// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2021, Stephan Gerhold <stephan@gerhold.net> */
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rpmsg.h>
#include <linux/wwan.h>

struct rpmsg_wwan_dev {
        /* Lower level is a rpmsg dev, upper level is a wwan port */
        struct rpmsg_device *rpdev;
        struct wwan_port *wwan_port;
        struct rpmsg_endpoint *ept;
};

static int rpmsg_wwan_ctrl_callback(struct rpmsg_device *rpdev,
                                    void *buf, int len, void *priv, u32 src)
{
        struct rpmsg_wwan_dev *rpwwan = priv;
        struct sk_buff *skb;

        skb = alloc_skb(len, GFP_ATOMIC);
        if (!skb)
                return -ENOMEM;

        skb_put_data(skb, buf, len);
        wwan_port_rx(rpwwan->wwan_port, skb);
        return 0;
}

static int rpmsg_wwan_ctrl_start(struct wwan_port *port)
{
        struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);
        struct rpmsg_channel_info chinfo = {
                .src = rpwwan->rpdev->src,
                .dst = RPMSG_ADDR_ANY,
        };

        strscpy(chinfo.name, rpwwan->rpdev->id.name, sizeof(chinfo.name));
        rpwwan->ept = rpmsg_create_ept(rpwwan->rpdev, rpmsg_wwan_ctrl_callback,
                                       rpwwan, chinfo);
        if (!rpwwan->ept)
                return -EREMOTEIO;

        return 0;
}

static void rpmsg_wwan_ctrl_stop(struct wwan_port *port)
{
        struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);

        rpmsg_destroy_ept(rpwwan->ept);
        rpwwan->ept = NULL;
}

static int rpmsg_wwan_ctrl_tx(struct wwan_port *port, struct sk_buff *skb)
{
        struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);
        int ret;

        ret = rpmsg_trysend(rpwwan->ept, skb->data, skb->len);
        if (ret)
                return ret;

        consume_skb(skb);
        return 0;
}

static int rpmsg_wwan_ctrl_tx_blocking(struct wwan_port *port, struct sk_buff *skb)
{
        struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);
        int ret;

        ret = rpmsg_send(rpwwan->ept, skb->data, skb->len);
        if (ret)
                return ret;

        consume_skb(skb);
        return 0;
}

static __poll_t rpmsg_wwan_ctrl_tx_poll(struct wwan_port *port,
                                        struct file *filp, poll_table *wait)
{
        struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);

        return rpmsg_poll(rpwwan->ept, filp, wait);
}

static const struct wwan_port_ops rpmsg_wwan_pops = {
        .start = rpmsg_wwan_ctrl_start,
        .stop = rpmsg_wwan_ctrl_stop,
        .tx = rpmsg_wwan_ctrl_tx,
        .tx_blocking = rpmsg_wwan_ctrl_tx_blocking,
        .tx_poll = rpmsg_wwan_ctrl_tx_poll,
};

static struct device *rpmsg_wwan_find_parent(struct device *dev)
{
        /* Select first platform device as parent for the WWAN ports.
         * On Qualcomm platforms this is usually the platform device that
         * represents the modem remote processor. This might need to be
         * adjusted when adding device IDs for other platforms.
         */
        for (dev = dev->parent; dev; dev = dev->parent) {
                if (dev_is_platform(dev))
                        return dev;
        }
        return NULL;
}

static int rpmsg_wwan_ctrl_probe(struct rpmsg_device *rpdev)
{
        struct rpmsg_wwan_dev *rpwwan;
        struct wwan_port *port;
        struct device *parent;

        parent = rpmsg_wwan_find_parent(&rpdev->dev);
        if (!parent)
                return -ENODEV;

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

        rpwwan->rpdev = rpdev;
        dev_set_drvdata(&rpdev->dev, rpwwan);

        /* Register as a wwan port, id.driver_data contains wwan port type */
        port = wwan_create_port(parent, rpdev->id.driver_data,
                                &rpmsg_wwan_pops, NULL, rpwwan);
        if (IS_ERR(port))
                return PTR_ERR(port);

        rpwwan->wwan_port = port;

        return 0;
};

static void rpmsg_wwan_ctrl_remove(struct rpmsg_device *rpdev)
{
        struct rpmsg_wwan_dev *rpwwan = dev_get_drvdata(&rpdev->dev);

        wwan_remove_port(rpwwan->wwan_port);
}

static const struct rpmsg_device_id rpmsg_wwan_ctrl_id_table[] = {
        /* RPMSG channels for Qualcomm SoCs with integrated modem */
        { .name = "DATA5_CNTL", .driver_data = WWAN_PORT_QMI },
        { .name = "DATA4", .driver_data = WWAN_PORT_AT },
        { .name = "DATA1", .driver_data = WWAN_PORT_AT },
        {},
};
MODULE_DEVICE_TABLE(rpmsg, rpmsg_wwan_ctrl_id_table);

static struct rpmsg_driver rpmsg_wwan_ctrl_driver = {
        .drv.name = "rpmsg_wwan_ctrl",
        .id_table = rpmsg_wwan_ctrl_id_table,
        .probe = rpmsg_wwan_ctrl_probe,
        .remove = rpmsg_wwan_ctrl_remove,
};
module_rpmsg_driver(rpmsg_wwan_ctrl_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("RPMSG WWAN CTRL Driver");
MODULE_AUTHOR("Stephan Gerhold <stephan@gerhold.net>");