@@ -3,7 +3,7 @@
# X86 Android tablet support Makefile
#
+obj-$(CONFIG_X86_ANDROID_TABLETS) += vexia_atla10_ec.o
obj-$(CONFIG_X86_ANDROID_TABLETS) += x86-android-tablets.o
-
x86-android-tablets-y := core.o dmi.o shared-psy-info.o \
asus.o lenovo.o other.o
new file mode 100644
@@ -0,0 +1,261 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * power_supply class (battery) driver for the I2C attached embedded controller
+ * found on Vexia EDU ATLA 10 (9V version) tablets.
+ *
+ * This is based on the ACPI Battery device in the DSDT which should work
+ * expect that it expects the I2C controller to be enumerated as an ACPI
+ * device and the tablet's BIOS enumerates all LPSS devices as PCI devices
+ * (and changing the LPSS BIOS settings from PCI -> ACPI does not work).
+ *
+ * Copyright (c) 2024 Hans de Goede <hansg@kernel.org>
+ */
+
+#include <linux/bits.h>
+#include <linux/devm-helpers.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/power_supply.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#include <asm/byteorder.h>
+
+/* State field uses ACPI Battery spec status bits */
+#define ACPI_BATTERY_STATE_DISCHARGING BIT(0)
+#define ACPI_BATTERY_STATE_CHARGING BIT(1)
+
+#define ATLA10_EC_BATTERY_STATE_COMMAND 0x87
+#define ATLA10_EC_BATTERY_INFO_COMMAND 0x88
+
+/* From broken ACPI battery device in DSDT */
+#define ATLA10_EC_VOLTAGE_MIN_DESIGN_uV 3750000
+
+/* Update data every 5 seconds */
+#define UPDATE_INTERVAL_JIFFIES (5 * HZ)
+
+struct atla10_ec_battery_state {
+ u8 status; /* Using ACPI Battery spec status bits */
+ u8 capacity; /* Percent */
+ __le16 charge_now_mAh;
+ __le16 voltage_now_mV;
+ __le16 current_now_mA;
+ __le16 charge_full_mAh;
+ __le16 temp; /* centi degrees Celsius */
+} __packed;
+
+struct atla10_ec_battery_info {
+ __le16 charge_full_design_mAh;
+ __le16 voltage_now_mV; /* Should be design voltage, but is not ? */
+ __le16 charge_full_design2_mAh;
+} __packed;
+
+struct atla10_ec_data {
+ struct i2c_client *client;
+ struct power_supply *psy;
+ struct delayed_work work;
+ struct mutex update_lock;
+ struct atla10_ec_battery_info info;
+ struct atla10_ec_battery_state state;
+ bool valid; /* true if state is valid */
+ unsigned long last_update; /* In jiffies */
+};
+
+static int atla10_ec_cmd(struct atla10_ec_data *data, u8 cmd, u8 len, u8 *values)
+{
+ struct device *dev = &data->client->dev;
+ u8 buf[I2C_SMBUS_BLOCK_MAX];
+ int ret;
+
+ ret = i2c_smbus_read_block_data(data->client, cmd, buf);
+ if (ret != len) {
+ dev_err(dev, "I2C command 0x%02x error: %d\n", cmd, ret);
+ return -EIO;
+ }
+
+ memcpy(values, buf, len);
+ return 0;
+}
+
+static int atla10_ec_update(struct atla10_ec_data *data)
+{
+ int ret;
+
+ if (data->valid && time_before(jiffies, data->last_update + UPDATE_INTERVAL_JIFFIES))
+ return 0;
+
+ ret = atla10_ec_cmd(data, ATLA10_EC_BATTERY_STATE_COMMAND,
+ sizeof(data->state), (u8 *)&data->state);
+ if (ret)
+ return ret;
+
+ data->last_update = jiffies;
+ data->valid = true;
+ return 0;
+}
+
+static int atla10_ec_psy_get_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ union power_supply_propval *val)
+{
+ struct atla10_ec_data *data = power_supply_get_drvdata(psy);
+ int charge_now_mAh, charge_full_mAh, ret;
+
+ guard(mutex)(&data->update_lock);
+
+ ret = atla10_ec_update(data);
+ if (ret)
+ return ret;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_STATUS:
+ if (data->state.status & ACPI_BATTERY_STATE_DISCHARGING)
+ val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
+ else if (data->state.status & ACPI_BATTERY_STATE_CHARGING)
+ val->intval = POWER_SUPPLY_STATUS_CHARGING;
+ else if (data->state.capacity == 100)
+ val->intval = POWER_SUPPLY_STATUS_FULL;
+ else
+ val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
+ break;
+ case POWER_SUPPLY_PROP_CAPACITY:
+ val->intval = data->state.capacity;
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_NOW:
+ /*
+ * The EC has a bug where it reports charge-full-design as
+ * charge-now when the battery is full. Clamp charge-now to
+ * charge-full to workaround this.
+ */
+ charge_now_mAh = le16_to_cpu(data->state.charge_now_mAh);
+ charge_full_mAh = le16_to_cpu(data->state.charge_full_mAh);
+ val->intval = min(charge_now_mAh, charge_full_mAh) * 1000;
+ break;
+ case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+ val->intval = le16_to_cpu(data->state.voltage_now_mV) * 1000;
+ break;
+ case POWER_SUPPLY_PROP_CURRENT_NOW:
+ val->intval = le16_to_cpu(data->state.current_now_mA) * 1000;
+ /*
+ * Documentation/ABI/testing/sysfs-class-power specifies
+ * negative current for discharging.
+ */
+ if (data->state.status & ACPI_BATTERY_STATE_DISCHARGING)
+ val->intval = -val->intval;
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_FULL:
+ val->intval = le16_to_cpu(data->state.charge_full_mAh) * 1000;
+ break;
+ case POWER_SUPPLY_PROP_TEMP:
+ val->intval = le16_to_cpu(data->state.temp) / 10;
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+ val->intval = le16_to_cpu(data->info.charge_full_design_mAh) * 1000;
+ break;
+ case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
+ val->intval = ATLA10_EC_VOLTAGE_MIN_DESIGN_uV;
+ break;
+ case POWER_SUPPLY_PROP_PRESENT:
+ val->intval = 1;
+ break;
+ case POWER_SUPPLY_PROP_TECHNOLOGY:
+ val->intval = POWER_SUPPLY_TECHNOLOGY_LIPO;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static void atla10_ec_external_power_changed_work(struct work_struct *work)
+{
+ struct atla10_ec_data *data = container_of(work, struct atla10_ec_data, work.work);
+
+ dev_dbg(&data->client->dev, "External power changed\n");
+ data->valid = false;
+ power_supply_changed(data->psy);
+}
+
+static void atla10_ec_external_power_changed(struct power_supply *psy)
+{
+ struct atla10_ec_data *data = power_supply_get_drvdata(psy);
+
+ /* After charger plug in/out wait 0.5s for things to stabilize */
+ mod_delayed_work(system_wq, &data->work, HZ / 2);
+}
+
+static const enum power_supply_property atla10_ec_psy_props[] = {
+ POWER_SUPPLY_PROP_STATUS,
+ POWER_SUPPLY_PROP_CAPACITY,
+ POWER_SUPPLY_PROP_CHARGE_NOW,
+ POWER_SUPPLY_PROP_VOLTAGE_NOW,
+ POWER_SUPPLY_PROP_CURRENT_NOW,
+ POWER_SUPPLY_PROP_CHARGE_FULL,
+ POWER_SUPPLY_PROP_TEMP,
+ POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
+ POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
+ POWER_SUPPLY_PROP_PRESENT,
+ POWER_SUPPLY_PROP_TECHNOLOGY,
+};
+
+static const struct power_supply_desc atla10_ec_psy_desc = {
+ .name = "atla10_ec_battery",
+ .type = POWER_SUPPLY_TYPE_BATTERY,
+ .properties = atla10_ec_psy_props,
+ .num_properties = ARRAY_SIZE(atla10_ec_psy_props),
+ .get_property = atla10_ec_psy_get_property,
+ .external_power_changed = atla10_ec_external_power_changed,
+};
+
+static int atla10_ec_probe(struct i2c_client *client)
+{
+ struct power_supply_config psy_cfg = { };
+ struct device *dev = &client->dev;
+ struct atla10_ec_data *data;
+ int ret;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ psy_cfg.drv_data = data;
+ data->client = client;
+
+ ret = devm_mutex_init(dev, &data->update_lock);
+ if (ret)
+ return ret;
+
+ ret = devm_delayed_work_autocancel(dev, &data->work,
+ atla10_ec_external_power_changed_work);
+ if (ret)
+ return ret;
+
+ ret = atla10_ec_cmd(data, ATLA10_EC_BATTERY_INFO_COMMAND,
+ sizeof(data->info), (u8 *)&data->info);
+ if (ret)
+ return ret;
+
+ data->psy = devm_power_supply_register(dev, &atla10_ec_psy_desc, &psy_cfg);
+ return PTR_ERR_OR_ZERO(data->psy);
+}
+
+static const struct i2c_device_id atla10_ec_id_table[] = {
+ { "vexia_atla10_ec" },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, atla10_ec_id_table);
+
+static struct i2c_driver atla10_ec_driver = {
+ .driver = {
+ .name = "vexia_atla10_ec",
+ },
+ .probe = atla10_ec_probe,
+ .id_table = atla10_ec_id_table,
+};
+module_i2c_driver(atla10_ec_driver);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_DESCRIPTION("Battery driver for Vexia EDU ATLA 10 tablet EC");
+MODULE_LICENSE("GPL");