--- /dev/null
+// 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 <luzmaximilian@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 const 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 char *battery_supplied_to[] = {
+ "BAT1",
+ "BAT2",
+};
+
+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 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 = ARRAY_SIZE(battery_supplied_to);
+
+ ac->psy = devm_power_supply_register(&ac->sdev->dev, &ac->psy_desc, &psy_cfg);
+ if (IS_ERR(ac->psy))
+ return PTR_ERR(ac->psy);
+
+ return ssam_notifier_register(ac->sdev->ctrl, &ac->notif);
+}
+
+
+/* -- 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;
+
+ 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);
+
+ return spwr_ac_register(ac);
+}
+
+static void surface_ac_remove(struct ssam_device *sdev)
+{
+ struct spwr_ac_device *ac = ssam_device_get_drvdata(sdev);
+
+ ssam_notifier_unregister(sdev->ctrl, &ac->notif);
+}
+
+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 <luzmaximilian@gmail.com>");
+MODULE_DESCRIPTION("AC driver for Surface System Aggregator Module");
+MODULE_LICENSE("GPL");
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