Hi,

On Tue, Mar 09, 2021 at 01:05:30AM +0100, Maximilian Luz wrote:
> On newer Microsoft Surface models (specifically 7th-generation, i.e.
> Surface Pro 7, Surface Book 3, Surface Laptop 3, and Surface Laptop Go),
> battery and AC status/information is no longer handled via standard ACPI
> devices, but instead directly via the Surface System Aggregator Module
> (SSAM), i.e. the embedded controller on those devices.
> 
> While on previous generation models, AC status is also handled via SSAM,
> an ACPI shim was present to translate the standard ACPI AC interface to
> SSAM requests. The SSAM interface itself, which is modeled closely after
> the ACPI interface, has not changed.
> 
> This commit introduces a new SSAM client device driver to support AC
> status/information via the aforementioned interface on said Surface
> models.
> 
> Signed-off-by: Maximilian Luz <luzmaximil...@gmail.com>
> ---
> 
> Note: This patch depends on the
> 
>     platform/surface: Add Surface Aggregator device registry
> 
> series. More specifically patch
> 
>     platform/surface: Set up Surface Aggregator device registry
> 
> The full series has been merged into the for-next branch of the
> platform-drivers-x86 tree [1]. The commit in question can be found at
> [2].
> 
> [1]: 
> https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=for-next
> [2]: 
> https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/commit/?h=for-next&id=fc622b3d36e6d91330fb21506b9ad1e3206a4dde
> 
> ---
>  MAINTAINERS                            |   1 +
>  drivers/power/supply/Kconfig           |  16 ++
>  drivers/power/supply/Makefile          |   1 +
>  drivers/power/supply/surface_charger.c | 296 +++++++++++++++++++++++++
>  4 files changed, 314 insertions(+)
>  create mode 100644 drivers/power/supply/surface_charger.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f44521abe8bf..d6651ba93997 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11867,6 +11867,7 @@ L:    linux...@vger.kernel.org
>  L:   platform-driver-...@vger.kernel.org
>  S:   Maintained
>  F:   drivers/power/supply/surface_battery.c
> +F:   drivers/power/supply/surface_charger.c
>  
>  MICROSOFT SURFACE GPE LID SUPPORT DRIVER
>  M:   Maximilian Luz <luzmaximil...@gmail.com>
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index cebeff10d543..91f7cf425ac9 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -817,4 +817,20 @@ config BATTERY_SURFACE
>         Microsoft Surface devices, i.e. Surface Pro 7, Surface Laptop 3,
>         Surface Book 3, and Surface Laptop Go.
>  
> +config CHARGER_SURFACE
> +     tristate "AC driver for 7th-generation Microsoft Surface devices"
> +     depends on SURFACE_AGGREGATOR_REGISTRY
> +     help
> +       Driver for AC devices connected via/managed by the Surface System
> +       Aggregator Module (SSAM).
> +
> +       This driver provides AC-information and -status support for Surface
> +       devices where said data is not exposed via the standard ACPI devices.
> +       On those models (7th-generation), AC-information is instead handled
> +       directly via a SSAM client device and this driver.
> +
> +       Say M or Y here to include AC status support for 7th-generation
> +       Microsoft Surface devices, i.e. Surface Pro 7, Surface Laptop 3,
> +       Surface Book 3, and Surface Laptop Go.
> +
>  endif # POWER_SUPPLY
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
> index 134041538d2c..a7309a3d1a47 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -102,3 +102,4 @@ obj-$(CONFIG_CHARGER_WILCO)       += wilco-charger.o
>  obj-$(CONFIG_RN5T618_POWER)  += rn5t618_power.o
>  obj-$(CONFIG_BATTERY_ACER_A500)      += acer_a500_battery.o
>  obj-$(CONFIG_BATTERY_SURFACE)        += surface_battery.o
> +obj-$(CONFIG_CHARGER_SURFACE)        += surface_charger.o
> diff --git a/drivers/power/supply/surface_charger.c 
> b/drivers/power/supply/surface_charger.c
> new file mode 100644
> index 000000000000..fe484523a2c2
> --- /dev/null
> +++ b/drivers/power/supply/surface_charger.c
> @@ -0,0 +1,296 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * AC driver for 7th-generation Microsoft Surface devices via Surface System
> + * Aggregator Module (SSAM).
> + *
> + * Copyright (C) 2019-2021 Maximilian Luz <luzmaximil...@gmail.com>
> + */
> +
> +#include <asm/unaligned.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/power_supply.h>
> +#include <linux/types.h>
> +
> +#include <linux/surface_aggregator/device.h>
> +
> +
> +/* -- SAM interface. 
> -------------------------------------------------------- */
> +
> +enum sam_event_cid_bat {
> +     SAM_EVENT_CID_BAT_ADP   = 0x17,
> +};
> +
> +enum sam_battery_sta {
> +     SAM_BATTERY_STA_OK      = 0x0f,
> +     SAM_BATTERY_STA_PRESENT = 0x10,
> +};
> +
> +/* Get battery status (_STA). */
> +SSAM_DEFINE_SYNC_REQUEST_CL_R(ssam_bat_get_sta, __le32, {
> +     .target_category = SSAM_SSH_TC_BAT,
> +     .command_id      = 0x01,
> +});
> +
> +/* Get platform power source for battery (_PSR / DPTF PSRC). */
> +SSAM_DEFINE_SYNC_REQUEST_CL_R(ssam_bat_get_psrc, __le32, {
> +     .target_category = SSAM_SSH_TC_BAT,
> +     .command_id      = 0x0d,
> +});
> +
> +
> +/* -- Device structures. 
> ---------------------------------------------------- */
> +
> +struct spwr_psy_properties {
> +     const char *name;
> +     struct ssam_event_registry registry;
> +};
> +
> +struct spwr_ac_device {
> +     struct ssam_device *sdev;
> +
> +     char name[32];
> +     struct power_supply *psy;
> +     struct power_supply_desc psy_desc;
> +
> +     struct ssam_event_notifier notif;
> +
> +     struct mutex lock;  /* Guards access to state below. */
> +
> +     __le32 state;
> +};
> +
> +
> +/* -- State management. 
> ----------------------------------------------------- */
> +
> +static int spwr_ac_update_unlocked(struct spwr_ac_device *ac)
> +{
> +     u32 old = ac->state;
> +     int status;
> +
> +     lockdep_assert_held(&ac->lock);
> +
> +     status = ssam_retry(ssam_bat_get_psrc, ac->sdev, &ac->state);
> +     if (status < 0)
> +             return status;
> +
> +     return old != ac->state;
> +}
> +
> +static int spwr_ac_update(struct spwr_ac_device *ac)
> +{
> +     int status;
> +
> +     mutex_lock(&ac->lock);
> +     status = spwr_ac_update_unlocked(ac);
> +     mutex_unlock(&ac->lock);
> +
> +     return status;
> +}
> +
> +static int spwr_ac_recheck(struct spwr_ac_device *ac)
> +{
> +     int status;
> +
> +     status = spwr_ac_update(ac);
> +     if (status > 0)
> +             power_supply_changed(ac->psy);
> +
> +     return status >= 0 ? 0 : status;
> +}
> +
> +static u32 spwr_notify_ac(struct ssam_event_notifier *nf, const struct 
> ssam_event *event)
> +{
> +     struct spwr_ac_device *ac;
> +     int status;
> +
> +     ac = container_of(nf, struct spwr_ac_device, notif);
> +
> +     dev_dbg(&ac->sdev->dev, "power event (cid = %#04x, iid = %#04x, tid = 
> %#04x)\n",
> +             event->command_id, event->instance_id, event->target_id);
> +
> +     /*
> +      * Allow events of all targets/instances here. Global adapter status
> +      * seems to be handled via target=1 and instance=1, but events are
> +      * reported on all targets/instances in use.
> +      *
> +      * While it should be enough to just listen on 1/1, listen everywhere to
> +      * make sure we don't miss anything.
> +      */
> +
> +     switch (event->command_id) {
> +     case SAM_EVENT_CID_BAT_ADP:
> +             status = spwr_ac_recheck(ac);
> +             return ssam_notifier_from_errno(status) | SSAM_NOTIF_HANDLED;
> +
> +     default:
> +             return 0;
> +     }
> +}
> +
> +
> +/* -- Properties. 
> ----------------------------------------------------------- */
> +
> +static enum power_supply_property spwr_ac_props[] = {
> +     POWER_SUPPLY_PROP_ONLINE,
> +};
> +
> +static int spwr_ac_get_property(struct power_supply *psy, enum 
> power_supply_property psp,
> +                             union power_supply_propval *val)
> +{
> +     struct spwr_ac_device *ac = power_supply_get_drvdata(psy);
> +     int status;
> +
> +     mutex_lock(&ac->lock);
> +
> +     status = spwr_ac_update_unlocked(ac);
> +     if (status)
> +             goto out;
> +
> +     switch (psp) {
> +     case POWER_SUPPLY_PROP_ONLINE:
> +             val->intval = !!le32_to_cpu(ac->state);
> +             break;
> +
> +     default:
> +             status = -EINVAL;
> +             goto out;
> +     }
> +
> +out:
> +     mutex_unlock(&ac->lock);
> +     return status;
> +}
> +
> +
> +/* -- Device setup. 
> --------------------------------------------------------- */
> +
> +static void spwr_ac_init(struct spwr_ac_device *ac, struct ssam_device *sdev,
> +                      struct ssam_event_registry registry, const char *name)
> +{
> +     mutex_init(&ac->lock);
> +     strncpy(ac->name, name, ARRAY_SIZE(ac->name) - 1);
> +
> +     ac->sdev = sdev;
> +
> +     ac->notif.base.priority = 1;
> +     ac->notif.base.fn = spwr_notify_ac;
> +     ac->notif.event.reg = registry;
> +     ac->notif.event.id.target_category = sdev->uid.category;
> +     ac->notif.event.id.instance = 0;
> +     ac->notif.event.mask = SSAM_EVENT_MASK_NONE;
> +     ac->notif.event.flags = SSAM_EVENT_SEQUENCED;
> +
> +     ac->psy_desc.name = ac->name;
> +     ac->psy_desc.type = POWER_SUPPLY_TYPE_MAINS;
> +     ac->psy_desc.properties = spwr_ac_props;
> +     ac->psy_desc.num_properties = ARRAY_SIZE(spwr_ac_props);
> +     ac->psy_desc.get_property = spwr_ac_get_property;
> +}
> +
> +static void spwr_ac_destroy(struct spwr_ac_device *ac)
> +{
> +     mutex_destroy(&ac->lock);

same as battery driver - use devm_add_action_or_reset or
just drop it. It's not very useful at the end of remove().

> +}

static char *battery_supplied_to[] = {
    "BAT1",
    "BAT2",
};

> +static int spwr_ac_register(struct spwr_ac_device *ac)
> +{
> +     struct power_supply_config psy_cfg = {};
> +     __le32 sta;
> +     int status;
> +
> +     /* Make sure the device is there and functioning properly. */
> +     status = ssam_retry(ssam_bat_get_sta, ac->sdev, &sta);
> +     if (status)
> +             return status;
> +
> +     if ((le32_to_cpu(sta) & SAM_BATTERY_STA_OK) != SAM_BATTERY_STA_OK)
> +             return -ENODEV;
> +
> +     psy_cfg.drv_data = ac;

psy_cfg.supplied_to = battery_supplied_to;
psy_cfg.num_supplicants = 2;

> +     ac->psy = power_supply_register(&ac->sdev->dev, &ac->psy_desc, 
> &psy_cfg);
> +     if (IS_ERR(ac->psy))
> +             return PTR_ERR(ac->psy);
> +
> +     status = ssam_notifier_register(ac->sdev->ctrl, &ac->notif);
> +     if (status)
> +             power_supply_unregister(ac->psy);
> +
> +     return status;
> +}
> +
> +static int spwr_ac_unregister(struct spwr_ac_device *ac)
> +{
> +     ssam_notifier_unregister(ac->sdev->ctrl, &ac->notif);
> +     power_supply_unregister(ac->psy);

This driver can also use devm_power_supply_register :)

> +     return 0;
> +}
> +
> +
> +/* -- Driver setup. 
> --------------------------------------------------------- */
> +
> +static int __maybe_unused surface_ac_resume(struct device *dev)
> +{
> +     return spwr_ac_recheck(dev_get_drvdata(dev));
> +}
> +SIMPLE_DEV_PM_OPS(surface_ac_pm_ops, NULL, surface_ac_resume);
> +
> +static int surface_ac_probe(struct ssam_device *sdev)
> +{
> +     const struct spwr_psy_properties *p;
> +     struct spwr_ac_device *ac;
> +     int status;
> +
> +     p = ssam_device_get_match_data(sdev);
> +     if (!p)
> +             return -ENODEV;
> +
> +     ac = devm_kzalloc(&sdev->dev, sizeof(*ac), GFP_KERNEL);
> +     if (!ac)
> +             return -ENOMEM;
> +
> +     spwr_ac_init(ac, sdev, p->registry, p->name);
> +     ssam_device_set_drvdata(sdev, ac);
> +
> +     status = spwr_ac_register(ac);
> +     if (status)
> +             spwr_ac_destroy(ac);
> +
> +     return status;
> +}
> +
> +static void surface_ac_remove(struct ssam_device *sdev)
> +{
> +     struct spwr_ac_device *ac = ssam_device_get_drvdata(sdev);
> +
> +     spwr_ac_unregister(ac);
> +     spwr_ac_destroy(ac);
> +}
> +
> +static const struct spwr_psy_properties spwr_psy_props_adp1 = {
> +     .name = "ADP1",
> +     .registry = SSAM_EVENT_REGISTRY_SAM,
> +};
> +
> +static const struct ssam_device_id surface_ac_match[] = {
> +     { SSAM_SDEV(BAT, 0x01, 0x01, 0x01), (unsigned long)&spwr_psy_props_adp1 
> },
> +     { },
> +};
> +MODULE_DEVICE_TABLE(ssam, surface_ac_match);
> +
> +static struct ssam_device_driver surface_ac_driver = {
> +     .probe = surface_ac_probe,
> +     .remove = surface_ac_remove,
> +     .match_table = surface_ac_match,
> +     .driver = {
> +             .name = "surface_ac",
> +             .pm = &surface_ac_pm_ops,
> +             .probe_type = PROBE_PREFER_ASYNCHRONOUS,
> +     },
> +};
> +module_ssam_device_driver(surface_ac_driver);
> +
> +MODULE_AUTHOR("Maximilian Luz <luzmaximil...@gmail.com>");
> +MODULE_DESCRIPTION("AC driver for Surface System Aggregator Module");
> +MODULE_LICENSE("GPL");

Otherwise LGTM.

Thanks,

-- Sebastian

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