[PATCH v6 0/2] Add Apple Silicon SMC power driver

[PATCH v6 0/2] Add Apple Silicon SMC power driver

[Michael Reeves via B4 Relay]

This series adds a power supply driver for the Apple SMC found on
Apple Silicon devices. This allows the kernel to report AC status,
battery charging status, and power metrics, and modify the charging
behaviour.

The first patch adds the driver itself, and the second patch wires it
up to the MFD core.

The driver is based on an original out-of-tree implementation by
Hector Martin. It has been refactored by myself for upstream inclusion, 
including support for newer SMC firmwares, devices without batteries,
dynamic property detection and improved state management, among other
things.

This series is based ontop of the current linux-next at time of writing,
the exact commit hash is listed below.

Tested on: Apple M3 (MacBook Air, J613)

Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
---
Changes in v6:
- Add FS header include for emergency_sync()
- Link to v5: https://lore.kernel.org/r/20260126-b4-macsmc-power-v5-0-302462673b18@gmail.com

Changes in v5:
- Readd cover subject that mistakenly got dropped, apologies.
- Link to v4: https://lore.kernel.org/r/20260126-b4-macsmc-power-v4-0-aa2a682ca650@gmail.com

Changes in v4:
- Restore Hector Martin as primary author for the series.
- Restore downstream Co-developed-by and Signed-off-by tags.
- Add Reviewed-by: Sven Peter <sven@kernel.org>.
- Simplify MFD patch authorship and remove redundant tags.
- Fix probe return value being overwritten by devm_work_autocancel.
- Return -ENODEV in probe if neither battery nor AC adapter are found.
- Add bounds check for nprops against MACSMC_MAX_BATT_PROPS.
- Refactor macsmc_battery_set_charge_behaviour to remove unnecessary resets.
- Improve critical_work shutdown flags and remove return.
- Add comments explaining SMC key firmware history and flag meanings.
- Clarify event ID descriptions and restore BSFC flag comments.
- Remove redundant dev_dbg logs for missing battery or AC.
- Link to v3: https://lore.kernel.org/r/20260115-b4-macsmc-power-v3-0-c236e09874be@gmail.com

Changes in v3:
- Rebase on top of latest linux-next
- Drop charge control threshold properties.
- Switch to devm_work_autocancel() for critical work.
- Add platform ID table and remove MODULE_ALIAS.
- Simplify property array management in struct macsmc_power.
- Improve probe error handling and device pointer usage.
- Minor style and indentation fixes.
- Link to v2: https://lore.kernel.org/r/20260109-b4-macsmc-power-v2-0-93818f1e7d62@gmail.com

Changes in v2:
- Added Reviewed-by: Neal Gompa <neal@gompa.dev> to all patches.
- Fixed Makefile alignment by using tabs for the macsmc-power entry.
- Upgraded physical battery exhaustion log level to EMERG.
- Downgraded software-triggered orderly poweroff log level to CRIT.
- Added check for CHIS key to skip AC registration on desktop models.
- Link to v1: https://lore.kernel.org/r/20260105-b4-macsmc-power-v1-0-62954c42a555@gmail.com

---
Hector Martin (2):
      power: supply: Add macsmc-power driver for Apple Silicon
      mfd: macsmc: Wire up Apple SMC power driver

 MAINTAINERS                         |   1 +
 drivers/mfd/macsmc.c                |   1 +
 drivers/power/supply/Kconfig        |  11 +
 drivers/power/supply/Makefile       |   1 +
 drivers/power/supply/macsmc-power.c | 852 ++++++++++++++++++++++++++++++++++++
 5 files changed, 866 insertions(+)
---
base-commit: ca3a02fda4da8e2c1cb6baee5d72352e9e2cfaea
change-id: 20260125-b4-macsmc-power-bb30389e05f1

Best regards,
-- 
Michael Reeves <michael.reeves077@gmail.com>

[PATCH v6 1/2] power: supply: Add macsmc-power driver for Apple Silicon

[Michael Reeves via B4 Relay]

From: Hector Martin <marcan@marcan.st>

This driver provides battery and AC status monitoring for Apple Silicon
Macs via the SMC (System Management Controller). It supports reporting
capacity, voltage, current, and charging status, and modifying the
charging behaviour across multiple generations of SMC firmware.

Signed-off-by: Hector Martin <marcan@marcan.st>
Co-developed-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Co-developed-by: Janne Grunau <j@jannau.net>
Signed-off-by: Janne Grunau <j@jannau.net>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Sven Peter <sven@kernel.org>
Co-developed-by: Michael Reeves <michael.reeves077@gmail.com>
Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
---
 MAINTAINERS                         |   1 +
 drivers/power/supply/Kconfig        |  11 +
 drivers/power/supply/Makefile       |   1 +
 drivers/power/supply/macsmc-power.c | 852 ++++++++++++++++++++++++++++++++++++
 4 files changed, 865 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 414f44093269..30b204595b2d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2529,6 +2529,7 @@ F:	drivers/nvmem/apple-spmi-nvmem.c
 F:	drivers/phy/apple/
 F:	drivers/pinctrl/pinctrl-apple-gpio.c
 F:	drivers/power/reset/macsmc-reboot.c
+F:	drivers/power/supply/macsmc-power.c
 F:	drivers/pwm/pwm-apple.c
 F:	drivers/rtc/rtc-macsmc.c
 F:	drivers/soc/apple/*
diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index 92f9f7aae92f..3a5b7d9234c2 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -1132,4 +1132,15 @@ config FUEL_GAUGE_MM8013
 	  the state of charge, temperature, cycle count, actual and design
 	  capacity, etc.
 
+config MACSMC_POWER
+	tristate "Apple SMC Battery and Power Driver"
+	depends on MFD_MACSMC
+	help
+	  This driver provides support for the battery and AC adapter on
+	  Apple Silicon machines. It exposes battery telemetry (voltage,
+	  current, health) and AC adapter status through the standard Linux
+	  power supply framework.
+
+	  Say Y or M here if you have an Apple Silicon based Mac.
+
 endif # POWER_SUPPLY
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 4b79d5abc49a..d14420b606d8 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -128,3 +128,4 @@ obj-$(CONFIG_CHARGER_SURFACE)	+= surface_charger.o
 obj-$(CONFIG_BATTERY_UG3105)	+= ug3105_battery.o
 obj-$(CONFIG_CHARGER_QCOM_SMB2)	+= qcom_smbx.o
 obj-$(CONFIG_FUEL_GAUGE_MM8013)	+= mm8013.o
+obj-$(CONFIG_MACSMC_POWER)	+= macsmc-power.o
diff --git a/drivers/power/supply/macsmc-power.c b/drivers/power/supply/macsmc-power.c
new file mode 100644
index 000000000000..99f2f8878c3d
--- /dev/null
+++ b/drivers/power/supply/macsmc-power.c
@@ -0,0 +1,852 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SMC Power/Battery Management Driver
+ *
+ * This driver exposes battery telemetry (voltage, current, temperature, health)
+ * and AC adapter status provided by the Apple SMC (System Management Controller)
+ * on Apple Silicon systems.
+ *
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/devm-helpers.h>
+#include <linux/fs.h>
+#include <linux/limits.h>
+#include <linux/module.h>
+#include <linux/mfd/macsmc.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/reboot.h>
+#include <linux/workqueue.h>
+
+#define MAX_STRING_LENGTH 256
+
+/*
+ * The SMC reports charge in mAh (Coulombs) but energy in mWh (Joules).
+ * We lack a register for "Nominal Voltage" or "Energy Accumulator".
+ * We use a fixed 3.8V/cell constant to approximate energy stats for userspace,
+ * derived from empirical data across supported MacBook models.
+ */
+#define MACSMC_NOMINAL_CELL_VOLTAGE_MV 3800
+
+/* SMC Key Flags */
+#define CHNC_BATTERY_FULL	BIT(0)
+#define CHNC_NO_CHARGER		BIT(7)
+#define CHNC_NOCHG_CH0C		BIT(14)
+#define CHNC_NOCHG_CH0B_CH0K	BIT(15)
+#define CHNC_BATTERY_FULL_2	BIT(18)
+#define CHNC_BMS_BUSY		BIT(23)
+#define CHNC_CHLS_LIMIT		BIT(24)
+#define CHNC_NOAC_CH0J		BIT(53)
+#define CHNC_NOAC_CH0I		BIT(54)
+
+#define CH0R_LOWER_FLAGS	GENMASK(15, 0)
+#define CH0R_NOAC_CH0I		BIT(0)
+#define CH0R_NOAC_DISCONNECTED	BIT(4)
+#define CH0R_NOAC_CH0J		BIT(5)
+#define CH0R_BMS_BUSY		BIT(8)
+#define CH0R_NOAC_CH0K		BIT(9)
+#define CH0R_NOAC_CHWA		BIT(11)
+
+#define CH0X_CH0C		BIT(0)
+#define CH0X_CH0B		BIT(1)
+
+#define ACSt_CAN_BOOT_AP	BIT(2)
+#define ACSt_CAN_BOOT_IBOOT	BIT(1)
+
+#define CHWA_CHLS_FIXED_START_OFFSET	5
+#define CHLS_MIN_END_THRESHOLD		10
+#define CHLS_FORCE_DISCHARGE		0x100
+#define CHWA_FIXED_END_THRESHOLD	80
+#define CHWA_PROP_WRITE_THRESHOLD	95
+
+#define MACSMC_MAX_BATT_PROPS		50
+#define MACSMC_MAX_AC_PROPS		10
+
+struct macsmc_power {
+	struct device *dev;
+	struct apple_smc *smc;
+
+	struct power_supply_desc ac_desc;
+	struct power_supply_desc batt_desc;
+
+	struct power_supply *batt;
+	struct power_supply *ac;
+
+	char model_name[MAX_STRING_LENGTH];
+	char serial_number[MAX_STRING_LENGTH];
+	char mfg_date[MAX_STRING_LENGTH];
+
+	/* Supported feature flags based on SMC key presence */
+	bool has_chwa; /* Charge limit (Modern firmware) */
+	bool has_chls; /* Charge limit (Older firmware) */
+	bool has_ch0i; /* Force discharge (Older firmware) */
+	bool has_ch0c; /* Inhibit charge (Older firmware) */
+	bool has_chte; /* Inhibit charge (Modern firmware) */
+
+	u8 num_cells;
+	int nominal_voltage_mv;
+
+	struct notifier_block nb;
+	struct work_struct critical_work;
+	bool emergency_shutdown_triggered;
+	bool orderly_shutdown_triggered;
+};
+
+static int macsmc_battery_get_status(struct macsmc_power *power)
+{
+	u64 nocharge_flags;
+	u32 nopower_flags;
+	u16 ac_current;
+	int charge_limit = 0;
+	bool limited = false;
+	bool flag;
+	int ret;
+
+	/*
+	 * B0AV (Voltage) is fundamental. If we can't read it, we assume the
+	 * battery is gone. CHCE (Hardware charger present) / CHCC (Hardware
+	 * charger capable) are fundamental status flags.
+	 * BSFC (System full charge) / CHSC (System charging) are fundamental
+	 * status flags.
+	 */
+
+	/* Check if power input is inhibited (e.g. BMS balancing cycle) */
+	ret = apple_smc_read_u32(power->smc, SMC_KEY(CH0R), &nopower_flags);
+	if (!ret && (nopower_flags & CH0R_LOWER_FLAGS & ~CH0R_BMS_BUSY))
+		return POWER_SUPPLY_STATUS_DISCHARGING;
+
+	/* Check if charger is present */
+	ret = apple_smc_read_flag(power->smc, SMC_KEY(CHCE), &flag);
+	if (ret < 0)
+		return ret;
+	if (!flag)
+		return POWER_SUPPLY_STATUS_DISCHARGING;
+
+	/* Check if AC is charge capable */
+	ret = apple_smc_read_flag(power->smc, SMC_KEY(CHCC), &flag);
+	if (ret < 0)
+		return ret;
+	if (!flag)
+		return POWER_SUPPLY_STATUS_DISCHARGING;
+
+	/* Check if AC input limit is too low */
+	ret = apple_smc_read_u16(power->smc, SMC_KEY(AC-i), &ac_current);
+	if (!ret && ac_current < 100)
+		return POWER_SUPPLY_STATUS_DISCHARGING;
+
+	/* Check if battery is full */
+	ret = apple_smc_read_flag(power->smc, SMC_KEY(BSFC), &flag);
+	if (ret < 0)
+		return ret;
+	if (flag)
+		return POWER_SUPPLY_STATUS_FULL;
+
+	/* Check for user-defined charge limits */
+	if (power->has_chls) {
+		u16 vu16;
+
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(CHLS), &vu16);
+		if (ret == 0 && (vu16 & 0xff) >= CHLS_MIN_END_THRESHOLD)
+			charge_limit = (vu16 & 0xff) - CHWA_CHLS_FIXED_START_OFFSET;
+	} else if (power->has_chwa) {
+		ret = apple_smc_read_flag(power->smc, SMC_KEY(CHWA), &flag);
+		if (ret == 0 && flag)
+			charge_limit = CHWA_FIXED_END_THRESHOLD - CHWA_CHLS_FIXED_START_OFFSET;
+	}
+
+	if (charge_limit > 0) {
+		u8 buic = 0;
+
+		if (apple_smc_read_u8(power->smc, SMC_KEY(BUIC), &buic) >= 0 &&
+		    buic >= charge_limit)
+			limited = true;
+	}
+
+	/* Check charging inhibitors */
+	ret = apple_smc_read_u64(power->smc, SMC_KEY(CHNC), &nocharge_flags);
+	if (!ret) {
+		if (nocharge_flags & CHNC_BATTERY_FULL)
+			return POWER_SUPPLY_STATUS_FULL;
+		/* BMS busy shows up as inhibit, but we treat it as charging */
+		else if (nocharge_flags == CHNC_BMS_BUSY && !limited)
+			return POWER_SUPPLY_STATUS_CHARGING;
+		else if (nocharge_flags)
+			return POWER_SUPPLY_STATUS_NOT_CHARGING;
+		else
+			return POWER_SUPPLY_STATUS_CHARGING;
+	}
+
+	/* Fallback: System charging flag */
+	ret = apple_smc_read_flag(power->smc, SMC_KEY(CHSC), &flag);
+	if (ret < 0)
+		return ret;
+	if (!flag)
+		return POWER_SUPPLY_STATUS_NOT_CHARGING;
+
+	return POWER_SUPPLY_STATUS_CHARGING;
+}
+
+static int macsmc_battery_get_charge_behaviour(struct macsmc_power *power)
+{
+	int ret;
+	u8 val8;
+	u8 chte_buf[4];
+
+	if (power->has_ch0i) {
+		ret = apple_smc_read_u8(power->smc, SMC_KEY(CH0I), &val8);
+		if (ret)
+			return ret;
+		if (val8 & CH0R_NOAC_CH0I)
+			return POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE;
+	}
+
+	if (power->has_chte) {
+		ret = apple_smc_read(power->smc, SMC_KEY(CHTE), chte_buf, 4);
+		if (ret < 0)
+			return ret;
+
+		if (chte_buf[0] == 0x01)
+			return POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE;
+	} else if (power->has_ch0c) {
+		ret = apple_smc_read_u8(power->smc, SMC_KEY(CH0C), &val8);
+		if (ret)
+			return ret;
+		if (val8 & CH0X_CH0C)
+			return POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE;
+	}
+
+	return POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO;
+}
+
+static int macsmc_battery_set_charge_behaviour(struct macsmc_power *power, int val)
+{
+	int ret;
+
+	switch (val) {
+	case POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO:
+		/* Reset all inhibitors to a known-good 'auto' state */
+		if (power->has_ch0i) {
+			ret = apple_smc_write_u8(power->smc, SMC_KEY(CH0I), 0);
+			if (ret)
+				return ret;
+		}
+
+		if (power->has_chte) {
+			ret = apple_smc_write_u32(power->smc, SMC_KEY(CHTE), 0);
+			if (ret)
+				return ret;
+		} else if (power->has_ch0c) {
+			ret = apple_smc_write_u8(power->smc, SMC_KEY(CH0C), 0);
+			if (ret)
+				return ret;
+		}
+		return 0;
+
+	case POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE:
+		if (power->has_chte)
+			return apple_smc_write_u32(power->smc, SMC_KEY(CHTE), 1);
+		else if (power->has_ch0c)
+			return apple_smc_write_u8(power->smc, SMC_KEY(CH0C), 1);
+		else
+			return -EOPNOTSUPP;
+
+	case POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE:
+		if (!power->has_ch0i)
+			return -EOPNOTSUPP;
+		return apple_smc_write_u8(power->smc, SMC_KEY(CH0I), 1);
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int macsmc_battery_get_date(const char *s, int *out)
+{
+	if (!isdigit(s[0]) || !isdigit(s[1]))
+		return -EOPNOTSUPP;
+
+	*out = (s[0] - '0') * 10 + s[1] - '0';
+	return 0;
+}
+
+static int macsmc_battery_get_capacity_level(struct macsmc_power *power)
+{
+	bool flag;
+	u32 val;
+	int ret;
+
+	/* Check for emergency shutdown condition */
+	if (apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val) >= 0 && val)
+		return POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL;
+
+	/* Check AC status for whether we could boot in this state */
+	if (apple_smc_read_u32(power->smc, SMC_KEY(ACSt), &val) >= 0) {
+		if (!(val & ACSt_CAN_BOOT_IBOOT))
+			return POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL;
+
+		if (!(val & ACSt_CAN_BOOT_AP))
+			return POWER_SUPPLY_CAPACITY_LEVEL_LOW;
+	}
+
+	/* BSFC = Battery System Full Charge */
+	ret = apple_smc_read_flag(power->smc, SMC_KEY(BSFC), &flag);
+	if (ret < 0)
+		return POWER_SUPPLY_CAPACITY_LEVEL_UNKNOWN;
+
+	if (flag)
+		return POWER_SUPPLY_CAPACITY_LEVEL_FULL;
+	else
+		return POWER_SUPPLY_CAPACITY_LEVEL_NORMAL;
+}
+
+static int macsmc_battery_get_property(struct power_supply *psy,
+				       enum power_supply_property psp,
+				       union power_supply_propval *val)
+{
+	struct macsmc_power *power = power_supply_get_drvdata(psy);
+	int ret = 0;
+	u8 vu8;
+	u16 vu16;
+	s16 vs16;
+	s32 vs32;
+	s64 vs64;
+	bool flag;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_STATUS:
+		val->intval = macsmc_battery_get_status(power);
+		ret = val->intval < 0 ? val->intval : 0;
+		break;
+	case POWER_SUPPLY_PROP_PRESENT:
+		val->intval = 1;
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
+		val->intval = macsmc_battery_get_charge_behaviour(power);
+		ret = val->intval < 0 ? val->intval : 0;
+		break;
+	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0TE), &vu16);
+		val->intval = vu16 == 0xffff ? 0 : vu16 * 60;
+		break;
+	case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0TF), &vu16);
+		val->intval = vu16 == 0xffff ? 0 : vu16 * 60;
+		break;
+	case POWER_SUPPLY_PROP_CAPACITY:
+		ret = apple_smc_read_u8(power->smc, SMC_KEY(BUIC), &vu8);
+		val->intval = vu8;
+		break;
+	case POWER_SUPPLY_PROP_CAPACITY_LEVEL:
+		val->intval = macsmc_battery_get_capacity_level(power);
+		ret = val->intval < 0 ? val->intval : 0;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0AV), &vu16);
+		val->intval = vu16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		ret = apple_smc_read_s16(power->smc, SMC_KEY(B0AC), &vs16);
+		val->intval = vs16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_POWER_NOW:
+		ret = apple_smc_read_s32(power->smc, SMC_KEY(B0AP), &vs32);
+		val->intval = vs32 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(BITV), &vu16);
+		val->intval = vu16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
+		/* Calculate total max design voltage from per-cell maximum voltage */
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(BVVN), &vu16);
+		val->intval = vu16 * 1000 * power->num_cells;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MIN:
+		/* Lifetime min */
+		ret = apple_smc_read_s16(power->smc, SMC_KEY(BLPM), &vs16);
+		val->intval = vs16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MAX:
+		/* Lifetime max */
+		ret = apple_smc_read_s16(power->smc, SMC_KEY(BLPX), &vs16);
+		val->intval = vs16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RC), &vu16);
+		val->intval = vu16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RI), &vu16);
+		val->intval = vu16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RV), &vu16);
+		val->intval = vu16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0DC), &vu16);
+		val->intval = vu16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0FC), &vu16);
+		val->intval = vu16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_NOW:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RM), &vu16);
+		/* B0RM is Big Endian, likely pass through from TI gas gauge */
+		val->intval = (s16)swab16(vu16) * 1000;
+		break;
+	case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0DC), &vu16);
+		val->intval = vu16 * power->nominal_voltage_mv;
+		break;
+	case POWER_SUPPLY_PROP_ENERGY_FULL:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0FC), &vu16);
+		val->intval = vu16 * power->nominal_voltage_mv;
+		break;
+	case POWER_SUPPLY_PROP_ENERGY_NOW:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RM), &vu16);
+		/* B0RM is Big Endian, likely pass through from TI gas gauge */
+		val->intval = (s16)swab16(vu16) * power->nominal_voltage_mv;
+		break;
+	case POWER_SUPPLY_PROP_TEMP:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0AT), &vu16);
+		val->intval = vu16 - 2732; /* Kelvin x10 to Celsius x10 */
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
+		ret = apple_smc_read_s64(power->smc, SMC_KEY(BAAC), &vs64);
+		val->intval = vs64;
+		break;
+	case POWER_SUPPLY_PROP_CYCLE_COUNT:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(B0CT), &vu16);
+		val->intval = vu16;
+		break;
+	case POWER_SUPPLY_PROP_SCOPE:
+		val->intval = POWER_SUPPLY_SCOPE_SYSTEM;
+		break;
+	case POWER_SUPPLY_PROP_HEALTH:
+		flag = false;
+		ret = apple_smc_read_flag(power->smc, SMC_KEY(BBAD), &flag);
+		val->intval = flag ? POWER_SUPPLY_HEALTH_DEAD : POWER_SUPPLY_HEALTH_GOOD;
+		break;
+	case POWER_SUPPLY_PROP_MODEL_NAME:
+		val->strval = power->model_name;
+		break;
+	case POWER_SUPPLY_PROP_SERIAL_NUMBER:
+		val->strval = power->serial_number;
+		break;
+	case POWER_SUPPLY_PROP_MANUFACTURE_YEAR:
+		ret = macsmc_battery_get_date(&power->mfg_date[0], &val->intval);
+		/* The SMC reports the manufacture year as an offset from 1992. */
+		val->intval += 1992;
+		break;
+	case POWER_SUPPLY_PROP_MANUFACTURE_MONTH:
+		ret = macsmc_battery_get_date(&power->mfg_date[2], &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_MANUFACTURE_DAY:
+		ret = macsmc_battery_get_date(&power->mfg_date[4], &val->intval);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static int macsmc_battery_set_property(struct power_supply *psy,
+				       enum power_supply_property psp,
+				       const union power_supply_propval *val)
+{
+	struct macsmc_power *power = power_supply_get_drvdata(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
+		return macsmc_battery_set_charge_behaviour(power, val->intval);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int macsmc_battery_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 macsmc_battery_desc_template = {
+	.name			= "macsmc-battery",
+	.type			= POWER_SUPPLY_TYPE_BATTERY,
+	.get_property		= macsmc_battery_get_property,
+	.set_property		= macsmc_battery_set_property,
+	.property_is_writeable	= macsmc_battery_property_is_writeable,
+};
+
+static int macsmc_ac_get_property(struct power_supply *psy,
+				  enum power_supply_property psp,
+				  union power_supply_propval *val)
+{
+	struct macsmc_power *power = power_supply_get_drvdata(psy);
+	int ret = 0;
+	u16 vu16;
+	u32 vu32;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_ONLINE:
+		ret = apple_smc_read_u32(power->smc, SMC_KEY(CHIS), &vu32);
+		val->intval = !!vu32;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(AC-n), &vu16);
+		val->intval = vu16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+		ret = apple_smc_read_u16(power->smc, SMC_KEY(AC-i), &vu16);
+		val->intval = vu16 * 1000;
+		break;
+	case POWER_SUPPLY_PROP_INPUT_POWER_LIMIT:
+		ret = apple_smc_read_u32(power->smc, SMC_KEY(ACPW), &vu32);
+		val->intval = vu32 * 1000;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static const struct power_supply_desc macsmc_ac_desc_template = {
+	.name			= "macsmc-ac",
+	.type			= POWER_SUPPLY_TYPE_MAINS,
+	.get_property		= macsmc_ac_get_property,
+};
+
+static void macsmc_power_critical_work(struct work_struct *wrk)
+{
+	struct macsmc_power *power = container_of(wrk, struct macsmc_power, critical_work);
+	u16 bitv, b0av;
+	u32 bcf0;
+
+	if (!power->batt)
+		return;
+
+	/*
+	 * Avoid duplicate atempts at emergency shutdown
+	 */
+	if (power->emergency_shutdown_triggered || system_state > SYSTEM_RUNNING)
+		return;
+
+	/*
+	 * EMERGENCY: Check voltage vs design minimum.
+	 * If we are below BITV, the battery is physically exhausted.
+	 * We must shut down NOW to protect the filesystem.
+	 */
+	if (apple_smc_read_u16(power->smc, SMC_KEY(BITV), &bitv) >= 0 &&
+	    apple_smc_read_u16(power->smc, SMC_KEY(B0AV), &b0av) >= 0 &&
+	    b0av < bitv) {
+		power->emergency_shutdown_triggered = true;
+		dev_emerg(power->dev,
+			  "Battery voltage (%d mV) below design minimum (%d mV)! Emergency shutdown.\n",
+			  b0av, bitv);
+		emergency_sync();
+		kernel_power_off();
+	}
+
+	/*
+	 * Avoid duplicate attempts at orderly shutdown.
+	 * Voltage check is above this as we may want to
+	 * "upgrade" an orderly shutdown to a critical power
+	 * off if voltage drops.
+	 */
+	if (power->orderly_shutdown_triggered || system_state > SYSTEM_RUNNING)
+		return;
+
+	/*
+	 * Check if SMC flagged the battery as empty.
+	 * We trigger a graceful shutdown to let the OS save data.
+	 */
+	if (apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &bcf0) == 0 && bcf0 != 0) {
+		power->orderly_shutdown_triggered = true;
+		dev_crit(power->dev, "Battery critical (empty flag set). Triggering orderly shutdown.\n");
+		orderly_poweroff(true);
+	}
+}
+
+static int macsmc_power_event(struct notifier_block *nb, unsigned long event, void *data)
+{
+	struct macsmc_power *power = container_of(nb, struct macsmc_power, nb);
+
+	/*
+	 * SMC Event IDs are correlated to physical events (e.g. charger
+	 * connect/disconnect) but the exact meaning of each ID is predicted.
+	 * 0x71... indicates power/battery events.
+	 */
+	if ((event & 0xffffff00) == 0x71010100 || /* Charger status change */
+	    (event & 0xffff0000) == 0x71060000 || /* Port charge state change */
+	    (event & 0xffff0000) == 0x71130000) { /* Connector insert/remove event */
+		if (power->batt)
+			power_supply_changed(power->batt);
+		if (power->ac)
+			power_supply_changed(power->ac);
+		return NOTIFY_OK;
+	} else if (event == 0x71020000) {
+		/* Critical battery warning */
+		if (power->batt)
+			schedule_work(&power->critical_work);
+		return NOTIFY_OK;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int macsmc_power_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
+	struct power_supply_config psy_cfg = {};
+	struct macsmc_power *power;
+	bool has_battery = false;
+	bool has_ac_adapter = false;
+	int ret = -ENODEV;
+	bool flag;
+	u16 vu16;
+	u32 val32;
+	enum power_supply_property *props;
+	size_t nprops;
+
+	if (!smc)
+		return -ENODEV;
+
+	power = devm_kzalloc(dev, sizeof(*power), GFP_KERNEL);
+	if (!power)
+		return -ENOMEM;
+
+	power->dev = dev;
+	power->smc = smc;
+	dev_set_drvdata(dev, power);
+
+	INIT_WORK(&power->critical_work, macsmc_power_critical_work);
+	ret = devm_work_autocancel(dev, &power->critical_work, macsmc_power_critical_work);
+	if (ret)
+		return ret;
+
+	/*
+	 * Check for battery presence.
+	 * B0AV is a fundamental key.
+	 */
+	if (apple_smc_read_u16(power->smc, SMC_KEY(B0AV), &vu16) == 0 &&
+	    macsmc_battery_get_status(power) > POWER_SUPPLY_STATUS_UNKNOWN)
+		has_battery = true;
+
+	/*
+	 * Check for AC adapter presence.
+	 * CHIS is a fundamental key.
+	 */
+	if (apple_smc_key_exists(smc, SMC_KEY(CHIS)))
+		has_ac_adapter = true;
+
+	if (!has_battery && !has_ac_adapter)
+		return -ENODEV;
+
+	if (has_battery) {
+		power->batt_desc = macsmc_battery_desc_template;
+		props = devm_kcalloc(dev, MACSMC_MAX_BATT_PROPS,
+				     sizeof(enum power_supply_property),
+				     GFP_KERNEL);
+		if (!props)
+			return -ENOMEM;
+
+		nprops = 0;
+
+		/* Fundamental properties */
+		props[nprops++] = POWER_SUPPLY_PROP_STATUS;
+		props[nprops++] = POWER_SUPPLY_PROP_PRESENT;
+		props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_NOW;
+		props[nprops++] = POWER_SUPPLY_PROP_CURRENT_NOW;
+		props[nprops++] = POWER_SUPPLY_PROP_POWER_NOW;
+		props[nprops++] = POWER_SUPPLY_PROP_CAPACITY;
+		props[nprops++] = POWER_SUPPLY_PROP_CAPACITY_LEVEL;
+		props[nprops++] = POWER_SUPPLY_PROP_TEMP;
+		props[nprops++] = POWER_SUPPLY_PROP_CYCLE_COUNT;
+		props[nprops++] = POWER_SUPPLY_PROP_HEALTH;
+		props[nprops++] = POWER_SUPPLY_PROP_SCOPE;
+		props[nprops++] = POWER_SUPPLY_PROP_MODEL_NAME;
+		props[nprops++] = POWER_SUPPLY_PROP_SERIAL_NUMBER;
+		props[nprops++] = POWER_SUPPLY_PROP_MANUFACTURE_YEAR;
+		props[nprops++] = POWER_SUPPLY_PROP_MANUFACTURE_MONTH;
+		props[nprops++] = POWER_SUPPLY_PROP_MANUFACTURE_DAY;
+
+		/* Extended properties usually present */
+		props[nprops++] = POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW;
+		props[nprops++] = POWER_SUPPLY_PROP_TIME_TO_FULL_NOW;
+		props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN;
+		props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN;
+		props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MIN;
+		props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MAX;
+		props[nprops++] = POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT;
+		props[nprops++] = POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX;
+		props[nprops++] = POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE;
+		props[nprops++] = POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN;
+		props[nprops++] = POWER_SUPPLY_PROP_CHARGE_FULL;
+		props[nprops++] = POWER_SUPPLY_PROP_CHARGE_NOW;
+		props[nprops++] = POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN;
+		props[nprops++] = POWER_SUPPLY_PROP_ENERGY_FULL;
+		props[nprops++] = POWER_SUPPLY_PROP_ENERGY_NOW;
+		props[nprops++] = POWER_SUPPLY_PROP_CHARGE_COUNTER;
+
+		/* Detect features based on key availability */
+		if (apple_smc_key_exists(smc, SMC_KEY(CHTE)))
+			power->has_chte = true;
+		if (apple_smc_key_exists(smc, SMC_KEY(CH0C)))
+			power->has_ch0c = true;
+		if (apple_smc_key_exists(smc, SMC_KEY(CH0I)))
+			power->has_ch0i = true;
+
+		/* Reset "Optimised Battery Charging" flags to default state */
+		if (power->has_chte)
+			apple_smc_write_u32(smc, SMC_KEY(CHTE), 0);
+		else if (power->has_ch0c)
+			apple_smc_write_u8(smc, SMC_KEY(CH0C), 0);
+
+		if (power->has_ch0i)
+			apple_smc_write_u8(smc, SMC_KEY(CH0I), 0);
+
+		apple_smc_write_u8(smc, SMC_KEY(CH0K), 0);
+		apple_smc_write_u8(smc, SMC_KEY(CH0B), 0);
+
+		/* Configure charge behaviour if supported */
+		if (power->has_ch0i || power->has_ch0c || power->has_chte) {
+			props[nprops++] = POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR;
+
+			power->batt_desc.charge_behaviours =
+				BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO);
+
+			if (power->has_ch0i)
+				power->batt_desc.charge_behaviours |=
+					BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE);
+
+			if (power->has_chte || power->has_ch0c)
+				power->batt_desc.charge_behaviours |=
+					BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE);
+		}
+
+		/* Detect charge limit method (CHWA vs CHLS) */
+		if (apple_smc_read_flag(power->smc, SMC_KEY(CHWA), &flag) == 0)
+			power->has_chwa = true;
+		else if (apple_smc_read_u16(power->smc, SMC_KEY(CHLS), &vu16) >= 0)
+			power->has_chls = true;
+
+		if (nprops > MACSMC_MAX_BATT_PROPS)
+			return -ENOMEM;
+
+		power->batt_desc.properties = props;
+		power->batt_desc.num_properties = nprops;
+
+		/* Fetch identity strings */
+		apple_smc_read(smc, SMC_KEY(BMDN), power->model_name,
+			       sizeof(power->model_name) - 1);
+		apple_smc_read(smc, SMC_KEY(BMSN), power->serial_number,
+			       sizeof(power->serial_number) - 1);
+		apple_smc_read(smc, SMC_KEY(BMDT), power->mfg_date,
+			       sizeof(power->mfg_date) - 1);
+
+		apple_smc_read_u8(power->smc, SMC_KEY(BNCB), &power->num_cells);
+		power->nominal_voltage_mv = MACSMC_NOMINAL_CELL_VOLTAGE_MV * power->num_cells;
+
+		/* Enable critical shutdown notifications by reading status once */
+		apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val32);
+
+		psy_cfg.drv_data = power;
+		power->batt = devm_power_supply_register(dev, &power->batt_desc, &psy_cfg);
+		if (IS_ERR(power->batt)) {
+			dev_err_probe(dev, PTR_ERR(power->batt),
+				      "Failed to register battery\n");
+			/* Don't return failure yet; try AC registration first */
+			power->batt = NULL;
+		}
+	}
+
+	if (has_ac_adapter) {
+		power->ac_desc = macsmc_ac_desc_template;
+		props = devm_kcalloc(dev, MACSMC_MAX_AC_PROPS,
+				     sizeof(enum power_supply_property),
+				     GFP_KERNEL);
+		if (!props)
+			return -ENOMEM;
+
+		nprops = 0;
+
+		/* Online status is fundamental */
+		props[nprops++] = POWER_SUPPLY_PROP_ONLINE;
+
+		/* Input power limits are usually available */
+		if (apple_smc_key_exists(power->smc, SMC_KEY(ACPW)))
+			props[nprops++] = POWER_SUPPLY_PROP_INPUT_POWER_LIMIT;
+
+		/* macOS 15.4+ firmware dropped legacy AC keys (AC-n, AC-i) */
+		if (apple_smc_read_u16(power->smc, SMC_KEY(AC-n), &vu16) >= 0) {
+			props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_NOW;
+			props[nprops++] = POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT;
+		}
+
+		if (nprops > MACSMC_MAX_AC_PROPS)
+			return -ENOMEM;
+
+		power->ac_desc.properties = props;
+		power->ac_desc.num_properties = nprops;
+
+		psy_cfg.drv_data = power;
+		power->ac = devm_power_supply_register(dev, &power->ac_desc, &psy_cfg);
+		if (IS_ERR(power->ac)) {
+			dev_err_probe(dev, PTR_ERR(power->ac),
+				      "Failed to register AC adapter\n");
+			power->ac = NULL;
+		}
+	}
+
+	/* Final check: did we register anything? */
+	if (!power->batt && !power->ac)
+		return -ENODEV;
+
+	power->nb.notifier_call = macsmc_power_event;
+	blocking_notifier_chain_register(&smc->event_handlers, &power->nb);
+
+	return 0;
+}
+
+static void macsmc_power_remove(struct platform_device *pdev)
+{
+	struct macsmc_power *power = dev_get_drvdata(&pdev->dev);
+
+	blocking_notifier_chain_unregister(&power->smc->event_handlers, &power->nb);
+}
+
+static const struct platform_device_id macsmc_power_id[] = {
+	{ "macsmc-power" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, macsmc_power_id);
+
+static struct platform_driver macsmc_power_driver = {
+	.driver = {
+		.name = "macsmc-power",
+	},
+	.id_table = macsmc_power_id,
+	.probe = macsmc_power_probe,
+	.remove = macsmc_power_remove,
+};
+module_platform_driver(macsmc_power_driver);
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_DESCRIPTION("Apple SMC battery and power management driver");
+MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
+MODULE_AUTHOR("Michael Reeves <michael.reeves077@gmail.com>");

-- 
2.51.2

[PATCH v6 2/2] mfd: macsmc: Wire up Apple SMC power driver

[Michael Reeves via B4 Relay]

From: Hector Martin <marcan@marcan.st>

Add the cell for the macsmc-power driver so it is probed by the
MFD core.

Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Sven Peter <sven@kernel.org>
Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
---
 drivers/mfd/macsmc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mfd/macsmc.c b/drivers/mfd/macsmc.c
index 1b7e7b3e785f..358feec2d088 100644
--- a/drivers/mfd/macsmc.c
+++ b/drivers/mfd/macsmc.c
@@ -46,6 +46,7 @@
 
 static const struct mfd_cell apple_smc_devs[] = {
 	MFD_CELL_NAME("macsmc-input"),
+	MFD_CELL_NAME("macsmc-power"),
 	MFD_CELL_OF("macsmc-gpio", NULL, NULL, 0, 0, "apple,smc-gpio"),
 	MFD_CELL_OF("macsmc-hwmon", NULL, NULL, 0, 0, "apple,smc-hwmon"),
 	MFD_CELL_OF("macsmc-reboot", NULL, NULL, 0, 0, "apple,smc-reboot"),

-- 
2.51.2

Re: [PATCH v6 0/2] Add Apple Silicon SMC power driver

[Sebastian Reichel]

[-- Attachment #1: Type: text/plain, Size: 4080 bytes --]

Hi,

On Mon, Jan 26, 2026 at 10:16:55AM +1100, Michael Reeves via B4 Relay wrote:
> This series adds a power supply driver for the Apple SMC found on
> Apple Silicon devices. This allows the kernel to report AC status,
> battery charging status, and power metrics, and modify the charging
> behaviour.
> 
> The first patch adds the driver itself, and the second patch wires it
> up to the MFD core.
> 
> The driver is based on an original out-of-tree implementation by
> Hector Martin. It has been refactored by myself for upstream inclusion, 
> including support for newer SMC firmwares, devices without batteries,
> dynamic property detection and improved state management, among other
> things.
> 
> This series is based ontop of the current linux-next at time of writing,
> the exact commit hash is listed below.
> 
> Tested on: Apple M3 (MacBook Air, J613)
> 
> Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
> ---
> Changes in v6:
> - Add FS header include for emergency_sync()
> - Link to v5: https://lore.kernel.org/r/20260126-b4-macsmc-power-v5-0-302462673b18@gmail.com

This fails to build as module, since emergency_sync() is not exported:

ERROR: modpost: "emergency_sync" [drivers/power/supply/macsmc-power.ko] undefined!
make[2]: *** [scripts/Makefile.modpost:147: Module.symvers] Error 1

Greetings,

-- Sebastian

> Changes in v5:
> - Readd cover subject that mistakenly got dropped, apologies.
> - Link to v4: https://lore.kernel.org/r/20260126-b4-macsmc-power-v4-0-aa2a682ca650@gmail.com
> 
> Changes in v4:
> - Restore Hector Martin as primary author for the series.
> - Restore downstream Co-developed-by and Signed-off-by tags.
> - Add Reviewed-by: Sven Peter <sven@kernel.org>.
> - Simplify MFD patch authorship and remove redundant tags.
> - Fix probe return value being overwritten by devm_work_autocancel.
> - Return -ENODEV in probe if neither battery nor AC adapter are found.
> - Add bounds check for nprops against MACSMC_MAX_BATT_PROPS.
> - Refactor macsmc_battery_set_charge_behaviour to remove unnecessary resets.
> - Improve critical_work shutdown flags and remove return.
> - Add comments explaining SMC key firmware history and flag meanings.
> - Clarify event ID descriptions and restore BSFC flag comments.
> - Remove redundant dev_dbg logs for missing battery or AC.
> - Link to v3: https://lore.kernel.org/r/20260115-b4-macsmc-power-v3-0-c236e09874be@gmail.com
> 
> Changes in v3:
> - Rebase on top of latest linux-next
> - Drop charge control threshold properties.
> - Switch to devm_work_autocancel() for critical work.
> - Add platform ID table and remove MODULE_ALIAS.
> - Simplify property array management in struct macsmc_power.
> - Improve probe error handling and device pointer usage.
> - Minor style and indentation fixes.
> - Link to v2: https://lore.kernel.org/r/20260109-b4-macsmc-power-v2-0-93818f1e7d62@gmail.com
> 
> Changes in v2:
> - Added Reviewed-by: Neal Gompa <neal@gompa.dev> to all patches.
> - Fixed Makefile alignment by using tabs for the macsmc-power entry.
> - Upgraded physical battery exhaustion log level to EMERG.
> - Downgraded software-triggered orderly poweroff log level to CRIT.
> - Added check for CHIS key to skip AC registration on desktop models.
> - Link to v1: https://lore.kernel.org/r/20260105-b4-macsmc-power-v1-0-62954c42a555@gmail.com
> 
> ---
> Hector Martin (2):
>       power: supply: Add macsmc-power driver for Apple Silicon
>       mfd: macsmc: Wire up Apple SMC power driver
> 
>  MAINTAINERS                         |   1 +
>  drivers/mfd/macsmc.c                |   1 +
>  drivers/power/supply/Kconfig        |  11 +
>  drivers/power/supply/Makefile       |   1 +
>  drivers/power/supply/macsmc-power.c | 852 ++++++++++++++++++++++++++++++++++++
>  5 files changed, 866 insertions(+)
> ---
> base-commit: ca3a02fda4da8e2c1cb6baee5d72352e9e2cfaea
> change-id: 20260125-b4-macsmc-power-bb30389e05f1
> 
> Best regards,
> -- 
> Michael Reeves <michael.reeves077@gmail.com>
> 
> 

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Re: [PATCH v6 0/2] Add Apple Silicon SMC power driver

[Michael Reeves]

Hi,
On Sat, Jan 31, 2026 at 6:54 AM Sebastian Reichel
<sebastian.reichel@collabora.com> wrote:
>
> Hi,
>
> On Mon, Jan 26, 2026 at 10:16:55AM +1100, Michael Reeves via B4 Relay wrote:
> > This series adds a power supply driver for the Apple SMC found on
> > Apple Silicon devices. This allows the kernel to report AC status,
> > battery charging status, and power metrics, and modify the charging
> > behaviour.
> >
> > The first patch adds the driver itself, and the second patch wires it
> > up to the MFD core.
> >
> > The driver is based on an original out-of-tree implementation by
> > Hector Martin. It has been refactored by myself for upstream inclusion,
> > including support for newer SMC firmwares, devices without batteries,
> > dynamic property detection and improved state management, among other
> > things.
> >
> > This series is based ontop of the current linux-next at time of writing,
> > the exact commit hash is listed below.
> >
> > Tested on: Apple M3 (MacBook Air, J613)
> >
> > Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
> > ---
> > Changes in v6:
> > - Add FS header include for emergency_sync()
> > - Link to v5: https://lore.kernel.org/r/20260126-b4-macsmc-power-v5-0-302462673b18@gmail.com
>
> This fails to build as module, since emergency_sync() is not exported:
>
> ERROR: modpost: "emergency_sync" [drivers/power/supply/macsmc-power.ko] undefined!
> make[2]: *** [scripts/Makefile.modpost:147: Module.symvers] Error 1
Thank you for finding this! Sorry, I didn't test building as a module,
only as built-in, I will do this
going forward in future. After some research I've found
hw_protection_trigger which is exported
and will emergency sync and power off (just like this) after a
customisable timeout, which
seems suitable for this usecase. I'll test it now and submit v7 shortly.
>
> Greetings,
>
> -- Sebastian
>
> > Changes in v5:
> > - Readd cover subject that mistakenly got dropped, apologies.
> > - Link to v4: https://lore.kernel.org/r/20260126-b4-macsmc-power-v4-0-aa2a682ca650@gmail.com
> >
> > Changes in v4:
> > - Restore Hector Martin as primary author for the series.
> > - Restore downstream Co-developed-by and Signed-off-by tags.
> > - Add Reviewed-by: Sven Peter <sven@kernel.org>.
> > - Simplify MFD patch authorship and remove redundant tags.
> > - Fix probe return value being overwritten by devm_work_autocancel.
> > - Return -ENODEV in probe if neither battery nor AC adapter are found.
> > - Add bounds check for nprops against MACSMC_MAX_BATT_PROPS.
> > - Refactor macsmc_battery_set_charge_behaviour to remove unnecessary resets.
> > - Improve critical_work shutdown flags and remove return.
> > - Add comments explaining SMC key firmware history and flag meanings.
> > - Clarify event ID descriptions and restore BSFC flag comments.
> > - Remove redundant dev_dbg logs for missing battery or AC.
> > - Link to v3: https://lore.kernel.org/r/20260115-b4-macsmc-power-v3-0-c236e09874be@gmail.com
> >
> > Changes in v3:
> > - Rebase on top of latest linux-next
> > - Drop charge control threshold properties.
> > - Switch to devm_work_autocancel() for critical work.
> > - Add platform ID table and remove MODULE_ALIAS.
> > - Simplify property array management in struct macsmc_power.
> > - Improve probe error handling and device pointer usage.
> > - Minor style and indentation fixes.
> > - Link to v2: https://lore.kernel.org/r/20260109-b4-macsmc-power-v2-0-93818f1e7d62@gmail.com
> >
> > Changes in v2:
> > - Added Reviewed-by: Neal Gompa <neal@gompa.dev> to all patches.
> > - Fixed Makefile alignment by using tabs for the macsmc-power entry.
> > - Upgraded physical battery exhaustion log level to EMERG.
> > - Downgraded software-triggered orderly poweroff log level to CRIT.
> > - Added check for CHIS key to skip AC registration on desktop models.
> > - Link to v1: https://lore.kernel.org/r/20260105-b4-macsmc-power-v1-0-62954c42a555@gmail.com
> >
> > ---
> > Hector Martin (2):
> >       power: supply: Add macsmc-power driver for Apple Silicon
> >       mfd: macsmc: Wire up Apple SMC power driver
> >
> >  MAINTAINERS                         |   1 +
> >  drivers/mfd/macsmc.c                |   1 +
> >  drivers/power/supply/Kconfig        |  11 +
> >  drivers/power/supply/Makefile       |   1 +
> >  drivers/power/supply/macsmc-power.c | 852 ++++++++++++++++++++++++++++++++++++
> >  5 files changed, 866 insertions(+)
> > ---
> > base-commit: ca3a02fda4da8e2c1cb6baee5d72352e9e2cfaea
> > change-id: 20260125-b4-macsmc-power-bb30389e05f1
> >
> > Best regards,
> > --
> > Michael Reeves <michael.reeves077@gmail.com>
> >
> >
Thanks again,
Michael