power: supply: Add HWMON compatibility layer

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@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Chris Healy <cphealy@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Cory Tusar <cory.tusar@zii.aero>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

5 files changed, 390 insertions, 0 deletions

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
+        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_core.c b/drivers/power/supply/power_supply_core.c
index f7033ecf6d0b..35624193a346 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -1072,6 +1072,10 @@ __power_supply_register(struct device *parent,
         if (rc)
                 goto create_triggers_failed;
 
+        rc = power_supply_add_hwmon_sysfs(psy);
+        if (rc)
+                goto add_hwmon_sysfs_failed;
+
         /*
          * Update use_cnt after any uevents (most notably from device_add()).
          * We are here still during driver's probe but
@@ -1090,6 +1094,8 @@ __power_supply_register(struct device *parent,
 
         return psy;
 
+add_hwmon_sysfs_failed:
+        power_supply_remove_triggers(psy);
 create_triggers_failed:
         psy_unregister_cooler(psy);
 register_cooler_failed:
@@ -1242,6 +1248,7 @@ void power_supply_unregister(struct power_supply *psy)
         cancel_work_sync(&psy->changed_work);
         cancel_delayed_work_sync(&psy->deferred_register_work);
         sysfs_remove_link(&psy->dev.kobj, "powers");
+        power_supply_remove_hwmon_sysfs(psy);
         power_supply_remove_triggers(psy);
         psy_unregister_cooler(psy);
         psy_unregister_thermal(psy);
diff --git a/drivers/power/supply/power_supply_hwmon.c b/drivers/power/supply/power_supply_hwmon.c
new file mode 100644
index 000000000000..51fe60440d12
--- /dev/null
+++ b/drivers/power/supply/power_supply_hwmon.c
@@ -0,0 +1,355 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  power_supply_hwmon.c - power supply hwmon support.
+ */
+
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/power_supply.h>
+#include <linux/slab.h>
+
+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:
+                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:
+                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:
+                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 bool power_supply_hwmon_is_writable(enum hwmon_sensor_types type,
+                                           u32 attr)
+{
+        switch (type) {
+        case hwmon_in:
+                return attr == hwmon_in_min ||
+                       attr == hwmon_in_max;
+        case hwmon_curr:
+                return attr == hwmon_curr_max;
+        case hwmon_temp:
+                return attr == hwmon_temp_max ||
+                       attr == hwmon_temp_min ||
+                       attr == hwmon_temp_min_alarm ||
+                       attr == hwmon_temp_max_alarm;
+        default:
+                return false;
+        }
+}
+
+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;
+
+
+        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;
+
+        if (power_supply_property_is_writeable(psyhw->psy, prop) > 0 &&
+            power_supply_hwmon_is_writable(type, attr))
+                return 0644;
+
+        return 0444;
+}
+
+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 = DIV_ROUND_CLOSEST(pspval.intval, 1000);
+                break;
+        /*
+         * Temp needs to be converted from 1/10 C to milli-C
+         */
+        case hwmon_temp:
+                if (check_mul_overflow(pspval.intval, 100,
+                                       &pspval.intval))
+                        return -EOVERFLOW;
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        *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:
+                if (check_mul_overflow(pspval.intval, 1000,
+                                       &pspval.intval))
+                        return -EOVERFLOW;
+                break;
+        /*
+         * Temp needs to be converted from 1/10 C to milli-C
+         */
+        case hwmon_temp:
+                pspval.intval = DIV_ROUND_CLOSEST(pspval.intval, 100);
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        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);
+}
+
+int 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, power_supply_add_hwmon_sysfs,
+                               GFP_KERNEL))
+                return -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_close_group(dev, power_supply_add_hwmon_sysfs);
+        return 0;
+error:
+        devres_release_group(dev, NULL);
+        return ret;
+}
+
+void power_supply_remove_hwmon_sysfs(struct power_supply *psy)
+{
+        devres_release_group(&psy->dev, power_supply_add_hwmon_sysfs);
+}
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index d9c0c094f8a0..d5b15e039f4f 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -481,4 +481,17 @@ static inline bool power_supply_is_watt_property(enum power_supply_property psp)
         return 0;
 }
 
+#ifdef CONFIG_POWER_SUPPLY_HWMON
+int power_supply_add_hwmon_sysfs(struct power_supply *psy);
+void power_supply_remove_hwmon_sysfs(struct power_supply *psy);
+#else
+static inline int power_supply_add_hwmon_sysfs(struct power_supply *psy)
+{
+        return 0;
+}
+
+static inline
+void power_supply_remove_hwmon_sysfs(struct power_supply *psy) {}
+#endif
+
 #endif /* __LINUX_POWER_SUPPLY_H__ */