From: Michał Mirosław <mirq-linux@rere.qmqm.pl>

Add support for charger detection capabilities found in the embedded
controller of ASUS Transformer devices.

Suggested-by: Maxim Schwalm <maxim.schwalm@gmail.com>
Suggested-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
---
 drivers/power/supply/Kconfig                  |  11 +
 drivers/power/supply/Makefile                 |   1 +
 .../supply/asus-transformer-ec-charger.c      | 193 ++++++++++++++++++
 3 files changed, 205 insertions(+)
 create mode 100644 drivers/power/supply/asus-transformer-ec-charger.c

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index 3c46b412632d..56800aab82f9 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -497,6 +497,17 @@ config CHARGER_88PM860X
 	help
 	  Say Y here to enable charger for Marvell 88PM860x chip.
 
+config CHARGER_ASUS_TRANSFORMER_EC
+	tristate "Asus Transformer's charger driver"
+	depends on MFD_ASUS_TRANSFORMER_EC
+	help
+	  Say Y here to enable support AC plug detection on Asus Transformer
+	  Dock.
+
+	  This sub-driver supports charger detection mechanism found in Asus
+	  Transformer tablets and mobile docks and controlled by special
+	  embedded controller.
+
 config CHARGER_PF1550
 	tristate "NXP PF1550 battery charger driver"
 	depends on MFD_PF1550
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index aa5e6b05b018..24679f09bb61 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -68,6 +68,7 @@ obj-$(CONFIG_CHARGER_RT9471)	+= rt9471.o
 obj-$(CONFIG_CHARGER_RT9756)	+= rt9756.o
 obj-$(CONFIG_BATTERY_TWL4030_MADC)	+= twl4030_madc_battery.o
 obj-$(CONFIG_CHARGER_88PM860X)	+= 88pm860x_charger.o
+obj-$(CONFIG_CHARGER_ASUS_TRANSFORMER_EC)	+= asus-transformer-ec-charger.o
 obj-$(CONFIG_CHARGER_PF1550)	+= pf1550-charger.o
 obj-$(CONFIG_BATTERY_RX51)	+= rx51_battery.o
 obj-$(CONFIG_AB8500_BM)		+= ab8500_bmdata.o ab8500_charger.o ab8500_fg.o ab8500_btemp.o ab8500_chargalg.o
diff --git a/drivers/power/supply/asus-transformer-ec-charger.c b/drivers/power/supply/asus-transformer-ec-charger.c
new file mode 100644
index 000000000000..de01f0bf2fd7
--- /dev/null
+++ b/drivers/power/supply/asus-transformer-ec-charger.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/err.h>
+#include <linux/mfd/asus-transformer-ec.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/property.h>
+
+struct asus_ec_charger_data {
+	struct notifier_block nb;
+	const struct asusec_info *ec;
+	struct power_supply *psy;
+	struct power_supply_desc psy_desc;
+};
+
+static enum power_supply_property asus_ec_charger_properties[] = {
+	POWER_SUPPLY_PROP_USB_TYPE,
+	POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR,
+	POWER_SUPPLY_PROP_ONLINE,
+	POWER_SUPPLY_PROP_MODEL_NAME,
+};
+
+static int asus_ec_charger_get_property(struct power_supply *psy,
+					enum power_supply_property psp,
+					union power_supply_propval *val)
+{
+	struct asus_ec_charger_data *priv = power_supply_get_drvdata(psy);
+	enum power_supply_usb_type psu;
+	int ret;
+	u64 ctl;
+
+	ret = asus_ec_get_ctl(priv->ec, &ctl);
+	if (ret)
+		return ret;
+
+	switch (ctl & (ASUSEC_CTL_FULL_POWER_SOURCE | ASUSEC_CTL_DIRECT_POWER_SOURCE)) {
+	case ASUSEC_CTL_FULL_POWER_SOURCE:
+		psu = POWER_SUPPLY_USB_TYPE_CDP;	/* DOCK */
+		break;
+	case ASUSEC_CTL_DIRECT_POWER_SOURCE:
+		psu = POWER_SUPPLY_USB_TYPE_SDP;	/* USB */
+		break;
+	case 0:
+		psu = POWER_SUPPLY_USB_TYPE_UNKNOWN;	/* no power source connected */
+		break;
+	default:
+		psu = POWER_SUPPLY_USB_TYPE_ACA;	/* power adapter */
+		break;
+	}
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_ONLINE:
+		val->intval = psu != POWER_SUPPLY_USB_TYPE_UNKNOWN;
+		return 0;
+
+	case POWER_SUPPLY_PROP_USB_TYPE:
+		val->intval = psu;
+		return 0;
+
+	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
+		if (ctl & ASUSEC_CTL_TEST_DISCHARGE)
+			val->intval = POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE;
+		else if (ctl & ASUSEC_CTL_USB_CHARGE)
+			val->intval = POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO;
+		else
+			val->intval = POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE;
+		return 0;
+
+	case POWER_SUPPLY_PROP_MODEL_NAME:
+		val->strval = priv->ec->model;
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int asus_ec_charger_set_property(struct power_supply *psy,
+					enum power_supply_property psp,
+					const union power_supply_propval *val)
+{
+	struct asus_ec_charger_data *priv = power_supply_get_drvdata(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
+		switch ((enum power_supply_charge_behaviour)val->intval) {
+		case POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO:
+			return asus_ec_update_ctl(priv->ec,
+				ASUSEC_CTL_TEST_DISCHARGE | ASUSEC_CTL_USB_CHARGE,
+				ASUSEC_CTL_USB_CHARGE);
+
+		case POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE:
+			return asus_ec_clear_ctl_bits(priv->ec,
+				ASUSEC_CTL_TEST_DISCHARGE | ASUSEC_CTL_USB_CHARGE);
+
+		case POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE:
+			return asus_ec_update_ctl(priv->ec,
+				ASUSEC_CTL_TEST_DISCHARGE | ASUSEC_CTL_USB_CHARGE,
+				ASUSEC_CTL_TEST_DISCHARGE);
+		default:
+			return -EINVAL;
+		}
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int asus_ec_charger_property_is_writeable(struct power_supply *psy,
+						 enum power_supply_property psp)
+{
+	switch (psp) {
+	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct power_supply_desc asus_ec_charger_desc = {
+	.name = "asus-ec-charger",
+	.type = POWER_SUPPLY_TYPE_USB,
+	.charge_behaviours = BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO) |
+			     BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE) |
+			     BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE),
+	.usb_types = BIT(POWER_SUPPLY_USB_TYPE_UNKNOWN) |
+		     BIT(POWER_SUPPLY_USB_TYPE_SDP) |
+		     BIT(POWER_SUPPLY_USB_TYPE_CDP) |
+		     BIT(POWER_SUPPLY_USB_TYPE_ACA),
+	.properties = asus_ec_charger_properties,
+	.num_properties = ARRAY_SIZE(asus_ec_charger_properties),
+	.get_property = asus_ec_charger_get_property,
+	.set_property = asus_ec_charger_set_property,
+	.property_is_writeable = asus_ec_charger_property_is_writeable,
+	.no_thermal = true,
+};
+
+static int asus_ec_charger_notify(struct notifier_block *nb,
+				  unsigned long action, void *data)
+{
+	struct asus_ec_charger_data *priv =
+		container_of(nb, struct asus_ec_charger_data, nb);
+
+	switch (action) {
+	case ASUSEC_SMI_ACTION(POWER_NOTIFY):
+	case ASUSEC_SMI_ACTION(ADAPTER_EVENT):
+		power_supply_changed(priv->psy);
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int asus_ec_charger_probe(struct platform_device *pdev)
+{
+	struct asus_ec_charger_data *priv;
+	struct device *dev = &pdev->dev;
+	struct power_supply_config cfg = { };
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+	priv->ec = cell_to_ec(pdev);
+
+	cfg.fwnode = dev_fwnode(dev->parent);
+	cfg.drv_data = priv;
+
+	memcpy(&priv->psy_desc, &asus_ec_charger_desc, sizeof(priv->psy_desc));
+	priv->psy_desc.name = devm_kasprintf(dev, GFP_KERNEL, "%s-charger",
+					     priv->ec->name);
+
+	priv->psy = devm_power_supply_register(dev, &priv->psy_desc, &cfg);
+	if (IS_ERR(priv->psy))
+		return dev_err_probe(dev, PTR_ERR(priv->psy),
+				     "Failed to register power supply\n");
+
+	priv->nb.notifier_call = asus_ec_charger_notify;
+
+	return devm_asus_ec_register_notifier(pdev, &priv->nb);
+}
+
+static struct platform_driver asus_ec_charger_driver = {
+	.driver.name = "asus-transformer-ec-charger",
+	.probe = asus_ec_charger_probe,
+};
+module_platform_driver(asus_ec_charger_driver);
+
+MODULE_AUTHOR("Michał Mirosław <mirq-linux@rere.qmqm.pl>");
+MODULE_DESCRIPTION("ASUS Transformer Pad battery charger driver");
+MODULE_LICENSE("GPL");
-- 
2.51.0

Hi,

On Wed, Mar 04, 2026 at 08:57:51PM +0200, Svyatoslav Ryhel wrote:
> From: Michał Mirosław <mirq-linux@rere.qmqm.pl>
> 
> Add support for charger detection capabilities found in the embedded
> controller of ASUS Transformer devices.
> 
> Suggested-by: Maxim Schwalm <maxim.schwalm@gmail.com>
> Suggested-by: Svyatoslav Ryhel <clamor95@gmail.com>
> Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
> Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
> ---

Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>

-- Sebastian

>  drivers/power/supply/Kconfig                  |  11 +
>  drivers/power/supply/Makefile                 |   1 +
>  .../supply/asus-transformer-ec-charger.c      | 193 ++++++++++++++++++
>  3 files changed, 205 insertions(+)
>  create mode 100644 drivers/power/supply/asus-transformer-ec-charger.c
> 
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index 3c46b412632d..56800aab82f9 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -497,6 +497,17 @@ config CHARGER_88PM860X
>  	help
>  	  Say Y here to enable charger for Marvell 88PM860x chip.
>  
> +config CHARGER_ASUS_TRANSFORMER_EC
> +	tristate "Asus Transformer's charger driver"
> +	depends on MFD_ASUS_TRANSFORMER_EC
> +	help
> +	  Say Y here to enable support AC plug detection on Asus Transformer
> +	  Dock.
> +
> +	  This sub-driver supports charger detection mechanism found in Asus
> +	  Transformer tablets and mobile docks and controlled by special
> +	  embedded controller.
> +
>  config CHARGER_PF1550
>  	tristate "NXP PF1550 battery charger driver"
>  	depends on MFD_PF1550
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
> index aa5e6b05b018..24679f09bb61 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -68,6 +68,7 @@ obj-$(CONFIG_CHARGER_RT9471)	+= rt9471.o
>  obj-$(CONFIG_CHARGER_RT9756)	+= rt9756.o
>  obj-$(CONFIG_BATTERY_TWL4030_MADC)	+= twl4030_madc_battery.o
>  obj-$(CONFIG_CHARGER_88PM860X)	+= 88pm860x_charger.o
> +obj-$(CONFIG_CHARGER_ASUS_TRANSFORMER_EC)	+= asus-transformer-ec-charger.o
>  obj-$(CONFIG_CHARGER_PF1550)	+= pf1550-charger.o
>  obj-$(CONFIG_BATTERY_RX51)	+= rx51_battery.o
>  obj-$(CONFIG_AB8500_BM)		+= ab8500_bmdata.o ab8500_charger.o ab8500_fg.o ab8500_btemp.o ab8500_chargalg.o
> diff --git a/drivers/power/supply/asus-transformer-ec-charger.c b/drivers/power/supply/asus-transformer-ec-charger.c
> new file mode 100644
> index 000000000000..de01f0bf2fd7
> --- /dev/null
> +++ b/drivers/power/supply/asus-transformer-ec-charger.c
> @@ -0,0 +1,193 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +#include <linux/err.h>
> +#include <linux/mfd/asus-transformer-ec.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/power_supply.h>
> +#include <linux/property.h>
> +
> +struct asus_ec_charger_data {
> +	struct notifier_block nb;
> +	const struct asusec_info *ec;
> +	struct power_supply *psy;
> +	struct power_supply_desc psy_desc;
> +};
> +
> +static enum power_supply_property asus_ec_charger_properties[] = {
> +	POWER_SUPPLY_PROP_USB_TYPE,
> +	POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR,
> +	POWER_SUPPLY_PROP_ONLINE,
> +	POWER_SUPPLY_PROP_MODEL_NAME,
> +};
> +
> +static int asus_ec_charger_get_property(struct power_supply *psy,
> +					enum power_supply_property psp,
> +					union power_supply_propval *val)
> +{
> +	struct asus_ec_charger_data *priv = power_supply_get_drvdata(psy);
> +	enum power_supply_usb_type psu;
> +	int ret;
> +	u64 ctl;
> +
> +	ret = asus_ec_get_ctl(priv->ec, &ctl);
> +	if (ret)
> +		return ret;
> +
> +	switch (ctl & (ASUSEC_CTL_FULL_POWER_SOURCE | ASUSEC_CTL_DIRECT_POWER_SOURCE)) {
> +	case ASUSEC_CTL_FULL_POWER_SOURCE:
> +		psu = POWER_SUPPLY_USB_TYPE_CDP;	/* DOCK */
> +		break;
> +	case ASUSEC_CTL_DIRECT_POWER_SOURCE:
> +		psu = POWER_SUPPLY_USB_TYPE_SDP;	/* USB */
> +		break;
> +	case 0:
> +		psu = POWER_SUPPLY_USB_TYPE_UNKNOWN;	/* no power source connected */
> +		break;
> +	default:
> +		psu = POWER_SUPPLY_USB_TYPE_ACA;	/* power adapter */
> +		break;
> +	}
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_ONLINE:
> +		val->intval = psu != POWER_SUPPLY_USB_TYPE_UNKNOWN;
> +		return 0;
> +
> +	case POWER_SUPPLY_PROP_USB_TYPE:
> +		val->intval = psu;
> +		return 0;
> +
> +	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
> +		if (ctl & ASUSEC_CTL_TEST_DISCHARGE)
> +			val->intval = POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE;
> +		else if (ctl & ASUSEC_CTL_USB_CHARGE)
> +			val->intval = POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO;
> +		else
> +			val->intval = POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE;
> +		return 0;
> +
> +	case POWER_SUPPLY_PROP_MODEL_NAME:
> +		val->strval = priv->ec->model;
> +		return 0;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int asus_ec_charger_set_property(struct power_supply *psy,
> +					enum power_supply_property psp,
> +					const union power_supply_propval *val)
> +{
> +	struct asus_ec_charger_data *priv = power_supply_get_drvdata(psy);
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
> +		switch ((enum power_supply_charge_behaviour)val->intval) {
> +		case POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO:
> +			return asus_ec_update_ctl(priv->ec,
> +				ASUSEC_CTL_TEST_DISCHARGE | ASUSEC_CTL_USB_CHARGE,
> +				ASUSEC_CTL_USB_CHARGE);
> +
> +		case POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE:
> +			return asus_ec_clear_ctl_bits(priv->ec,
> +				ASUSEC_CTL_TEST_DISCHARGE | ASUSEC_CTL_USB_CHARGE);
> +
> +		case POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE:
> +			return asus_ec_update_ctl(priv->ec,
> +				ASUSEC_CTL_TEST_DISCHARGE | ASUSEC_CTL_USB_CHARGE,
> +				ASUSEC_CTL_TEST_DISCHARGE);
> +		default:
> +			return -EINVAL;
> +		}
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int asus_ec_charger_property_is_writeable(struct power_supply *psy,
> +						 enum power_supply_property psp)
> +{
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static const struct power_supply_desc asus_ec_charger_desc = {
> +	.name = "asus-ec-charger",
> +	.type = POWER_SUPPLY_TYPE_USB,
> +	.charge_behaviours = BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO) |
> +			     BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE) |
> +			     BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE),
> +	.usb_types = BIT(POWER_SUPPLY_USB_TYPE_UNKNOWN) |
> +		     BIT(POWER_SUPPLY_USB_TYPE_SDP) |
> +		     BIT(POWER_SUPPLY_USB_TYPE_CDP) |
> +		     BIT(POWER_SUPPLY_USB_TYPE_ACA),
> +	.properties = asus_ec_charger_properties,
> +	.num_properties = ARRAY_SIZE(asus_ec_charger_properties),
> +	.get_property = asus_ec_charger_get_property,
> +	.set_property = asus_ec_charger_set_property,
> +	.property_is_writeable = asus_ec_charger_property_is_writeable,
> +	.no_thermal = true,
> +};
> +
> +static int asus_ec_charger_notify(struct notifier_block *nb,
> +				  unsigned long action, void *data)
> +{
> +	struct asus_ec_charger_data *priv =
> +		container_of(nb, struct asus_ec_charger_data, nb);
> +
> +	switch (action) {
> +	case ASUSEC_SMI_ACTION(POWER_NOTIFY):
> +	case ASUSEC_SMI_ACTION(ADAPTER_EVENT):
> +		power_supply_changed(priv->psy);
> +		break;
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static int asus_ec_charger_probe(struct platform_device *pdev)
> +{
> +	struct asus_ec_charger_data *priv;
> +	struct device *dev = &pdev->dev;
> +	struct power_supply_config cfg = { };
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, priv);
> +	priv->ec = cell_to_ec(pdev);
> +
> +	cfg.fwnode = dev_fwnode(dev->parent);
> +	cfg.drv_data = priv;
> +
> +	memcpy(&priv->psy_desc, &asus_ec_charger_desc, sizeof(priv->psy_desc));
> +	priv->psy_desc.name = devm_kasprintf(dev, GFP_KERNEL, "%s-charger",
> +					     priv->ec->name);
> +
> +	priv->psy = devm_power_supply_register(dev, &priv->psy_desc, &cfg);
> +	if (IS_ERR(priv->psy))
> +		return dev_err_probe(dev, PTR_ERR(priv->psy),
> +				     "Failed to register power supply\n");
> +
> +	priv->nb.notifier_call = asus_ec_charger_notify;
> +
> +	return devm_asus_ec_register_notifier(pdev, &priv->nb);
> +}
> +
> +static struct platform_driver asus_ec_charger_driver = {
> +	.driver.name = "asus-transformer-ec-charger",
> +	.probe = asus_ec_charger_probe,
> +};
> +module_platform_driver(asus_ec_charger_driver);
> +
> +MODULE_AUTHOR("Michał Mirosław <mirq-linux@rere.qmqm.pl>");
> +MODULE_DESCRIPTION("ASUS Transformer Pad battery charger driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.51.0
> 
>