// 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 <linux/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)
{
        __le32 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);
        strscpy(ac->name, name, sizeof(ac->name));

        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_device_notifier_register(ac->sdev, &ac->notif);
}


/* -- Driver setup. --------------------------------------------------------- */

static int __maybe_unused surface_ac_resume(struct device *dev)
{
        return spwr_ac_recheck(dev_get_drvdata(dev));
}
static 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_device_notifier_unregister(sdev, &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, SAM, 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");