platform/x86: Battery charge mode in toshiba_acpi (internals)

This commit adds the internal functions to control the Toshiba laptop.

Unlike for example ThinkPads where this control is granular here it is
just off/on. When off it charges to 100%. When on it charges to about 80%.

Controlling this setting is done via HCI register 0x00ba. Setting to value
1 will result in limiting the charing to 80% of the battery capacity,
while setting it to 0 will allow charging to 100%.

Reading the current state is a bit weird, and needs a 1 set in the last
position of the query for whatever reason. In addition, the read may
return 0x8d20 (Data not available) rarely, so a retry mechanism is needed.

According to the Windows program used to control the feature the setting
will not take effect until the battery has been discharged to around 50%.
However, in my testing it takes effect as soon as the charge drops below
80%. On Windows Toshiba branded this feature as "Eco charging".
Signed-off-by: Arvid Norlander <lkml@vorpal.se>
Link: https://lore.kernel.org/r/20220902180037.1728546-2-lkml@vorpal.seReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/toshiba_acpi.c

@@ -114,6 +114,7 @@ MODULE_LICENSE("GPL");
 #define HCI_KBD_ILLUMINATION		0x0095
 #define HCI_ECO_MODE			0x0097
 #define HCI_ACCELEROMETER2		0x00a6
+#define HCI_BATTERY_CHARGE_MODE		0x00ba
 #define HCI_SYSTEM_INFO			0xc000
 #define SCI_PANEL_POWER_ON		0x010d
 #define SCI_ILLUMINATION		0x014e
@@ -207,6 +208,7 @@ struct toshiba_acpi_dev {
 	unsigned int usb_three_supported:1;
 	unsigned int wwan_supported:1;
 	unsigned int cooling_method_supported:1;
+	unsigned int battery_charge_mode_supported:1;
 	unsigned int sysfs_created:1;
 	unsigned int special_functions;
 
@@ -1283,6 +1285,69 @@ static int toshiba_cooling_method_set(struct toshiba_acpi_dev *dev, u32 state)
 	return (result == TOS_SUCCESS || result == TOS_SUCCESS2) ? 0 : -EIO;
 }
 
+/* Battery charge control */
+static void toshiba_battery_charge_mode_available(struct toshiba_acpi_dev *dev)
+{
+	u32 in[TCI_WORDS] = { HCI_GET, HCI_BATTERY_CHARGE_MODE, 0, 0, 0, 0 };
+	u32 out[TCI_WORDS];
+	acpi_status status;
+
+	dev->battery_charge_mode_supported = 0;
+
+	status = tci_raw(dev, in, out);
+	if (ACPI_FAILURE(status)) {
+		pr_err("ACPI call to get Battery Charge Mode failed\n");
+		return;
+	}
+
+	if (out[0] != TOS_SUCCESS && out[0] != TOS_SUCCESS2)
+		return;
+
+	dev->battery_charge_mode_supported = 1;
+}
+
+static int toshiba_battery_charge_mode_get(struct toshiba_acpi_dev *dev, u32 *state)
+{
+	u32 in[TCI_WORDS] = { HCI_GET, HCI_BATTERY_CHARGE_MODE, 0, 0, 0, 0x1 };
+	u32 out[TCI_WORDS];
+	int retries = 3;
+
+	do {
+		acpi_status status = tci_raw(dev, in, out);
+
+		if (ACPI_FAILURE(status))
+			pr_err("ACPI call to get Battery Charge Mode failed\n");
+		switch (out[0]) {
+		case TOS_SUCCESS:
+		case TOS_SUCCESS2:
+			*state = out[2];
+			return 0;
+		case TOS_NOT_SUPPORTED:
+			return -ENODEV;
+		case TOS_DATA_NOT_AVAILABLE:
+			retries--;
+			break;
+		default:
+			return -EIO;
+		}
+	} while (retries);
+
+	return -EIO;
+}
+
+static int toshiba_battery_charge_mode_set(struct toshiba_acpi_dev *dev, u32 state)
+{
+	u32 result = hci_write(dev, HCI_BATTERY_CHARGE_MODE, state);
+
+	if (result == TOS_FAILURE)
+		pr_err("ACPI call to set Battery Charge Mode failed\n");
+
+	if (result == TOS_NOT_SUPPORTED)
+		return -ENODEV;
+
+	return (result == TOS_SUCCESS || result == TOS_SUCCESS2) ? 0 : -EIO;
+}
+
 /* Transflective Backlight */
 static int get_tr_backlight_status(struct toshiba_acpi_dev *dev, u32 *status)
 {
@@ -3022,6 +3087,8 @@ static void print_supported_features(struct toshiba_acpi_dev *dev)
 		pr_cont(" wwan");
 	if (dev->cooling_method_supported)
 		pr_cont(" cooling-method");
+	if (dev->battery_charge_mode_supported)
+		pr_cont(" battery-charge-mode");
 
 	pr_cont("\n");
 }
@@ -3249,6 +3316,8 @@ static int toshiba_acpi_add(struct acpi_device *acpi_dev)
 
 	toshiba_cooling_method_available(dev);
 
+	toshiba_battery_charge_mode_available(dev);
+
 	print_supported_features(dev);
 
 	ret = sysfs_create_group(&dev->acpi_dev->dev.kobj,