linux-kernel - Re: [PATCH v4 1/2] power_supply: Add more charge types and CHARGE_CONTROL

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Date:   Wed, 17 Apr 2019 23:40:22 +0200
From:   Sebastian Reichel <sre@...nel.org>
To:     Nick Crews <ncrews@...omium.org>
Cc:     enric.balletbo@...labora.com, bleung@...omium.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        dlaurie@...omium.org, lamzin@...gle.com, bartfab@...gle.com,
        derat@...gle.com, dtor@...gle.com, sjg@...omium.org,
        jchwong@...omium.org
Subject: Re: [PATCH v4 1/2] power_supply: Add more charge types and
 CHARGE_CONTROL_* properties

Hi,

The changes itself look all good to me, but this does multiple
things in a single patch, so please split it into multiple commits.

-- Sebastian

On Tue, Apr 16, 2019 at 06:43:19PM -0600, Nick Crews wrote:
> Add "Standard", "Adaptive", and "Custom" modes to the charge_type
> property, to expand the existing "Trickle" and "Fast" modes.
> In addition, add POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD
> and POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD properties, to expand
> the existing CHARGE_CONTROL_* properties. I am adding them in order
> to support a new Chrome OS device, but these properties should be
> general enough that they can be used on other devices.
> 
> The meaning of "Standard" is obvious, but "Adaptive" and "Custom" are
> more tricky: "Adaptive" means that the charge controller uses some
> custom algorithm to change the charge type automatically, with no
> configuration needed. "Custom" means that the charge controller uses the
> POWER_SUPPLY_PROP_CHARGE_CONTROL_* properties as configuration for some
> other algorithm. For example, in the use case that I am supporting,
> this means the battery begins charging when the percentage
> level drops below POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD and
> charging ceases when the percentage level goes above
> POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD.
> 
> v4 changes:
> - Add documentation for the new properties, and add documentation for
>   the the previously missing charge_control_limit and
>   charge_control_limit_max properties.
> 
> Signed-off-by: Nick Crews <ncrews@...omium.org>
> ---
>  Documentation/ABI/testing/sysfs-class-power | 51 +++++++++++++++++++--
>  drivers/power/supply/power_supply_sysfs.c   |  4 +-
>  include/linux/power_supply.h                | 10 +++-
>  3 files changed, 59 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> index 5e23e22dce1b..b77e30b9014e 100644
> --- a/Documentation/ABI/testing/sysfs-class-power
> +++ b/Documentation/ABI/testing/sysfs-class-power
> @@ -114,15 +114,60 @@ Description:
>  		Access: Read
>  		Valid values: Represented in microamps
>  
> +What:		/sys/class/power_supply/<supply_name>/charge_control_limit
> +Date:		Oct 2012
> +Contact:	linux-pm@...r.kernel.org
> +Description:
> +		Maximum allowable charging current. Used for charge rate
> +		throttling for thermal cooling or improving battery health.
> +
> +		Access: Read, Write
> +		Valid values: Represented in microamps
> +
> +What:		/sys/class/power_supply/<supply_name>/charge_control_limit_max
> +Date:		Oct 2012
> +Contact:	linux-pm@...r.kernel.org
> +Description:
> +		Maximum legal value for the charge_control_limit property.
> +
> +		Access: Read
> +		Valid values: Represented in microamps
> +
> +What:		/sys/class/power_supply/<supply_name>/charge_control_start_threshold
> +Date:		April 2019
> +Contact:	linux-pm@...r.kernel.org
> +Description:
> +		Represents a battery percentage level, below which charging will
> +		begin.
> +
> +		Access: Read, Write
> +		Valid values: 0 - 100 (percent)
> +
> +What:		/sys/class/power_supply/<supply_name>/charge_control_end_threshold
> +Date:		April 2019
> +Contact:	linux-pm@...r.kernel.org
> +Description:
> +		Represents a battery percentage level, above which charging will
> +		stop.
> +
> +		Access: Read, Write
> +		Valid values: 0 - 100 (percent)
> +
>  What:		/sys/class/power_supply/<supply_name>/charge_type
>  Date:		July 2009
>  Contact:	linux-pm@...r.kernel.org
>  Description:
>  		Represents the type of charging currently being applied to the
> -		battery.
> +		battery. "Trickle", "Fast", and "Standard" all mean different
> +		charging speeds. "Adaptive" means that the charger uses some
> +		algorithm to adjust the charge rate dynamically, without
> +		any user configuration required. "Custom" means that the charger
> +		uses the charge_control_* properties as configuration for some
> +		different algorithm.
>  
> -		Access: Read
> -		Valid values: "Unknown", "N/A", "Trickle", "Fast"
> +		Access: Read, Write
> +		Valid values: "Unknown", "N/A", "Trickle", "Fast", "Standard",
> +			      "Adaptive", "Custom"
>  
>  What:		/sys/class/power_supply/<supply_name>/charge_term_current
>  Date:		July 2014
> diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> index dce24f596160..6104a3f03d46 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -56,7 +56,7 @@ static const char * const power_supply_status_text[] = {
>  };
>  
>  static const char * const power_supply_charge_type_text[] = {
> -	"Unknown", "N/A", "Trickle", "Fast"
> +	"Unknown", "N/A", "Trickle", "Fast", "Standard", "Adaptive", "Custom"
>  };
>  
>  static const char * const power_supply_health_text[] = {
> @@ -274,6 +274,8 @@ static struct device_attribute power_supply_attrs[] = {
>  	POWER_SUPPLY_ATTR(constant_charge_voltage_max),
>  	POWER_SUPPLY_ATTR(charge_control_limit),
>  	POWER_SUPPLY_ATTR(charge_control_limit_max),
> +	POWER_SUPPLY_ATTR(charge_control_start_threshold),
> +	POWER_SUPPLY_ATTR(charge_control_end_threshold),
>  	POWER_SUPPLY_ATTR(input_current_limit),
>  	POWER_SUPPLY_ATTR(energy_full_design),
>  	POWER_SUPPLY_ATTR(energy_empty_design),
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index 2f9c201a54d1..d59205170232 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -40,11 +40,15 @@ enum {
>  	POWER_SUPPLY_STATUS_FULL,
>  };
>  
> +/* What algorithm is the charger using? */
>  enum {
>  	POWER_SUPPLY_CHARGE_TYPE_UNKNOWN = 0,
>  	POWER_SUPPLY_CHARGE_TYPE_NONE,
> -	POWER_SUPPLY_CHARGE_TYPE_TRICKLE,
> -	POWER_SUPPLY_CHARGE_TYPE_FAST,
> +	POWER_SUPPLY_CHARGE_TYPE_TRICKLE,	/* slow speed */
> +	POWER_SUPPLY_CHARGE_TYPE_FAST,		/* fast speed */
> +	POWER_SUPPLY_CHARGE_TYPE_STANDARD,	/* normal speed */
> +	POWER_SUPPLY_CHARGE_TYPE_ADAPTIVE,	/* dynamically adjusted speed */
> +	POWER_SUPPLY_CHARGE_TYPE_CUSTOM,	/* use CHARGE_CONTROL_* props */
>  };
>  
>  enum {
> @@ -121,6 +125,8 @@ enum power_supply_property {
>  	POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE_MAX,
>  	POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT,
>  	POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX,
> +	POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD, /* in percents! */
> +	POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD, /* in percents! */
>  	POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
>  	POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
>  	POWER_SUPPLY_PROP_ENERGY_EMPTY_DESIGN,
> -- 
> 2.20.1
> 

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