[PATCH 1/3] thinkpad_acpi: add support for inhibit_charge

[Ognjen Galic <smclt30p-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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 <smclt30p-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 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
+		 * 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)
+			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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