// SPDX-License-Identifier: GPL-2.0
//
// Copyright 2018 Google LLC.

#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_device.h>
#include <linux/rpmsg.h>
#include <linux/slab.h>

#include "cros_ec.h"

#define EC_MSG_TIMEOUT_MS       200
#define HOST_COMMAND_MARK       1
#define HOST_EVENT_MARK         2

/**
 * struct cros_ec_rpmsg_response - rpmsg message format from from EC.
 *
 * @type:       The type of message, should be either HOST_COMMAND_MARK or
 *              HOST_EVENT_MARK, representing that the message is a response to
 *              host command, or a host event.
 * @data:       ec_host_response for host command.
 */
struct cros_ec_rpmsg_response {
        u8 type;
        u8 data[] __aligned(4);
};

/**
 * struct cros_ec_rpmsg - information about a EC over rpmsg.
 *
 * @rpdev:      rpmsg device we are connected to
 * @xfer_ack:   completion for host command transfer.
 * @host_event_work:    Work struct for pending host event.
 * @ept: The rpmsg endpoint of this channel.
 * @has_pending_host_event: Boolean used to check if there is a pending event.
 * @probe_done: Flag to indicate that probe is done.
 */
struct cros_ec_rpmsg {
        struct rpmsg_device *rpdev;
        struct completion xfer_ack;
        struct work_struct host_event_work;
        struct rpmsg_endpoint *ept;
        bool has_pending_host_event;
        bool probe_done;
};

/**
 * cros_ec_cmd_xfer_rpmsg - Transfer a message over rpmsg and receive the reply
 *
 * @ec_dev: ChromeOS EC device
 * @ec_msg: Message to transfer
 *
 * This is only used for old EC proto version, and is not supported for this
 * driver.
 *
 * Return: -EINVAL
 */
static int cros_ec_cmd_xfer_rpmsg(struct cros_ec_device *ec_dev,
                                  struct cros_ec_command *ec_msg)
{
        return -EINVAL;
}

/**
 * cros_ec_pkt_xfer_rpmsg - Transfer a packet over rpmsg and receive the reply
 *
 * @ec_dev: ChromeOS EC device
 * @ec_msg: Message to transfer
 *
 * Return: number of bytes of the reply on success or negative error code.
 */
static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device *ec_dev,
                                  struct cros_ec_command *ec_msg)
{
        struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
        struct ec_host_response *response;
        unsigned long timeout;
        int len;
        int ret;
        u8 sum;
        int i;

        ec_msg->result = 0;
        len = cros_ec_prepare_tx(ec_dev, ec_msg);
        dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);

        reinit_completion(&ec_rpmsg->xfer_ack);
        ret = rpmsg_send(ec_rpmsg->ept, ec_dev->dout, len);
        if (ret) {
                dev_err(ec_dev->dev, "rpmsg send failed\n");
                return ret;
        }

        timeout = msecs_to_jiffies(EC_MSG_TIMEOUT_MS);
        ret = wait_for_completion_timeout(&ec_rpmsg->xfer_ack, timeout);
        if (!ret) {
                dev_err(ec_dev->dev, "rpmsg send timeout\n");
                return -EIO;
        }

        /* check response error code */
        response = (struct ec_host_response *)ec_dev->din;
        ec_msg->result = response->result;

        ret = cros_ec_check_result(ec_dev, ec_msg);
        if (ret)
                goto exit;

        if (response->data_len > ec_msg->insize) {
                dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
                        response->data_len, ec_msg->insize);
                ret = -EMSGSIZE;
                goto exit;
        }

        /* copy response packet payload and compute checksum */
        memcpy(ec_msg->data, ec_dev->din + sizeof(*response),
               response->data_len);

        sum = 0;
        for (i = 0; i < sizeof(*response) + response->data_len; i++)
                sum += ec_dev->din[i];

        if (sum) {
                dev_err(ec_dev->dev, "bad packet checksum, calculated %x\n",
                        sum);
                ret = -EBADMSG;
                goto exit;
        }

        ret = response->data_len;
exit:
        if (ec_msg->command == EC_CMD_REBOOT_EC)
                msleep(EC_REBOOT_DELAY_MS);

        return ret;
}

static void
cros_ec_rpmsg_host_event_function(struct work_struct *host_event_work)
{
        struct cros_ec_rpmsg *ec_rpmsg = container_of(host_event_work,
                                                      struct cros_ec_rpmsg,
                                                      host_event_work);

        cros_ec_irq_thread(0, dev_get_drvdata(&ec_rpmsg->rpdev->dev));
}

static int cros_ec_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
                                  int len, void *priv, u32 src)
{
        struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
        struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
        struct cros_ec_rpmsg_response *resp;

        if (!len) {
                dev_warn(ec_dev->dev, "rpmsg received empty response");
                return -EINVAL;
        }

        resp = data;
        len -= offsetof(struct cros_ec_rpmsg_response, data);
        if (resp->type == HOST_COMMAND_MARK) {
                if (len > ec_dev->din_size) {
                        dev_warn(ec_dev->dev,
                                 "received length %d > din_size %d, truncating",
                                 len, ec_dev->din_size);
                        len = ec_dev->din_size;
                }

                memcpy(ec_dev->din, resp->data, len);
                complete(&ec_rpmsg->xfer_ack);
        } else if (resp->type == HOST_EVENT_MARK) {
                /*
                 * If the host event is sent before cros_ec_register is
                 * finished, queue the host event.
                 */
                if (ec_rpmsg->probe_done)
                        schedule_work(&ec_rpmsg->host_event_work);
                else
                        ec_rpmsg->has_pending_host_event = true;
        } else {
                dev_warn(ec_dev->dev, "rpmsg received invalid type = %d",
                         resp->type);
                return -EINVAL;
        }

        return 0;
}

static struct rpmsg_endpoint *
cros_ec_rpmsg_create_ept(struct rpmsg_device *rpdev)
{
        struct rpmsg_channel_info chinfo = {};

        strscpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
        chinfo.src = rpdev->src;
        chinfo.dst = RPMSG_ADDR_ANY;

        return rpmsg_create_ept(rpdev, cros_ec_rpmsg_callback, NULL, chinfo);
}

static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
{
        struct device *dev = &rpdev->dev;
        struct cros_ec_rpmsg *ec_rpmsg;
        struct cros_ec_device *ec_dev;
        int ret;

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

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

        ec_dev->dev = dev;
        ec_dev->priv = ec_rpmsg;
        ec_dev->cmd_xfer = cros_ec_cmd_xfer_rpmsg;
        ec_dev->pkt_xfer = cros_ec_pkt_xfer_rpmsg;
        ec_dev->phys_name = dev_name(&rpdev->dev);
        ec_dev->din_size = sizeof(struct ec_host_response) +
                           sizeof(struct ec_response_get_protocol_info);
        ec_dev->dout_size = sizeof(struct ec_host_request);
        dev_set_drvdata(dev, ec_dev);

        ec_rpmsg->rpdev = rpdev;
        init_completion(&ec_rpmsg->xfer_ack);
        INIT_WORK(&ec_rpmsg->host_event_work,
                  cros_ec_rpmsg_host_event_function);

        ec_rpmsg->ept = cros_ec_rpmsg_create_ept(rpdev);
        if (!ec_rpmsg->ept)
                return -ENOMEM;

        ret = cros_ec_register(ec_dev);
        if (ret < 0) {
                rpmsg_destroy_ept(ec_rpmsg->ept);
                cancel_work_sync(&ec_rpmsg->host_event_work);
                return ret;
        }

        ec_rpmsg->probe_done = true;

        if (ec_rpmsg->has_pending_host_event)
                schedule_work(&ec_rpmsg->host_event_work);

        return 0;
}

static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
{
        struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
        struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;

        cros_ec_unregister(ec_dev);
        rpmsg_destroy_ept(ec_rpmsg->ept);
        cancel_work_sync(&ec_rpmsg->host_event_work);
}

#ifdef CONFIG_PM_SLEEP
static int cros_ec_rpmsg_suspend(struct device *dev)
{
        struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

        return cros_ec_suspend(ec_dev);
}

static int cros_ec_rpmsg_resume(struct device *dev)
{
        struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

        return cros_ec_resume(ec_dev);
}
#endif

static SIMPLE_DEV_PM_OPS(cros_ec_rpmsg_pm_ops, cros_ec_rpmsg_suspend,
                         cros_ec_rpmsg_resume);

static const struct of_device_id cros_ec_rpmsg_of_match[] = {
        { .compatible = "google,cros-ec-rpmsg", },
        { }
};
MODULE_DEVICE_TABLE(of, cros_ec_rpmsg_of_match);

static struct rpmsg_driver cros_ec_driver_rpmsg = {
        .drv = {
                .name   = "cros-ec-rpmsg",
                .of_match_table = cros_ec_rpmsg_of_match,
                .pm     = &cros_ec_rpmsg_pm_ops,
        },
        .probe          = cros_ec_rpmsg_probe,
        .remove         = cros_ec_rpmsg_remove,
};

module_rpmsg_driver(cros_ec_driver_rpmsg);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ChromeOS EC multi function device (rpmsg)");