// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
 */

#include <linux/atomic.h>
#include <linux/bug.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/wait.h>

#include <soc/qcom/rpmh.h>

#include "rpmh-internal.h"

#define RPMH_TIMEOUT_MS                 msecs_to_jiffies(10000)

#define DEFINE_RPMH_MSG_ONSTACK(dev, s, q, name)        \
        struct rpmh_request name = {                    \
                .msg = {                                \
                        .state = s,                     \
                        .cmds = name.cmd,               \
                        .num_cmds = 0,                  \
                        .wait_for_compl = true,         \
                },                                      \
                .cmd = { { 0 } },                       \
                .completion = q,                        \
                .dev = dev,                             \
                .needs_free = false,                            \
        }

#define ctrlr_to_drv(ctrlr) container_of(ctrlr, struct rsc_drv, client)

/**
 * struct cache_req: the request object for caching
 *
 * @addr: the address of the resource
 * @sleep_val: the sleep vote
 * @wake_val: the wake vote
 * @list: linked list obj
 */
struct cache_req {
        u32 addr;
        u32 sleep_val;
        u32 wake_val;
        struct list_head list;
};

/**
 * struct batch_cache_req - An entry in our batch catch
 *
 * @list: linked list obj
 * @count: number of messages
 * @rpm_msgs: the messages
 */

struct batch_cache_req {
        struct list_head list;
        int count;
        struct rpmh_request rpm_msgs[];
};

static struct rpmh_ctrlr *get_rpmh_ctrlr(const struct device *dev)
{
        struct rsc_drv *drv = dev_get_drvdata(dev->parent);

        return &drv->client;
}

void rpmh_tx_done(const struct tcs_request *msg, int r)
{
        struct rpmh_request *rpm_msg = container_of(msg, struct rpmh_request,
                                                    msg);
        struct completion *compl = rpm_msg->completion;
        bool free = rpm_msg->needs_free;

        rpm_msg->err = r;

        if (r)
                dev_err(rpm_msg->dev, "RPMH TX fail in msg addr=%#x, err=%d\n",
                        rpm_msg->msg.cmds[0].addr, r);

        if (!compl)
                goto exit;

        /* Signal the blocking thread we are done */
        complete(compl);

exit:
        if (free)
                kfree(rpm_msg);
}

static struct cache_req *__find_req(struct rpmh_ctrlr *ctrlr, u32 addr)
{
        struct cache_req *p, *req = NULL;

        list_for_each_entry(p, &ctrlr->cache, list) {
                if (p->addr == addr) {
                        req = p;
                        break;
                }
        }

        return req;
}

static struct cache_req *cache_rpm_request(struct rpmh_ctrlr *ctrlr,
                                           enum rpmh_state state,
                                           struct tcs_cmd *cmd)
{
        struct cache_req *req;
        unsigned long flags;

        spin_lock_irqsave(&ctrlr->cache_lock, flags);
        req = __find_req(ctrlr, cmd->addr);
        if (req)
                goto existing;

        req = kzalloc(sizeof(*req), GFP_ATOMIC);
        if (!req) {
                req = ERR_PTR(-ENOMEM);
                goto unlock;
        }

        req->addr = cmd->addr;
        req->sleep_val = req->wake_val = UINT_MAX;
        INIT_LIST_HEAD(&req->list);
        list_add_tail(&req->list, &ctrlr->cache);

existing:
        switch (state) {
        case RPMH_ACTIVE_ONLY_STATE:
                if (req->sleep_val != UINT_MAX)
                        req->wake_val = cmd->data;
                break;
        case RPMH_WAKE_ONLY_STATE:
                req->wake_val = cmd->data;
                break;
        case RPMH_SLEEP_STATE:
                req->sleep_val = cmd->data;
                break;
        default:
                break;
        }

        ctrlr->dirty = true;
unlock:
        spin_unlock_irqrestore(&ctrlr->cache_lock, flags);

        return req;
}

/**
 * __rpmh_write: Cache and send the RPMH request
 *
 * @dev: The device making the request
 * @state: Active/Sleep request type
 * @rpm_msg: The data that needs to be sent (cmds).
 *
 * Cache the RPMH request and send if the state is ACTIVE_ONLY.
 * SLEEP/WAKE_ONLY requests are not sent to the controller at
 * this time. Use rpmh_flush() to send them to the controller.
 */
static int __rpmh_write(const struct device *dev, enum rpmh_state state,
                        struct rpmh_request *rpm_msg)
{
        struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
        int ret = -EINVAL;
        struct cache_req *req;
        int i;

        rpm_msg->msg.state = state;

        /* Cache the request in our store and link the payload */
        for (i = 0; i < rpm_msg->msg.num_cmds; i++) {
                req = cache_rpm_request(ctrlr, state, &rpm_msg->msg.cmds[i]);
                if (IS_ERR(req))
                        return PTR_ERR(req);
        }

        rpm_msg->msg.state = state;

        if (state == RPMH_ACTIVE_ONLY_STATE) {
                WARN_ON(irqs_disabled());
                ret = rpmh_rsc_send_data(ctrlr_to_drv(ctrlr), &rpm_msg->msg);
        } else {
                /* Clean up our call by spoofing tx_done */
                ret = 0;
                rpmh_tx_done(&rpm_msg->msg, ret);
        }

        return ret;
}

static int __fill_rpmh_msg(struct rpmh_request *req, enum rpmh_state state,
                const struct tcs_cmd *cmd, u32 n)
{
        if (!cmd || !n || n > MAX_RPMH_PAYLOAD)
                return -EINVAL;

        memcpy(req->cmd, cmd, n * sizeof(*cmd));

        req->msg.state = state;
        req->msg.cmds = req->cmd;
        req->msg.num_cmds = n;

        return 0;
}

/**
 * rpmh_write_async: Write a set of RPMH commands
 *
 * @dev: The device making the request
 * @state: Active/sleep set
 * @cmd: The payload data
 * @n: The number of elements in payload
 *
 * Write a set of RPMH commands, the order of commands is maintained
 * and will be sent as a single shot.
 */
int rpmh_write_async(const struct device *dev, enum rpmh_state state,
                     const struct tcs_cmd *cmd, u32 n)
{
        struct rpmh_request *rpm_msg;
        int ret;

        rpm_msg = kzalloc(sizeof(*rpm_msg), GFP_ATOMIC);
        if (!rpm_msg)
                return -ENOMEM;
        rpm_msg->needs_free = true;

        ret = __fill_rpmh_msg(rpm_msg, state, cmd, n);
        if (ret) {
                kfree(rpm_msg);
                return ret;
        }

        return __rpmh_write(dev, state, rpm_msg);
}
EXPORT_SYMBOL(rpmh_write_async);

/**
 * rpmh_write: Write a set of RPMH commands and block until response
 *
 * @rc: The RPMH handle got from rpmh_get_client
 * @state: Active/sleep set
 * @cmd: The payload data
 * @n: The number of elements in @cmd
 *
 * May sleep. Do not call from atomic contexts.
 */
int rpmh_write(const struct device *dev, enum rpmh_state state,
               const struct tcs_cmd *cmd, u32 n)
{
        DECLARE_COMPLETION_ONSTACK(compl);
        DEFINE_RPMH_MSG_ONSTACK(dev, state, &compl, rpm_msg);
        int ret;

        if (!cmd || !n || n > MAX_RPMH_PAYLOAD)
                return -EINVAL;

        memcpy(rpm_msg.cmd, cmd, n * sizeof(*cmd));
        rpm_msg.msg.num_cmds = n;

        ret = __rpmh_write(dev, state, &rpm_msg);
        if (ret)
                return ret;

        ret = wait_for_completion_timeout(&compl, RPMH_TIMEOUT_MS);
        WARN_ON(!ret);
        return (ret > 0) ? 0 : -ETIMEDOUT;
}
EXPORT_SYMBOL(rpmh_write);

static void cache_batch(struct rpmh_ctrlr *ctrlr, struct batch_cache_req *req)
{
        unsigned long flags;

        spin_lock_irqsave(&ctrlr->cache_lock, flags);
        list_add_tail(&req->list, &ctrlr->batch_cache);
        spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
}

static int flush_batch(struct rpmh_ctrlr *ctrlr)
{
        struct batch_cache_req *req;
        const struct rpmh_request *rpm_msg;
        unsigned long flags;
        int ret = 0;
        int i;

        /* Send Sleep/Wake requests to the controller, expect no response */
        spin_lock_irqsave(&ctrlr->cache_lock, flags);
        list_for_each_entry(req, &ctrlr->batch_cache, list) {
                for (i = 0; i < req->count; i++) {
                        rpm_msg = req->rpm_msgs + i;
                        ret = rpmh_rsc_write_ctrl_data(ctrlr_to_drv(ctrlr),
                                                       &rpm_msg->msg);
                        if (ret)
                                break;
                }
        }
        spin_unlock_irqrestore(&ctrlr->cache_lock, flags);

        return ret;
}

static void invalidate_batch(struct rpmh_ctrlr *ctrlr)
{
        struct batch_cache_req *req, *tmp;
        unsigned long flags;

        spin_lock_irqsave(&ctrlr->cache_lock, flags);
        list_for_each_entry_safe(req, tmp, &ctrlr->batch_cache, list)
                kfree(req);
        INIT_LIST_HEAD(&ctrlr->batch_cache);
        spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
}

/**
 * rpmh_write_batch: Write multiple sets of RPMH commands and wait for the
 * batch to finish.
 *
 * @dev: the device making the request
 * @state: Active/sleep set
 * @cmd: The payload data
 * @n: The array of count of elements in each batch, 0 terminated.
 *
 * Write a request to the RSC controller without caching. If the request
 * state is ACTIVE, then the requests are treated as completion request
 * and sent to the controller immediately. The function waits until all the
 * commands are complete. If the request was to SLEEP or WAKE_ONLY, then the
 * request is sent as fire-n-forget and no ack is expected.
 *
 * May sleep. Do not call from atomic contexts for ACTIVE_ONLY requests.
 */
int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
                     const struct tcs_cmd *cmd, u32 *n)
{
        struct batch_cache_req *req;
        struct rpmh_request *rpm_msgs;
        struct completion *compls;
        struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
        unsigned long time_left;
        int count = 0;
        int ret, i;
        void *ptr;

        if (!cmd || !n)
                return -EINVAL;

        while (n[count] > 0)
                count++;
        if (!count)
                return -EINVAL;

        ptr = kzalloc(sizeof(*req) +
                      count * (sizeof(req->rpm_msgs[0]) + sizeof(*compls)),
                      GFP_ATOMIC);
        if (!ptr)
                return -ENOMEM;

        req = ptr;
        compls = ptr + sizeof(*req) + count * sizeof(*rpm_msgs);

        req->count = count;
        rpm_msgs = req->rpm_msgs;

        for (i = 0; i < count; i++) {
                __fill_rpmh_msg(rpm_msgs + i, state, cmd, n[i]);
                cmd += n[i];
        }

        if (state != RPMH_ACTIVE_ONLY_STATE) {
                cache_batch(ctrlr, req);
                return 0;
        }

        for (i = 0; i < count; i++) {
                struct completion *compl = &compls[i];

                init_completion(compl);
                rpm_msgs[i].completion = compl;
                ret = rpmh_rsc_send_data(ctrlr_to_drv(ctrlr), &rpm_msgs[i].msg);
                if (ret) {
                        pr_err("Error(%d) sending RPMH message addr=%#x\n",
                               ret, rpm_msgs[i].msg.cmds[0].addr);
                        break;
                }
        }

        time_left = RPMH_TIMEOUT_MS;
        while (i--) {
                time_left = wait_for_completion_timeout(&compls[i], time_left);
                if (!time_left) {
                        /*
                         * Better hope they never finish because they'll signal
                         * the completion that we're going to free once
                         * we've returned from this function.
                         */
                        WARN_ON(1);
                        ret = -ETIMEDOUT;
                        goto exit;
                }
        }

exit:
        kfree(ptr);

        return ret;
}
EXPORT_SYMBOL(rpmh_write_batch);

static int is_req_valid(struct cache_req *req)
{
        return (req->sleep_val != UINT_MAX &&
                req->wake_val != UINT_MAX &&
                req->sleep_val != req->wake_val);
}

static int send_single(const struct device *dev, enum rpmh_state state,
                       u32 addr, u32 data)
{
        DEFINE_RPMH_MSG_ONSTACK(dev, state, NULL, rpm_msg);
        struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);

        /* Wake sets are always complete and sleep sets are not */
        rpm_msg.msg.wait_for_compl = (state == RPMH_WAKE_ONLY_STATE);
        rpm_msg.cmd[0].addr = addr;
        rpm_msg.cmd[0].data = data;
        rpm_msg.msg.num_cmds = 1;

        return rpmh_rsc_write_ctrl_data(ctrlr_to_drv(ctrlr), &rpm_msg.msg);
}

/**
 * rpmh_flush: Flushes the buffered active and sleep sets to TCS
 *
 * @dev: The device making the request
 *
 * Return: -EBUSY if the controller is busy, probably waiting on a response
 * to a RPMH request sent earlier.
 *
 * This function is always called from the sleep code from the last CPU
 * that is powering down the entire system. Since no other RPMH API would be
 * executing at this time, it is safe to run lockless.
 */
int rpmh_flush(const struct device *dev)
{
        struct cache_req *p;
        struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
        int ret;

        if (!ctrlr->dirty) {
                pr_debug("Skipping flush, TCS has latest data.\n");
                return 0;
        }

        /* First flush the cached batch requests */
        ret = flush_batch(ctrlr);
        if (ret)
                return ret;

        /*
         * Nobody else should be calling this function other than system PM,
         * hence we can run without locks.
         */
        list_for_each_entry(p, &ctrlr->cache, list) {
                if (!is_req_valid(p)) {
                        pr_debug("%s: skipping RPMH req: a:%#x s:%#x w:%#x",
                                 __func__, p->addr, p->sleep_val, p->wake_val);
                        continue;
                }
                ret = send_single(dev, RPMH_SLEEP_STATE, p->addr, p->sleep_val);
                if (ret)
                        return ret;
                ret = send_single(dev, RPMH_WAKE_ONLY_STATE,
                                  p->addr, p->wake_val);
                if (ret)
                        return ret;
        }

        ctrlr->dirty = false;

        return 0;
}
EXPORT_SYMBOL(rpmh_flush);

/**
 * rpmh_invalidate: Invalidate all sleep and active sets
 * sets.
 *
 * @dev: The device making the request
 *
 * Invalidate the sleep and active values in the TCS blocks.
 */
int rpmh_invalidate(const struct device *dev)
{
        struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
        int ret;

        invalidate_batch(ctrlr);
        ctrlr->dirty = true;

        do {
                ret = rpmh_rsc_invalidate(ctrlr_to_drv(ctrlr));
        } while (ret == -EAGAIN);

        return ret;
}
EXPORT_SYMBOL(rpmh_invalidate);