Messages in this thread Patch in this message | | | From | Krzysztof Kozlowski <> | Subject | [PATCH 2/2] power: supply: bq27xxx_battery: Notify about voltage and current changes | Date | Mon, 25 May 2020 16:12:00 +0200 |
| |
Read voltage and current and store them in the cache (like other properties). This has benefits: 1. User-space will be notified on voltage or current change. These are important properties of charging so user-space might be interested in getting them. 2. Closes possible resource exhaustion attack through continuous I2C reads triggered by unprivileged power supply sysfs API. User could just keep reading voltage_now or current_now sysfs entries leading to excessive I2C transfers.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> --- drivers/power/supply/bq27xxx_battery.c | 97 ++++++++++++-------------- include/linux/power/bq27xxx_battery.h | 2 + 2 files changed, 48 insertions(+), 51 deletions(-)
diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c index 33c26d42cd02..048618c13e17 100644 --- a/drivers/power/supply/bq27xxx_battery.c +++ b/drivers/power/supply/bq27xxx_battery.c @@ -1520,6 +1520,48 @@ static int bq27xxx_battery_read_pwr_avg(struct bq27xxx_device_info *di) return tval; } +/* + * Return the battery average current in µA + * Note that current can be negative signed as well + * Or 0 if something fails. + */ +static int bq27xxx_battery_read_current(struct bq27xxx_device_info *di, + int flags) +{ + int curr; + + curr = bq27xxx_read(di, BQ27XXX_REG_AI, false); + if (curr < 0) { + dev_err(di->dev, "error reading current\n"); + return 0; + } + + if (di->opts & BQ27XXX_O_ZERO) { + if (flags & BQ27000_FLAG_CHGS) { + dev_dbg(di->dev, "negative current!\n"); + curr = -curr; + } + + return curr * BQ27XXX_CURRENT_CONSTANT / BQ27XXX_RS; + } + + /* else: Other gauges return signed value */ + return (int)((s16)curr) * 1000; +} + +static int bq27xxx_battery_read_voltage(struct bq27xxx_device_info *di) +{ + int volt; + + volt = bq27xxx_read(di, BQ27XXX_REG_VOLT, false); + if (volt < 0) { + dev_err(di->dev, "error reading voltage\n"); + return volt; + } + + return volt * 1000; +} + /* * Returns true if a battery over temperature condition is detected */ @@ -1606,6 +1648,8 @@ void bq27xxx_battery_update(struct bq27xxx_device_info *di) cache.cycle_count = bq27xxx_battery_read_cyct(di); if (di->regs[BQ27XXX_REG_AP] != INVALID_REG_ADDR) cache.power_avg = bq27xxx_battery_read_pwr_avg(di); + cache.curr = bq27xxx_battery_read_current(di, cache.flags); + cache.voltage = bq27xxx_battery_read_voltage(di); /* We only have to read charge design full once */ if (di->charge_design_full <= 0) @@ -1633,39 +1677,6 @@ static void bq27xxx_battery_poll(struct work_struct *work) schedule_delayed_work(&di->work, poll_interval * HZ); } -/* - * Return the battery average current in µA - * Note that current can be negative signed as well - * Or 0 if something fails. - */ -static int bq27xxx_battery_current(struct bq27xxx_device_info *di, - union power_supply_propval *val) -{ - int curr; - int flags; - - curr = bq27xxx_read(di, BQ27XXX_REG_AI, false); - if (curr < 0) { - dev_err(di->dev, "error reading current\n"); - return curr; - } - - if (di->opts & BQ27XXX_O_ZERO) { - flags = bq27xxx_read(di, BQ27XXX_REG_FLAGS, true); - if (flags & BQ27000_FLAG_CHGS) { - dev_dbg(di->dev, "negative current!\n"); - curr = -curr; - } - - val->intval = curr * BQ27XXX_CURRENT_CONSTANT / BQ27XXX_RS; - } else { - /* Other gauges return signed value */ - val->intval = (int)((s16)curr) * 1000; - } - - return 0; -} - static int bq27xxx_battery_status(struct bq27xxx_device_info *di, union power_supply_propval *val) { @@ -1728,22 +1739,6 @@ static int bq27xxx_battery_capacity_level(struct bq27xxx_device_info *di, * Return the battery Voltage in millivolts * Or < 0 if something fails. */ -static int bq27xxx_battery_voltage(struct bq27xxx_device_info *di, - union power_supply_propval *val) -{ - int volt; - - volt = bq27xxx_read(di, BQ27XXX_REG_VOLT, false); - if (volt < 0) { - dev_err(di->dev, "error reading voltage\n"); - return volt; - } - - val->intval = volt * 1000; - - return 0; -} - static int bq27xxx_simple_value(int value, union power_supply_propval *val) { @@ -1777,13 +1772,13 @@ static int bq27xxx_battery_get_property(struct power_supply *psy, ret = bq27xxx_battery_status(di, val); break; case POWER_SUPPLY_PROP_VOLTAGE_NOW: - ret = bq27xxx_battery_voltage(di, val); + ret = bq27xxx_simple_value(di->cache.voltage, val); break; case POWER_SUPPLY_PROP_PRESENT: val->intval = di->cache.flags < 0 ? 0 : 1; break; case POWER_SUPPLY_PROP_CURRENT_NOW: - ret = bq27xxx_battery_current(di, val); + val->intval = di->cache.curr; /* Can be negative */ break; case POWER_SUPPLY_PROP_CAPACITY: ret = bq27xxx_simple_value(di->cache.capacity, val); diff --git a/include/linux/power/bq27xxx_battery.h b/include/linux/power/bq27xxx_battery.h index 507c5e214c42..418ba5e4029a 100644 --- a/include/linux/power/bq27xxx_battery.h +++ b/include/linux/power/bq27xxx_battery.h @@ -49,6 +49,8 @@ struct bq27xxx_reg_cache { int cycle_count; int capacity; int energy; + int curr; + int voltage; int flags; int power_avg; int health; -- 2.17.1
| |