// SPDX-License-Identifier: GPL-2.0+
/*
 * Surface System Aggregator Module (SSAM) client device registry.
 *
 * Registry for non-platform/non-ACPI SSAM client devices, i.e. devices that
 * cannot be auto-detected. Provides device-hubs and performs instantiation
 * for these devices.
 *
 * Copyright (C) 2020-2021 Maximilian Luz <luzmaximilian@gmail.com>
 */

#include <linux/acpi.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/types.h>
#include <linux/workqueue.h>

#include <linux/surface_aggregator/controller.h>
#include <linux/surface_aggregator/device.h>


/* -- Device registry. ------------------------------------------------------ */

/*
 * SSAM device names follow the SSAM module alias, meaning they are prefixed
 * with 'ssam:', followed by domain, category, target ID, instance ID, and
 * function, each encoded as two-digit hexadecimal, separated by ':'. In other
 * words, it follows the scheme
 *
 *      ssam:dd:cc:tt:ii:ff
 *
 * Where, 'dd', 'cc', 'tt', 'ii', and 'ff' are the two-digit hexadecimal
 * values mentioned above, respectively.
 */

/* Root node. */
static const struct software_node ssam_node_root = {
        .name = "ssam_platform_hub",
};

/* Base device hub (devices attached to Surface Book 3 base). */
static const struct software_node ssam_node_hub_base = {
        .name = "ssam:00:00:02:00:00",
        .parent = &ssam_node_root,
};

/* AC adapter. */
static const struct software_node ssam_node_bat_ac = {
        .name = "ssam:01:02:01:01:01",
        .parent = &ssam_node_root,
};

/* Primary battery. */
static const struct software_node ssam_node_bat_main = {
        .name = "ssam:01:02:01:01:00",
        .parent = &ssam_node_root,
};

/* Secondary battery (Surface Book 3). */
static const struct software_node ssam_node_bat_sb3base = {
        .name = "ssam:01:02:02:01:00",
        .parent = &ssam_node_hub_base,
};

/* Platform profile / performance-mode device. */
static const struct software_node ssam_node_tmp_pprof = {
        .name = "ssam:01:03:01:00:01",
        .parent = &ssam_node_root,
};

/* DTX / detachment-system device (Surface Book 3). */
static const struct software_node ssam_node_bas_dtx = {
        .name = "ssam:01:11:01:00:00",
        .parent = &ssam_node_root,
};

/* HID keyboard. */
static const struct software_node ssam_node_hid_main_keyboard = {
        .name = "ssam:01:15:02:01:00",
        .parent = &ssam_node_root,
};

/* HID touchpad. */
static const struct software_node ssam_node_hid_main_touchpad = {
        .name = "ssam:01:15:02:03:00",
        .parent = &ssam_node_root,
};

/* HID device instance 5 (unknown HID device). */
static const struct software_node ssam_node_hid_main_iid5 = {
        .name = "ssam:01:15:02:05:00",
        .parent = &ssam_node_root,
};

/* HID keyboard (base hub). */
static const struct software_node ssam_node_hid_base_keyboard = {
        .name = "ssam:01:15:02:01:00",
        .parent = &ssam_node_hub_base,
};

/* HID touchpad (base hub). */
static const struct software_node ssam_node_hid_base_touchpad = {
        .name = "ssam:01:15:02:03:00",
        .parent = &ssam_node_hub_base,
};

/* HID device instance 5 (unknown HID device, base hub). */
static const struct software_node ssam_node_hid_base_iid5 = {
        .name = "ssam:01:15:02:05:00",
        .parent = &ssam_node_hub_base,
};

/* HID device instance 6 (unknown HID device, base hub). */
static const struct software_node ssam_node_hid_base_iid6 = {
        .name = "ssam:01:15:02:06:00",
        .parent = &ssam_node_hub_base,
};

/* Devices for Surface Book 2. */
static const struct software_node *ssam_node_group_sb2[] = {
        &ssam_node_root,
        &ssam_node_tmp_pprof,
        NULL,
};

/* Devices for Surface Book 3. */
static const struct software_node *ssam_node_group_sb3[] = {
        &ssam_node_root,
        &ssam_node_hub_base,
        &ssam_node_bat_ac,
        &ssam_node_bat_main,
        &ssam_node_bat_sb3base,
        &ssam_node_tmp_pprof,
        &ssam_node_bas_dtx,
        &ssam_node_hid_base_keyboard,
        &ssam_node_hid_base_touchpad,
        &ssam_node_hid_base_iid5,
        &ssam_node_hid_base_iid6,
        NULL,
};

/* Devices for Surface Laptop 1. */
static const struct software_node *ssam_node_group_sl1[] = {
        &ssam_node_root,
        &ssam_node_tmp_pprof,
        NULL,
};

/* Devices for Surface Laptop 2. */
static const struct software_node *ssam_node_group_sl2[] = {
        &ssam_node_root,
        &ssam_node_tmp_pprof,
        NULL,
};

/* Devices for Surface Laptop 3 and 4. */
static const struct software_node *ssam_node_group_sl3[] = {
        &ssam_node_root,
        &ssam_node_bat_ac,
        &ssam_node_bat_main,
        &ssam_node_tmp_pprof,
        &ssam_node_hid_main_keyboard,
        &ssam_node_hid_main_touchpad,
        &ssam_node_hid_main_iid5,
        NULL,
};

/* Devices for Surface Laptop Go. */
static const struct software_node *ssam_node_group_slg1[] = {
        &ssam_node_root,
        &ssam_node_bat_ac,
        &ssam_node_bat_main,
        &ssam_node_tmp_pprof,
        NULL,
};

/* Devices for Surface Pro 5. */
static const struct software_node *ssam_node_group_sp5[] = {
        &ssam_node_root,
        &ssam_node_tmp_pprof,
        NULL,
};

/* Devices for Surface Pro 6. */
static const struct software_node *ssam_node_group_sp6[] = {
        &ssam_node_root,
        &ssam_node_tmp_pprof,
        NULL,
};

/* Devices for Surface Pro 7 and Surface Pro 7+. */
static const struct software_node *ssam_node_group_sp7[] = {
        &ssam_node_root,
        &ssam_node_bat_ac,
        &ssam_node_bat_main,
        &ssam_node_tmp_pprof,
        NULL,
};


/* -- Device registry helper functions. ------------------------------------- */

static int ssam_uid_from_string(const char *str, struct ssam_device_uid *uid)
{
        u8 d, tc, tid, iid, fn;
        int n;

        n = sscanf(str, "ssam:%hhx:%hhx:%hhx:%hhx:%hhx", &d, &tc, &tid, &iid, &fn);
        if (n != 5)
                return -EINVAL;

        uid->domain = d;
        uid->category = tc;
        uid->target = tid;
        uid->instance = iid;
        uid->function = fn;

        return 0;
}

static int ssam_hub_remove_devices_fn(struct device *dev, void *data)
{
        if (!is_ssam_device(dev))
                return 0;

        ssam_device_remove(to_ssam_device(dev));
        return 0;
}

static void ssam_hub_remove_devices(struct device *parent)
{
        device_for_each_child_reverse(parent, NULL, ssam_hub_remove_devices_fn);
}

static int ssam_hub_add_device(struct device *parent, struct ssam_controller *ctrl,
                               struct fwnode_handle *node)
{
        struct ssam_device_uid uid;
        struct ssam_device *sdev;
        int status;

        status = ssam_uid_from_string(fwnode_get_name(node), &uid);
        if (status)
                return status;

        sdev = ssam_device_alloc(ctrl, uid);
        if (!sdev)
                return -ENOMEM;

        sdev->dev.parent = parent;
        sdev->dev.fwnode = node;

        status = ssam_device_add(sdev);
        if (status)
                ssam_device_put(sdev);

        return status;
}

static int ssam_hub_add_devices(struct device *parent, struct ssam_controller *ctrl,
                                struct fwnode_handle *node)
{
        struct fwnode_handle *child;
        int status;

        fwnode_for_each_child_node(node, child) {
                /*
                 * Try to add the device specified in the firmware node. If
                 * this fails with -EINVAL, the node does not specify any SSAM
                 * device, so ignore it and continue with the next one.
                 */

                status = ssam_hub_add_device(parent, ctrl, child);
                if (status && status != -EINVAL)
                        goto err;
        }

        return 0;
err:
        ssam_hub_remove_devices(parent);
        return status;
}


/* -- SSAM base-hub driver. ------------------------------------------------- */

/*
 * Some devices (especially battery) may need a bit of time to be fully usable
 * after being (re-)connected. This delay has been determined via
 * experimentation.
 */
#define SSAM_BASE_UPDATE_CONNECT_DELAY          msecs_to_jiffies(2500)

enum ssam_base_hub_state {
        SSAM_BASE_HUB_UNINITIALIZED,
        SSAM_BASE_HUB_CONNECTED,
        SSAM_BASE_HUB_DISCONNECTED,
};

struct ssam_base_hub {
        struct ssam_device *sdev;

        enum ssam_base_hub_state state;
        struct delayed_work update_work;

        struct ssam_event_notifier notif;
};

SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_query_opmode, u8, {
        .target_category = SSAM_SSH_TC_BAS,
        .target_id       = 0x01,
        .command_id      = 0x0d,
        .instance_id     = 0x00,
});

#define SSAM_BAS_OPMODE_TABLET          0x00
#define SSAM_EVENT_BAS_CID_CONNECTION   0x0c

static int ssam_base_hub_query_state(struct ssam_base_hub *hub, enum ssam_base_hub_state *state)
{
        u8 opmode;
        int status;

        status = ssam_retry(ssam_bas_query_opmode, hub->sdev->ctrl, &opmode);
        if (status < 0) {
                dev_err(&hub->sdev->dev, "failed to query base state: %d\n", status);
                return status;
        }

        if (opmode != SSAM_BAS_OPMODE_TABLET)
                *state = SSAM_BASE_HUB_CONNECTED;
        else
                *state = SSAM_BASE_HUB_DISCONNECTED;

        return 0;
}

static ssize_t ssam_base_hub_state_show(struct device *dev, struct device_attribute *attr,
                                        char *buf)
{
        struct ssam_base_hub *hub = dev_get_drvdata(dev);
        bool connected = hub->state == SSAM_BASE_HUB_CONNECTED;

        return sysfs_emit(buf, "%d\n", connected);
}

static struct device_attribute ssam_base_hub_attr_state =
        __ATTR(state, 0444, ssam_base_hub_state_show, NULL);

static struct attribute *ssam_base_hub_attrs[] = {
        &ssam_base_hub_attr_state.attr,
        NULL,
};

static const struct attribute_group ssam_base_hub_group = {
        .attrs = ssam_base_hub_attrs,
};

static void ssam_base_hub_update_workfn(struct work_struct *work)
{
        struct ssam_base_hub *hub = container_of(work, struct ssam_base_hub, update_work.work);
        struct fwnode_handle *node = dev_fwnode(&hub->sdev->dev);
        enum ssam_base_hub_state state;
        int status = 0;

        status = ssam_base_hub_query_state(hub, &state);
        if (status)
                return;

        if (hub->state == state)
                return;
        hub->state = state;

        if (hub->state == SSAM_BASE_HUB_CONNECTED)
                status = ssam_hub_add_devices(&hub->sdev->dev, hub->sdev->ctrl, node);
        else
                ssam_hub_remove_devices(&hub->sdev->dev);

        if (status)
                dev_err(&hub->sdev->dev, "failed to update base-hub devices: %d\n", status);
}

static u32 ssam_base_hub_notif(struct ssam_event_notifier *nf, const struct ssam_event *event)
{
        struct ssam_base_hub *hub = container_of(nf, struct ssam_base_hub, notif);
        unsigned long delay;

        if (event->command_id != SSAM_EVENT_BAS_CID_CONNECTION)
                return 0;

        if (event->length < 1) {
                dev_err(&hub->sdev->dev, "unexpected payload size: %u\n", event->length);
                return 0;
        }

        /*
         * Delay update when the base is being connected to give devices/EC
         * some time to set up.
         */
        delay = event->data[0] ? SSAM_BASE_UPDATE_CONNECT_DELAY : 0;

        schedule_delayed_work(&hub->update_work, delay);

        /*
         * Do not return SSAM_NOTIF_HANDLED: The event should be picked up and
         * consumed by the detachment system driver. We're just a (more or less)
         * silent observer.
         */
        return 0;
}

static int __maybe_unused ssam_base_hub_resume(struct device *dev)
{
        struct ssam_base_hub *hub = dev_get_drvdata(dev);

        schedule_delayed_work(&hub->update_work, 0);
        return 0;
}
static SIMPLE_DEV_PM_OPS(ssam_base_hub_pm_ops, NULL, ssam_base_hub_resume);

static int ssam_base_hub_probe(struct ssam_device *sdev)
{
        struct ssam_base_hub *hub;
        int status;

        hub = devm_kzalloc(&sdev->dev, sizeof(*hub), GFP_KERNEL);
        if (!hub)
                return -ENOMEM;

        hub->sdev = sdev;
        hub->state = SSAM_BASE_HUB_UNINITIALIZED;

        hub->notif.base.priority = INT_MAX;  /* This notifier should run first. */
        hub->notif.base.fn = ssam_base_hub_notif;
        hub->notif.event.reg = SSAM_EVENT_REGISTRY_SAM;
        hub->notif.event.id.target_category = SSAM_SSH_TC_BAS,
        hub->notif.event.id.instance = 0,
        hub->notif.event.mask = SSAM_EVENT_MASK_NONE;
        hub->notif.event.flags = SSAM_EVENT_SEQUENCED;

        INIT_DELAYED_WORK(&hub->update_work, ssam_base_hub_update_workfn);

        ssam_device_set_drvdata(sdev, hub);

        status = ssam_notifier_register(sdev->ctrl, &hub->notif);
        if (status)
                return status;

        status = sysfs_create_group(&sdev->dev.kobj, &ssam_base_hub_group);
        if (status)
                goto err;

        schedule_delayed_work(&hub->update_work, 0);
        return 0;

err:
        ssam_notifier_unregister(sdev->ctrl, &hub->notif);
        cancel_delayed_work_sync(&hub->update_work);
        ssam_hub_remove_devices(&sdev->dev);
        return status;
}

static void ssam_base_hub_remove(struct ssam_device *sdev)
{
        struct ssam_base_hub *hub = ssam_device_get_drvdata(sdev);

        sysfs_remove_group(&sdev->dev.kobj, &ssam_base_hub_group);

        ssam_notifier_unregister(sdev->ctrl, &hub->notif);
        cancel_delayed_work_sync(&hub->update_work);
        ssam_hub_remove_devices(&sdev->dev);
}

static const struct ssam_device_id ssam_base_hub_match[] = {
        { SSAM_VDEV(HUB, 0x02, SSAM_ANY_IID, 0x00) },
        { },
};

static struct ssam_device_driver ssam_base_hub_driver = {
        .probe = ssam_base_hub_probe,
        .remove = ssam_base_hub_remove,
        .match_table = ssam_base_hub_match,
        .driver = {
                .name = "surface_aggregator_base_hub",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .pm = &ssam_base_hub_pm_ops,
        },
};


/* -- SSAM platform/meta-hub driver. ---------------------------------------- */

static const struct acpi_device_id ssam_platform_hub_match[] = {
        /* Surface Pro 4, 5, and 6 (OMBR < 0x10) */
        { "MSHW0081", (unsigned long)ssam_node_group_sp5 },

        /* Surface Pro 6 (OMBR >= 0x10) */
        { "MSHW0111", (unsigned long)ssam_node_group_sp6 },

        /* Surface Pro 7 */
        { "MSHW0116", (unsigned long)ssam_node_group_sp7 },

        /* Surface Pro 7+ */
        { "MSHW0119", (unsigned long)ssam_node_group_sp7 },

        /* Surface Book 2 */
        { "MSHW0107", (unsigned long)ssam_node_group_sb2 },

        /* Surface Book 3 */
        { "MSHW0117", (unsigned long)ssam_node_group_sb3 },

        /* Surface Laptop 1 */
        { "MSHW0086", (unsigned long)ssam_node_group_sl1 },

        /* Surface Laptop 2 */
        { "MSHW0112", (unsigned long)ssam_node_group_sl2 },

        /* Surface Laptop 3 (13", Intel) */
        { "MSHW0114", (unsigned long)ssam_node_group_sl3 },

        /* Surface Laptop 3 (15", AMD) and 4 (15", AMD) */
        { "MSHW0110", (unsigned long)ssam_node_group_sl3 },

        /* Surface Laptop 4 (13", Intel) */
        { "MSHW0250", (unsigned long)ssam_node_group_sl3 },

        /* Surface Laptop Go 1 */
        { "MSHW0118", (unsigned long)ssam_node_group_slg1 },

        { },
};
MODULE_DEVICE_TABLE(acpi, ssam_platform_hub_match);

static int ssam_platform_hub_probe(struct platform_device *pdev)
{
        const struct software_node **nodes;
        struct ssam_controller *ctrl;
        struct fwnode_handle *root;
        int status;

        nodes = (const struct software_node **)acpi_device_get_match_data(&pdev->dev);
        if (!nodes)
                return -ENODEV;

        /*
         * As we're adding the SSAM client devices as children under this device
         * and not the SSAM controller, we need to add a device link to the
         * controller to ensure that we remove all of our devices before the
         * controller is removed. This also guarantees proper ordering for
         * suspend/resume of the devices on this hub.
         */
        ctrl = ssam_client_bind(&pdev->dev);
        if (IS_ERR(ctrl))
                return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);

        status = software_node_register_node_group(nodes);
        if (status)
                return status;

        root = software_node_fwnode(&ssam_node_root);
        if (!root) {
                software_node_unregister_node_group(nodes);
                return -ENOENT;
        }

        set_secondary_fwnode(&pdev->dev, root);

        status = ssam_hub_add_devices(&pdev->dev, ctrl, root);
        if (status) {
                set_secondary_fwnode(&pdev->dev, NULL);
                software_node_unregister_node_group(nodes);
        }

        platform_set_drvdata(pdev, nodes);
        return status;
}

static int ssam_platform_hub_remove(struct platform_device *pdev)
{
        const struct software_node **nodes = platform_get_drvdata(pdev);

        ssam_hub_remove_devices(&pdev->dev);
        set_secondary_fwnode(&pdev->dev, NULL);
        software_node_unregister_node_group(nodes);
        return 0;
}

static struct platform_driver ssam_platform_hub_driver = {
        .probe = ssam_platform_hub_probe,
        .remove = ssam_platform_hub_remove,
        .driver = {
                .name = "surface_aggregator_platform_hub",
                .acpi_match_table = ssam_platform_hub_match,
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
        },
};


/* -- Module initialization. ------------------------------------------------ */

static int __init ssam_device_hub_init(void)
{
        int status;

        status = platform_driver_register(&ssam_platform_hub_driver);
        if (status)
                return status;

        status = ssam_device_driver_register(&ssam_base_hub_driver);
        if (status)
                platform_driver_unregister(&ssam_platform_hub_driver);

        return status;
}
module_init(ssam_device_hub_init);

static void __exit ssam_device_hub_exit(void)
{
        ssam_device_driver_unregister(&ssam_base_hub_driver);
        platform_driver_unregister(&ssam_platform_hub_driver);
}
module_exit(ssam_device_hub_exit);

MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
MODULE_DESCRIPTION("Device-registry for Surface System Aggregator Module");
MODULE_LICENSE("GPL");