power: supply: macsmc: add "auto-discharge" charge behaviour for CHLS by BoiledElectricity · Pull Request #521 · AsahiLinux/linux

BoiledElectricity · 2026-06-24T21:51:00Z

Lowering the charge limit on CHLS machines always sets CHLS_FORCE_DISCHARGE, so the battery actively drains down to the limit even on AC. Per review feedback, this is now implemented as a new charge_behaviour value instead of a module parameter:

New auto-discharge value (enum + sysfs string + ABI doc): like auto, but actively discharge down to the charge control end threshold.
End-threshold writes preserve the current CHLS_FORCE_DISCHARGE bit instead of forcing it on; auto keeps its documented cap-only meaning.
The selection lives in the CHLS key itself: no driver state, persists across reboots, and systems upgrading from the old behaviour keep force-discharge until they explicitly write auto.

Resolves the in-code TODO. Tested on M1 MacBook Pro (j293), see comments.

Apple Silicon based laptop use SPI as transport for HID. Add support for SPI-based HID devices and and Apple keyboard and trackpad devices. Intel based laptops using the keyboard input driver applespi use the same HID over SPI protocol and can be supported later. This requires SPI keyboard/mouse HID types since Apple's intenal keyboards/trackpads use the same product id. Signed-off-by: Janne Grunau <j@jannau.net>

Apple M2* chips have an embedded MTP processor that handles all HID functions, and does not go over a traditional bus like SPI. The devices still have real IDs, so add them here. Signed-off-by: Hector Martin <marcan@marcan.st>

Signed-off-by: Hector Martin <marcan@marcan.st>

This maximum is arbitrary. Recent Apple devices have some vendor-defined reports with 16384 here which fail to parse without this, so let's bump it to that. This value is used as follows: report->size += parser->global.report_size * parser->global.report_count; [...] /* Total size check: Allow for possible report index byte */ if (report->size > (max_buffer_size - 1) << 3) { hid_err(parser->device, "report is too long\n"); return -1; } All of these fields are unsigned integers, and report_count is bounded by HID_MAX_USAGES (12288). Therefore, as long as the respective maximums do not overflow an unsigned integer (let's say a signed integer just in case), we're safe. This holds for 16384. Signed-off-by: Hector Martin <marcan@marcan.st>

Apple MacBook keyboards started using HID over SPI in 2015. With the addition of the SPI HID transport they can be supported by this driver. Support all product ids over with the Apple SPI vendor id for now. The Macbook Pro (M1, 13-inch, 2020) uses the same function key mapping as other Macbook Pros with touchbar and dedicated ESC key. Apple silicon Macbooks use the same function key mapping as the 2021 and later Magic Keyboards. Signed-off-by: Janne Grunau <j@jannau.net>

We use BUS_HOST for MTP HID subdevices Signed-off-by: Hector Martin <marcan@marcan.st>

This mode is added to ease adding new xkeyboard configs for Apple silicon Macbook keyboards. The existing ones have strange quirks [1] and as the keyboard sends a key code for the 'fn' there is desire to use it as additional modifier [2]. [1]: https://pagure.io/fedora-asahi/remix-bugs/issue/17 [2]: https://asahilinux.org/docs/project/help-wanted/ (Keyboard layout cleanup) Signed-off-by: Janne Grunau <j@jannau.net>

Signed-off-by: Janne Grunau <j@jannau.net>

Will be used for supporting MacBook trackpads connected via SPI. Signed-off-by: Janne Grunau <j@jannau.net>

The trackpads in Macbooks beginning in 2015 are HID devices connected over SPI. On Intel Macbooks they are currently supported by applespi.c. This chang adds support for the trackpads on Apple Silicon Macbooks starting in late 2020. They use a new HID over SPI transport driver. The touch report format differs from USB/BT Magic Trackpads. It is the same format as the type 4 format supported by bcm5974.c. Signed-off-by: Janne Grunau <j@jannau.net>

Apple M2 devices expose the multi-touch device over the HID over DockChannel transport, which we represent as the HOST bus type. The report format is the same, except the legacy mouse header is gone and there is no enable request needed. Signed-off-by: Hector Martin <marcan@marcan.st>

The trackpad has to request multi touch reports during resume. Signed-off-by: Janne Grunau <j@jannau.net>

On at least some SPI devices (e.g. recent Apple Silicon machines), the Broadcom touch controller is prone to crashing. When this happens, the STM eventually notices and resets it. It then notifies the driver via HID report 0x60, and the driver needs to re-enable MT mode to make things work again. This poses an additional issue: the hidinput core will close the low-level transport while the device is closed, which can cause us to miss a reset notification. To fix this, override the input open/close callbacks and send the MT enable every time the HID device is opened, instead of only once on probe. This should increase general robustness, even if the reset mechanism doesn't work for some reason, so it's worth doing it for USB devices too. MTP devices are exempt since they do not require the MT enable at all. Signed-off-by: Hector Martin <marcan@marcan.st>

For SPI/MTP trackpads, query the dimensions via HID report instead of hardcoding values. TODO: Does this work for the USB/BT devices? Maybe we can get rid of the hardcoded sizes everywhere? Signed-off-by: Hector Martin <marcan@marcan.st>

Keyboard and trackpad of Apple Sillicon SoCs (M1, M1 Pro/Max) laptops are are HID devices connected via SPI. This is the same protocol as implemented by applespi.c. It was not noticed that protocol is a transport for HID. Adding support for ACPI based Intel MacBooks will be done in a separate commit. How HID is mapped in this protocol is not yet fully understood. Microsoft has a specification for HID over SPI [1] incompatible with the transport protocol used by Apple. [1] https://docs.microsoft.com/en-us/windows-hardware/drivers/hid/hid-over-spi Contains "HID: transport: spi: apple: Increase receive buffer size" The SPI receive buffer is passed directly to hid_input_report() if it contains a complete report. It is then passed to hid_report_raw_event() which computes the expected report size and memsets the "missing trailing data up to HID_MAX_BUFFER_SIZE (16K) or hid_ll_driver.max_buffer_size (if set) to zero. Co-developed-by: Hector Martin <marcan@marcan.st> Signed-off-by: Hector Martin <marcan@marcan.st> Signed-off-by: Janne Grunau <j@jannau.net>

DockChannel is a simple FIFO interface used to communicate between SoC blocks. Add a driver that represents the shared interrupt controller for the DockChannel block, and then exposes probe and data transfer functions that child device drivers can use to instantiate individual FIFOs. Signed-off-by: Hector Martin <marcan@marcan.st>

Apple M2 devices have an MTP coprocessor embedded in the SoC that handles HID for the integrated touchpad/keyboard, and communicates over the DockChannel interface. This driver implements this new interface. Signed-off-by: Hector Martin <marcan@marcan.st>

This driver can be used for coprocessors that do some background task or communicate out-of-band, and do not do any mailbox I/O beyond the standard RTKit initialization. Signed-off-by: Hector Martin <marcan@marcan.st>

The SMC firmware included in macOS 27 changed the size of BCF0 key from 4 to 1 bytes. This key is used for indicating that battery state is critically low. Reviewed-by: Sven Peter <sven@kernel.org> Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

BoiledElectricity · 2026-06-24T21:55:29Z

Tested on Apple MacBook Pro 13" M1 (j293), kernel 6.19.14, on AC at 100% (this firmware uses the CHLS path, has_chls=1):

force_discharge=N + set 90% limit → battery just caps charging, no discharge (Full, current_now=0)
force_discharge=Y (default) + set 90% limit → actively discharges (Discharging, ~-360 mA)

force_discharge=N, end_threshold=90:
  status=Full  current_now=0 uA        x4 samples over 8s

force_discharge=Y, end_threshold=90:
  status=Full         current_now=0 uA
  status=Discharging  current_now=-347000 uA
  status=Discharging  current_now=-376000 uA
  status=Discharging  current_now=-361000 uA

Battery restored to 100% / default afterwards.

Signed-off-by: Janne Grunau <j@jannau.net>

Apple M3 Pro and Max devices are using 'gp00' keys for GPIO in addition to 'gP00' keys. Add a second compatible to handle this keys with an additional macsmc-gpio instance. Signed-off-by: Janne Grunau <j@jannau.net>

Add support for SMC GPIO keys with a lower letter 'p' via the "apple,smc-low-gpio" compatible. This adds support for a second macsmc-gpio controller using 'gp00' keys. These keys are used on Apple M3 Pro and Max MacBooks in the controller for keyboard and trackpad and for the built-in DisplayPort to HDMI converter. Signed-off-by: Janne Grunau <j@jannau.net>

Apple M3 Pro and Max devices are using 'gp00' keys for GPIO in addition to 'gP00' keys. These keys are handled by an additional macsmc-gpio instance using the "apple,smc-low-gpio" compatible. Signed-off-by: Janne Grunau <j@jannau.net>

Signed-off-by: Janne Grunau <j@jannau.net>

Signed-off-by: sofus <sofus.c@icloud.com>

Since immediate mode was enabled, unmapping a GPU VA can defer drm_gpuvm_bo destruction until drm_gpuvm_bo_deferred_cleanup() is called. The GEM bind and unbind paths drain that list, but Vm::drop() unmaps the remaining user ranges without doing so. Drain the deferred list after both teardown unmaps. Otherwise a deferred drm_gpuvm_bo retains the imported GEM and dma-buf after its DRM file is closed, leaving its backing pages pinned. Fixes: 2aeee2d ("drm/asahi: Switch gpuvm to DRM_GPUVM_IMMEDIATE_MODE") Signed-off-by: DesktopECHO <33142753+DesktopECHO@users.noreply.github.com>

Add CONFIG_VIDEO_APPLE_AVD for AVD (Apple video decoder) support. Signed-off-by: Janne Grunau <j@jannau.net>

Signed-off-by: sofus <sofus.c@icloud.com>

This is a hardcoded charge threshold feature present in firmware 13.0 or newer. Userspace settings are rounded to one of the two possible behaviors. Since macOS Sequoia firmware, CHLS replaced CHWA and now allows an arbitrary end charge threshold to be configured. Prefer CHWA over CHLS since the SMC firmware from iBoot-10151.1.1 (macOS 14.0) is not compatible with our CHGLS usage. It was working with the SMC firmware from iBoot-10151.121.1 (macOS 14.5). Signed-off-by: Janne Grunau <j@jannau.net> Co-developed-by: Janne Grunau <j@jannau.net> Signed-off-by: Hector Martin <marcan@marcan.st>

Signed-off-by: Janne Grunau <j@jannau.net>

The admacs seen in M3-generation SoCs (t603x, t8122) need additional configuration writes and so are getting a new compatible chain. Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

The admacs present on t8122 and t603x SoCs need additional writes in order to operate correctly. The exact purpose of this register is unknown Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

Those get a new "HF" decimator, and an extra component that needs to be attached Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

Signed-off-by: Janne Grunau <j@jannau.net>

jannau · 2026-08-01T09:23:29Z

Using a module option is not a good idea. It most likely will not be accepted upstream and we do not want to carry non-upstreamable patches unless they bring clear benefits.

A possible alternative solution might be to add a charge behaviour to control this. See charge_behaviour in Documentation/ABI/testing/sysfs-class-power and add either auto-discharge or auto-inhibit-discharge. I'm not sure what what the better default is from battery health perspective. Keeping the battery full charged for a long periods is not healthy but constantly charging and discharging the battery from 80% to 100% when the laptop is powered off isn't healthy either.

It would be worth checking if the charge thresholds are now respected while the laptop is powered off now that macOS has charge thresholds in 26.4 / 26.5 and later.

Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

When lowering the charge-control end threshold on machines that use the CHLS key, the driver unconditionally sets CHLS_FORCE_DISCHARGE, actively draining the battery down to the limit even on AC power. Most laptop charge-limit implementations instead just cap charging at the threshold and let the battery drain naturally through use. Add a new "auto-discharge" charge_behaviour value that opts into the active discharge, and make end-threshold writes preserve the current CHLS_FORCE_DISCHARGE bit instead of forcing it on. "auto" keeps its documented meaning of only respecting the thresholds. The selection lives in the CHLS key itself, so no state is kept in the driver, it persists across reboots, and systems upgrading from the old behaviour keep force-discharge enabled until they explicitly write "auto". Resolves the existing TODO. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: James A DellaMorte <james.dellamorte@gmail.com>

BoiledElectricity · 2026-08-01T17:11:57Z

Reworked as suggested, I also rebased.

Tested on Apple MacBook Pro 13" M1 (j293), kernel 7.1.5-asahidev+, on AC at 96%, has_chls=1:

threshold=90, behaviour=auto:            status=Not charging  current_now=0 uA        (cap-only, x4 samples)
threshold=90, behaviour=auto-discharge:  status=Discharging   current_now=-330000 uA  (active drain)
threshold 90 -> 85:                      selection survives the threshold write
threshold -> 100 (CHLS=0x100):           no errors, firmware charges normally, selection retained
threshold -> 90 again:                   discharge resumes (-330 mA)

@jannau

jannau and others added 20 commits June 20, 2026 17:01

HID: add HOST vendor/device IDs for Apple MTP devices

42c2f66

Apple M2* chips have an embedded MTP processor that handles all HID functions, and does not go over a traditional bus like SPI. The devices still have real IDs, so add them here. Signed-off-by: Hector Martin <marcan@marcan.st>

HID: core: Handle HOST bus type when announcing devices

63c2994

Signed-off-by: Hector Martin <marcan@marcan.st>

HID: apple: Bind to HOST devices for MTP

4cdbfc2

We use BUS_HOST for MTP HID subdevices Signed-off-by: Hector Martin <marcan@marcan.st>

HID: magicmouse: use a define of the max number of touch contacts

604082f

Signed-off-by: Janne Grunau <j@jannau.net>

HID: magicmouse: use struct input_mt_pos for X/Y

d45b52d

Signed-off-by: Janne Grunau <j@jannau.net>

HID: magicmouse: use ops function pointers for input functionality

0091e01

Will be used for supporting MacBook trackpads connected via SPI. Signed-off-by: Janne Grunau <j@jannau.net>

HID: magicmouse: Add .reset_resume for SPI trackpads

fdc798c

The trackpad has to request multi touch reports during resume. Signed-off-by: Janne Grunau <j@jannau.net>

soc: apple: Add RTKit helper driver

f77f12b

This driver can be used for coprocessors that do some background task or communicate out-of-band, and do not do any mailbox I/O beyond the standard RTKit initialization. Signed-off-by: Hector Martin <marcan@marcan.st>

jannau force-pushed the asahi-wip branch from 030248d to c872c81 Compare June 28, 2026 20:20

jannau force-pushed the asahi-wip branch from 64554fe to 9015099 Compare July 9, 2026 18:13

jannau added 7 commits July 24, 2026 20:44

Merge branch 'bits/000-devicetree' into asahi-wip

bd0ad90

Merge branch 'bits/010-soc' into asahi-wip

27b59a6

Merge branch 'bits/020-dart' into asahi-wip

362cb01

Merge branch 'bits/030-misc' into asahi-wip

f497157

Merge branch 'bits/050-nvme' into asahi-wip

21bb5f3

Merge branch 'bits/070-audio' into asahi-wip

ef40893

Merge branch 'bits/080-wifi' into asahi-wip

41aaa40

jannau and others added 8 commits July 24, 2026 20:51

driver-core: Add error message to device_links_missing_supplier WARN()

49e2583

Signed-off-by: Janne Grunau <j@jannau.net>

dt-bindings: gpio: apple,smc: Add compatible for 'gp00' keys

073f294

Apple M3 Pro and Max devices are using 'gp00' keys for GPIO in addition to 'gP00' keys. Add a second compatible to handle this keys with an additional macsmc-gpio instance. Signed-off-by: Janne Grunau <j@jannau.net>

phy: apple: atc: Handle dummy pipehandler transisions

ffff3d1

Signed-off-by: Janne Grunau <j@jannau.net>

fixup! media: apple: avd: make get_ref_buf shared

28962a3

Signed-off-by: sofus <sofus.c@icloud.com>

arm64: configs: asahi: Add new configs for v7.1

a326e00

Add CONFIG_VIDEO_APPLE_AVD for AVD (Apple video decoder) support. Signed-off-by: Janne Grunau <j@jannau.net>

jannau force-pushed the asahi-wip branch from f4dd286 to a326e00 Compare July 25, 2026 18:37

sofus13 and others added 9 commits July 25, 2026 22:15

fixup! media: apple: avd: add hevc support

42762d1

Signed-off-by: sofus <sofus.c@icloud.com>

fixup! arm64: configs: asahi: Add new configs for v7.1

e256605

Signed-off-by: Janne Grunau <j@jannau.net>

dt-bindings: dma: apple,admac: Add M3 generation ADMACs

1668fc6

The admacs seen in M3-generation SoCs (t603x, t8122) need additional configuration writes and so are getting a new compatible chain. Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

arm64: dts: apple: t8122: Add aop/admac nodes

972c782

Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

dts: apple: t603x: Add aop/admac nodes

e2bfaf7

Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

dmaengine: apple-admac: Add M3 generation ADMACs

12c43f3

The admacs present on t8122 and t603x SoCs need additional writes in order to operate correctly. The exact purpose of this register is unknown Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

ASoC: apple: aop: Add M3 generation built-in mics

f3cf4b1

Those get a new "HF" decimator, and an extra component that needs to be attached Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

fixup! dt-bindings: dma: apple,admac: Add M3 generation ADMACs

7ef0f7c

Signed-off-by: Janne Grunau <j@jannau.net>

WhatAmISupposedToPutHere and others added 3 commits August 1, 2026 11:33

media: apple: isp: add t6030 support

a79dc5b

Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

dts: apple: t6030: Add isp nodes

ac8d3c4

Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

BoiledElectricity force-pushed the macsmc-force-discharge-configurable branch from 0ed7acc to 922f0e1 Compare August 1, 2026 17:10

BoiledElectricity changed the title ~~power: supply: macsmc: make force-discharge to the charge limit configurable~~ power: supply: macsmc: add "auto-discharge" charge behaviour for CHLS Aug 1, 2026

jannau force-pushed the asahi-wip branch 2 times, most recently from c1cb252 to 96fa2b9 Compare August 11, 2026 13:25

jannau force-pushed the asahi-wip branch 2 times, most recently from 77cb8f2 to b02aba8 Compare August 26, 2026 09:11

jannau force-pushed the asahi-wip branch from ccce11a to ca9a850 Compare August 30, 2026 09:57

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power: supply: macsmc: add "auto-discharge" charge behaviour for CHLS - #521

power: supply: macsmc: add "auto-discharge" charge behaviour for CHLS#521
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