Re: [PATCH v2 9/9] platform/surface: Add Surface ACPI Notify driver

Hans de Goede
2020-12-15T17:20:11Z

Hi,

On 12/3/20 10:26 PM, Maximilian Luz wrote:
> The Surface ACPI Notify (SAN) device provides an ACPI interface to the
> Surface Aggregator EC, specifically the Surface Serial Hub interface.
> This interface allows EC requests to be made from ACPI code and can
> convert a subset of EC events back to ACPI notifications.
>
> Specifically, this interface provides a GenericSerialBus operation
> region ACPI code can execute a request by writing the request command
> data and payload to this operation region and reading back the
> corresponding response via a write-then-read operation. Furthermore,
> this interface provides a _DSM method to be called when certain events
> from the EC have been received, essentially turning them into ACPI
> notifications.
>
> The driver provided in this commit essentially takes care of translating
> the request data written to the operation region, executing the request,
> waiting for it to finish, and finally writing and translating back the
> response (if the request has one). Furthermore, this driver takes care
> of enabling the events handled via ACPI _DSM calls. Lastly, this driver
> also exposes an interface providing discrete GPU (dGPU) power-on
> notifications on the Surface Book 2, which are also received via the
> operation region interface (but not handled by the SAN driver directly),
> making them accessible to other drivers (such as a dGPU hot-plug driver
> that may be added later on).
>
> On 5th and 6th generation Surface devices (Surface Pro 5/2017, Pro 6,
> Book 2, Laptop 1 and 2), the SAN interface provides full battery and
> thermal subsystem access, as well as other EC based functionality. On
> those models, battery and thermal sensor devices are implemented as
> standard ACPI devices of that type, however, forward ACPI calls to the
> corresponding Surface Aggregator EC request via the SAN interface and
> receive corresponding notifications (e.g. battery information change)
> from it. This interface is therefore required to provide said
> functionality on those devices.
>
> Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>

Thanks, patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans

> ---
>
> Changes in v1 (from RFC):
> - add copyright lines
> - change SPDX identifier to GPL-2.0+ (was GPL-2.0-or-later)
> - fix invalid pointer calculation in san_evt_tmp
> - add explicit dependency on CONFIG_ACPI
> - remove default in Kconfig
>
> Changes in v2:
> - drop explicit dependency on ACPI in Kconfig
> - use printk specifier for hex prefix instead of hard-coding it
> - spell check comments and strings, fix typos
> - unify comment style
> - run checkpatch --strict, fix warnings and style issues
>
> ---
> .../surface_aggregator/clients/index.rst | 1 +
> .../surface_aggregator/clients/san.rst | 44 +
> MAINTAINERS | 2 +
> drivers/platform/surface/Kconfig | 19 +
> drivers/platform/surface/Makefile | 1 +
> .../platform/surface/surface_acpi_notify.c | 886 ++++++++++++++++++
> include/linux/surface_acpi_notify.h | 39 +
> 7 files changed, 992 insertions(+)
> create mode 100644 Documentation/driver-api/surface_aggregator/clients/san.rst
> create mode 100644 drivers/platform/surface/surface_acpi_notify.c
> create mode 100644 include/linux/surface_acpi_notify.h
>
> diff --git a/Documentation/driver-api/surface_aggregator/clients/index.rst b/Documentation/driver-api/surface_aggregator/clients/index.rst
> index ab260ec82cfb..3ccabce23271 100644
> --- a/Documentation/driver-api/surface_aggregator/clients/index.rst
> +++ b/Documentation/driver-api/surface_aggregator/clients/index.rst
> @@ -11,6 +11,7 @@ This is the documentation for client drivers themselves. Refer to
> :maxdepth: 1
>
> cdev
> + san
>
> .. only:: subproject and html
>
> diff --git a/Documentation/driver-api/surface_aggregator/clients/san.rst b/Documentation/driver-api/surface_aggregator/clients/san.rst
> new file mode 100644
> index 000000000000..38c2580e7758
> --- /dev/null
> +++ b/Documentation/driver-api/surface_aggregator/clients/san.rst
> @@ -0,0 +1,44 @@
> +.. SPDX-License-Identifier: GPL-2.0+
> +
> +.. |san_client_link| replace:: :c:func:`san_client_link`
> +.. |san_dgpu_notifier_register| replace:: :c:func:`san_dgpu_notifier_register`
> +.. |san_dgpu_notifier_unregister| replace:: :c:func:`san_dgpu_notifier_unregister`
> +
> +===================
> +Surface ACPI Notify
> +===================
> +
> +The Surface ACPI Notify (SAN) device provides the bridge between ACPI and
> +SAM controller. Specifically, ACPI code can execute requests and handle
> +battery and thermal events via this interface. In addition to this, events
> +relating to the discrete GPU (dGPU) of the Surface Book 2 can be sent from
> +ACPI code (note: the Surface Book 3 uses a different method for this). The
> +only currently known event sent via this interface is a dGPU power-on
> +notification. While this driver handles the former part internally, it only
> +relays the dGPU events to any other driver interested via its public API and
> +does not handle them.
> +
> +The public interface of this driver is split into two parts: Client
> +registration and notifier-block registration.
> +
> +A client to the SAN interface can be linked as consumer to the SAN device
> +via |san_client_link|. This can be used to ensure that the a client
> +receiving dGPU events does not miss any events due to the SAN interface not
> +being set up as this forces the client driver to unbind once the SAN driver
> +is unbound.
> +
> +Notifier-blocks can be registered by any device for as long as the module is
> +loaded, regardless of being linked as client or not. Registration is done
> +with |san_dgpu_notifier_register|. If the notifier is not needed any more, it
> +should be unregistered via |san_dgpu_notifier_unregister|.
> +
> +Consult the API documentation below for more details.
> +
> +
> +API Documentation
> +=================
> +
> +.. kernel-doc:: include/linux/surface_acpi_notify.h
> +
> +.. kernel-doc:: drivers/platform/surface/surface_acpi_notify.c
> + :export:
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f5a788f445a4..894c9ef1b8d6 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11699,7 +11699,9 @@ W: https://github.com/linux-surface/surface-aggregator-module
> C: irc://chat.freenode.net/##linux-surface
> F: Documentation/driver-api/surface_aggregator/
> F: drivers/platform/surface/aggregator/
> +F: drivers/platform/surface/surface_acpi_notify.c
> F: drivers/platform/surface/surface_aggregator_cdev.c
> +F: include/linux/surface_acpi_notify.h
> F: include/linux/surface_aggregator/
> F: include/uapi/linux/surface_aggregator/
>
> diff --git a/drivers/platform/surface/Kconfig b/drivers/platform/surface/Kconfig
> index cecad7a0cb7b..88818320105e 100644
> --- a/drivers/platform/surface/Kconfig
> +++ b/drivers/platform/surface/Kconfig
> @@ -40,6 +40,25 @@ config SURFACE_3_POWER_OPREGION
> This driver provides support for ACPI operation
> region of the Surface 3 battery platform driver.
>
> +config SURFACE_ACPI_NOTIFY
> + tristate "Surface ACPI Notify Driver"
> + depends on SURFACE_AGGREGATOR
> + help
> + Surface ACPI Notify (SAN) driver for Microsoft Surface devices.
> +
> + This driver provides support for the ACPI interface (called SAN) of
> + the Surface System Aggregator Module (SSAM) EC. This interface is used
> + on 5th- and 6th-generation Microsoft Surface devices (including
> + Surface Pro 5 and 6, Surface Book 2, Surface Laptops 1 and 2, and in
> + reduced functionality on the Surface Laptop 3) to execute SSAM
> + requests directly from ACPI code, as well as receive SSAM events and
> + turn them into ACPI notifications. It essentially acts as a
> + translation layer between the SSAM controller and ACPI.
> +
> + Specifically, this driver may be needed for battery status reporting,
> + thermal sensor access, and real-time clock information, depending on
> + the Surface device in question.
> +
> config SURFACE_AGGREGATOR_CDEV
> tristate "Surface System Aggregator Module User-Space Interface"
> depends on SURFACE_AGGREGATOR
> diff --git a/drivers/platform/surface/Makefile b/drivers/platform/surface/Makefile
> index 161f0ad05795..3eb971006877 100644
> --- a/drivers/platform/surface/Makefile
> +++ b/drivers/platform/surface/Makefile
> @@ -7,6 +7,7 @@
> obj-$(CONFIG_SURFACE3_WMI) += surface3-wmi.o
> obj-$(CONFIG_SURFACE_3_BUTTON) += surface3_button.o
> obj-$(CONFIG_SURFACE_3_POWER_OPREGION) += surface3_power.o
> +obj-$(CONFIG_SURFACE_ACPI_NOTIFY) += surface_acpi_notify.o
> obj-$(CONFIG_SURFACE_AGGREGATOR) += aggregator/
> obj-$(CONFIG_SURFACE_AGGREGATOR_CDEV) += surface_aggregator_cdev.o
> obj-$(CONFIG_SURFACE_GPE) += surface_gpe.o
> diff --git a/drivers/platform/surface/surface_acpi_notify.c b/drivers/platform/surface/surface_acpi_notify.c
> new file mode 100644
> index 000000000000..8cd67a669c86
> --- /dev/null
> +++ b/drivers/platform/surface/surface_acpi_notify.c
> @@ -0,0 +1,886 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Driver for the Surface ACPI Notify (SAN) interface/shim.
> + *
> + * Translates communication from ACPI to Surface System Aggregator Module
> + * (SSAM/SAM) requests and back, specifically SAM-over-SSH. Translates SSAM
> + * events back to ACPI notifications. Allows handling of discrete GPU
> + * notifications sent from ACPI via the SAN interface by providing them to any
> + * registered external driver.
> + *
> + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
> + */
> +
> +#include <asm/unaligned.h>
> +#include <linux/acpi.h>
> +#include <linux/delay.h>
> +#include <linux/jiffies.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/notifier.h>
> +#include <linux/platform_device.h>
> +#include <linux/rwsem.h>
> +
> +#include <linux/surface_aggregator/controller.h>
> +#include <linux/surface_acpi_notify.h>
> +
> +struct san_data {
> + struct device *dev;
> + struct ssam_controller *ctrl;
> +
> + struct acpi_connection_info info;
> +
> + struct ssam_event_notifier nf_bat;
> + struct ssam_event_notifier nf_tmp;
> +};
> +
> +#define to_san_data(ptr, member) \
> + container_of(ptr, struct san_data, member)
> +
> +
> +/* -- dGPU notifier interface. ---------------------------------------------- */
> +
> +struct san_rqsg_if {
> + struct rw_semaphore lock;
> + struct device *dev;
> + struct blocking_notifier_head nh;
> +};
> +
> +static struct san_rqsg_if san_rqsg_if = {
> + .lock = __RWSEM_INITIALIZER(san_rqsg_if.lock),
> + .dev = NULL,
> + .nh = BLOCKING_NOTIFIER_INIT(san_rqsg_if.nh),
> +};
> +
> +static int san_set_rqsg_interface_device(struct device *dev)
> +{
> + int status = 0;
> +
> + down_write(&san_rqsg_if.lock);
> + if (!san_rqsg_if.dev && dev)
> + san_rqsg_if.dev = dev;
> + else
> + status = -EBUSY;
> + up_write(&san_rqsg_if.lock);
> +
> + return status;
> +}
> +
> +/**
> + * san_client_link() - Link client as consumer to SAN device.
> + * @client: The client to link.
> + *
> + * Sets up a device link between the provided client device as consumer and
> + * the SAN device as provider. This function can be used to ensure that the
> + * SAN interface has been set up and will be set up for as long as the driver
> + * of the client device is bound. This guarantees that, during that time, all
> + * dGPU events will be received by any registered notifier.
> + *
> + * The link will be automatically removed once the client device's driver is
> + * unbound.
> + *
> + * Return: Returns zero on success, %-ENXIO if the SAN interface has not been
> + * set up yet, and %-ENOMEM if device link creation failed.
> + */
> +int san_client_link(struct device *client)
> +{
> + const u32 flags = DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_CONSUMER;
> + struct device_link *link;
> +
> + down_read(&san_rqsg_if.lock);
> +
> + if (!san_rqsg_if.dev) {
> + up_read(&san_rqsg_if.lock);
> + return -ENXIO;
> + }
> +
> + link = device_link_add(client, san_rqsg_if.dev, flags);
> + if (!link) {
> + up_read(&san_rqsg_if.lock);
> + return -ENOMEM;
> + }
> +
> + if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND) {
> + up_read(&san_rqsg_if.lock);
> + return -ENXIO;
> + }
> +
> + up_read(&san_rqsg_if.lock);
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(san_client_link);
> +
> +/**
> + * san_dgpu_notifier_register() - Register a SAN dGPU notifier.
> + * @nb: The notifier-block to register.
> + *
> + * Registers a SAN dGPU notifier, receiving any new SAN dGPU events sent from
> + * ACPI. The registered notifier will be called with &struct san_dgpu_event
> + * as notifier data and the command ID of that event as notifier action.
> + */
> +int san_dgpu_notifier_register(struct notifier_block *nb)
> +{
> + return blocking_notifier_chain_register(&san_rqsg_if.nh, nb);
> +}
> +EXPORT_SYMBOL_GPL(san_dgpu_notifier_register);
> +
> +/**
> + * san_dgpu_notifier_unregister() - Unregister a SAN dGPU notifier.
> + * @nb: The notifier-block to unregister.
> + */
> +int san_dgpu_notifier_unregister(struct notifier_block *nb)
> +{
> + return blocking_notifier_chain_unregister(&san_rqsg_if.nh, nb);
> +}
> +EXPORT_SYMBOL_GPL(san_dgpu_notifier_unregister);
> +
> +static int san_dgpu_notifier_call(struct san_dgpu_event *evt)
> +{
> + int ret;
> +
> + ret = blocking_notifier_call_chain(&san_rqsg_if.nh, evt->command, evt);
> + return notifier_to_errno(ret);
> +}
> +
> +
> +/* -- ACPI _DSM event relay. ------------------------------------------------ */
> +
> +#define SAN_DSM_REVISION 0
> +
> +/* 93b666c5-70c6-469f-a215-3d487c91ab3c */
> +static const guid_t SAN_DSM_UUID =
> + GUID_INIT(0x93b666c5, 0x70c6, 0x469f, 0xa2, 0x15, 0x3d,
> + 0x48, 0x7c, 0x91, 0xab, 0x3c);
> +
> +enum san_dsm_event_fn {
> + SAN_DSM_EVENT_FN_BAT1_STAT = 0x03,
> + SAN_DSM_EVENT_FN_BAT1_INFO = 0x04,
> + SAN_DSM_EVENT_FN_ADP1_STAT = 0x05,
> + SAN_DSM_EVENT_FN_ADP1_INFO = 0x06,
> + SAN_DSM_EVENT_FN_BAT2_STAT = 0x07,
> + SAN_DSM_EVENT_FN_BAT2_INFO = 0x08,
> + SAN_DSM_EVENT_FN_THERMAL = 0x09,
> + SAN_DSM_EVENT_FN_DPTF = 0x0a,
> +};
> +
> +enum sam_event_cid_bat {
> + SAM_EVENT_CID_BAT_BIX = 0x15,
> + SAM_EVENT_CID_BAT_BST = 0x16,
> + SAM_EVENT_CID_BAT_ADP = 0x17,
> + SAM_EVENT_CID_BAT_PROT = 0x18,
> + SAM_EVENT_CID_BAT_DPTF = 0x4f,
> +};
> +
> +enum sam_event_cid_tmp {
> + SAM_EVENT_CID_TMP_TRIP = 0x0b,
> +};
> +
> +struct san_event_work {
> + struct delayed_work work;
> + struct device *dev;
> + struct ssam_event event; /* must be last */
> +};
> +
> +static int san_acpi_notify_event(struct device *dev, u64 func,
> + union acpi_object *param)
> +{
> + acpi_handle san = ACPI_HANDLE(dev);
> + union acpi_object *obj;
> + int status = 0;
> +
> + if (!acpi_check_dsm(san, &SAN_DSM_UUID, SAN_DSM_REVISION, 1 << func))
> + return 0;
> +
> + dev_dbg(dev, "notify event %#04llx\n", func);
> +
> + obj = acpi_evaluate_dsm_typed(san, &SAN_DSM_UUID, SAN_DSM_REVISION,
> + func, param, ACPI_TYPE_BUFFER);
> + if (!obj)
> + return -EFAULT;
> +
> + if (obj->buffer.length != 1 || obj->buffer.pointer[0] != 0) {
> + dev_err(dev, "got unexpected result from _DSM\n");
> + status = -EPROTO;
> + }
> +
> + ACPI_FREE(obj);
> + return status;
> +}
> +
> +static int san_evt_bat_adp(struct device *dev, const struct ssam_event *event)
> +{
> + int status;
> +
> + status = san_acpi_notify_event(dev, SAN_DSM_EVENT_FN_ADP1_STAT, NULL);
> + if (status)
> + return status;
> +
> + /*
> + * Ensure that the battery states get updated correctly. When the
> + * battery is fully charged and an adapter is plugged in, it sometimes
> + * is not updated correctly, instead showing it as charging.
> + * Explicitly trigger battery updates to fix this.
> + */
> +
> + status = san_acpi_notify_event(dev, SAN_DSM_EVENT_FN_BAT1_STAT, NULL);
> + if (status)
> + return status;
> +
> + return san_acpi_notify_event(dev, SAN_DSM_EVENT_FN_BAT2_STAT, NULL);
> +}
> +
> +static int san_evt_bat_bix(struct device *dev, const struct ssam_event *event)
> +{
> + enum san_dsm_event_fn fn;
> +
> + if (event->instance_id == 0x02)
> + fn = SAN_DSM_EVENT_FN_BAT2_INFO;
> + else
> + fn = SAN_DSM_EVENT_FN_BAT1_INFO;
> +
> + return san_acpi_notify_event(dev, fn, NULL);
> +}
> +
> +static int san_evt_bat_bst(struct device *dev, const struct ssam_event *event)
> +{
> + enum san_dsm_event_fn fn;
> +
> + if (event->instance_id == 0x02)
> + fn = SAN_DSM_EVENT_FN_BAT2_STAT;
> + else
> + fn = SAN_DSM_EVENT_FN_BAT1_STAT;
> +
> + return san_acpi_notify_event(dev, fn, NULL);
> +}
> +
> +static int san_evt_bat_dptf(struct device *dev, const struct ssam_event *event)
> +{
> + union acpi_object payload;
> +
> + /*
> + * The Surface ACPI expects a buffer and not a package. It specifically
> + * checks for ObjectType (Arg3) == 0x03. This will cause a warning in
> + * acpica/nsarguments.c, but that warning can be safely ignored.
> + */
> + payload.type = ACPI_TYPE_BUFFER;
> + payload.buffer.length = event->length;
> + payload.buffer.pointer = (u8 *)&event->data[0];
> +
> + return san_acpi_notify_event(dev, SAN_DSM_EVENT_FN_DPTF, &payload);
> +}
> +
> +static unsigned long san_evt_bat_delay(u8 cid)
> +{
> + switch (cid) {
> + case SAM_EVENT_CID_BAT_ADP:
> + /*
> + * Wait for battery state to update before signaling adapter
> + * change.
> + */
> + return msecs_to_jiffies(5000);
> +
> + case SAM_EVENT_CID_BAT_BST:
> + /* Ensure we do not miss anything important due to caching. */
> + return msecs_to_jiffies(2000);
> +
> + default:
> + return 0;
> + }
> +}
> +
> +static bool san_evt_bat(const struct ssam_event *event, struct device *dev)
> +{
> + int status;
> +
> + switch (event->command_id) {
> + case SAM_EVENT_CID_BAT_BIX:
> + status = san_evt_bat_bix(dev, event);
> + break;
> +
> + case SAM_EVENT_CID_BAT_BST:
> + status = san_evt_bat_bst(dev, event);
> + break;
> +
> + case SAM_EVENT_CID_BAT_ADP:
> + status = san_evt_bat_adp(dev, event);
> + break;
> +
> + case SAM_EVENT_CID_BAT_PROT:
> + /*
> + * TODO: Implement support for battery protection status change
> + * event.
> + */
> + return true;
> +
> + case SAM_EVENT_CID_BAT_DPTF:
> + status = san_evt_bat_dptf(dev, event);
> + break;
> +
> + default:
> + return false;
> + }
> +
> + if (status) {
> + dev_err(dev, "error handling power event (cid = %#04x)\n",
> + event->command_id);
> + }
> +
> + return true;
> +}
> +
> +static void san_evt_bat_workfn(struct work_struct *work)
> +{
> + struct san_event_work *ev;
> +
> + ev = container_of(work, struct san_event_work, work.work);
> + san_evt_bat(&ev->event, ev->dev);
> + kfree(ev);
> +}
> +
> +static u32 san_evt_bat_nf(struct ssam_event_notifier *nf,
> + const struct ssam_event *event)
> +{
> + struct san_data *d = to_san_data(nf, nf_bat);
> + struct san_event_work *work;
> + unsigned long delay = san_evt_bat_delay(event->command_id);
> +
> + if (delay == 0)
> + return san_evt_bat(event, d->dev) ? SSAM_NOTIF_HANDLED : 0;
> +
> + work = kzalloc(sizeof(*work) + event->length, GFP_KERNEL);
> + if (!work)
> + return ssam_notifier_from_errno(-ENOMEM);
> +
> + INIT_DELAYED_WORK(&work->work, san_evt_bat_workfn);
> + work->dev = d->dev;
> +
> + memcpy(&work->event, event, sizeof(struct ssam_event) + event->length);
> +
> + schedule_delayed_work(&work->work, delay);
> + return SSAM_NOTIF_HANDLED;
> +}
> +
> +static int san_evt_tmp_trip(struct device *dev, const struct ssam_event *event)
> +{
> + union acpi_object param;
> +
> + /*
> + * The Surface ACPI expects an integer and not a package. This will
> + * cause a warning in acpica/nsarguments.c, but that warning can be
> + * safely ignored.
> + */
> + param.type = ACPI_TYPE_INTEGER;
> + param.integer.value = event->instance_id;
> +
> + return san_acpi_notify_event(dev, SAN_DSM_EVENT_FN_THERMAL, &param);
> +}
> +
> +static bool san_evt_tmp(const struct ssam_event *event, struct device *dev)
> +{
> + int status;
> +
> + switch (event->command_id) {
> + case SAM_EVENT_CID_TMP_TRIP:
> + status = san_evt_tmp_trip(dev, event);
> + break;
> +
> + default:
> + return false;
> + }
> +
> + if (status) {
> + dev_err(dev, "error handling thermal event (cid = %#04x)\n",
> + event->command_id);
> + }
> +
> + return true;
> +}
> +
> +static u32 san_evt_tmp_nf(struct ssam_event_notifier *nf,
> + const struct ssam_event *event)
> +{
> + struct san_data *d = to_san_data(nf, nf_tmp);
> +
> + return san_evt_tmp(event, d->dev) ? SSAM_NOTIF_HANDLED : 0;
> +}
> +
> +
> +/* -- ACPI GSB OperationRegion handler -------------------------------------- */
> +
> +struct gsb_data_in {
> + u8 cv;
> +} __packed;
> +
> +struct gsb_data_rqsx {
> + u8 cv; /* Command value (san_gsb_request_cv). */
> + u8 tc; /* Target category. */
> + u8 tid; /* Target ID. */
> + u8 iid; /* Instance ID. */
> + u8 snc; /* Expect-response-flag. */
> + u8 cid; /* Command ID. */
> + u16 cdl; /* Payload length. */
> + u8 pld[]; /* Payload. */
> +} __packed;
> +
> +struct gsb_data_etwl {
> + u8 cv; /* Command value (should be 0x02). */
> + u8 etw3; /* Unknown. */
> + u8 etw4; /* Unknown. */
> + u8 msg[]; /* Error message (ASCIIZ). */
> +} __packed;
> +
> +struct gsb_data_out {
> + u8 status; /* _SSH communication status. */
> + u8 len; /* _SSH payload length. */
> + u8 pld[]; /* _SSH payload. */
> +} __packed;
> +
> +union gsb_buffer_data {
> + struct gsb_data_in in; /* Common input. */
> + struct gsb_data_rqsx rqsx; /* RQSX input. */
> + struct gsb_data_etwl etwl; /* ETWL input. */
> + struct gsb_data_out out; /* Output. */
> +};
> +
> +struct gsb_buffer {
> + u8 status; /* GSB AttribRawProcess status. */
> + u8 len; /* GSB AttribRawProcess length. */
> + union gsb_buffer_data data;
> +} __packed;
> +
> +#define SAN_GSB_MAX_RQSX_PAYLOAD (U8_MAX - 2 - sizeof(struct gsb_data_rqsx))
> +#define SAN_GSB_MAX_RESPONSE (U8_MAX - 2 - sizeof(struct gsb_data_out))
> +
> +#define SAN_GSB_COMMAND 0
> +
> +enum san_gsb_request_cv {
> + SAN_GSB_REQUEST_CV_RQST = 0x01,
> + SAN_GSB_REQUEST_CV_ETWL = 0x02,
> + SAN_GSB_REQUEST_CV_RQSG = 0x03,
> +};
> +
> +#define SAN_REQUEST_NUM_TRIES 5
> +
> +static acpi_status san_etwl(struct san_data *d, struct gsb_buffer *b)
> +{
> + struct gsb_data_etwl *etwl = &b->data.etwl;
> +
> + if (b->len < sizeof(struct gsb_data_etwl)) {
> + dev_err(d->dev, "invalid ETWL package (len = %d)\n", b->len);
> + return AE_OK;
> + }
> +
> + dev_err(d->dev, "ETWL(%#04x, %#04x): %.*s\n", etwl->etw3, etwl->etw4,
> + (unsigned int)(b->len - sizeof(struct gsb_data_etwl)),
> + (char *)etwl->msg);
> +
> + /* Indicate success. */
> + b->status = 0x00;
> + b->len = 0x00;
> +
> + return AE_OK;
> +}
> +
> +static
> +struct gsb_data_rqsx *san_validate_rqsx(struct device *dev, const char *type,
> + struct gsb_buffer *b)
> +{
> + struct gsb_data_rqsx *rqsx = &b->data.rqsx;
> +
> + if (b->len < sizeof(struct gsb_data_rqsx)) {
> + dev_err(dev, "invalid %s package (len = %d)\n", type, b->len);
> + return NULL;
> + }
> +
> + if (get_unaligned(&rqsx->cdl) != b->len - sizeof(struct gsb_data_rqsx)) {
> + dev_err(dev, "bogus %s package (len = %d, cdl = %d)\n",
> + type, b->len, get_unaligned(&rqsx->cdl));
> + return NULL;
> + }
> +
> + if (get_unaligned(&rqsx->cdl) > SAN_GSB_MAX_RQSX_PAYLOAD) {
> + dev_err(dev, "payload for %s package too large (cdl = %d)\n",
> + type, get_unaligned(&rqsx->cdl));
> + return NULL;
> + }
> +
> + return rqsx;
> +}
> +
> +static void gsb_rqsx_response_error(struct gsb_buffer *gsb, int status)
> +{
> + gsb->status = 0x00;
> + gsb->len = 0x02;
> + gsb->data.out.status = (u8)(-status);
> + gsb->data.out.len = 0x00;
> +}
> +
> +static void gsb_rqsx_response_success(struct gsb_buffer *gsb, u8 *ptr, size_t len)
> +{
> + gsb->status = 0x00;
> + gsb->len = len + 2;
> + gsb->data.out.status = 0x00;
> + gsb->data.out.len = len;
> +
> + if (len)
> + memcpy(&gsb->data.out.pld[0], ptr, len);
> +}
> +
> +static acpi_status san_rqst_fixup_suspended(struct san_data *d,
> + struct ssam_request *rqst,
> + struct gsb_buffer *gsb)
> +{
> + if (rqst->target_category == SSAM_SSH_TC_BAS && rqst->command_id == 0x0D) {
> + u8 base_state = 1;
> +
> + /* Base state quirk:
> + * The base state may be queried from ACPI when the EC is still
> + * suspended. In this case it will return '-EPERM'. This query
> + * will only be triggered from the ACPI lid GPE interrupt, thus
> + * we are either in laptop or studio mode (base status 0x01 or
> + * 0x02). Furthermore, we will only get here if the device (and
> + * EC) have been suspended.
> + *
> + * We now assume that the device is in laptop mode (0x01). This
> + * has the drawback that it will wake the device when unfolding
> + * it in studio mode, but it also allows us to avoid actively
> + * waiting for the EC to wake up, which may incur a notable
> + * delay.
> + */
> +
> + dev_dbg(d->dev, "rqst: fixup: base-state quirk\n");
> +
> + gsb_rqsx_response_success(gsb, &base_state, sizeof(base_state));
> + return AE_OK;
> + }
> +
> + gsb_rqsx_response_error(gsb, -ENXIO);
> + return AE_OK;
> +}
> +
> +static acpi_status san_rqst(struct san_data *d, struct gsb_buffer *buffer)
> +{
> + u8 rspbuf[SAN_GSB_MAX_RESPONSE];
> + struct gsb_data_rqsx *gsb_rqst;
> + struct ssam_request rqst;
> + struct ssam_response rsp;
> + int status = 0;
> +
> + gsb_rqst = san_validate_rqsx(d->dev, "RQST", buffer);
> + if (!gsb_rqst)
> + return AE_OK;
> +
> + rqst.target_category = gsb_rqst->tc;
> + rqst.target_id = gsb_rqst->tid;
> + rqst.command_id = gsb_rqst->cid;
> + rqst.instance_id = gsb_rqst->iid;
> + rqst.flags = gsb_rqst->snc ? SSAM_REQUEST_HAS_RESPONSE : 0;
> + rqst.length = get_unaligned(&gsb_rqst->cdl);
> + rqst.payload = &gsb_rqst->pld[0];
> +
> + rsp.capacity = ARRAY_SIZE(rspbuf);
> + rsp.length = 0;
> + rsp.pointer = &rspbuf[0];
> +
> + /* Handle suspended device. */
> + if (d->dev->power.is_suspended) {
> + dev_warn(d->dev, "rqst: device is suspended, not executing\n");
> + return san_rqst_fixup_suspended(d, &rqst, buffer);
> + }
> +
> + status = __ssam_retry(ssam_request_sync_onstack, SAN_REQUEST_NUM_TRIES,
> + d->ctrl, &rqst, &rsp, SAN_GSB_MAX_RQSX_PAYLOAD);
> +
> + if (!status) {
> + gsb_rqsx_response_success(buffer, rsp.pointer, rsp.length);
> + } else {
> + dev_err(d->dev, "rqst: failed with error %d\n", status);
> + gsb_rqsx_response_error(buffer, status);
> + }
> +
> + return AE_OK;
> +}
> +
> +static acpi_status san_rqsg(struct san_data *d, struct gsb_buffer *buffer)
> +{
> + struct gsb_data_rqsx *gsb_rqsg;
> + struct san_dgpu_event evt;
> + int status;
> +
> + gsb_rqsg = san_validate_rqsx(d->dev, "RQSG", buffer);
> + if (!gsb_rqsg)
> + return AE_OK;
> +
> + evt.category = gsb_rqsg->tc;
> + evt.target = gsb_rqsg->tid;
> + evt.command = gsb_rqsg->cid;
> + evt.instance = gsb_rqsg->iid;
> + evt.length = get_unaligned(&gsb_rqsg->cdl);
> + evt.payload = &gsb_rqsg->pld[0];
> +
> + status = san_dgpu_notifier_call(&evt);
> + if (!status) {
> + gsb_rqsx_response_success(buffer, NULL, 0);
> + } else {
> + dev_err(d->dev, "rqsg: failed with error %d\n", status);
> + gsb_rqsx_response_error(buffer, status);
> + }
> +
> + return AE_OK;
> +}
> +
> +static acpi_status san_opreg_handler(u32 function, acpi_physical_address command,
> + u32 bits, u64 *value64, void *opreg_context,
> + void *region_context)
> +{
> + struct san_data *d = to_san_data(opreg_context, info);
> + struct gsb_buffer *buffer = (struct gsb_buffer *)value64;
> + int accessor_type = (function & 0xFFFF0000) >> 16;
> +
> + if (command != SAN_GSB_COMMAND) {
> + dev_warn(d->dev, "unsupported command: %#04llx\n", command);
> + return AE_OK;
> + }
> +
> + if (accessor_type != ACPI_GSB_ACCESS_ATTRIB_RAW_PROCESS) {
> + dev_err(d->dev, "invalid access type: %#04x\n", accessor_type);
> + return AE_OK;
> + }
> +
> + /* Buffer must have at least contain the command-value. */
> + if (buffer->len == 0) {
> + dev_err(d->dev, "request-package too small\n");
> + return AE_OK;
> + }
> +
> + switch (buffer->data.in.cv) {
> + case SAN_GSB_REQUEST_CV_RQST:
> + return san_rqst(d, buffer);
> +
> + case SAN_GSB_REQUEST_CV_ETWL:
> + return san_etwl(d, buffer);
> +
> + case SAN_GSB_REQUEST_CV_RQSG:
> + return san_rqsg(d, buffer);
> +
> + default:
> + dev_warn(d->dev, "unsupported SAN0 request (cv: %#04x)\n",
> + buffer->data.in.cv);
> + return AE_OK;
> + }
> +}
> +
> +
> +/* -- Driver setup. --------------------------------------------------------- */
> +
> +static int san_events_register(struct platform_device *pdev)
> +{
> + struct san_data *d = platform_get_drvdata(pdev);
> + int status;
> +
> + d->nf_bat.base.priority = 1;
> + d->nf_bat.base.fn = san_evt_bat_nf;
> + d->nf_bat.event.reg = SSAM_EVENT_REGISTRY_SAM;
> + d->nf_bat.event.id.target_category = SSAM_SSH_TC_BAT;
> + d->nf_bat.event.id.instance = 0;
> + d->nf_bat.event.mask = SSAM_EVENT_MASK_TARGET;
> + d->nf_bat.event.flags = SSAM_EVENT_SEQUENCED;
> +
> + d->nf_tmp.base.priority = 1;
> + d->nf_tmp.base.fn = san_evt_tmp_nf;
> + d->nf_tmp.event.reg = SSAM_EVENT_REGISTRY_SAM;
> + d->nf_tmp.event.id.target_category = SSAM_SSH_TC_TMP;
> + d->nf_tmp.event.id.instance = 0;
> + d->nf_tmp.event.mask = SSAM_EVENT_MASK_TARGET;
> + d->nf_tmp.event.flags = SSAM_EVENT_SEQUENCED;
> +
> + status = ssam_notifier_register(d->ctrl, &d->nf_bat);
> + if (status)
> + return status;
> +
> + status = ssam_notifier_register(d->ctrl, &d->nf_tmp);
> + if (status)
> + ssam_notifier_unregister(d->ctrl, &d->nf_bat);
> +
> + return status;
> +}
> +
> +static void san_events_unregister(struct platform_device *pdev)
> +{
> + struct san_data *d = platform_get_drvdata(pdev);
> +
> + ssam_notifier_unregister(d->ctrl, &d->nf_bat);
> + ssam_notifier_unregister(d->ctrl, &d->nf_tmp);
> +}
> +
> +#define san_consumer_printk(level, dev, handle, fmt, ...) \
> +do { \
> + char *path = "<error getting consumer path>"; \
> + struct acpi_buffer buffer = { \
> + .length = ACPI_ALLOCATE_BUFFER, \
> + .pointer = NULL, \
> + }; \
> + \
> + if (ACPI_SUCCESS(acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer))) \
> + path = buffer.pointer; \
> + \
> + dev_##level(dev, "[%s]: " fmt, path, ##__VA_ARGS__); \
> + kfree(buffer.pointer); \
> +} while (0)
> +
> +#define san_consumer_dbg(dev, handle, fmt, ...) \
> + san_consumer_printk(dbg, dev, handle, fmt, ##__VA_ARGS__)
> +
> +#define san_consumer_warn(dev, handle, fmt, ...) \
> + san_consumer_printk(warn, dev, handle, fmt, ##__VA_ARGS__)
> +
> +static bool is_san_consumer(struct platform_device *pdev, acpi_handle handle)
> +{
> + struct acpi_handle_list dep_devices;
> + acpi_handle supplier = ACPI_HANDLE(&pdev->dev);
> + acpi_status status;
> + int i;
> +
> + if (!acpi_has_method(handle, "_DEP"))
> + return false;
> +
> + status = acpi_evaluate_reference(handle, "_DEP", NULL, &dep_devices);
> + if (ACPI_FAILURE(status)) {
> + san_consumer_dbg(&pdev->dev, handle, "failed to evaluate _DEP\n");
> + return false;
> + }
> +
> + for (i = 0; i < dep_devices.count; i++) {
> + if (dep_devices.handles[i] == supplier)
> + return true;
> + }
> +
> + return false;
> +}
> +
> +static acpi_status san_consumer_setup(acpi_handle handle, u32 lvl,
> + void *context, void **rv)
> +{
> + const u32 flags = DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER;
> + struct platform_device *pdev = context;
> + struct acpi_device *adev;
> + struct device_link *link;
> +
> + if (!is_san_consumer(pdev, handle))
> + return AE_OK;
> +
> + /* Ignore ACPI devices that are not present. */
> + if (acpi_bus_get_device(handle, &adev) != 0)
> + return AE_OK;
> +
> + san_consumer_dbg(&pdev->dev, handle, "creating device link\n");
> +
> + /* Try to set up device links, ignore but log errors. */
> + link = device_link_add(&adev->dev, &pdev->dev, flags);
> + if (!link) {
> + san_consumer_warn(&pdev->dev, handle, "failed to create device link\n");
> + return AE_OK;
> + }
> +
> + return AE_OK;
> +}
> +
> +static int san_consumer_links_setup(struct platform_device *pdev)
> +{
> + acpi_status status;
> +
> + status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
> + ACPI_UINT32_MAX, san_consumer_setup, NULL,
> + pdev, NULL);
> +
> + return status ? -EFAULT : 0;
> +}
> +
> +static int san_probe(struct platform_device *pdev)
> +{
> + acpi_handle san = ACPI_HANDLE(&pdev->dev);
> + struct ssam_controller *ctrl;
> + struct san_data *data;
> + acpi_status astatus;
> + int status;
> +
> + ctrl = ssam_client_bind(&pdev->dev);
> + if (IS_ERR(ctrl))
> + return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);
> +
> + status = san_consumer_links_setup(pdev);
> + if (status)
> + return status;
> +
> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + data->dev = &pdev->dev;
> + data->ctrl = ctrl;
> +
> + platform_set_drvdata(pdev, data);
> +
> + astatus = acpi_install_address_space_handler(san, ACPI_ADR_SPACE_GSBUS,
> + &san_opreg_handler, NULL,
> + &data->info);
> + if (ACPI_FAILURE(astatus))
> + return -ENXIO;
> +
> + status = san_events_register(pdev);
> + if (status)
> + goto err_enable_events;
> +
> + status = san_set_rqsg_interface_device(&pdev->dev);
> + if (status)
> + goto err_install_dev;
> +
> + acpi_walk_dep_device_list(san);
> + return 0;
> +
> +err_install_dev:
> + san_events_unregister(pdev);
> +err_enable_events:
> + acpi_remove_address_space_handler(san, ACPI_ADR_SPACE_GSBUS,
> + &san_opreg_handler);
> + return status;
> +}
> +
> +static int san_remove(struct platform_device *pdev)
> +{
> + acpi_handle san = ACPI_HANDLE(&pdev->dev);
> +
> + san_set_rqsg_interface_device(NULL);
> + acpi_remove_address_space_handler(san, ACPI_ADR_SPACE_GSBUS,
> + &san_opreg_handler);
> + san_events_unregister(pdev);
> +
> + /*
> + * We have unregistered our event sources. Now we need to ensure that
> + * all delayed works they may have spawned are run to completion.
> + */
> + flush_scheduled_work();
> +
> + return 0;
> +}
> +
> +static const struct acpi_device_id san_match[] = {
> + { "MSHW0091" },
> + { },
> +};
> +MODULE_DEVICE_TABLE(acpi, san_match);
> +
> +static struct platform_driver surface_acpi_notify = {
> + .probe = san_probe,
> + .remove = san_remove,
> + .driver = {
> + .name = "surface_acpi_notify",
> + .acpi_match_table = san_match,
> + .probe_type = PROBE_PREFER_ASYNCHRONOUS,
> + },
> +};
> +module_platform_driver(surface_acpi_notify);
> +
> +MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
> +MODULE_DESCRIPTION("Surface ACPI Notify driver for Surface System Aggregator Module");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/surface_acpi_notify.h b/include/linux/surface_acpi_notify.h
> new file mode 100644
> index 000000000000..8e3e86c7d78c
> --- /dev/null
> +++ b/include/linux/surface_acpi_notify.h
> @@ -0,0 +1,39 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Interface for Surface ACPI Notify (SAN) driver.
> + *
> + * Provides access to discrete GPU notifications sent from ACPI via the SAN
> + * driver, which are not handled by this driver directly.
> + *
> + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
> + */
> +
> +#ifndef _LINUX_SURFACE_ACPI_NOTIFY_H
> +#define _LINUX_SURFACE_ACPI_NOTIFY_H
> +
> +#include <linux/notifier.h>
> +#include <linux/types.h>
> +
> +/**
> + * struct san_dgpu_event - Discrete GPU ACPI event.
> + * @category: Category of the event.
> + * @target: Target ID of the event source.
> + * @command: Command ID of the event.
> + * @instance: Instance ID of the event source.
> + * @length: Length of the event's payload data (in bytes).
> + * @payload: Pointer to the event's payload data.
> + */
> +struct san_dgpu_event {
> + u8 category;
> + u8 target;
> + u8 command;
> + u8 instance;
> + u16 length;
> + u8 *payload;
> +};
> +
> +int san_client_link(struct device *client);
> +int san_dgpu_notifier_register(struct notifier_block *nb);
> +int san_dgpu_notifier_unregister(struct notifier_block *nb);
> +
> +#endif /* _LINUX_SURFACE_ACPI_NOTIFY_H */
> --
> 2.29.2
>