From aee3b283827bba837ad8ae7da228d048d25797ed Mon Sep 17 00:00:00 2001 From: Michael Reeves Date: Fri, 2 Jan 2026 14:10:30 +1100 Subject: [PATCH] power: supply: macsmc: support charge_behaviour on newer SMC firmware Newer Apple SMC firmware (found on M3 devices and updated M1/M2) has removed the legacy `CH0C` (Inhibit Charge) and `CH0I` (Force Discharge) keys. Reading these missing keys results in -EIO (-5) errors, causing the `charge_behaviour` sysfs property to fail completely. This patch adds support for the new `CHTE` key used for charge inhibition on these devices. For now, it seems that `auto` and `inhibit-charge` are the only possible behaviours to set using this new key, however further macOS tracing may reveal additional behaviour states in future. Changes: 1. Detects the presence of `CHTE`, `CH0C`, and `CH0I` during probe. 2. Only exposes `force_discharge` capability if `CH0I` is actually present. 3. Implements read/write support for `CHTE` using raw byte buffers (this is to avoid endianness issues with the kernel's u32 helpers) Fully backwards compatible with both old and new firmwares. Tested on M3 with new firmware. Signed-off-by: Michael Reeves --- drivers/power/supply/macsmc-power.c | 160 ++++++++++++++++++++++------ 1 file changed, 126 insertions(+), 34 deletions(-) diff --git a/drivers/power/supply/macsmc-power.c b/drivers/power/supply/macsmc-power.c index 0948ede776cf70..70258fccd72508 100644 --- a/drivers/power/supply/macsmc-power.c +++ b/drivers/power/supply/macsmc-power.c @@ -39,8 +39,13 @@ struct macsmc_power { char model_name[MAX_STRING_LENGTH]; char serial_number[MAX_STRING_LENGTH]; char mfg_date[MAX_STRING_LENGTH]; + bool has_chwa; bool has_chls; + bool has_ch0i; + bool has_ch0c; + bool has_chte; + u8 num_cells; int nominal_voltage_mv; @@ -57,8 +62,8 @@ struct macsmc_power { static int macsmc_log_power_set(const char *val, const struct kernel_param *kp); static const struct kernel_param_ops macsmc_log_power_ops = { - .set = macsmc_log_power_set, - .get = param_get_bool, + .set = macsmc_log_power_set, + .get = param_get_bool, }; static bool log_power = false; @@ -242,6 +247,7 @@ static int macsmc_battery_get_status(struct macsmc_power *power) */ if (power->has_chls) { u16 vu16; + ret = apple_smc_read_u16(power->smc, SMC_KEY(CHLS), &vu16); if (ret == sizeof(vu16) && (vu16 & 0xff) >= CHLS_MIN_END_THRESHOLD) charge_limit = (vu16 & 0xff) - CHWA_CHLS_FIXED_START_OFFSET; @@ -253,6 +259,7 @@ static int macsmc_battery_get_status(struct macsmc_power *power) if (charge_limit > 0) { u8 buic = 0; + if (apple_smc_read_u8(power->smc, SMC_KEY(BUIC), &buic) >= 0 && buic >= charge_limit) limited = true; @@ -291,55 +298,113 @@ static int macsmc_battery_get_status(struct macsmc_power *power) static int macsmc_battery_get_charge_behaviour(struct macsmc_power *power) { int ret; - u8 val; + u8 val8; + u8 chte_buf[4]; + + if (power->has_ch0i) { + /* CH0I returns a bitmask like the low byte of CH0R */ + 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; + } - /* CH0I returns a bitmask like the low byte of CH0R */ - ret = apple_smc_read_u8(power->smc, SMC_KEY(CH0I), &val); - if (ret) - return ret; - if (val & CH0R_NOAC_CH0I) - return POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE; + /* Prefer CHTE available in newer firmwares */ + 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) { + /* CH0C returns a bitmask containing CH0B/CH0C flags */ + 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; + } - /* CH0C returns a bitmask containing CH0B/CH0C flags */ - ret = apple_smc_read_u8(power->smc, SMC_KEY(CH0C), &val); - if (ret) - return ret; - if (val & CH0X_CH0C) - return POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE; - else - return POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO; + return POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO; } static int macsmc_battery_set_charge_behaviour(struct macsmc_power *power, int val) { - u8 ch0i, ch0c; int ret; /* - * CH0I/CH0C are "hard" controls that will allow the battery to run down to 0. + * apple_smc_write_u32 does weird things with endianess, + * so we write raw bytes to ensure correctness of CHTE + */ + u8 chte_inhibit[4] = {0x01, 0x00, 0x00, 0x00}; + u8 chte_auto[4] = {0x00, 0x00, 0x00, 0x00}; + + /* + * CH0I/CH0C/CHTE are "hard" controls that will allow the battery to run down to 0. * CH0K/CH0B are "soft" controls that are reset to 0 when SOC drops below 50%; * we don't expose these yet. */ - + switch (val) { case POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO: - ch0i = ch0c = 0; + 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(power->smc, SMC_KEY(CHTE), chte_auto, 4); + if (ret) + return ret; + } else if (power->has_ch0c) { + ret = apple_smc_write_u8(power->smc, SMC_KEY(CH0C), 0); + if (ret) + return ret; + } break; + case POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE: - ch0i = 0; - ch0c = 1; + if (power->has_ch0i) { + ret = apple_smc_write_u8(power->smc, SMC_KEY(CH0I), 0); + if (ret) + return ret; + } + + /* Prefer CHTE available in newer firmwares */ + if (power->has_chte) + return apple_smc_write(power->smc, SMC_KEY(CHTE), chte_inhibit, 4); + else if (power->has_ch0c) + return apple_smc_write_u8(power->smc, SMC_KEY(CH0C), 1); + else + return -EINVAL; break; + case POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE: - ch0i = 1; - ch0c = 0; - break; + if (!power->has_ch0i) + return -EINVAL; + + /* Prefer CHTE available in newer firmwares */ + if (power->has_chte) { + ret = apple_smc_write(power->smc, SMC_KEY(CHTE), chte_auto, 4); + 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 apple_smc_write_u8(power->smc, SMC_KEY(CH0I), 1); + default: return -EINVAL; } - ret = apple_smc_write_u8(power->smc, SMC_KEY(CH0I), ch0i); - if (ret) - return ret; - return apple_smc_write_u8(power->smc, SMC_KEY(CH0C), ch0c); + + return 0; } static int macsmc_battery_get_date(const char *s, int *out) @@ -539,8 +604,7 @@ static int macsmc_battery_get_property(struct power_supply *psy, val->intval = vu16 & 0xff; if (val->intval < CHLS_MIN_END_THRESHOLD || val->intval >= 100) val->intval = 100; - } - else if (power->has_chwa) { + } else if (power->has_chwa) { flag = false; ret = apple_smc_read_flag(power->smc, SMC_KEY(CHWA), &flag); val->intval = flag ? CHWA_FIXED_END_THRESHOLD : 100; @@ -838,8 +902,9 @@ static int macsmc_power_probe(struct platform_device *pdev) struct power_supply_config psy_cfg = {}; struct macsmc_power *power; bool flag; - u32 val; + u8 val8; u16 vu16; + u32 val32; int ret; power = devm_kzalloc(&pdev->dev, sizeof(*power), GFP_KERNEL); @@ -861,10 +926,37 @@ static int macsmc_power_probe(struct platform_device *pdev) 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); + if (apple_smc_read_u32(power->smc, SMC_KEY(CHTE), &val32) >= 0) + power->has_chte = true; + + if (apple_smc_read_u8(power->smc, SMC_KEY(CH0C), &val8) >= 0) + power->has_ch0c = true; + + if (apple_smc_read_u8(power->smc, SMC_KEY(CH0I), &val8) >= 0) + power->has_ch0i = true; + /* Turn off the "optimized battery charging" flags, in case macOS left them on */ + if (power->has_chte) + apple_smc_write_u32(power->smc, SMC_KEY(CHTE), 0); + else if (power->has_ch0c) + apple_smc_write_u8(power->smc, SMC_KEY(CH0C), 0); + + if (power->has_ch0i) + apple_smc_write_u8(power->smc, SMC_KEY(CH0I), 0); + apple_smc_write_u8(power->smc, SMC_KEY(CH0K), 0); apple_smc_write_u8(power->smc, SMC_KEY(CH0B), 0); + power->batt_desc.charge_behaviours = BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO); + + /* Newer firmwares do not have force discharge, so check if it's supported */ + if (power->has_ch0i) + power->batt_desc.charge_behaviours |= BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE); + + /* Older firmware uses CH0C, and newer firmware uses CHTE, so check if at least one is present*/ + if (power->has_chte || power->has_ch0c) + power->batt_desc.charge_behaviours |= BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE); + /* * Prefer CHWA as the SMC firmware from iBoot-10151.1.1 is not compatible with * this CHLS usage. @@ -882,7 +974,7 @@ static int macsmc_power_probe(struct platform_device *pdev) power->nominal_voltage_mv = MACSMC_NOMINAL_CELL_VOLTAGE_MV * power->num_cells; /* Doing one read of this flag enables critical shutdown notifications */ - apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val); + apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val32); psy_cfg.drv_data = power; power->batt = devm_power_supply_register(&pdev->dev, &power->batt_desc, &psy_cfg);