// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2020 Google LLC
 *
 * This driver serves as the receiver of cros_ec PD host events.
 */

#include <linux/acpi.h>
#include <linux/fwnode.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_data/cros_usbpd_notify.h>
#include <linux/platform_device.h>

#define DRV_NAME "cros-usbpd-notify"
#define DRV_NAME_PLAT_ACPI "cros-usbpd-notify-acpi"
#define ACPI_DRV_NAME "GOOG0003"
#define CREC_DRV_NAME "GOOG0004"

static BLOCKING_NOTIFIER_HEAD(cros_usbpd_notifier_list);

struct cros_usbpd_notify_data {
        struct device *dev;
        struct cros_ec_device *ec;
        struct notifier_block nb;
};

/**
 * cros_usbpd_register_notify - Register a notifier callback for PD events.
 * @nb: Notifier block pointer to register
 *
 * On ACPI platforms this corresponds to host events on the ECPD
 * "GOOG0003" ACPI device. On non-ACPI platforms this will filter mkbp events
 * for USB PD events.
 *
 * Return: 0 on success or negative error code.
 */
int cros_usbpd_register_notify(struct notifier_block *nb)
{
        return blocking_notifier_chain_register(&cros_usbpd_notifier_list,
                                                nb);
}
EXPORT_SYMBOL_GPL(cros_usbpd_register_notify);

/**
 * cros_usbpd_unregister_notify - Unregister notifier callback for PD events.
 * @nb: Notifier block pointer to unregister
 *
 * Unregister a notifier callback that was previously registered with
 * cros_usbpd_register_notify().
 */
void cros_usbpd_unregister_notify(struct notifier_block *nb)
{
        blocking_notifier_chain_unregister(&cros_usbpd_notifier_list, nb);
}
EXPORT_SYMBOL_GPL(cros_usbpd_unregister_notify);

static void cros_usbpd_get_event_and_notify(struct device  *dev,
                                            struct cros_ec_device *ec_dev)
{
        struct ec_response_host_event_status host_event_status;
        u32 event = 0;
        int ret;

        /*
         * We still send a 0 event out to older devices which don't
         * have the updated device heirarchy.
         */
        if (!ec_dev) {
                dev_dbg(dev,
                        "EC device inaccessible; sending 0 event status.\n");
                goto send_notify;
        }

        /* Check for PD host events on EC. */
        ret = cros_ec_cmd(ec_dev, 0, EC_CMD_PD_HOST_EVENT_STATUS,
                          NULL, 0, &host_event_status, sizeof(host_event_status));
        if (ret < 0) {
                dev_warn(dev, "Can't get host event status (err: %d)\n", ret);
                goto send_notify;
        }

        event = host_event_status.status;

send_notify:
        blocking_notifier_call_chain(&cros_usbpd_notifier_list, event, NULL);
}

#ifdef CONFIG_ACPI

static void cros_usbpd_notify_acpi(acpi_handle device, u32 event, void *data)
{
        struct cros_usbpd_notify_data *pdnotify = data;

        cros_usbpd_get_event_and_notify(pdnotify->dev, pdnotify->ec);
}

static int cros_usbpd_notify_probe_acpi(struct platform_device *pdev)
{
        struct cros_usbpd_notify_data *pdnotify;
        struct device *dev = &pdev->dev;
        struct acpi_device *adev, *parent_adev;
        struct cros_ec_device *ec_dev;
        struct fwnode_handle *parent_fwnode;
        acpi_status status;

        adev = ACPI_COMPANION(dev);

        pdnotify = devm_kzalloc(dev, sizeof(*pdnotify), GFP_KERNEL);
        if (!pdnotify)
                return -ENOMEM;

        /* Get the EC device pointer needed to talk to the EC. */
        ec_dev = dev_get_drvdata(dev->parent);
        if (!ec_dev) {
                /*
                 * We continue even for older devices which don't have the
                 * correct device heirarchy, namely, GOOG0003 is a child
                 * of GOOG0004. If GOOG0003 is a child of GOOG0004 and we
                 * can't get a pointer to the Chrome EC device, defer the
                 * probe function.
                 */
                parent_fwnode = fwnode_get_parent(dev->fwnode);
                if (parent_fwnode) {
                        parent_adev = to_acpi_device_node(parent_fwnode);
                        if (parent_adev &&
                            acpi_dev_hid_match(parent_adev, CREC_DRV_NAME)) {
                                return -EPROBE_DEFER;
                        }
                }
                dev_warn(dev, "Couldn't get Chrome EC device pointer.\n");
        }

        pdnotify->dev = dev;
        pdnotify->ec = ec_dev;

        status = acpi_install_notify_handler(adev->handle,
                                             ACPI_ALL_NOTIFY,
                                             cros_usbpd_notify_acpi,
                                             pdnotify);
        if (ACPI_FAILURE(status)) {
                dev_warn(dev, "Failed to register notify handler %08x\n",
                         status);
                return -EINVAL;
        }

        return 0;
}

static void cros_usbpd_notify_remove_acpi(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct acpi_device *adev = ACPI_COMPANION(dev);

        acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
                                   cros_usbpd_notify_acpi);
}

static const struct acpi_device_id cros_usbpd_notify_acpi_device_ids[] = {
        { ACPI_DRV_NAME, 0 },
        { }
};
MODULE_DEVICE_TABLE(acpi, cros_usbpd_notify_acpi_device_ids);

static struct platform_driver cros_usbpd_notify_acpi_driver = {
        .driver = {
                .name = DRV_NAME_PLAT_ACPI,
                .acpi_match_table = cros_usbpd_notify_acpi_device_ids,
        },
        .probe = cros_usbpd_notify_probe_acpi,
        .remove = cros_usbpd_notify_remove_acpi,
};

#endif /* CONFIG_ACPI */

static int cros_usbpd_notify_plat(struct notifier_block *nb,
                                  unsigned long queued_during_suspend,
                                  void *data)
{
        struct cros_usbpd_notify_data *pdnotify = container_of(nb,
                        struct cros_usbpd_notify_data, nb);
        struct cros_ec_device *ec_dev = (struct cros_ec_device *)data;
        u32 host_event = cros_ec_get_host_event(ec_dev);

        if (!host_event)
                return NOTIFY_DONE;

        if (host_event & (EC_HOST_EVENT_MASK(EC_HOST_EVENT_PD_MCU) |
                          EC_HOST_EVENT_MASK(EC_HOST_EVENT_USB_MUX))) {
                cros_usbpd_get_event_and_notify(pdnotify->dev, ec_dev);
                return NOTIFY_OK;
        }
        return NOTIFY_DONE;
}

static int cros_usbpd_notify_probe_plat(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct cros_ec_dev *ecdev = dev_get_drvdata(dev->parent);
        struct cros_usbpd_notify_data *pdnotify;
        int ret;

        pdnotify = devm_kzalloc(dev, sizeof(*pdnotify), GFP_KERNEL);
        if (!pdnotify)
                return -ENOMEM;

        pdnotify->dev = dev;
        pdnotify->ec = ecdev->ec_dev;
        pdnotify->nb.notifier_call = cros_usbpd_notify_plat;

        dev_set_drvdata(dev, pdnotify);

        ret = blocking_notifier_chain_register(&ecdev->ec_dev->event_notifier,
                                               &pdnotify->nb);
        if (ret < 0) {
                dev_err(dev, "Failed to register notifier\n");
                return ret;
        }

        return 0;
}

static void cros_usbpd_notify_remove_plat(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct cros_ec_dev *ecdev = dev_get_drvdata(dev->parent);
        struct cros_usbpd_notify_data *pdnotify =
                (struct cros_usbpd_notify_data *)dev_get_drvdata(dev);

        blocking_notifier_chain_unregister(&ecdev->ec_dev->event_notifier,
                                           &pdnotify->nb);
}

static const struct platform_device_id cros_usbpd_notify_id[] = {
        { DRV_NAME, 0 },
        {}
};
MODULE_DEVICE_TABLE(platform, cros_usbpd_notify_id);

static struct platform_driver cros_usbpd_notify_plat_driver = {
        .driver = {
                .name = DRV_NAME,
        },
        .probe = cros_usbpd_notify_probe_plat,
        .remove = cros_usbpd_notify_remove_plat,
        .id_table = cros_usbpd_notify_id,
};

static int __init cros_usbpd_notify_init(void)
{
        int ret;

        ret = platform_driver_register(&cros_usbpd_notify_plat_driver);
        if (ret < 0)
                return ret;

#ifdef CONFIG_ACPI
        ret = platform_driver_register(&cros_usbpd_notify_acpi_driver);
        if (ret) {
                platform_driver_unregister(&cros_usbpd_notify_plat_driver);
                return ret;
        }
#endif
        return 0;
}

static void __exit cros_usbpd_notify_exit(void)
{
#ifdef CONFIG_ACPI
        platform_driver_unregister(&cros_usbpd_notify_acpi_driver);
#endif
        platform_driver_unregister(&cros_usbpd_notify_plat_driver);
}

module_init(cros_usbpd_notify_init);
module_exit(cros_usbpd_notify_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ChromeOS power delivery notifier device");
MODULE_AUTHOR("Jon Flatley <jflat@chromium.org>");