// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2014-2017, The Linux Foundation. All rights reserved.
 * Copyright (c) 2017, Linaro Ltd.
 */

#include <linux/completion.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/rpmsg.h>
#include <linux/rpmsg/qcom_glink.h>
#include <linux/remoteproc/qcom_rproc.h>

/**
 * struct do_cleanup_msg - The data structure for an SSR do_cleanup message
 * @version:    The G-Link SSR protocol version
 * @command:    The G-Link SSR command - do_cleanup
 * @seq_num:    Sequence number
 * @name_len:   Length of the name of the subsystem being restarted
 * @name:       G-Link edge name of the subsystem being restarted
 */
struct do_cleanup_msg {
        __le32 version;
        __le32 command;
        __le32 seq_num;
        __le32 name_len;
        char name[32];
};

/**
 * struct cleanup_done_msg - The data structure for an SSR cleanup_done message
 * @version:    The G-Link SSR protocol version
 * @response:   The G-Link SSR response to a do_cleanup command, cleanup_done
 * @seq_num:    Sequence number
 */
struct cleanup_done_msg {
        __le32 version;
        __le32 response;
        __le32 seq_num;
};

/*
 * G-Link SSR protocol commands
 */
#define GLINK_SSR_DO_CLEANUP    0
#define GLINK_SSR_CLEANUP_DONE  1

struct glink_ssr {
        struct device *dev;
        struct rpmsg_endpoint *ept;

        struct notifier_block nb;

        u32 seq_num;
        struct completion completion;
};

/* Notifier list for all registered glink_ssr instances */
static BLOCKING_NOTIFIER_HEAD(ssr_notifiers);

/**
 * qcom_glink_ssr_notify() - notify GLINK SSR about stopped remoteproc
 * @ssr_name:   name of the remoteproc that has been stopped
 */
void qcom_glink_ssr_notify(const char *ssr_name)
{
        blocking_notifier_call_chain(&ssr_notifiers, 0, (void *)ssr_name);
}
EXPORT_SYMBOL_GPL(qcom_glink_ssr_notify);

static int qcom_glink_ssr_callback(struct rpmsg_device *rpdev,
                                   void *data, int len, void *priv, u32 addr)
{
        struct cleanup_done_msg *msg = data;
        struct glink_ssr *ssr = dev_get_drvdata(&rpdev->dev);

        if (len < sizeof(*msg)) {
                dev_err(ssr->dev, "message too short\n");
                return -EINVAL;
        }

        if (le32_to_cpu(msg->version) != 0)
                return -EINVAL;

        if (le32_to_cpu(msg->response) != GLINK_SSR_CLEANUP_DONE)
                return 0;

        if (le32_to_cpu(msg->seq_num) != ssr->seq_num) {
                dev_err(ssr->dev, "invalid sequence number of response\n");
                return -EINVAL;
        }

        complete(&ssr->completion);

        return 0;
}

static int qcom_glink_ssr_notifier_call(struct notifier_block *nb,
                                        unsigned long event,
                                        void *data)
{
        struct glink_ssr *ssr = container_of(nb, struct glink_ssr, nb);
        struct do_cleanup_msg msg;
        char *ssr_name = data;
        int ret;

        ssr->seq_num++;
        reinit_completion(&ssr->completion);

        memset(&msg, 0, sizeof(msg));
        msg.command = cpu_to_le32(GLINK_SSR_DO_CLEANUP);
        msg.seq_num = cpu_to_le32(ssr->seq_num);
        msg.name_len = cpu_to_le32(strlen(ssr_name));
        strscpy(msg.name, ssr_name, sizeof(msg.name));

        ret = rpmsg_send(ssr->ept, &msg, sizeof(msg));
        if (ret < 0)
                dev_err(ssr->dev, "failed to send cleanup message\n");

        ret = wait_for_completion_timeout(&ssr->completion, HZ);
        if (!ret)
                dev_err(ssr->dev, "timeout waiting for cleanup done message\n");

        return NOTIFY_DONE;
}

static int qcom_glink_ssr_probe(struct rpmsg_device *rpdev)
{
        struct glink_ssr *ssr;

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

        init_completion(&ssr->completion);

        ssr->dev = &rpdev->dev;
        ssr->ept = rpdev->ept;
        ssr->nb.notifier_call = qcom_glink_ssr_notifier_call;

        dev_set_drvdata(&rpdev->dev, ssr);

        return blocking_notifier_chain_register(&ssr_notifiers, &ssr->nb);
}

static void qcom_glink_ssr_remove(struct rpmsg_device *rpdev)
{
        struct glink_ssr *ssr = dev_get_drvdata(&rpdev->dev);

        blocking_notifier_chain_unregister(&ssr_notifiers, &ssr->nb);
}

static const struct rpmsg_device_id qcom_glink_ssr_match[] = {
        { "glink_ssr" },
        {}
};
MODULE_DEVICE_TABLE(rpmsg, qcom_glink_ssr_match);

static struct rpmsg_driver qcom_glink_ssr_driver = {
        .probe = qcom_glink_ssr_probe,
        .remove = qcom_glink_ssr_remove,
        .callback = qcom_glink_ssr_callback,
        .id_table = qcom_glink_ssr_match,
        .drv = {
                .name = "qcom_glink_ssr",
        },
};
module_rpmsg_driver(qcom_glink_ssr_driver);