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Message-Id: <20200525141200.17199-2-krzk@kernel.org>
Date: Mon, 25 May 2020 16:12:00 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: "Andrew F. Davis" <afd@...com>,
Pali Rohár <pali@...nel.org>,
Sebastian Reichel <sre@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski@...ceq.com>,
linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Cc: Krzysztof Kozlowski <krzk@...nel.org>
Subject: [PATCH 2/2] power: supply: bq27xxx_battery: Notify about voltage and current changes
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@...nel.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
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