On Sun, May 13, 2018 at 05:29:37PM +0200, Ognjen Galic wrote:
> Lenovo ThinkPad systems support the prevention of
> battery charging via a manual override called Inhibit Charge.
> 
> This patch adds support for that attribute and exposes it via the
> battery ACPI driver in the generic location:
> 
> /sys/class/power_supply/BATX/inhibit_charge
> 
> Signed-off-by: Ognjen Galic <smclt...@gmail.com>
> ---
>  drivers/platform/x86/thinkpad_acpi.c | 66 +++++++++++++++++++++++++++-
>  1 file changed, 64 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/thinkpad_acpi.c 
> b/drivers/platform/x86/thinkpad_acpi.c
> index da1ca485..b8b74889 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -9233,6 +9233,11 @@ static struct ibm_struct mute_led_driver_data = {
>  #define GET_STOP     "BCSG"
>  #define SET_STOP     "BCSS"
>  
> +#define SET_INHIBIT  "BICS"
> +#define GET_INHIBIT  "BICG"
> +
> +#define INHIBIT_ATTR "inhibit_charge"
> +
>  #define START_ATTR "charge_start_threshold"
>  #define STOP_ATTR  "charge_stop_threshold"
>  
> @@ -9251,6 +9256,7 @@ enum {
>       /* This is used in the get/set helpers */
>       THRESHOLD_START,
>       THRESHOLD_STOP,
> +     INHIBIT_CHARGE
>  };
>  
>  struct tpacpi_battery_data {
> @@ -9258,6 +9264,7 @@ struct tpacpi_battery_data {
>       int start_support;
>       int charge_stop;
>       int stop_support;
> +     int inhibit_support;
>  };
>  
>  struct tpacpi_battery_driver_data {
> @@ -9315,6 +9322,13 @@ static int tpacpi_battery_get(int what, int battery, 
> int *ret)
>               if (*ret == 0)
>                       *ret = 100;
>               return 0;
> +     case INHIBIT_CHARGE:
> +             if ACPI_FAILURE(tpacpi_battery_acpi_eval(GET_INHIBIT, ret, 
> battery))
> +                     return -ENODEV;
> +
> +             /* The inhibit charge status is in the first bit */
> +             *ret = *ret & 0x01;
> +             return 0;
>       default:
>               pr_crit("wrong parameter: %d", what);
>               return -EINVAL;
> @@ -9343,6 +9357,21 @@ static int tpacpi_battery_set(int what, int battery, 
> int value)
>                       return -ENODEV;
>               }
>               return 0;
> +     case INHIBIT_CHARGE:
> +             /* When setting inhbitit charge, we set a default vaulue of

This comment does not adhere to the Linux coding style

> +              * always breaking on AC detach and the effective time is set to
> +              * be permanent.
> +              * The battery ID is in bits 4-5, 2 bits and the effective time
> +              * is in bits 8-23, 2 bytes. A time of FFFF indicates forever.
> +              */
> +             param = value;
> +             param |= battery << 4;
> +             param |= 0xFFFF << 8;
> +             if ACPI_FAILURE(tpacpi_battery_acpi_eval(SET_INHIBIT, &ret, 
> param)) {
> +                     pr_err("failed to set inhibit charge on %d", battery);
> +                     return -ENODEV;
> +             }
> +             return 0;
>       default:
>               pr_crit("wrong parameter: %d", what);
>               return -EINVAL;
> @@ -9359,6 +9388,8 @@ static int tpacpi_battery_probe(int battery)
>        * 2) Check for support
>        * 3) Get the current stop threshold
>        * 4) Check for support
> +      * 5) Check for inhibit charge support
> +      * 6) Get the current inhibit charge status
>        */
>       if (acpi_has_method(hkey_handle, GET_START)) {
>               if ACPI_FAILURE(tpacpi_battery_acpi_eval(GET_START, &ret, 
> battery)) {
> @@ -9395,10 +9426,16 @@ static int tpacpi_battery_probe(int battery)
>                       return -ENODEV;
>               }
>       }
> -     pr_info("battery %d registered (start %d, stop %d)",
> +     if (acpi_has_method(hkey_handle, GET_INHIBIT))
> +             if (!ACPI_FAILURE(tpacpi_battery_acpi_eval(GET_INHIBIT, &ret, 
> battery)))
> +                     /* Support is marked in bit 5 */
> +                     battery_info.batteries[battery].inhibit_support = ret & 
> BIT(5);
> +
> +     pr_info("battery %d registered (start %d, stop %d, inhibit: %d)",
>                       battery,
>                       battery_info.batteries[battery].charge_start,
> -                     battery_info.batteries[battery].charge_stop);
> +                     battery_info.batteries[battery].charge_stop,
> +                     battery_info.batteries[battery].inhibit_support);
>  
>       return 0;
>  }
> @@ -9484,6 +9521,15 @@ static ssize_t tpacpi_battery_store(int what,
>               if (tpacpi_battery_set(THRESHOLD_STOP, battery, value))
>                       return -EINVAL;
>               return count;
> +     case INHIBIT_CHARGE:
> +             if (!battery_info.batteries[battery].inhibit_support)
> +                     return -ENODEV;
> +             /* The only valid values are 1 and 0 */
> +             if (value != 0 && value != 1)

I'm not sure, but maybe `if (value < 2)` is better here?

> +                     return -EINVAL;
> +             if (tpacpi_battery_set(INHIBIT_CHARGE, battery, value))
> +                     return -ENODEV;
> +             return count;
>       default:
>               pr_crit("Wrong parameter: %d", what);
>               return -EINVAL;
> @@ -9546,12 +9592,28 @@ static ssize_t charge_stop_threshold_store(struct 
> device *dev,
>       return tpacpi_battery_store(THRESHOLD_STOP, dev, buf, count);
>  }
>  
> +static ssize_t inhibit_charge_store(struct device *dev,
> +                             struct device_attribute *attr,
> +                             const char *buf, size_t count)
> +{
> +     return tpacpi_battery_store(INHIBIT_CHARGE, dev, buf, count);
> +}
> +
> +static ssize_t inhibit_charge_show(struct device *device,
> +                             struct device_attribute *attr,
> +                             char *buf)
> +{
> +     return tpacpi_battery_show(INHIBIT_CHARGE, device, buf);
> +}
> +
>  static DEVICE_ATTR_RW(charge_start_threshold);
>  static DEVICE_ATTR_RW(charge_stop_threshold);
> +static DEVICE_ATTR_RW(inhibit_charge);
>  
>  static struct attribute *tpacpi_battery_attrs[] = {
>       &dev_attr_charge_start_threshold.attr,
>       &dev_attr_charge_stop_threshold.attr,
> +     &dev_attr_inhibit_charge.attr,
>       NULL,
>  };
>  
> -- 
> 2.17.0
> 

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