@@ -1,9 +1,10 @@
-binding for LTC2941 and LTC2943 battery gauges
+binding for LTC2941, LTC2942 and LTC2943 battery gauges
-Both the LTC2941 and LTC2943 measure battery capacity.
-The LTC2943 is compatible with the LTC2941, it adds voltage and
-temperature monitoring, and uses a slightly different conversion
-formula for the charge counter.
+All chips measure battery capacity.
+The LTC2942 is pin compatible with the LTC2941, it adds voltage and
+temperature monitoring, and is runtime detected. LTC2943 is software
+compatible, uses a slightly different conversion formula for the
+charge counter and adds voltage, current and temperature monitoring.
Required properties:
- compatible: Should contain "lltc,ltc2941" or "lltc,ltc2943" which also
@@ -44,8 +44,10 @@ enum ltc294x_reg {
LTC2943_REG_TEMPERATURE_LSB = 0x15,
};
-#define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
-#define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
+#define LTC2941_REG_STATUS_CHIP_ID BIT(7)
+
+#define LTC2942_REG_CONTROL_MODE_SCAN (BIT(7) | BIT(6))
+#define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
#define LTC294X_REG_CONTROL_PRESCALER_MASK (BIT(5) | BIT(4) | BIT(3))
#define LTC294X_REG_CONTROL_SHUTDOWN_MASK (BIT(0))
#define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
@@ -144,9 +146,15 @@ static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
- /* Put the 2943 into "monitor" mode, so it measures every 10 sec */
- if (info->num_regs == LTC2943_NUM_REGS)
+ /* Put device into "monitor" mode */
+ switch (info->num_regs) {
+ case LTC2942_NUM_REGS: /* 2942 measures every 2 sec */
+ control |= LTC2942_REG_CONTROL_MODE_SCAN;
+ break;
+ case LTC2943_NUM_REGS: /* 2943 measures every 10 sec */
control |= LTC2943_REG_CONTROL_MODE_SCAN;
+ break;
+ }
if (value != control) {
ret = ltc294x_write_regs(info->client,
@@ -251,7 +259,16 @@ static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
ret = ltc294x_read_regs(info->client,
LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
value = (datar[0] << 8) | datar[1];
- *val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
+ if (info->num_regs == LTC2943_NUM_REGS) {
+ value *= 23600 * 2;
+ value /= 0xFFFF;
+ value *= 1000 / 2;
+ } else {
+ value *= 6000 * 10;
+ value /= 0xFFFF;
+ value *= 1000 / 10;
+ }
+ *val = value;
return ret;
}
@@ -274,15 +291,22 @@ static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
{
+ enum ltc294x_reg reg;
int ret;
u8 datar[2];
u32 value;
- ret = ltc294x_read_regs(info->client,
- LTC2943_REG_TEMPERATURE_MSB, &datar[0], 2);
- value = (datar[0] << 8) | datar[1];
- /* Full-scale is 510 Kelvin, convert to centidegrees */
- *val = (((51000 * value) / 0xFFFF) - 27215);
+ if (info->num_regs == LTC2943_NUM_REGS) {
+ reg = LTC2943_REG_TEMPERATURE_MSB;
+ value = 51000; /* Full-scale is 510 Kelvin */
+ } else {
+ reg = LTC2942_REG_TEMPERATURE_MSB;
+ value = 60000; /* Full-scale is 600 Kelvin */
+ }
+ ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
+ value *= (datar[0] << 8) | datar[1];
+ /* Convert to centidegrees */
+ *val = value / 0xFFFF - 27215;
return ret;
}
@@ -356,8 +380,8 @@ static enum power_supply_property ltc294x_properties[] = {
POWER_SUPPLY_PROP_CHARGE_COUNTER,
POWER_SUPPLY_PROP_CHARGE_NOW,
POWER_SUPPLY_PROP_VOLTAGE_NOW,
- POWER_SUPPLY_PROP_CURRENT_NOW,
POWER_SUPPLY_PROP_TEMP,
+ POWER_SUPPLY_PROP_CURRENT_NOW,
};
static int ltc294x_i2c_remove(struct i2c_client *client)
@@ -374,10 +398,11 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
{
struct power_supply_config psy_cfg = {};
struct ltc294x_info *info;
+ struct device_node *np;
int ret;
u32 prescaler_exp;
s32 r_sense;
- struct device_node *np;
+ u8 status;
info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
if (info == NULL)
@@ -420,21 +445,36 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
(128 / (1 << prescaler_exp));
}
+ /* Read status register to check for LTC2942 */
+ if (info->num_regs == LTC2941_NUM_REGS) {
+ ret = ltc294x_read_regs(client, LTC294X_REG_STATUS, &status, 1);
+ if (ret < 0) {
+ dev_err(&client->dev,
+ "Could not read status register\n");
+ return ret;
+ }
+ if (!(status & LTC2941_REG_STATUS_CHIP_ID))
+ info->num_regs = LTC2942_NUM_REGS;
+ }
+
info->client = client;
info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
info->supply_desc.properties = ltc294x_properties;
- if (info->num_regs >= LTC2943_REG_TEMPERATURE_LSB)
+ switch (info->num_regs) {
+ case LTC2943_NUM_REGS:
info->supply_desc.num_properties =
ARRAY_SIZE(ltc294x_properties);
- else if (info->num_regs >= LTC2943_REG_CURRENT_LSB)
+ break;
+ case LTC2942_NUM_REGS:
info->supply_desc.num_properties =
ARRAY_SIZE(ltc294x_properties) - 1;
- else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
- info->supply_desc.num_properties =
- ARRAY_SIZE(ltc294x_properties) - 2;
- else
+ break;
+ case LTC2941_NUM_REGS:
+ default:
info->supply_desc.num_properties =
ARRAY_SIZE(ltc294x_properties) - 3;
+ break;
+ }
info->supply_desc.get_property = ltc294x_get_property;
info->supply_desc.set_property = ltc294x_set_property;
info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
LTC2942 is pin compatible with LTC2941 providing additional informations about battery voltage and temperature. It can be runtime detected using bit A7 in the Status register. Signed-off-by: Ladislav Michl <ladis@linux-mips.org> --- Changes: - v2: reworked voltage computing to not overflow and keep presision - v3: update devicetree binding documentation .../devicetree/bindings/power/supply/ltc2941.txt | 11 ++-- drivers/power/supply/ltc2941-battery-gauge.c | 76 +++++++++++++++++----- 2 files changed, 64 insertions(+), 23 deletions(-)