
Wouldn't this be an error ?
> + }
> +
> + return power_supply_set_property(psy, prop, &pspval);
> +}
> +
> +static const struct hwmon_ops power_supply_hwmon_ops = {
> + .is_visible = power_supply_hwmon_is_visible,
> + .read = power_supply_hwmon_read,
> + .write = power_supply_hwmon_write,
> + .read_string = power_supply_hwmon_read_string,
> +};
> +
> +static const struct hwmon_channel_info *power_supply_hwmon_info[] = {
> + HWMON_CHANNEL_INFO(temp,
> + HWMON_T_LABEL |
> + HWMON_T_INPUT |
> + HWMON_T_MAX |
> + HWMON_T_MIN |
> + HWMON_T_MIN_ALARM |
> + HWMON_T_MIN_ALARM,
> +
> + HWMON_T_LABEL |
> + HWMON_T_INPUT |
> + HWMON_T_MIN_ALARM |
> + HWMON_T_LABEL |
> + HWMON_T_MAX_ALARM),
> +
> + HWMON_CHANNEL_INFO(curr,
> + HWMON_C_AVERAGE |
> + HWMON_C_MAX |
> + HWMON_C_INPUT),
> +
> + HWMON_CHANNEL_INFO(in,
> + HWMON_I_AVERAGE |
> + HWMON_I_MIN |
> + HWMON_I_MAX |
> + HWMON_I_INPUT),
> + NULL
> +};
> +
> +static const struct hwmon_chip_info power_supply_hwmon_chip_info = {
> + .ops = &power_supply_hwmon_ops,
> + .info = power_supply_hwmon_info,
> +};
> +
> +static void power_supply_hwmon_bitmap_free(void *data)
> +{
> + bitmap_free(data);
> +}
> +
> +struct device *devm_power_supply_add_hwmon_sysfs(struct power_supply *psy)
> +{
> + const struct power_supply_desc *desc = psy->desc;
> + struct power_supply_hwmon *psyhw;
> + struct device *dev = &psy->dev;
> + struct device *hwmon;
> + int ret, i;
> +
> + if (!devres_open_group(dev, NULL, GFP_KERNEL))
> + return ERR_PTR(-ENOMEM);
> +
> + psyhw = devm_kzalloc(dev, sizeof(*psyhw), GFP_KERNEL);
> + if (!psyhw) {
> + ret = -ENOMEM;
> + goto error;
> + }
> +
> + psyhw->psy = psy;
> + psyhw->props = bitmap_zalloc(POWER_SUPPLY_PROP_TIME_TO_FULL_AVG + 1,
> + GFP_KERNEL);
> + if (!psyhw->props) {
> + ret = -ENOMEM;
> + goto error;
> + }
> +
> + ret = devm_add_action(dev, power_supply_hwmon_bitmap_free,
> + psyhw->props);
> + if (ret)
> + goto error;
> +
> + for (i = 0; i < desc->num_properties; i++) {
> + const enum power_supply_property prop = desc->properties[i];
> +
> + switch (prop) {
> + case POWER_SUPPLY_PROP_CURRENT_AVG:
> + case POWER_SUPPLY_PROP_CURRENT_MAX:
> + case POWER_SUPPLY_PROP_CURRENT_NOW:
> + case POWER_SUPPLY_PROP_TEMP:
> + case POWER_SUPPLY_PROP_TEMP_MAX:
> + case POWER_SUPPLY_PROP_TEMP_MIN:
> + case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
> + case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
> + case POWER_SUPPLY_PROP_TEMP_AMBIENT:
> + case POWER_SUPPLY_PROP_TEMP_AMBIENT_ALERT_MIN:
> + case POWER_SUPPLY_PROP_TEMP_AMBIENT_ALERT_MAX:
> + case POWER_SUPPLY_PROP_VOLTAGE_AVG:
> + case POWER_SUPPLY_PROP_VOLTAGE_MIN:
> + case POWER_SUPPLY_PROP_VOLTAGE_MAX:
> + case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> + set_bit(prop, psyhw->props);
> + break;
> + default:
> + break;
> + }
> + }
> +
> + hwmon = devm_hwmon_device_register_with_info(dev, psy->desc->name,
> + psyhw,
> + &power_supply_hwmon_chip_info,
> + NULL);
> + ret = PTR_ERR_OR_ZERO(hwmon);
> + if (ret)
> + goto error;
> +
> + devres_remove_group(dev, NULL);
Why devres_remove_group() and not devres_close_group() ?
> + return hwmon;
Why return a pointer to the hwmon device and not just an error code ?
> +error:
> + devres_release_group(dev, NULL);
> + return ERR_PTR(ret);
> +}
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index d9c0c094f8a0..839abfa2c640 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -481,4 +481,15 @@ static inline bool power_supply_is_watt_property(enum power_supply_property psp)
> return 0;
> }
>
> +#ifdef CONFIG_POWER_SUPPLY_HWMON
> +extern struct device *
> +devm_power_supply_add_hwmon_sysfs(struct power_supply *psy);
> +#else
> +static struct device *
> +devm_power_supply_add_hwmon_sysfs(struct power_supply *psy)
> +{
> + return 0;
You might consider making the return code an int. Otherwise this gets difficult
for the caller, who would have to check for IS_ERR() and NULL (if the device
pointer is supposed to be used for anything).
> +}
> +#endif
> +
> #endif /* __LINUX_POWER_SUPPLY_H__ */
>
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