// SPDX-License-Identifier: GPL-2.0+
/*
 *  HID driver for Google Hammer device.
 *
 *  Copyright (c) 2017 Google Inc.
 *  Author: Wei-Ning Huang <wnhuang@google.com>
 */

/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 */

#include <linux/acpi.h>
#include <linux/hid.h>
#include <linux/leds.h>
#include <linux/mfd/cros_ec.h>
#include <linux/mfd/cros_ec_commands.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_wakeup.h>
#include <asm/unaligned.h>

#include "hid-ids.h"

/*
 * C(hrome)B(ase)A(ttached)S(witch) - switch exported by Chrome EC and reporting
 * state of the "Whiskers" base - attached or detached. Whiskers USB device also
 * reports position of the keyboard - folded or not. Combining base state and
 * position allows us to generate proper "Tablet mode" events.
 */
struct cbas_ec {
        struct device *dev;     /* The platform device (EC) */
        struct input_dev *input;
        bool base_present;
        struct notifier_block notifier;
};

static struct cbas_ec cbas_ec;
static DEFINE_SPINLOCK(cbas_ec_lock);
static DEFINE_MUTEX(cbas_ec_reglock);

static bool cbas_parse_base_state(const void *data)
{
        u32 switches = get_unaligned_le32(data);

        return !!(switches & BIT(EC_MKBP_BASE_ATTACHED));
}

static int cbas_ec_query_base(struct cros_ec_device *ec_dev, bool get_state,
                                  bool *state)
{
        struct ec_params_mkbp_info *params;
        struct cros_ec_command *msg;
        int ret;

        msg = kzalloc(sizeof(*msg) + max(sizeof(u32), sizeof(*params)),
                      GFP_KERNEL);
        if (!msg)
                return -ENOMEM;

        msg->command = EC_CMD_MKBP_INFO;
        msg->version = 1;
        msg->outsize = sizeof(*params);
        msg->insize = sizeof(u32);
        params = (struct ec_params_mkbp_info *)msg->data;
        params->info_type = get_state ?
                EC_MKBP_INFO_CURRENT : EC_MKBP_INFO_SUPPORTED;
        params->event_type = EC_MKBP_EVENT_SWITCH;

        ret = cros_ec_cmd_xfer_status(ec_dev, msg);
        if (ret >= 0) {
                if (ret != sizeof(u32)) {
                        dev_warn(ec_dev->dev, "wrong result size: %d != %zu\n",
                                 ret, sizeof(u32));
                        ret = -EPROTO;
                } else {
                        *state = cbas_parse_base_state(msg->data);
                        ret = 0;
                }
        }

        kfree(msg);

        return ret;
}

static int cbas_ec_notify(struct notifier_block *nb,
                              unsigned long queued_during_suspend,
                              void *_notify)
{
        struct cros_ec_device *ec = _notify;
        unsigned long flags;
        bool base_present;

        if (ec->event_data.event_type == EC_MKBP_EVENT_SWITCH) {
                base_present = cbas_parse_base_state(
                                        &ec->event_data.data.switches);
                dev_dbg(cbas_ec.dev,
                        "%s: base: %d\n", __func__, base_present);

                if (device_may_wakeup(cbas_ec.dev) ||
                    !queued_during_suspend) {

                        pm_wakeup_event(cbas_ec.dev, 0);

                        spin_lock_irqsave(&cbas_ec_lock, flags);

                        /*
                         * While input layer dedupes the events, we do not want
                         * to disrupt the state reported by the base by
                         * overriding it with state reported by the LID. Only
                         * report changes, as we assume that on attach the base
                         * is not folded.
                         */
                        if (base_present != cbas_ec.base_present) {
                                input_report_switch(cbas_ec.input,
                                                    SW_TABLET_MODE,
                                                    !base_present);
                                input_sync(cbas_ec.input);
                                cbas_ec.base_present = base_present;
                        }

                        spin_unlock_irqrestore(&cbas_ec_lock, flags);
                }
        }

        return NOTIFY_OK;
}

static __maybe_unused int cbas_ec_resume(struct device *dev)
{
        struct cros_ec_device *ec = dev_get_drvdata(dev->parent);
        bool base_present;
        int error;

        error = cbas_ec_query_base(ec, true, &base_present);
        if (error) {
                dev_warn(dev, "failed to fetch base state on resume: %d\n",
                         error);
        } else {
                spin_lock_irq(&cbas_ec_lock);

                cbas_ec.base_present = base_present;

                /*
                 * Only report if base is disconnected. If base is connected,
                 * it will resend its state on resume, and we'll update it
                 * in hammer_event().
                 */
                if (!cbas_ec.base_present) {
                        input_report_switch(cbas_ec.input, SW_TABLET_MODE, 1);
                        input_sync(cbas_ec.input);
                }

                spin_unlock_irq(&cbas_ec_lock);
        }

        return 0;
}

static SIMPLE_DEV_PM_OPS(cbas_ec_pm_ops, NULL, cbas_ec_resume);

static void cbas_ec_set_input(struct input_dev *input)
{
        /* Take the lock so hammer_event() does not race with us here */
        spin_lock_irq(&cbas_ec_lock);
        cbas_ec.input = input;
        spin_unlock_irq(&cbas_ec_lock);
}

static int __cbas_ec_probe(struct platform_device *pdev)
{
        struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
        struct input_dev *input;
        bool base_supported;
        int error;

        error = cbas_ec_query_base(ec, false, &base_supported);
        if (error)
                return error;

        if (!base_supported)
                return -ENXIO;

        input = devm_input_allocate_device(&pdev->dev);
        if (!input)
                return -ENOMEM;

        input->name = "Whiskers Tablet Mode Switch";
        input->id.bustype = BUS_HOST;

        input_set_capability(input, EV_SW, SW_TABLET_MODE);

        error = input_register_device(input);
        if (error) {
                dev_err(&pdev->dev, "cannot register input device: %d\n",
                        error);
                return error;
        }

        /* Seed the state */
        error = cbas_ec_query_base(ec, true, &cbas_ec.base_present);
        if (error) {
                dev_err(&pdev->dev, "cannot query base state: %d\n", error);
                return error;
        }

        input_report_switch(input, SW_TABLET_MODE, !cbas_ec.base_present);

        cbas_ec_set_input(input);

        cbas_ec.dev = &pdev->dev;
        cbas_ec.notifier.notifier_call = cbas_ec_notify;
        error = blocking_notifier_chain_register(&ec->event_notifier,
                                                 &cbas_ec.notifier);
        if (error) {
                dev_err(&pdev->dev, "cannot register notifier: %d\n", error);
                cbas_ec_set_input(NULL);
                return error;
        }

        device_init_wakeup(&pdev->dev, true);
        return 0;
}

static int cbas_ec_probe(struct platform_device *pdev)
{
        int retval;

        mutex_lock(&cbas_ec_reglock);

        if (cbas_ec.input) {
                retval = -EBUSY;
                goto out;
        }

        retval = __cbas_ec_probe(pdev);

out:
        mutex_unlock(&cbas_ec_reglock);
        return retval;
}

static int cbas_ec_remove(struct platform_device *pdev)
{
        struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);

        mutex_lock(&cbas_ec_reglock);

        blocking_notifier_chain_unregister(&ec->event_notifier,
                                           &cbas_ec.notifier);
        cbas_ec_set_input(NULL);

        mutex_unlock(&cbas_ec_reglock);
        return 0;
}

static const struct acpi_device_id cbas_ec_acpi_ids[] = {
        { "GOOG000B", 0 },
        { }
};
MODULE_DEVICE_TABLE(acpi, cbas_ec_acpi_ids);

static struct platform_driver cbas_ec_driver = {
        .probe = cbas_ec_probe,
        .remove = cbas_ec_remove,
        .driver = {
                .name = "cbas_ec",
                .acpi_match_table = ACPI_PTR(cbas_ec_acpi_ids),
                .pm = &cbas_ec_pm_ops,
        },
};

#define MAX_BRIGHTNESS 100

struct hammer_kbd_leds {
        struct led_classdev cdev;
        struct hid_device *hdev;
        u8 buf[2] ____cacheline_aligned;
};

static int hammer_kbd_brightness_set_blocking(struct led_classdev *cdev,
                enum led_brightness br)
{
        struct hammer_kbd_leds *led = container_of(cdev,
                                                   struct hammer_kbd_leds,
                                                   cdev);
        int ret;

        led->buf[0] = 0;
        led->buf[1] = br;

        /*
         * Request USB HID device to be in Full On mode, so that sending
         * hardware output report and hardware raw request won't fail.
         */
        ret = hid_hw_power(led->hdev, PM_HINT_FULLON);
        if (ret < 0) {
                hid_err(led->hdev, "failed: device not resumed %d\n", ret);
                return ret;
        }

        ret = hid_hw_output_report(led->hdev, led->buf, sizeof(led->buf));
        if (ret == -ENOSYS)
                ret = hid_hw_raw_request(led->hdev, 0, led->buf,
                                         sizeof(led->buf),
                                         HID_OUTPUT_REPORT,
                                         HID_REQ_SET_REPORT);
        if (ret < 0)
                hid_err(led->hdev, "failed to set keyboard backlight: %d\n",
                        ret);

        /* Request USB HID device back to Normal Mode. */
        hid_hw_power(led->hdev, PM_HINT_NORMAL);

        return ret;
}

static int hammer_register_leds(struct hid_device *hdev)
{
        struct hammer_kbd_leds *kbd_backlight;

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

        kbd_backlight->hdev = hdev;
        kbd_backlight->cdev.name = "hammer::kbd_backlight";
        kbd_backlight->cdev.max_brightness = MAX_BRIGHTNESS;
        kbd_backlight->cdev.brightness_set_blocking =
                hammer_kbd_brightness_set_blocking;
        kbd_backlight->cdev.flags = LED_HW_PLUGGABLE;

        /* Set backlight to 0% initially. */
        hammer_kbd_brightness_set_blocking(&kbd_backlight->cdev, 0);

        return devm_led_classdev_register(&hdev->dev, &kbd_backlight->cdev);
}

#define HID_UP_GOOGLEVENDOR     0xffd10000
#define HID_VD_KBD_FOLDED       0x00000019
#define WHISKERS_KBD_FOLDED     (HID_UP_GOOGLEVENDOR | HID_VD_KBD_FOLDED)

/* HID usage for keyboard backlight (Alphanumeric display brightness) */
#define HID_AD_BRIGHTNESS       0x00140046

static int hammer_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                                struct hid_field *field,
                                struct hid_usage *usage,
                                unsigned long **bit, int *max)
{
        if (hdev->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
            usage->hid == WHISKERS_KBD_FOLDED) {
                /*
                 * We do not want to have this usage mapped as it will get
                 * mixed in with "base attached" signal and delivered over
                 * separate input device for tablet switch mode.
                 */
                return -1;
        }

        return 0;
}

static int hammer_event(struct hid_device *hid, struct hid_field *field,
                        struct hid_usage *usage, __s32 value)
{
        unsigned long flags;

        if (hid->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
            usage->hid == WHISKERS_KBD_FOLDED) {
                spin_lock_irqsave(&cbas_ec_lock, flags);

                hid_dbg(hid, "%s: base: %d, folded: %d\n", __func__,
                        cbas_ec.base_present, value);

                /*
                 * We should not get event if base is detached, but in case
                 * we happen to service HID and EC notifications out of order
                 * let's still check the "base present" flag.
                 */
                if (cbas_ec.input && cbas_ec.base_present) {
                        input_report_switch(cbas_ec.input,
                                            SW_TABLET_MODE, value);
                        input_sync(cbas_ec.input);
                }

                spin_unlock_irqrestore(&cbas_ec_lock, flags);
                return 1; /* We handled this event */
        }

        return 0;
}

static bool hammer_is_keyboard_interface(struct hid_device *hdev)
{
        struct hid_report_enum *re = &hdev->report_enum[HID_INPUT_REPORT];
        struct hid_report *report;

        list_for_each_entry(report, &re->report_list, list)
                if (report->application == HID_GD_KEYBOARD)
                        return true;

        return false;
}

static bool hammer_has_backlight_control(struct hid_device *hdev)
{
        struct hid_report_enum *re = &hdev->report_enum[HID_OUTPUT_REPORT];
        struct hid_report *report;
        int i, j;

        list_for_each_entry(report, &re->report_list, list) {
                if (report->application != HID_GD_KEYBOARD)
                        continue;

                for (i = 0; i < report->maxfield; i++) {
                        struct hid_field *field = report->field[i];

                        for (j = 0; j < field->maxusage; j++)
                                if (field->usage[j].hid == HID_AD_BRIGHTNESS)
                                        return true;
                }
        }

        return false;
}

static int hammer_probe(struct hid_device *hdev,
                        const struct hid_device_id *id)
{
        int error;

        /*
         * We always want to poll for, and handle tablet mode events from
         * Whiskers, even when nobody has opened the input device. This also
         * prevents the hid core from dropping early tablet mode events from
         * the device.
         */
        if (hdev->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
                        hammer_is_keyboard_interface(hdev))
                hdev->quirks |= HID_QUIRK_ALWAYS_POLL;

        error = hid_parse(hdev);
        if (error)
                return error;

        error = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
        if (error)
                return error;

        if (hammer_has_backlight_control(hdev)) {
                error = hammer_register_leds(hdev);
                if (error)
                        hid_warn(hdev,
                                "Failed to register keyboard backlight: %d\n",
                                error);
        }

        return 0;
}


static const struct hid_device_id hammer_devices[] = {
        { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
                     USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_HAMMER) },
        { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
                     USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_STAFF) },
        { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
                     USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_WAND) },
        { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
                     USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_WHISKERS) },
        { }
};
MODULE_DEVICE_TABLE(hid, hammer_devices);

static struct hid_driver hammer_driver = {
        .name = "hammer",
        .id_table = hammer_devices,
        .probe = hammer_probe,
        .input_mapping = hammer_input_mapping,
        .event = hammer_event,
};

static int __init hammer_init(void)
{
        int error;

        error = platform_driver_register(&cbas_ec_driver);
        if (error)
                return error;

        error = hid_register_driver(&hammer_driver);
        if (error) {
                platform_driver_unregister(&cbas_ec_driver);
                return error;
        }

        return 0;
}
module_init(hammer_init);

static void __exit hammer_exit(void)
{
        hid_unregister_driver(&hammer_driver);
        platform_driver_unregister(&cbas_ec_driver);
}
module_exit(hammer_exit);

MODULE_LICENSE("GPL");