The battery device communicates battery state to the guest via ACPI.
It supports two modes of operation:
1. QMP control mode (default): Battery state is controlled programmatically
via QMP commands, making the device deterministic and migration-safe.
2. Host mirroring mode (optional): The device reflects the host's battery
state from sysfs. Probing occurs on guest ACPI requests and at timed
intervals (default 2 seconds, configurable via 'probe_interval' property
in milliseconds). State changes trigger ACPI notifications to the guest.
Properties:
- 'use-qmp': Enable QMP control mode (default: true)
- 'enable-sysfs': Enable host battery mirroring (default: false)
- 'probe_interval': Probe interval in ms for sysfs mode (default: 2000)
- 'sysfs_path': Override default sysfs path /sys/class/power_supply/
The device implements the ACPI_DEV_AML_IF interface to generate its
own AML code, placing the BAT0 device directly under \_SB scope as
per ACPI specification.
QMP commands:
- battery-set-state: Set battery state (present, charging, capacity, rate)
- query-battery: Query current battery state
This allows testing without host battery access and provides a stable
interface for virtualization management systems.
Signed-off-by: Leonid Bloch <lb.workbox@gmail.com>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
---
MAINTAINERS | 6 +
docs/specs/battery.rst | 225 ++++++++
docs/specs/index.rst | 1 +
hw/acpi/Kconfig | 4 +
hw/acpi/battery.c | 735 +++++++++++++++++++++++++++
hw/acpi/meson.build | 1 +
hw/acpi/trace-events | 5 +
hw/i386/Kconfig | 1 +
hw/i386/acpi-build.c | 1 +
include/hw/acpi/acpi_dev_interface.h | 1 +
include/hw/acpi/battery.h | 33 ++
qapi/acpi.json | 73 +++
12 files changed, 1086 insertions(+)
create mode 100644 docs/specs/battery.rst
create mode 100644 hw/acpi/battery.c
create mode 100644 include/hw/acpi/battery.h
diff --git a/MAINTAINERS b/MAINTAINERS
index a64b5b849b..eb71a4a4b7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2928,6 +2928,12 @@ F: hw/vmapple/*
F: include/hw/vmapple/*
F: docs/system/arm/vmapple.rst
+Battery
+M: Leonid Bloch <lb.workbox@gmail.com>
+S: Maintained
+F: hw/acpi/battery.*
+F: docs/specs/battery.rst
+
Subsystems
----------
Overall Audio backends
diff --git a/docs/specs/battery.rst b/docs/specs/battery.rst
new file mode 100644
index 0000000000..e426b91ea5
--- /dev/null
+++ b/docs/specs/battery.rst
@@ -0,0 +1,225 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+==============
+Battery Device
+==============
+
+The battery device provides battery state information to the guest. It supports
+two operating modes:
+
+1. **QMP Control Mode** (default): Battery state is controlled via QMP commands,
+ providing deterministic control for testing and migration safety.
+2. **Sysfs Mode**: Battery state mirrors the host's physical battery, useful
+ for desktop virtualization where the guest should see the host's battery.
+
+Configuration
+-------------
+
+The battery device is created as an ISA device using ``-device battery``.
+
+Operating Modes
+~~~~~~~~~~~~~~~
+
+**QMP Control Mode** (``use-qmp=true``, default)
+ Battery state is controlled via QMP commands. This mode is recommended for:
+
+ * Production environments requiring migration support
+ * Testing with predictable battery states
+ * Environments without host battery access
+ * Security-sensitive deployments
+
+**Sysfs Mode** (``enable-sysfs=true``)
+ Battery mirrors the host's physical battery. This mode is useful for:
+
+ * Desktop virtualization on laptops
+ * Development and testing with real battery behavior
+
+ Note: Sysfs mode reads host files and runs timers, which may impact
+ security and migration. Use with caution in production.
+
+Properties
+~~~~~~~~~~
+
+``ioport`` (default: 0x530)
+ I/O port base address for the battery device registers.
+
+``use-qmp`` (default: true)
+ Enable QMP control mode. When true, battery state is controlled via
+ QMP commands. Cannot be used together with ``enable-sysfs=true``.
+
+``enable-sysfs`` (default: false)
+ Enable sysfs mode to mirror the host's battery. Cannot be used together
+ with ``use-qmp=true``.
+
+``probe_interval`` (default: 2000)
+ Time interval between periodic probes in milliseconds (sysfs mode only).
+ A zero value disables the periodic probes, and makes the battery state
+ updates occur on guest requests only.
+
+``sysfs_path`` (default: auto-detected)
+ Path to the host's battery sysfs directory (sysfs mode only). If not
+ specified, the device will automatically detect the battery from
+ ``/sys/class/power_supply/``. This property allows overriding the default
+ path if:
+
+ * The sysfs path differs from the standard location
+ * A different battery needs to be probed
+ * A "fake" host battery is to be provided for testing
+
+Host Battery Detection
+----------------------
+
+The host's battery information is taken from the sysfs battery data,
+located in::
+
+ /sys/class/power_supply/[device of type "Battery"]
+
+The device automatically scans for the first available battery device
+with type "Battery" in the power_supply directory.
+
+ACPI Interface
+--------------
+
+The battery device exposes itself as an ACPI battery device with:
+
+* **_HID**: ``PNP0C0A`` (Control Method Battery)
+* **Device path**: ``\_SB.BAT0``
+
+The device implements standard ACPI battery methods:
+
+``_STA`` (Status)
+ Returns the battery presence status.
+
+``_BIF`` (Battery Information)
+ Returns static battery information including design capacity,
+ technology, and model information.
+
+``_BST`` (Battery Status)
+ Returns dynamic battery status including current state
+ (charging/discharging), present rate, and remaining capacity.
+
+I/O Interface
+-------------
+
+The battery device exposes 12 bytes of I/O space at the configured
+I/O port address with the following layout:
+
+* **Bytes 0-3**: Battery state (DWORD)
+
+ * 1 = Discharging
+ * 2 = Charging
+
+* **Bytes 4-7**: Battery rate (DWORD)
+
+ Current charge/discharge rate normalized to design capacity.
+
+* **Bytes 8-11**: Battery charge (DWORD)
+
+ Current battery charge level normalized to design capacity.
+
+All values are normalized where the design capacity equals 10000 units.
+Unknown values are represented as 0xFFFFFFFF.
+
+ACPI Notifications
+------------------
+
+The battery device generates ACPI notifications through GPE events:
+
+* **GPE._E07**: Device Check (0x01) - Battery insertion/removal
+* **GPE._E08**: Status Change (0x80) - Battery state change
+* **GPE._E09**: Information Change (0x81) - Battery information update
+
+QMP Commands
+------------
+
+When using QMP control mode (default), the following commands are available:
+
+``battery-set-state``
+ Set the battery state. Parameters:
+
+ * ``present``: Whether the battery is present (boolean)
+ * ``charging``: Whether the battery is charging (boolean)
+ * ``discharging``: Whether the battery is discharging (boolean)
+ * ``charge-percent``: Battery charge percentage 0-100 (integer)
+ * ``rate``: Charge/discharge rate in mW (optional integer)
+
+ Example::
+
+ -> { "execute": "battery-set-state",
+ "arguments": { "state": {
+ "present": true,
+ "charging": true,
+ "discharging": false,
+ "charge-percent": 85,
+ "rate": 500
+ }}}
+ <- { "return": {} }
+
+``query-battery``
+ Query the current battery state. Returns the same fields as above.
+
+ Example::
+
+ -> { "execute": "query-battery" }
+ <- { "return": {
+ "present": true,
+ "charging": true,
+ "discharging": false,
+ "charge-percent": 85,
+ "rate": 500,
+ "design-capacity": 10000
+ }}
+
+Examples
+--------
+
+QMP control mode (default - recommended)::
+
+ # Start with QMP control
+ qemu-system-x86_64 -device battery -qmp tcp:localhost:4444,server,wait=off
+
+ # From another terminal, set battery state via QMP:
+ echo '{"execute":"qmp_capabilities"}
+ {"execute":"battery-set-state",
+ "arguments":{"state":{"present":true,"charging":false,
+ "discharging":true,"charge-percent":42,
+ "rate":500}}}' | \
+ nc -N localhost 4444
+
+Sysfs mode (mirror host battery)::
+
+ # Enable sysfs mode to mirror host battery
+ qemu-system-x86_64 -device battery,use-qmp=false,enable-sysfs=true
+
+ # Custom probe interval (5 seconds)
+ qemu-system-x86_64 -device battery,use-qmp=false,enable-sysfs=true,probe_interval=5000
+
+ # Specific battery path
+ qemu-system-x86_64 -device battery,use-qmp=false,enable-sysfs=true,sysfs_path=/sys/class/power_supply/BAT1
+
+Testing with fake battery::
+
+ # Create fake battery files for testing
+ mkdir -p /tmp/fake_battery
+ echo "Battery" > /tmp/fake_battery/type
+ echo "Discharging" > /tmp/fake_battery/status
+ echo "50" > /tmp/fake_battery/capacity
+ echo "1500000" > /tmp/fake_battery/energy_now # Current energy in μWh
+ echo "3000000" > /tmp/fake_battery/energy_full # Full capacity in μWh
+ echo "500000" > /tmp/fake_battery/power_now # Current power in μW
+
+ # Use fake battery in sysfs mode
+ qemu-system-x86_64 -device battery,use-qmp=false,enable-sysfs=true,sysfs_path=/tmp/fake_battery
+
+ # Update battery state while VM is running (from another terminal)
+ # Change to 75% charging:
+ echo "Charging" > /tmp/fake_battery/status
+ echo "75" > /tmp/fake_battery/capacity
+ echo "2250000" > /tmp/fake_battery/energy_now # 75% of 3000000
+ echo "500000" > /tmp/fake_battery/power_now # Charging rate (500 mW)
+
+ # Change to 25% discharging:
+ echo "Discharging" > /tmp/fake_battery/status
+ echo "25" > /tmp/fake_battery/capacity
+ echo "750000" > /tmp/fake_battery/energy_now # 25% of 3000000
+ echo "300000" > /tmp/fake_battery/power_now # Discharge rate (300 mW)
diff --git a/docs/specs/index.rst b/docs/specs/index.rst
index f19d73c9f6..616e8228cc 100644
--- a/docs/specs/index.rst
+++ b/docs/specs/index.rst
@@ -22,6 +22,7 @@ guest hardware that is specific to QEMU.
acpi_pci_hotplug
acpi_nvdimm
acpi_erst
+ battery
sev-guest-firmware
fw_cfg
fsi
diff --git a/hw/acpi/Kconfig b/hw/acpi/Kconfig
index 1d4e9f0845..64403378bd 100644
--- a/hw/acpi/Kconfig
+++ b/hw/acpi/Kconfig
@@ -83,3 +83,7 @@ config ACPI_ERST
config ACPI_CXL
bool
depends on ACPI
+
+config BATTERY
+ bool
+ depends on ACPI
diff --git a/hw/acpi/battery.c b/hw/acpi/battery.c
new file mode 100644
index 0000000000..5ab3ab7472
--- /dev/null
+++ b/hw/acpi/battery.c
@@ -0,0 +1,735 @@
+/*
+ * QEMU emulated battery device.
+ *
+ * Copyright (c) 2019 Janus Technologies, Inc. (http://janustech.com)
+ *
+ * Authors:
+ * Leonid Bloch <lb.workbox@gmail.com>
+ * Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
+ * Dmitry Fleytman <dmitry.fleytman@gmail.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "trace.h"
+#include "hw/isa/isa.h"
+#include "hw/acpi/acpi.h"
+#include "hw/nvram/fw_cfg.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+#include "hw/qdev-properties.h"
+#include "migration/vmstate.h"
+#include "hw/acpi/acpi_aml_interface.h"
+#include "qapi/qapi-commands-acpi.h"
+
+#include "hw/acpi/battery.h"
+
+#define BATTERY_DEVICE(obj) OBJECT_CHECK(BatteryState, (obj), TYPE_BATTERY)
+
+#define BATTERY_DISCHARGING 0x01 /* ACPI _BST bit 0 */
+#define BATTERY_CHARGING 0x02 /* ACPI _BST bit 1 */
+#define BATTERY_CRITICAL 0x04 /* ACPI _BST bit 2 */
+
+#define SYSFS_PATH "/sys/class/power_supply"
+#define BATTERY_TYPE "Battery"
+
+#define MAX_ALLOWED_STATE_LENGTH 32 /* For convinience when comparing */
+
+#define NORMALIZE_BY_FULL(val, full) \
+ ((full == 0) ? BATTERY_VAL_UNKNOWN \
+ : (uint32_t)(val * BATTERY_FULL_CAP / full))
+
+typedef union bat_metric {
+ uint32_t val;
+ uint8_t acc[4];
+} bat_metric;
+
+typedef struct BatteryState {
+ ISADevice dev;
+ MemoryRegion io;
+ uint16_t ioport;
+ bat_metric state;
+ bat_metric rate;
+ bat_metric charge;
+ uint32_t charge_full;
+ int units; /* 0 - mWh, 1 - mAh */
+ bool use_qmp_control;
+ bool qmp_present;
+ bool qmp_charging;
+ bool qmp_discharging;
+ int qmp_charge_percent;
+ int qmp_rate;
+ bool enable_sysfs;
+
+ QEMUTimer *probe_state_timer;
+ uint64_t probe_state_interval;
+
+ char *bat_path;
+} BatteryState;
+
+/* Access addresses */
+enum acc_addr {
+ bsta_addr0, bsta_addr1, bsta_addr2, bsta_addr3,
+ brte_addr0, brte_addr1, brte_addr2, brte_addr3,
+ bcrg_addr0, bcrg_addr1, bcrg_addr2, bcrg_addr3
+};
+
+/* Files used when the units are: mWh mAh */
+static const char *full_file[] = { "energy_full", "charge_full" };
+static const char *now_file[] = { "energy_now", "charge_now" };
+static const char *rate_file[] = { "power_now", "current_now" };
+
+static const char *stat_file = "status";
+static const char *type_file = "type";
+
+static const char *discharging_states[] = { "Discharging", "Not charging" };
+static const char *charging_states[] = { "Charging", "Full", "Unknown" };
+
+static inline bool battery_file_accessible(char *path, const char *file)
+{
+ char full_path[PATH_MAX];
+ int path_len;
+
+ path_len = snprintf(full_path, PATH_MAX, "%s/%s", path, file);
+ if (path_len < 0 || path_len >= PATH_MAX) {
+ return false;
+ }
+ if (access(full_path, R_OK) == 0) {
+ return true;
+ }
+ return false;
+}
+
+static inline int battery_select_file(char *path, const char **file)
+{
+ if (battery_file_accessible(path, file[0])) {
+ return 0;
+ } else if (battery_file_accessible(path, file[1])) {
+ return 1;
+ } else {
+ return -1;
+ }
+}
+
+static void battery_get_full_charge(BatteryState *s, Error **errp)
+{
+ char file_path[PATH_MAX];
+ int path_len;
+ uint32_t val;
+ FILE *ff;
+
+ path_len = snprintf(file_path, PATH_MAX, "%s/%s", s->bat_path,
+ full_file[s->units]);
+ if (path_len < 0 || path_len >= PATH_MAX) {
+ error_setg(errp, "Full capacity file path is inaccessible.");
+ return;
+ }
+
+ ff = fopen(file_path, "r");
+ if (ff == NULL) {
+ error_setg_errno(errp, errno, "Could not read the full charge file.");
+ return;
+ }
+
+ if (fscanf(ff, "%u", &val) != 1) {
+ error_setg(errp, "Full capacity undetermined.");
+ return;
+ } else {
+ s->charge_full = val;
+ }
+ fclose(ff);
+}
+
+static inline bool battery_is_discharging(char *val)
+{
+ static const int discharging_len = ARRAY_SIZE(discharging_states);
+ int i;
+
+ for (i = 0; i < discharging_len; i++) {
+ if (!strncmp(val, discharging_states[i], MAX_ALLOWED_STATE_LENGTH)) {
+ return true;
+ }
+ }
+ return false;
+}
+
+static inline bool battery_is_charging(char *val)
+{
+ static const int charging_len = ARRAY_SIZE(charging_states);
+ int i;
+
+ for (i = 0; i < charging_len; i++) {
+ if (!strncmp(val, charging_states[i], MAX_ALLOWED_STATE_LENGTH)) {
+ return true;
+ }
+ }
+ return false;
+}
+
+static void battery_get_state(BatteryState *s)
+{
+ char file_path[PATH_MAX];
+ int path_len;
+ char val[MAX_ALLOWED_STATE_LENGTH];
+ FILE *ff;
+
+ path_len = snprintf(file_path, PATH_MAX, "%s/%s", s->bat_path, stat_file);
+ if (path_len < 0 || path_len >= PATH_MAX) {
+ warn_report("Could not read the battery state.");
+ return;
+ }
+
+ ff = fopen(file_path, "r");
+ if (ff == NULL) {
+ warn_report("Could not read the battery state.");
+ return;
+ }
+
+ if (fgets(val, MAX_ALLOWED_STATE_LENGTH, ff) == NULL) {
+ warn_report("Battery state unreadable.");
+ } else {
+ val[strcspn(val, "\n")] = 0;
+ if (battery_is_discharging(val)) {
+ s->state.val = BATTERY_DISCHARGING;
+ } else if (battery_is_charging(val)) {
+ s->state.val = BATTERY_CHARGING;
+ } else {
+ s->state.val = 0;
+ warn_report("Battery state undetermined.");
+ }
+ }
+ fclose(ff);
+}
+
+static void battery_get_rate(BatteryState *s)
+{
+ char file_path[PATH_MAX];
+ int path_len;
+ uint64_t val;
+ FILE *ff;
+
+ path_len = snprintf(file_path, PATH_MAX, "%s/%s", s->bat_path,
+ rate_file[s->units]);
+ if (path_len < 0 || path_len >= PATH_MAX) {
+ warn_report("Could not read the battery rate.");
+ s->rate.val = BATTERY_VAL_UNKNOWN;
+ return;
+ }
+
+ ff = fopen(file_path, "r");
+ if (ff == NULL) {
+ warn_report("Could not read the battery rate.");
+ s->rate.val = BATTERY_VAL_UNKNOWN;
+ return;
+ }
+
+ if (fscanf(ff, "%lu", &val) != 1) {
+ warn_report("Battery rate undetermined.");
+ s->rate.val = BATTERY_VAL_UNKNOWN;
+ } else {
+ s->rate.val = NORMALIZE_BY_FULL(val, s->charge_full);
+ }
+ fclose(ff);
+}
+
+static void battery_get_charge(BatteryState *s)
+{
+ char file_path[PATH_MAX];
+ int path_len;
+ uint64_t val;
+ FILE *ff;
+
+ path_len = snprintf(file_path, PATH_MAX, "%s/%s", s->bat_path,
+ now_file[s->units]);
+ if (path_len < 0 || path_len >= PATH_MAX) {
+ warn_report("Could not read the battery charge.");
+ s->charge.val = BATTERY_VAL_UNKNOWN;
+ return;
+ }
+
+ ff = fopen(file_path, "r");
+ if (ff == NULL) {
+ warn_report("Could not read the battery charge.");
+ s->charge.val = BATTERY_VAL_UNKNOWN;
+ return;
+ }
+
+ if (fscanf(ff, "%lu", &val) != 1) {
+ warn_report("Battery charge undetermined.");
+ s->charge.val = BATTERY_VAL_UNKNOWN;
+ } else {
+ s->charge.val = NORMALIZE_BY_FULL(val, s->charge_full);
+ }
+ fclose(ff);
+}
+
+static void battery_get_dynamic_status(BatteryState *s)
+{
+ if (s->use_qmp_control) {
+ s->state.val = 0;
+ if (s->qmp_present) {
+ if (s->qmp_charging) {
+ s->state.val |= BATTERY_CHARGING;
+ }
+ if (s->qmp_discharging) {
+ s->state.val |= BATTERY_DISCHARGING;
+ }
+ }
+ s->rate.val = s->qmp_rate;
+ s->charge.val = (s->qmp_charge_percent * BATTERY_FULL_CAP) / 100;
+ } else if (s->enable_sysfs) {
+ battery_get_state(s);
+ battery_get_rate(s);
+ battery_get_charge(s);
+ } else {
+ s->state.val = 0;
+ s->rate.val = 0;
+ s->charge.val = 0;
+ }
+
+ trace_battery_get_dynamic_status(s->state.val, s->rate.val, s->charge.val);
+}
+
+static void battery_probe_state(void *opaque)
+{
+ BatteryState *s = opaque;
+
+ uint32_t state_before = s->state.val;
+ uint32_t rate_before = s->rate.val;
+ uint32_t charge_before = s->charge.val;
+
+ battery_get_dynamic_status(s);
+
+ if (state_before != s->state.val || rate_before != s->rate.val ||
+ charge_before != s->charge.val) {
+ Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
+ switch (charge_before) {
+ case 0:
+ break; /* Avoid marking initiation as an update */
+ default:
+ acpi_send_event(DEVICE(obj), ACPI_BATTERY_CHANGE_STATUS);
+ }
+ }
+ timer_mod(s->probe_state_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
+ s->probe_state_interval);
+}
+
+static void battery_probe_state_timer_init(BatteryState *s)
+{
+ if (s->enable_sysfs && s->probe_state_interval > 0) {
+ s->probe_state_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
+ battery_probe_state, s);
+ timer_mod(s->probe_state_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
+ s->probe_state_interval);
+ }
+}
+
+static bool battery_verify_sysfs(BatteryState *s, char *path)
+{
+ int units;
+ FILE *ff;
+ char type_path[PATH_MAX];
+ int path_len;
+ char val[MAX_ALLOWED_STATE_LENGTH];
+
+ path_len = snprintf(type_path, PATH_MAX, "%s/%s", path, type_file);
+ if (path_len < 0 || path_len >= PATH_MAX) {
+ return false;
+ }
+ ff = fopen(type_path, "r");
+ if (ff == NULL) {
+ return false;
+ }
+
+ if (fgets(val, MAX_ALLOWED_STATE_LENGTH, ff) == NULL) {
+ fclose(ff);
+ return false;
+ } else {
+ val[strcspn(val, "\n")] = 0;
+ if (strncmp(val, BATTERY_TYPE, MAX_ALLOWED_STATE_LENGTH)) {
+ fclose(ff);
+ return false;
+ }
+ }
+ fclose(ff);
+
+ units = battery_select_file(path, full_file);
+
+ if (units < 0) {
+ return false;
+ } else {
+ s->units = units;
+ }
+
+ return (battery_file_accessible(path, now_file[s->units])
+ & battery_file_accessible(path, rate_file[s->units])
+ & battery_file_accessible(path, stat_file));
+}
+
+static bool get_battery_path(DeviceState *dev)
+{
+ BatteryState *s = BATTERY_DEVICE(dev);
+ DIR *dir;
+ struct dirent *ent;
+ char bp[PATH_MAX];
+ int path_len;
+
+ if (s->bat_path) {
+ return battery_verify_sysfs(s, s->bat_path);
+ }
+
+ dir = opendir(SYSFS_PATH);
+ if (dir == NULL) {
+ return false;
+ }
+
+ ent = readdir(dir);
+ while (ent != NULL) {
+ if (ent->d_name[0] != '.') {
+ path_len = snprintf(bp, PATH_MAX, "%s/%s", SYSFS_PATH,
+ ent->d_name);
+ if (path_len < 0 || path_len >= PATH_MAX) {
+ return false;
+ }
+ if (battery_verify_sysfs(s, bp)) {
+ qdev_prop_set_string(dev, BATTERY_PATH_PROP, bp);
+ closedir(dir);
+ return true;
+ }
+ }
+ ent = readdir(dir);
+ }
+ closedir(dir);
+
+ return false;
+}
+
+static void battery_realize(DeviceState *dev, Error **errp)
+{
+ ISADevice *d = ISA_DEVICE(dev);
+ BatteryState *s = BATTERY_DEVICE(dev);
+ FWCfgState *fw_cfg = fw_cfg_find();
+ uint16_t *battery_port;
+ char err_details[0x20] = {};
+
+ trace_battery_realize();
+
+ if (s->use_qmp_control && s->enable_sysfs) {
+ error_setg(errp, "Cannot enable both QMP control and sysfs mode");
+ return;
+ }
+
+ /* Initialize QMP state to sensible defaults when in QMP mode */
+ if (s->use_qmp_control) {
+ s->qmp_present = true;
+ s->qmp_charging = false;
+ s->qmp_discharging = true;
+ s->qmp_charge_percent = 50;
+ s->qmp_rate = 1000; /* 1000 mW discharge rate */
+ }
+
+ if (s->enable_sysfs) {
+ if (!s->bat_path) {
+ strcpy(err_details, " Try using 'sysfs_path='");
+ }
+
+ if (!get_battery_path(dev)) {
+ error_setg(errp, "Battery sysfs path not found or unreadable.%s",
+ err_details);
+ return;
+ }
+ battery_get_full_charge(s, errp);
+ } else {
+ s->charge_full = BATTERY_FULL_CAP;
+ }
+
+ isa_register_ioport(d, &s->io, s->ioport);
+
+ battery_probe_state_timer_init(s);
+
+ if (!fw_cfg) {
+ return;
+ }
+
+ battery_port = g_malloc(sizeof(*battery_port));
+ *battery_port = cpu_to_le16(s->ioport);
+ fw_cfg_add_file(fw_cfg, "etc/battery-port", battery_port,
+ sizeof(*battery_port));
+}
+
+static const Property battery_device_properties[] = {
+ DEFINE_PROP_UINT16(BATTERY_IOPORT_PROP, BatteryState, ioport, 0x530),
+ DEFINE_PROP_BOOL("use-qmp", BatteryState, use_qmp_control, true),
+ DEFINE_PROP_BOOL("enable-sysfs", BatteryState, enable_sysfs, false),
+ DEFINE_PROP_UINT64(BATTERY_PROBE_STATE_INTERVAL, BatteryState,
+ probe_state_interval, 2000),
+ DEFINE_PROP_STRING(BATTERY_PATH_PROP, BatteryState, bat_path),
+};
+
+static const VMStateDescription battery_vmstate = {
+ .name = "battery",
+ .version_id = 1,
+ .minimum_version_id = 1,
+ .fields = (VMStateField[]) {
+ VMSTATE_UINT16(ioport, BatteryState),
+ VMSTATE_UINT64(probe_state_interval, BatteryState),
+ VMSTATE_END_OF_LIST()
+ }
+};
+
+static void build_battery_aml(AcpiDevAmlIf *adev, Aml *scope)
+{
+ Aml *dev, *field, *method, *pkg;
+ Aml *bat_state, *bat_rate, *bat_charge;
+ Aml *sb_scope;
+ BatteryState *s = BATTERY_DEVICE(adev);
+
+ bat_state = aml_local(0);
+ bat_rate = aml_local(1);
+ bat_charge = aml_local(2);
+
+ sb_scope = aml_scope("\\_SB");
+ dev = aml_device("BAT0");
+ aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0C0A")));
+
+ method = aml_method("_STA", 0, AML_NOTSERIALIZED);
+ aml_append(method, aml_return(aml_int(0x1F)));
+ aml_append(dev, method);
+
+ aml_append(dev, aml_operation_region("DBST", AML_SYSTEM_IO,
+ aml_int(s->ioport),
+ BATTERY_LEN));
+ field = aml_field("DBST", AML_DWORD_ACC, AML_NOLOCK, AML_PRESERVE);
+ aml_append(field, aml_named_field("BSTA", 32));
+ aml_append(field, aml_named_field("BRTE", 32));
+ aml_append(field, aml_named_field("BCRG", 32));
+ aml_append(dev, field);
+
+ method = aml_method("_BIF", 0, AML_NOTSERIALIZED);
+ pkg = aml_package(13);
+ /* Power Unit */
+ aml_append(pkg, aml_int(0)); /* mW */
+ /* Design Capacity */
+ aml_append(pkg, aml_int(BATTERY_FULL_CAP));
+ /* Last Full Charge Capacity */
+ aml_append(pkg, aml_int(BATTERY_FULL_CAP));
+ /* Battery Technology */
+ aml_append(pkg, aml_int(1)); /* Secondary */
+ /* Design Voltage */
+ aml_append(pkg, aml_int(BATTERY_VAL_UNKNOWN));
+ /* Design Capacity of Warning */
+ aml_append(pkg, aml_int(BATTERY_CAPACITY_OF_WARNING));
+ /* Design Capacity of Low */
+ aml_append(pkg, aml_int(BATTERY_CAPACITY_OF_LOW));
+ /* Battery Capacity Granularity 1 */
+ aml_append(pkg, aml_int(BATTERY_CAPACITY_GRANULARITY));
+ /* Battery Capacity Granularity 2 */
+ aml_append(pkg, aml_int(BATTERY_CAPACITY_GRANULARITY));
+ /* Model Number */
+ aml_append(pkg, aml_string("QBAT001")); /* Model Number */
+ /* Serial Number */
+ aml_append(pkg, aml_string("SN00000")); /* Serial Number */
+ /* Battery Type */
+ aml_append(pkg, aml_string("Virtual")); /* Battery Type */
+ /* OEM Information */
+ aml_append(pkg, aml_string("QEMU")); /* OEM Information */
+ aml_append(method, aml_return(pkg));
+ aml_append(dev, method);
+
+ pkg = aml_package(4);
+ /* Battery State */
+ aml_append(pkg, aml_int(0));
+ /* Battery Present Rate */
+ aml_append(pkg, aml_int(BATTERY_VAL_UNKNOWN));
+ /* Battery Remaining Capacity */
+ aml_append(pkg, aml_int(BATTERY_VAL_UNKNOWN));
+ /* Battery Present Voltage */
+ aml_append(pkg, aml_int(BATTERY_VAL_UNKNOWN));
+ aml_append(dev, aml_name_decl("DBPR", pkg));
+
+ method = aml_method("_BST", 0, AML_NOTSERIALIZED);
+ aml_append(method, aml_store(aml_name("BSTA"), bat_state));
+ aml_append(method, aml_store(aml_name("BRTE"), bat_rate));
+ aml_append(method, aml_store(aml_name("BCRG"), bat_charge));
+ aml_append(method, aml_store(bat_state,
+ aml_index(aml_name("DBPR"), aml_int(0))));
+ aml_append(method, aml_store(bat_rate,
+ aml_index(aml_name("DBPR"), aml_int(1))));
+ aml_append(method, aml_store(bat_charge,
+ aml_index(aml_name("DBPR"), aml_int(2))));
+ aml_append(method, aml_return(aml_name("DBPR")));
+ aml_append(dev, method);
+
+ aml_append(sb_scope, dev);
+ aml_append(scope, sb_scope);
+
+ /* Device Check */
+ method = aml_method("\\_GPE._E07", 0, AML_NOTSERIALIZED);
+ aml_append(method, aml_notify(aml_name("\\_SB.BAT0"), aml_int(0x01)));
+ aml_append(scope, method);
+
+ /* Status Change */
+ method = aml_method("\\_GPE._E08", 0, AML_NOTSERIALIZED);
+ aml_append(method, aml_notify(aml_name("\\_SB.BAT0"), aml_int(0x80)));
+ aml_append(scope, method);
+
+ /* Information Change */
+ method = aml_method("\\_GPE._E09", 0, AML_NOTSERIALIZED);
+ aml_append(method, aml_notify(aml_name("\\_SB.BAT0"), aml_int(0x81)));
+ aml_append(scope, method);
+}
+
+static void battery_class_init(ObjectClass *class, const void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(class);
+ AcpiDevAmlIfClass *adevc = ACPI_DEV_AML_IF_CLASS(class);
+
+ dc->realize = battery_realize;
+ device_class_set_props(dc, battery_device_properties);
+ dc->vmsd = &battery_vmstate;
+ adevc->build_dev_aml = build_battery_aml;
+}
+
+static uint64_t battery_ioport_read(void *opaque, hwaddr addr, unsigned size)
+{
+ BatteryState *s = opaque;
+
+ battery_get_dynamic_status(s);
+
+ switch (addr) {
+ case bsta_addr0:
+ return s->state.acc[0];
+ case bsta_addr1:
+ return s->state.acc[1];
+ case bsta_addr2:
+ return s->state.acc[2];
+ case bsta_addr3:
+ return s->state.acc[3];
+ case brte_addr0:
+ return s->rate.acc[0];
+ case brte_addr1:
+ return s->rate.acc[1];
+ case brte_addr2:
+ return s->rate.acc[2];
+ case brte_addr3:
+ return s->rate.acc[3];
+ case bcrg_addr0:
+ return s->charge.acc[0];
+ case bcrg_addr1:
+ return s->charge.acc[1];
+ case bcrg_addr2:
+ return s->charge.acc[2];
+ case bcrg_addr3:
+ return s->charge.acc[3];
+ default:
+ warn_report("Battery: guest read unknown value.");
+ trace_battery_ioport_read_unknown();
+ return 0;
+ }
+}
+
+static const MemoryRegionOps battery_ops = {
+ .read = battery_ioport_read,
+ .impl = {
+ .min_access_size = 1,
+ .max_access_size = 1,
+ },
+};
+
+static void battery_instance_init(Object *obj)
+{
+ BatteryState *s = BATTERY_DEVICE(obj);
+
+ memory_region_init_io(&s->io, obj, &battery_ops, s, "battery",
+ BATTERY_LEN);
+}
+
+static const TypeInfo battery_info = {
+ .name = TYPE_BATTERY,
+ .parent = TYPE_ISA_DEVICE,
+ .instance_size = sizeof(BatteryState),
+ .class_init = battery_class_init,
+ .instance_init = battery_instance_init,
+ .interfaces = (InterfaceInfo[]) {
+ { TYPE_ACPI_DEV_AML_IF },
+ { },
+ },
+};
+
+static BatteryState *find_battery_device(void)
+{
+ Object *o = object_resolve_path_type("", TYPE_BATTERY, NULL);
+ if (!o) {
+ return NULL;
+ }
+ return BATTERY_DEVICE(o);
+}
+
+void qmp_battery_set_state(BatteryInfo *state, Error **errp)
+{
+ BatteryState *s = find_battery_device();
+
+ if (!s) {
+ error_setg(errp, "No battery device found");
+ return;
+ }
+
+ s->qmp_present = state->present;
+ s->qmp_charging = state->charging;
+ s->qmp_discharging = state->discharging;
+ s->qmp_charge_percent = state->charge_percent;
+
+ if (state->has_rate) {
+ s->qmp_rate = state->rate;
+ }
+
+ Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
+ if (obj) {
+ acpi_send_event(DEVICE(obj), ACPI_BATTERY_CHANGE_STATUS);
+ }
+}
+
+BatteryInfo *qmp_query_battery(Error **errp)
+{
+ BatteryState *s = find_battery_device();
+ BatteryInfo *ret;
+
+ if (!s) {
+ error_setg(errp, "No battery device found");
+ return NULL;
+ }
+
+ ret = g_new0(BatteryInfo, 1);
+
+ if (s->use_qmp_control) {
+ ret->present = s->qmp_present;
+ ret->charging = s->qmp_charging;
+ ret->discharging = s->qmp_discharging;
+ ret->charge_percent = s->qmp_charge_percent;
+ ret->has_rate = true;
+ ret->rate = s->qmp_rate;
+ } else {
+ battery_get_dynamic_status(s);
+ ret->present = true;
+ ret->charging = !!(s->state.val & BATTERY_CHARGING);
+ ret->discharging = !!(s->state.val & BATTERY_DISCHARGING);
+ ret->charge_percent = (s->charge.val * 100) / BATTERY_FULL_CAP;
+ ret->has_rate = true;
+ ret->rate = s->rate.val;
+ }
+
+ ret->has_remaining_capacity = false;
+ ret->has_design_capacity = true;
+ ret->design_capacity = BATTERY_FULL_CAP;
+
+ return ret;
+}
+
+static void battery_register_types(void)
+{
+ type_register_static(&battery_info);
+}
+
+type_init(battery_register_types)
diff --git a/hw/acpi/meson.build b/hw/acpi/meson.build
index 73f02b9691..10379a7b2c 100644
--- a/hw/acpi/meson.build
+++ b/hw/acpi/meson.build
@@ -31,6 +31,7 @@ acpi_ss.add(when: 'CONFIG_PC', if_false: files('acpi-x86-stub.c'))
if have_tpm
acpi_ss.add(files('tpm.c'))
endif
+acpi_ss.add(when: 'CONFIG_BATTERY', if_true: files('battery.c'))
system_ss.add(when: 'CONFIG_ACPI', if_false: files('acpi-stub.c', 'aml-build-stub.c', 'ghes-stub.c', 'acpi_interface.c'))
system_ss.add(when: 'CONFIG_ACPI_PCI_BRIDGE', if_false: files('pci-bridge-stub.c'))
system_ss.add_all(when: 'CONFIG_ACPI', if_true: acpi_ss)
diff --git a/hw/acpi/trace-events b/hw/acpi/trace-events
index edc93e703c..dd3e815482 100644
--- a/hw/acpi/trace-events
+++ b/hw/acpi/trace-events
@@ -87,3 +87,8 @@ acpi_nvdimm_read_io_port(void) "Alert: we never read _DSM IO Port"
acpi_nvdimm_dsm_mem_addr(uint64_t dsm_mem_addr) "dsm memory address 0x%" PRIx64
acpi_nvdimm_dsm_info(uint32_t revision, uint32_t handle, uint32_t function) "Revision 0x%" PRIx32 " Handle 0x%" PRIx32 " Function 0x%" PRIx32
acpi_nvdimm_invalid_revision(uint32_t revision) "Revision 0x%" PRIx32 " is not supported, expect 0x1"
+
+# battery.c
+battery_realize(void) "Battery device realize entry"
+battery_get_dynamic_status(uint32_t state, uint32_t rate, uint32_t charge) "Battery read state: 0x%"PRIx32", rate: %"PRIu32", charge: %"PRIu32
+battery_ioport_read_unknown(void) "Battery read unknown"
diff --git a/hw/i386/Kconfig b/hw/i386/Kconfig
index 3a0e2b8ebb..2c878fd112 100644
--- a/hw/i386/Kconfig
+++ b/hw/i386/Kconfig
@@ -39,6 +39,7 @@ config PC
imply VIRTIO_VGA
imply NVDIMM
imply FDC_ISA
+ imply BATTERY
select I8259
select I8254
select PCKBD
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 423c4959fe..790b16e582 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1248,6 +1248,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
aml_append(sb_scope, dev);
}
+
aml_append(dsdt, sb_scope);
if (pm->pcihp_bridge_en || pm->pcihp_root_en) {
diff --git a/include/hw/acpi/acpi_dev_interface.h b/include/hw/acpi/acpi_dev_interface.h
index 68d9d15f50..3064ef6734 100644
--- a/include/hw/acpi/acpi_dev_interface.h
+++ b/include/hw/acpi/acpi_dev_interface.h
@@ -13,6 +13,7 @@ typedef enum {
ACPI_NVDIMM_HOTPLUG_STATUS = 16,
ACPI_VMGENID_CHANGE_STATUS = 32,
ACPI_POWER_DOWN_STATUS = 64,
+ ACPI_BATTERY_CHANGE_STATUS = 128,
} AcpiEventStatusBits;
#define TYPE_ACPI_DEVICE_IF "acpi-device-interface"
diff --git a/include/hw/acpi/battery.h b/include/hw/acpi/battery.h
new file mode 100644
index 0000000000..5c5e83abfa
--- /dev/null
+++ b/include/hw/acpi/battery.h
@@ -0,0 +1,33 @@
+/*
+ * QEMU emulated battery device.
+ *
+ * Copyright (c) 2019 Janus Technologies, Inc. (http://janustech.com)
+ *
+ * Authors:
+ * Leonid Bloch <lb.workbox@gmail.com>
+ * Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
+ * Dmitry Fleytman <dmitry.fleytman@gmail.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ */
+
+#ifndef HW_ACPI_BATTERY_H
+#define HW_ACPI_BATTERY_H
+
+#define TYPE_BATTERY "battery"
+#define BATTERY_IOPORT_PROP "ioport"
+#define BATTERY_PATH_PROP "sysfs_path"
+#define BATTERY_PROBE_STATE_INTERVAL "probe_interval"
+
+#define BATTERY_FULL_CAP 10000 /* mWh */
+
+#define BATTERY_CAPACITY_OF_WARNING (BATTERY_FULL_CAP / 10) /* 10% */
+#define BATTERY_CAPACITY_OF_LOW (BATTERY_FULL_CAP / 25) /* 4% */
+#define BATTERY_CAPACITY_GRANULARITY (BATTERY_FULL_CAP / 100) /* 1% */
+
+#define BATTERY_VAL_UNKNOWN 0xFFFFFFFF
+
+#define BATTERY_LEN 0x0C
+
+#endif
diff --git a/qapi/acpi.json b/qapi/acpi.json
index 906b3687a5..d1ad663bfd 100644
--- a/qapi/acpi.json
+++ b/qapi/acpi.json
@@ -142,3 +142,76 @@
##
{ 'event': 'ACPI_DEVICE_OST',
'data': { 'info': 'ACPIOSTInfo' } }
+
+##
+# @BatteryInfo:
+#
+# Battery state information
+#
+# @present: whether the battery is present
+#
+# @charging: whether the battery is charging
+#
+# @discharging: whether the battery is discharging
+#
+# @charge-percent: battery charge percentage (0-100)
+#
+# @rate: charge/discharge rate in mW (optional)
+#
+# @remaining-capacity: remaining capacity in mWh (optional)
+#
+# @design-capacity: design capacity in mWh (optional)
+#
+# Since: 10.2
+##
+{ 'struct': 'BatteryInfo',
+ 'data': { 'present': 'bool',
+ 'charging': 'bool',
+ 'discharging': 'bool',
+ 'charge-percent': 'int',
+ '*rate': 'int',
+ '*remaining-capacity': 'int',
+ '*design-capacity': 'int' } }
+
+##
+# @battery-set-state:
+#
+# Set the state of the emulated battery device
+#
+# @state: new battery state
+#
+
+#
+# Since: 10.2
+#
+# .. qmp-example::
+#
+# -> { "execute": "battery-set-state",
+# "arguments": { "state": { "present": true,
+# "charging": true,
+# "discharging": false,
+# "charge-percent": 85 } } }
+# <- { "return": {} }
+##
+{ 'command': 'battery-set-state',
+ 'data': { 'state': 'BatteryInfo' } }
+
+##
+# @query-battery:
+#
+# Query the current state of the emulated battery device
+#
+# Returns: current battery state
+#
+# Since: 10.2
+#
+# .. qmp-example::
+#
+# -> { "execute": "query-battery" }
+# <- { "return": { "present": true,
+# "charging": true,
+# "discharging": false,
+# "charge-percent": 85 } }
+##
+{ 'command': 'query-battery',
+ 'returns': 'BatteryInfo' }
--
2.51.0
On Thu, 28 Aug 2025 01:00:48 +0300
Leonid Bloch <lb.workbox@gmail.com> wrote:
> The battery device communicates battery state to the guest via ACPI.
> It supports two modes of operation:
>
> 1. QMP control mode (default): Battery state is controlled programmatically
> via QMP commands, making the device deterministic and migration-safe.
>
> 2. Host mirroring mode (optional): The device reflects the host's battery
> state from sysfs. Probing occurs on guest ACPI requests and at timed
> intervals (default 2 seconds, configurable via 'probe_interval' property
> in milliseconds). State changes trigger ACPI notifications to the guest.
>
> Properties:
> - 'use-qmp': Enable QMP control mode (default: true)
> - 'enable-sysfs': Enable host battery mirroring (default: false)
> - 'probe_interval': Probe interval in ms for sysfs mode (default: 2000)
> - 'sysfs_path': Override default sysfs path /sys/class/power_supply/
>
> The device implements the ACPI_DEV_AML_IF interface to generate its
> own AML code, placing the BAT0 device directly under \_SB scope as
> per ACPI specification.
>
> QMP commands:
> - battery-set-state: Set battery state (present, charging, capacity, rate)
> - query-battery: Query current battery state
>
> This allows testing without host battery access and provides a stable
> interface for virtualization management systems.
>
> Signed-off-by: Leonid Bloch <lb.workbox@gmail.com>
> Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
[...]
> +
> +static void build_battery_aml(AcpiDevAmlIf *adev, Aml *scope)
> +{
> + Aml *dev, *field, *method, *pkg;
> + Aml *bat_state, *bat_rate, *bat_charge;
> + Aml *sb_scope;
> + BatteryState *s = BATTERY_DEVICE(adev);
> +
> + bat_state = aml_local(0);
> + bat_rate = aml_local(1);
> + bat_charge = aml_local(2);
> +
> + sb_scope = aml_scope("\\_SB");
> + dev = aml_device("BAT0");
> + aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0C0A")));
> +
> + method = aml_method("_STA", 0, AML_NOTSERIALIZED);
> + aml_append(method, aml_return(aml_int(0x1F)));
> + aml_append(dev, method);
> +
> + aml_append(dev, aml_operation_region("DBST", AML_SYSTEM_IO,
> + aml_int(s->ioport),
> + BATTERY_LEN));
> + field = aml_field("DBST", AML_DWORD_ACC, AML_NOLOCK, AML_PRESERVE);
> + aml_append(field, aml_named_field("BSTA", 32));
> + aml_append(field, aml_named_field("BRTE", 32));
> + aml_append(field, aml_named_field("BCRG", 32));
> + aml_append(dev, field);
> +
> + method = aml_method("_BIF", 0, AML_NOTSERIALIZED);
> + pkg = aml_package(13);
> + /* Power Unit */
> + aml_append(pkg, aml_int(0)); /* mW */
> + /* Design Capacity */
> + aml_append(pkg, aml_int(BATTERY_FULL_CAP));
> + /* Last Full Charge Capacity */
> + aml_append(pkg, aml_int(BATTERY_FULL_CAP));
> + /* Battery Technology */
> + aml_append(pkg, aml_int(1)); /* Secondary */
> + /* Design Voltage */
> + aml_append(pkg, aml_int(BATTERY_VAL_UNKNOWN));
> + /* Design Capacity of Warning */
> + aml_append(pkg, aml_int(BATTERY_CAPACITY_OF_WARNING));
> + /* Design Capacity of Low */
> + aml_append(pkg, aml_int(BATTERY_CAPACITY_OF_LOW));
> + /* Battery Capacity Granularity 1 */
> + aml_append(pkg, aml_int(BATTERY_CAPACITY_GRANULARITY));
> + /* Battery Capacity Granularity 2 */
> + aml_append(pkg, aml_int(BATTERY_CAPACITY_GRANULARITY));
> + /* Model Number */
> + aml_append(pkg, aml_string("QBAT001")); /* Model Number */
> + /* Serial Number */
> + aml_append(pkg, aml_string("SN00000")); /* Serial Number */
> + /* Battery Type */
> + aml_append(pkg, aml_string("Virtual")); /* Battery Type */
> + /* OEM Information */
> + aml_append(pkg, aml_string("QEMU")); /* OEM Information */
> + aml_append(method, aml_return(pkg));
> + aml_append(dev, method);
> +
> + pkg = aml_package(4);
> + /* Battery State */
> + aml_append(pkg, aml_int(0));
> + /* Battery Present Rate */
> + aml_append(pkg, aml_int(BATTERY_VAL_UNKNOWN));
> + /* Battery Remaining Capacity */
> + aml_append(pkg, aml_int(BATTERY_VAL_UNKNOWN));
> + /* Battery Present Voltage */
> + aml_append(pkg, aml_int(BATTERY_VAL_UNKNOWN));
> + aml_append(dev, aml_name_decl("DBPR", pkg));
> +
> + method = aml_method("_BST", 0, AML_NOTSERIALIZED);
> + aml_append(method, aml_store(aml_name("BSTA"), bat_state));
> + aml_append(method, aml_store(aml_name("BRTE"), bat_rate));
> + aml_append(method, aml_store(aml_name("BCRG"), bat_charge));
> + aml_append(method, aml_store(bat_state,
> + aml_index(aml_name("DBPR"), aml_int(0))));
> + aml_append(method, aml_store(bat_rate,
> + aml_index(aml_name("DBPR"), aml_int(1))));
> + aml_append(method, aml_store(bat_charge,
> + aml_index(aml_name("DBPR"), aml_int(2))));
> + aml_append(method, aml_return(aml_name("DBPR")));
> + aml_append(dev, method);
> +
> + aml_append(sb_scope, dev);
> + aml_append(scope, sb_scope);
> +
> + /* Device Check */
> + method = aml_method("\\_GPE._E07", 0, AML_NOTSERIALIZED);
> + aml_append(method, aml_notify(aml_name("\\_SB.BAT0"), aml_int(0x01)));
> + aml_append(scope, method);
> +
> + /* Status Change */
> + method = aml_method("\\_GPE._E08", 0, AML_NOTSERIALIZED);
> + aml_append(method, aml_notify(aml_name("\\_SB.BAT0"), aml_int(0x80)));
> + aml_append(scope, method);
> +
> + /* Information Change */
> + method = aml_method("\\_GPE._E09", 0, AML_NOTSERIALIZED);
> + aml_append(method, aml_notify(aml_name("\\_SB.BAT0"), aml_int(0x81)));
> + aml_append(scope, method);
> +}
> +
> +static void battery_class_init(ObjectClass *class, const void *data)
> +{
> + DeviceClass *dc = DEVICE_CLASS(class);
> + AcpiDevAmlIfClass *adevc = ACPI_DEV_AML_IF_CLASS(class);
> +
> + dc->realize = battery_realize;
> + device_class_set_props(dc, battery_device_properties);
> + dc->vmsd = &battery_vmstate;
> + adevc->build_dev_aml = build_battery_aml;
> +}
> +
> +static uint64_t battery_ioport_read(void *opaque, hwaddr addr, unsigned size)
> +{
> + BatteryState *s = opaque;
> +
> + battery_get_dynamic_status(s);
> +
> + switch (addr) {
> + case bsta_addr0:
> + return s->state.acc[0];
> + case bsta_addr1:
> + return s->state.acc[1];
> + case bsta_addr2:
> + return s->state.acc[2];
> + case bsta_addr3:
> + return s->state.acc[3];
> + case brte_addr0:
> + return s->rate.acc[0];
> + case brte_addr1:
> + return s->rate.acc[1];
> + case brte_addr2:
> + return s->rate.acc[2];
> + case brte_addr3:
> + return s->rate.acc[3];
> + case bcrg_addr0:
> + return s->charge.acc[0];
> + case bcrg_addr1:
> + return s->charge.acc[1];
> + case bcrg_addr2:
> + return s->charge.acc[2];
> + case bcrg_addr3:
> + return s->charge.acc[3];
why do you handle it as byte access when in AML fields are
declared as DWORD access?
> + default:
> + warn_report("Battery: guest read unknown value.");
abort here, but I doubt that you can get here at all
if memory region is correctly sized.
> + trace_battery_ioport_read_unknown();
> + return 0;
> + }
> +}
> +
> +static const MemoryRegionOps battery_ops = {
> + .read = battery_ioport_read,
> + .impl = {
> + .min_access_size = 1,
> + .max_access_size = 1,
same question wrt access size.
Suggest making it explicitly 4 byte and little-endinan
> + },
> +};
> +
> +static void battery_instance_init(Object *obj)
> +{
> + BatteryState *s = BATTERY_DEVICE(obj);
> +
> + memory_region_init_io(&s->io, obj, &battery_ops, s, "battery",
> + BATTERY_LEN);
> +}
> +
> +static const TypeInfo battery_info = {
> + .name = TYPE_BATTERY,
> + .parent = TYPE_ISA_DEVICE,
> + .instance_size = sizeof(BatteryState),
> + .class_init = battery_class_init,
> + .instance_init = battery_instance_init,
> + .interfaces = (InterfaceInfo[]) {
> + { TYPE_ACPI_DEV_AML_IF },
> + { },
> + },
> +};
> +
> +static BatteryState *find_battery_device(void)
> +{
> + Object *o = object_resolve_path_type("", TYPE_BATTERY, NULL);
also use 3rd argument and error out in case it's true,
so user would know what went wrong.
> + if (!o) {
> + return NULL;
> + }
> + return BATTERY_DEVICE(o);
> +}
> +
> +void qmp_battery_set_state(BatteryInfo *state, Error **errp)
> +{
> + BatteryState *s = find_battery_device();
> +
> + if (!s) {
> + error_setg(errp, "No battery device found");
> + return;
> + }
> +
> + s->qmp_present = state->present;
> + s->qmp_charging = state->charging;
> + s->qmp_discharging = state->discharging;
> + s->qmp_charge_percent = state->charge_percent;
> +
> + if (state->has_rate) {
> + s->qmp_rate = state->rate;
> + }
> +
> + Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
> + if (obj) {
> + acpi_send_event(DEVICE(obj), ACPI_BATTERY_CHANGE_STATUS);
> + }
> +}
> +
> +BatteryInfo *qmp_query_battery(Error **errp)
> +{
> + BatteryState *s = find_battery_device();
> + BatteryInfo *ret;
> +
> + if (!s) {
> + error_setg(errp, "No battery device found");
> + return NULL;
> + }
> +
> + ret = g_new0(BatteryInfo, 1);
> +
> + if (s->use_qmp_control) {
> + ret->present = s->qmp_present;
> + ret->charging = s->qmp_charging;
> + ret->discharging = s->qmp_discharging;
> + ret->charge_percent = s->qmp_charge_percent;
> + ret->has_rate = true;
> + ret->rate = s->qmp_rate;
> + } else {
> + battery_get_dynamic_status(s);
> + ret->present = true;
> + ret->charging = !!(s->state.val & BATTERY_CHARGING);
> + ret->discharging = !!(s->state.val & BATTERY_DISCHARGING);
> + ret->charge_percent = (s->charge.val * 100) / BATTERY_FULL_CAP;
> + ret->has_rate = true;
> + ret->rate = s->rate.val;
> + }
> +
> + ret->has_remaining_capacity = false;
> + ret->has_design_capacity = true;
> + ret->design_capacity = BATTERY_FULL_CAP;
> +
> + return ret;
> +}
> +
> +static void battery_register_types(void)
> +{
> + type_register_static(&battery_info);
> +}
> +
> +type_init(battery_register_types)
> diff --git a/hw/acpi/meson.build b/hw/acpi/meson.build
> index 73f02b9691..10379a7b2c 100644
> --- a/hw/acpi/meson.build
> +++ b/hw/acpi/meson.build
> @@ -31,6 +31,7 @@ acpi_ss.add(when: 'CONFIG_PC', if_false: files('acpi-x86-stub.c'))
> if have_tpm
> acpi_ss.add(files('tpm.c'))
> endif
> +acpi_ss.add(when: 'CONFIG_BATTERY', if_true: files('battery.c'))
> system_ss.add(when: 'CONFIG_ACPI', if_false: files('acpi-stub.c', 'aml-build-stub.c', 'ghes-stub.c', 'acpi_interface.c'))
> system_ss.add(when: 'CONFIG_ACPI_PCI_BRIDGE', if_false: files('pci-bridge-stub.c'))
> system_ss.add_all(when: 'CONFIG_ACPI', if_true: acpi_ss)
> diff --git a/hw/acpi/trace-events b/hw/acpi/trace-events
> index edc93e703c..dd3e815482 100644
> --- a/hw/acpi/trace-events
> +++ b/hw/acpi/trace-events
> @@ -87,3 +87,8 @@ acpi_nvdimm_read_io_port(void) "Alert: we never read _DSM IO Port"
> acpi_nvdimm_dsm_mem_addr(uint64_t dsm_mem_addr) "dsm memory address 0x%" PRIx64
> acpi_nvdimm_dsm_info(uint32_t revision, uint32_t handle, uint32_t function) "Revision 0x%" PRIx32 " Handle 0x%" PRIx32 " Function 0x%" PRIx32
> acpi_nvdimm_invalid_revision(uint32_t revision) "Revision 0x%" PRIx32 " is not supported, expect 0x1"
> +
> +# battery.c
> +battery_realize(void) "Battery device realize entry"
> +battery_get_dynamic_status(uint32_t state, uint32_t rate, uint32_t charge) "Battery read state: 0x%"PRIx32", rate: %"PRIu32", charge: %"PRIu32
> +battery_ioport_read_unknown(void) "Battery read unknown"
> diff --git a/hw/i386/Kconfig b/hw/i386/Kconfig
> index 3a0e2b8ebb..2c878fd112 100644
> --- a/hw/i386/Kconfig
> +++ b/hw/i386/Kconfig
> @@ -39,6 +39,7 @@ config PC
> imply VIRTIO_VGA
> imply NVDIMM
> imply FDC_ISA
> + imply BATTERY
> select I8259
> select I8254
> select PCKBD
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 423c4959fe..790b16e582 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1248,6 +1248,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
>
> aml_append(sb_scope, dev);
> }
> +
> aml_append(dsdt, sb_scope);
>
> if (pm->pcihp_bridge_en || pm->pcihp_root_en) {
> diff --git a/include/hw/acpi/acpi_dev_interface.h b/include/hw/acpi/acpi_dev_interface.h
> index 68d9d15f50..3064ef6734 100644
> --- a/include/hw/acpi/acpi_dev_interface.h
> +++ b/include/hw/acpi/acpi_dev_interface.h
> @@ -13,6 +13,7 @@ typedef enum {
> ACPI_NVDIMM_HOTPLUG_STATUS = 16,
> ACPI_VMGENID_CHANGE_STATUS = 32,
> ACPI_POWER_DOWN_STATUS = 64,
> + ACPI_BATTERY_CHANGE_STATUS = 128,
> } AcpiEventStatusBits;
>
> #define TYPE_ACPI_DEVICE_IF "acpi-device-interface"
> diff --git a/include/hw/acpi/battery.h b/include/hw/acpi/battery.h
> new file mode 100644
> index 0000000000..5c5e83abfa
> --- /dev/null
> +++ b/include/hw/acpi/battery.h
> @@ -0,0 +1,33 @@
> +/*
> + * QEMU emulated battery device.
> + *
> + * Copyright (c) 2019 Janus Technologies, Inc. (http://janustech.com)
> + *
> + * Authors:
> + * Leonid Bloch <lb.workbox@gmail.com>
> + * Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> + * Dmitry Fleytman <dmitry.fleytman@gmail.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + */
> +
> +#ifndef HW_ACPI_BATTERY_H
> +#define HW_ACPI_BATTERY_H
> +
> +#define TYPE_BATTERY "battery"
> +#define BATTERY_IOPORT_PROP "ioport"
> +#define BATTERY_PATH_PROP "sysfs_path"
> +#define BATTERY_PROBE_STATE_INTERVAL "probe_interval"
> +
> +#define BATTERY_FULL_CAP 10000 /* mWh */
> +
> +#define BATTERY_CAPACITY_OF_WARNING (BATTERY_FULL_CAP / 10) /* 10% */
> +#define BATTERY_CAPACITY_OF_LOW (BATTERY_FULL_CAP / 25) /* 4% */
> +#define BATTERY_CAPACITY_GRANULARITY (BATTERY_FULL_CAP / 100) /* 1% */
> +
> +#define BATTERY_VAL_UNKNOWN 0xFFFFFFFF
> +
> +#define BATTERY_LEN 0x0C
> +
> +#endif
> diff --git a/qapi/acpi.json b/qapi/acpi.json
> index 906b3687a5..d1ad663bfd 100644
> --- a/qapi/acpi.json
> +++ b/qapi/acpi.json
> @@ -142,3 +142,76 @@
> ##
> { 'event': 'ACPI_DEVICE_OST',
> 'data': { 'info': 'ACPIOSTInfo' } }
> +
> +##
> +# @BatteryInfo:
> +#
> +# Battery state information
> +#
> +# @present: whether the battery is present
> +#
> +# @charging: whether the battery is charging
> +#
> +# @discharging: whether the battery is discharging
> +#
> +# @charge-percent: battery charge percentage (0-100)
> +#
> +# @rate: charge/discharge rate in mW (optional)
> +#
> +# @remaining-capacity: remaining capacity in mWh (optional)
> +#
> +# @design-capacity: design capacity in mWh (optional)
> +#
> +# Since: 10.2
> +##
> +{ 'struct': 'BatteryInfo',
> + 'data': { 'present': 'bool',
> + 'charging': 'bool',
> + 'discharging': 'bool',
> + 'charge-percent': 'int',
> + '*rate': 'int',
> + '*remaining-capacity': 'int',
> + '*design-capacity': 'int' } }
> +
> +##
> +# @battery-set-state:
> +#
> +# Set the state of the emulated battery device
> +#
> +# @state: new battery state
> +#
> +
> +#
> +# Since: 10.2
> +#
> +# .. qmp-example::
> +#
> +# -> { "execute": "battery-set-state",
> +# "arguments": { "state": { "present": true,
> +# "charging": true,
> +# "discharging": false,
> +# "charge-percent": 85 } } }
> +# <- { "return": {} }
> +##
> +{ 'command': 'battery-set-state',
> + 'data': { 'state': 'BatteryInfo' } }
> +
> +##
> +# @query-battery:
> +#
> +# Query the current state of the emulated battery device
> +#
> +# Returns: current battery state
> +#
> +# Since: 10.2
> +#
> +# .. qmp-example::
> +#
> +# -> { "execute": "query-battery" }
> +# <- { "return": { "present": true,
> +# "charging": true,
> +# "discharging": false,
> +# "charge-percent": 85 } }
> +##
> +{ 'command': 'query-battery',
> + 'returns': 'BatteryInfo' }
© 2016 - 2025 Red Hat, Inc.