/*
 * Copyright (c) 2015, Sony Mobile Communications AB.
 * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/of_platform.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/slab.h>

#include <linux/soc/qcom/smd.h>
#include <linux/soc/qcom/smd-rpm.h>

#define RPM_REQUEST_TIMEOUT     (5 * HZ)

/**
 * struct qcom_smd_rpm - state of the rpm device driver
 * @rpm_channel:        reference to the smd channel
 * @ack:                completion for acks
 * @lock:               mutual exclusion around the send/complete pair
 * @ack_status:         result of the rpm request
 */
struct qcom_smd_rpm {
        struct qcom_smd_channel *rpm_channel;
        struct device *dev;

        struct completion ack;
        struct mutex lock;
        int ack_status;
};

/**
 * struct qcom_rpm_header - header for all rpm requests and responses
 * @service_type:       identifier of the service
 * @length:             length of the payload
 */
struct qcom_rpm_header {
        __le32 service_type;
        __le32 length;
};

/**
 * struct qcom_rpm_request - request message to the rpm
 * @msg_id:     identifier of the outgoing message
 * @flags:      active/sleep state flags
 * @type:       resource type
 * @id:         resource id
 * @data_len:   length of the payload following this header
 */
struct qcom_rpm_request {
        __le32 msg_id;
        __le32 flags;
        __le32 type;
        __le32 id;
        __le32 data_len;
};

/**
 * struct qcom_rpm_message - response message from the rpm
 * @msg_type:   indicator of the type of message
 * @length:     the size of this message, including the message header
 * @msg_id:     message id
 * @message:    textual message from the rpm
 *
 * Multiple of these messages can be stacked in an rpm message.
 */
struct qcom_rpm_message {
        __le32 msg_type;
        __le32 length;
        union {
                __le32 msg_id;
                u8 message[0];
        };
};

#define RPM_SERVICE_TYPE_REQUEST        0x00716572 /* "req\0" */

#define RPM_MSG_TYPE_ERR                0x00727265 /* "err\0" */
#define RPM_MSG_TYPE_MSG_ID             0x2367736d /* "msg#" */

/**
 * qcom_rpm_smd_write - write @buf to @type:@id
 * @rpm:        rpm handle
 * @type:       resource type
 * @id:         resource identifier
 * @buf:        the data to be written
 * @count:      number of bytes in @buf
 */
int qcom_rpm_smd_write(struct qcom_smd_rpm *rpm,
                       int state,
                       u32 type, u32 id,
                       void *buf,
                       size_t count)
{
        static unsigned msg_id = 1;
        int left;
        int ret;
        struct {
                struct qcom_rpm_header hdr;
                struct qcom_rpm_request req;
                u8 payload[];
        } *pkt;
        size_t size = sizeof(*pkt) + count;

        /* SMD packets to the RPM may not exceed 256 bytes */
        if (WARN_ON(size >= 256))
                return -EINVAL;

        pkt = kmalloc(size, GFP_KERNEL);
        if (!pkt)
                return -ENOMEM;

        mutex_lock(&rpm->lock);

        pkt->hdr.service_type = cpu_to_le32(RPM_SERVICE_TYPE_REQUEST);
        pkt->hdr.length = cpu_to_le32(sizeof(struct qcom_rpm_request) + count);

        pkt->req.msg_id = cpu_to_le32(msg_id++);
        pkt->req.flags = cpu_to_le32(state);
        pkt->req.type = cpu_to_le32(type);
        pkt->req.id = cpu_to_le32(id);
        pkt->req.data_len = cpu_to_le32(count);
        memcpy(pkt->payload, buf, count);

        ret = qcom_smd_send(rpm->rpm_channel, pkt, size);
        if (ret)
                goto out;

        left = wait_for_completion_timeout(&rpm->ack, RPM_REQUEST_TIMEOUT);
        if (!left)
                ret = -ETIMEDOUT;
        else
                ret = rpm->ack_status;

out:
        kfree(pkt);
        mutex_unlock(&rpm->lock);
        return ret;
}
EXPORT_SYMBOL(qcom_rpm_smd_write);

static int qcom_smd_rpm_callback(struct qcom_smd_channel *channel,
                                 const void *data,
                                 size_t count)
{
        const struct qcom_rpm_header *hdr = data;
        size_t hdr_length = le32_to_cpu(hdr->length);
        const struct qcom_rpm_message *msg;
        struct qcom_smd_rpm *rpm = qcom_smd_get_drvdata(channel);
        const u8 *buf = data + sizeof(struct qcom_rpm_header);
        const u8 *end = buf + hdr_length;
        char msgbuf[32];
        int status = 0;
        u32 len, msg_length;

        if (le32_to_cpu(hdr->service_type) != RPM_SERVICE_TYPE_REQUEST ||
            hdr_length < sizeof(struct qcom_rpm_message)) {
                dev_err(rpm->dev, "invalid request\n");
                return 0;
        }

        while (buf < end) {
                msg = (struct qcom_rpm_message *)buf;
                msg_length = le32_to_cpu(msg->length);
                switch (le32_to_cpu(msg->msg_type)) {
                case RPM_MSG_TYPE_MSG_ID:
                        break;
                case RPM_MSG_TYPE_ERR:
                        len = min_t(u32, ALIGN(msg_length, 4), sizeof(msgbuf));
                        memcpy_fromio(msgbuf, msg->message, len);
                        msgbuf[len - 1] = 0;

                        if (!strcmp(msgbuf, "resource does not exist"))
                                status = -ENXIO;
                        else
                                status = -EINVAL;
                        break;
                }

                buf = PTR_ALIGN(buf + 2 * sizeof(u32) + msg_length, 4);
        }

        rpm->ack_status = status;
        complete(&rpm->ack);
        return 0;
}

static int qcom_smd_rpm_probe(struct qcom_smd_device *sdev)
{
        struct qcom_smd_rpm *rpm;

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

        mutex_init(&rpm->lock);
        init_completion(&rpm->ack);

        rpm->dev = &sdev->dev;
        rpm->rpm_channel = sdev->channel;
        qcom_smd_set_drvdata(sdev->channel, rpm);

        dev_set_drvdata(&sdev->dev, rpm);

        return of_platform_populate(sdev->dev.of_node, NULL, NULL, &sdev->dev);
}

static void qcom_smd_rpm_remove(struct qcom_smd_device *sdev)
{
        of_platform_depopulate(&sdev->dev);
}

static const struct of_device_id qcom_smd_rpm_of_match[] = {
        { .compatible = "qcom,rpm-apq8084" },
        { .compatible = "qcom,rpm-msm8916" },
        { .compatible = "qcom,rpm-msm8974" },
        {}
};
MODULE_DEVICE_TABLE(of, qcom_smd_rpm_of_match);

static struct qcom_smd_driver qcom_smd_rpm_driver = {
        .probe = qcom_smd_rpm_probe,
        .remove = qcom_smd_rpm_remove,
        .callback = qcom_smd_rpm_callback,
        .driver  = {
                .name  = "qcom_smd_rpm",
                .owner = THIS_MODULE,
                .of_match_table = qcom_smd_rpm_of_match,
        },
};

static int __init qcom_smd_rpm_init(void)
{
        return qcom_smd_driver_register(&qcom_smd_rpm_driver);
}
arch_initcall(qcom_smd_rpm_init);

static void __exit qcom_smd_rpm_exit(void)
{
        qcom_smd_driver_unregister(&qcom_smd_rpm_driver);
}
module_exit(qcom_smd_rpm_exit);

MODULE_AUTHOR("Bjorn Andersson <bjorn.andersson@sonymobile.com>");
MODULE_DESCRIPTION("Qualcomm SMD backed RPM driver");
MODULE_LICENSE("GPL v2");