Re: [PATCH v11 04/10] power: power_supply: Add power_supply_battery_info and API

Liam Breck
2017-03-20T20:59:03Z

Hi Sebastian,

On Mon, Mar 20, 2017 at 2:43 AM, Liam Breck <liam@networkimprov.net> wrote:
> From: Liam Breck <kernel@networkimprov.net>
>
> power_supply_get_battery_info() reads battery data from devicetree.
> struct power_supply_battery_info provides battery data to drivers.
> Drivers may surface battery data in sysfs via corresponding
> POWER_SUPPLY_PROP_* fields.
>
> Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
> Signed-off-by: Liam Breck <kernel@networkimprov.net>
> ---
> Documentation/power/power_supply_class.txt | 12 ++++++++
> drivers/power/supply/power_supply_core.c | 45 ++++++++++++++++++++++++++++++
> include/linux/power_supply.h | 18 ++++++++++++
> 3 files changed, 75 insertions(+)
>
> diff --git a/Documentation/power/power_supply_class.txt b/Documentation/power/power_supply_class.txt
> index 0c72588..dc92c77 100644
> --- a/Documentation/power/power_supply_class.txt
> +++ b/Documentation/power/power_supply_class.txt
> @@ -174,6 +174,18 @@ issued by external power supply will notify supplicants via
> external_power_changed callback.
>
>
> +Devicetree battery characteristics
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +Drivers should call power_supply_get_battery_info() to obtain battery
> +characteristics from a devicetree battery node, defined in
> +Documentation/devicetree/bindings/power/supply/battery.txt. This is
> +implemented in drivers/power/supply/bq27xxx_battery.c.
> +
> +Properties in struct power_supply_battery_info and their counterparts in the
> +battery node have names corresponding to elements in enum power_supply_property,
> +for naming consistency between sysfs attributes and battery node properties.
> +
> +
> QA
> ~~
> Q: Where is POWER_SUPPLY_PROP_XYZ attribute?
> diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
> index a74d8ca..61e20b1 100644
> --- a/drivers/power/supply/power_supply_core.c
> +++ b/drivers/power/supply/power_supply_core.c
> @@ -17,6 +17,7 @@
> #include <linux/device.h>
> #include <linux/notifier.h>
> #include <linux/err.h>
> +#include <linux/of.h>
> #include <linux/power_supply.h>
> #include <linux/thermal.h>
> #include "power_supply.h"
> @@ -487,6 +488,50 @@ struct power_supply *devm_power_supply_get_by_phandle(struct device *dev,
> EXPORT_SYMBOL_GPL(devm_power_supply_get_by_phandle);
> #endif /* CONFIG_OF */
>
> +int power_supply_get_battery_info(struct power_supply *psy,
> + struct power_supply_battery_info *info)
> +{
> + struct device_node *battery_np;
> + const char *value;
> + int err;
> +
> + info->energy_full_design_uwh = -EINVAL;
> + info->charge_full_design_uah = -EINVAL;
> + info->voltage_min_design_uv = -EINVAL;
> +
> + if (!psy->of_node) {
> + dev_warn(&psy->dev, "%s currently only supports devicetree\n",
> + __func__);
> + return -ENXIO;
> + }
> +
> + battery_np = of_parse_phandle(psy->of_node, "monitored-battery", 0);
> + if (!battery_np)
> + return -ENODEV;
> +
> + err = of_property_read_string(battery_np, "compatible", &value);
> + if (err)
> + return err;
> +
> + if (strcmp("simple-battery", value))
> + return -ENODEV;
> +
> + /* The property and field names below must correspond to elements
> + * in enum power_supply_property. For reasoning, see
> + * Documentation/power/power_supply_class.txt.
> + */
> +
> + of_property_read_u32(battery_np, "energy-full-design-microwatt-hours",
> + &info->energy_full_design_uwh);
> + of_property_read_u32(battery_np, "charge-full-design-microamp-hours",
> + &info->charge_full_design_uah);
> + of_property_read_u32(battery_np, "voltage-min-design-microvolt",
> + &info->voltage_min_design_uv);

Should we also check for an acpi_handle, and use
device_property_read_* here? Tho presumably the acpi property names
would be different...

I wouldn't have a way to test that however.

> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(power_supply_get_battery_info);
> +
> int power_supply_get_property(struct power_supply *psy,
> enum power_supply_property psp,
> union power_supply_propval *val)
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index 3965503..e84f1d3 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -288,6 +288,21 @@ struct power_supply_info {
> int use_for_apm;
> };
>
> +/*
> + * This is the recommended struct to manage static battery parameters,
> + * populated by power_supply_get_battery_info(). Most platform drivers should
> + * use these for consistency.
> + * Its field names must correspond to elements in enum power_supply_property.
> + * The default field value is -EINVAL.
> + * Power supply class itself doesn't use this.
> + */
> +
> +struct power_supply_battery_info {
> + int energy_full_design_uwh; /* microWatt-hours */
> + int charge_full_design_uah; /* microAmp-hours */
> + int voltage_min_design_uv; /* microVolts */
> +};
> +
> extern struct atomic_notifier_head power_supply_notifier;
> extern int power_supply_reg_notifier(struct notifier_block *nb);
> extern void power_supply_unreg_notifier(struct notifier_block *nb);
> @@ -306,6 +321,9 @@ static inline struct power_supply *
> devm_power_supply_get_by_phandle(struct device *dev, const char *property)
> { return NULL; }
> #endif /* CONFIG_OF */
> +
> +extern int power_supply_get_battery_info(struct power_supply *psy,
> + struct power_supply_battery_info *info);
> extern void power_supply_changed(struct power_supply *psy);
> extern int power_supply_am_i_supplied(struct power_supply *psy);
> extern int power_supply_set_battery_charged(struct power_supply *psy);
> --
> 2.9.3
>