[PATCH 2/3] thinkpad_acpi: add support for inhibit_charge

[Nicolo' Piazzalunga <nicolopiazzalunga@gmail.com>]

Lenovo ThinkPad systems support to hold battery charging
via a manual override called Inhibit Charge.

This patch implements that feature and exposes it via the generic
ACPI battery driver in the generic location:

/sys/class/power_supply/BATx/inhibit_charge

Signed-off-by: Ognjen Galic <smclt30p@gmail.com>
Signed-off-by: Thomas Koch <linrunner@gmx.net>
Signed-off-by: Nicolo' Piazzalunga <nicolopiazzalunga@gmail.com>
---
 drivers/platform/x86/thinkpad_acpi.c | 68 ++++++++++++++++++++++++++--
 1 file changed, 63 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 6c7dca3a10d2..a13feb1d7313 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -9319,6 +9319,8 @@ static struct ibm_struct mute_led_driver_data = {
 #define SET_STOP	"BCSS"
 #define GET_DISCHARGE	"BDSG"
 #define SET_DISCHARGE	"BDSS"
+#define GET_INHIBIT	"PSSG"
+#define SET_INHIBIT	"BICS"
 
 enum {
 	BAT_ANY = 0,
@@ -9335,7 +9337,8 @@ enum {
 	/* This is used in the get/set helpers */
 	THRESHOLD_START,
 	THRESHOLD_STOP,
-	FORCE_DISCHARGE
+	FORCE_DISCHARGE,
+	INHIBIT_CHARGE
 };
 
 struct tpacpi_battery_data {
@@ -9344,6 +9347,7 @@ struct tpacpi_battery_data {
 	int charge_stop;
 	int stop_support;
 	int discharge_support;
+	int inhibit_support;
 };
 
 struct tpacpi_battery_driver_data {
@@ -9407,6 +9411,13 @@ static int tpacpi_battery_get(int what, int battery, int *ret)
 		/* The force discharge status is in bit 0 */
 		*ret = *ret & 0x01;
 		return 0;
+	case INHIBIT_CHARGE:
+		/* This is actually reading peak shift state, like tpacpi-bat does */
+		if ACPI_FAILURE(tpacpi_battery_acpi_eval(GET_INHIBIT, ret, battery))
+			return -ENODEV;
+		/* The inhibit charge status is in bit 0 */
+		*ret = *ret & 0x01;
+		return 0;
 	default:
 		pr_crit("wrong parameter: %d", what);
 		return -EINVAL;
@@ -9445,6 +9456,22 @@ static int tpacpi_battery_set(int what, int battery, int value)
 			return -ENODEV;
 		}
 		return 0;
+	case INHIBIT_CHARGE:
+		/* When setting inhibit charge, we set a default value of
+		 * always breaking on AC detach and the effective time is set to
+		 * be permanent.
+		 * The battery ID is in bits 4-5, 2 bits,
+		 * 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;
@@ -9465,6 +9492,8 @@ static int tpacpi_battery_probe(int battery)
 	 * 4) Check for support
 	 * 5) Get the current force discharge status
 	 * 6) Check for support
+	 * 7) Get the current inhibit charge status
+	 * 8) Check for support
 	 */
 	if (acpi_has_method(hkey_handle, GET_START)) {
 		if ACPI_FAILURE(tpacpi_battery_acpi_eval(GET_START, &ret, battery)) {
@@ -9505,12 +9534,17 @@ static int tpacpi_battery_probe(int battery)
 		if (!ACPI_FAILURE(tpacpi_battery_acpi_eval(GET_DISCHARGE, &ret, battery)))
 			/* Support is marked in bit 8 */
 			battery_info.batteries[battery].discharge_support = ret & BIT(8);
+	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, force: %d)",
+	pr_info("battery %d registered (start %d, stop %d, force: %d, inhibit: %d)",
 			battery,
 			battery_info.batteries[battery].charge_start,
 			battery_info.batteries[battery].charge_stop,
-			battery_info.batteries[battery].discharge_support);
+			battery_info.batteries[battery].discharge_support,
+			battery_info.batteries[battery].inhibit_support);
 	return 0;
 }
 
@@ -9576,7 +9610,6 @@ static ssize_t tpacpi_battery_store(int what,
 			return -ENODEV;
 		battery_info.batteries[battery].charge_start = value;
 		return count;
-
 	case THRESHOLD_STOP:
 		if (!battery_info.batteries[battery].stop_support)
 			return -ENODEV;
@@ -9605,6 +9638,15 @@ static ssize_t tpacpi_battery_store(int what,
 		if (tpacpi_battery_set(FORCE_DISCHARGE, battery, value))
 			return -ENODEV;
 		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)
+			return -EINVAL;
+		if (tpacpi_battery_set(INHIBIT_CHARGE, battery, value))
+			return -ENODEV;
+		return count;
 	default:
 		pr_crit("Wrong parameter: %d", what);
 		return -EINVAL;
@@ -9660,6 +9702,13 @@ static ssize_t force_discharge_show(struct device *device,
 	return tpacpi_battery_show(FORCE_DISCHARGE, device, buf);
 }
 
+static ssize_t inhibit_charge_show(struct device *device,
+				struct device_attribute *attr,
+				char *buf)
+{
+	return tpacpi_battery_show(INHIBIT_CHARGE, device, buf);
+}
+
 static ssize_t charge_control_start_threshold_store(struct device *dev,
 				struct device_attribute *attr,
 				const char *buf, size_t count)
@@ -9681,9 +9730,17 @@ static ssize_t force_discharge_store(struct device *dev,
 	return tpacpi_battery_store(FORCE_DISCHARGE, 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 DEVICE_ATTR_RW(charge_control_start_threshold);
 static DEVICE_ATTR_RW(charge_control_end_threshold);
 static DEVICE_ATTR_RW(force_discharge);
+static DEVICE_ATTR_RW(inhibit_charge);
 static struct device_attribute dev_attr_charge_start_threshold = __ATTR(
 	charge_start_threshold,
 	0644,
@@ -9702,7 +9759,8 @@ static struct attribute *tpacpi_battery_attrs[] = {
 	&dev_attr_charge_start_threshold.attr,
 	&dev_attr_charge_stop_threshold.attr,
 	&dev_attr_force_discharge.attr,
-	NULL,
+	&dev_attr_inhibit_charge.attr,
+	NULL
 };
 
 ATTRIBUTE_GROUPS(tpacpi_battery);
-- 
2.25.1