Re: [PATCH 1/2] power: supply: Add HWMON compatibility layer
From: Guenter Roeck
Date: Wed May 29 2019 - 08:44:03 EST
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@xxxxxxxxx>
Cc: Chris Healy <cphealy@xxxxxxxxx>
Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Cc: Fabio Estevam <fabio.estevam@xxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Sebastian Reichel <sre@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-pm@xxxxxxxxxxxxxxx
---
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__ */