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// 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");
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