// SPDX-License-Identifier: GPL-2.0
/*
 * Microchip PolarFire SoC (MPFS) system controller driver
 *
 * Copyright (c) 2020-2021 Microchip Corporation. All rights reserved.
 *
 * Author: Conor Dooley <conor.dooley@microchip.com>
 *
 */

#include <linux/slab.h>
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/mtd/mtd.h>
#include <linux/spi/spi.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/mailbox_client.h>
#include <linux/platform_device.h>
#include <soc/microchip/mpfs.h>

/*
 * This timeout must be long, as some services (example: image authentication)
 * take significant time to complete
 */
#define MPFS_SYS_CTRL_TIMEOUT_MS 30000

static DEFINE_MUTEX(transaction_lock);

struct mpfs_sys_controller {
        struct mbox_client client;
        struct mbox_chan *chan;
        struct completion c;
        struct mtd_info *flash;
        struct kref consumers;
};

int mpfs_blocking_transaction(struct mpfs_sys_controller *sys_controller, struct mpfs_mss_msg *msg)
{
        unsigned long timeout = msecs_to_jiffies(MPFS_SYS_CTRL_TIMEOUT_MS);
        int ret;

        ret = mutex_lock_interruptible(&transaction_lock);
        if (ret)
                return ret;

        reinit_completion(&sys_controller->c);

        ret = mbox_send_message(sys_controller->chan, msg);
        if (ret < 0) {
                dev_warn(sys_controller->client.dev, "MPFS sys controller service timeout\n");
                goto out;
        }

        /*
         * Unfortunately, the system controller will only deliver an interrupt
         * if a service succeeds. mbox_send_message() will block until the busy
         * flag is gone. If the busy flag is gone but no interrupt has arrived
         * to trigger the rx callback then the service can be deemed to have
         * failed.
         * The caller can then interrogate msg::response::resp_status to
         * determine the cause of the failure.
         * mbox_send_message() returns positive integers in the success path, so
         * ret needs to be cleared if we do get an interrupt.
         */
        if (!wait_for_completion_timeout(&sys_controller->c, timeout)) {
                ret = -EBADMSG;
                dev_warn(sys_controller->client.dev,
                         "MPFS sys controller service failed with status: %d\n",
                         msg->response->resp_status);
        } else {
                ret = 0;
        }

out:
        mutex_unlock(&transaction_lock);

        return ret;
}
EXPORT_SYMBOL(mpfs_blocking_transaction);

static void mpfs_sys_controller_rx_callback(struct mbox_client *client, void *msg)
{
        struct mpfs_sys_controller *sys_controller =
                container_of(client, struct mpfs_sys_controller, client);

        complete(&sys_controller->c);
}

static void mpfs_sys_controller_delete(struct kref *kref)
{
        struct mpfs_sys_controller *sys_controller =
                container_of(kref, struct mpfs_sys_controller, consumers);

        mbox_free_channel(sys_controller->chan);
        kfree(sys_controller);
}

static void mpfs_sys_controller_put(void *data)
{
        struct mpfs_sys_controller *sys_controller = data;

        kref_put(&sys_controller->consumers, mpfs_sys_controller_delete);
}

struct mtd_info *mpfs_sys_controller_get_flash(struct mpfs_sys_controller *mpfs_client)
{
        return mpfs_client->flash;
}
EXPORT_SYMBOL(mpfs_sys_controller_get_flash);

static struct platform_device subdevs[] = {
        {
                .name           = "mpfs-rng",
                .id             = -1,
        },
        {
                .name           = "mpfs-generic-service",
                .id             = -1,
        },
        {
                .name           = "mpfs-auto-update",
                .id             = -1,
        },
};

static int mpfs_sys_controller_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct mpfs_sys_controller *sys_controller;
        struct device_node *np;
        int i, ret;

        sys_controller = kzalloc_obj(*sys_controller);
        if (!sys_controller)
                return -ENOMEM;

        np = of_parse_phandle(dev->of_node, "microchip,bitstream-flash", 0);
        if (!np)
                goto no_flash;

        sys_controller->flash = of_get_mtd_device_by_node(np);
        of_node_put(np);
        if (IS_ERR(sys_controller->flash)) {
                ret = dev_err_probe(dev, PTR_ERR(sys_controller->flash), "Failed to get flash\n");
                goto out_free;
        }

no_flash:
        sys_controller->client.dev = dev;
        sys_controller->client.rx_callback = mpfs_sys_controller_rx_callback;
        sys_controller->client.tx_block = 1U;
        sys_controller->client.tx_tout = msecs_to_jiffies(MPFS_SYS_CTRL_TIMEOUT_MS);

        sys_controller->chan = mbox_request_channel(&sys_controller->client, 0);
        if (IS_ERR(sys_controller->chan)) {
                ret = dev_err_probe(dev, PTR_ERR(sys_controller->chan),
                                    "Failed to get mbox channel\n");
                goto out_free;
        }

        init_completion(&sys_controller->c);
        kref_init(&sys_controller->consumers);

        platform_set_drvdata(pdev, sys_controller);


        for (i = 0; i < ARRAY_SIZE(subdevs); i++) {
                subdevs[i].dev.parent = dev;
                if (platform_device_register(&subdevs[i]))
                        dev_warn(dev, "Error registering sub device %s\n", subdevs[i].name);
        }

        dev_info(&pdev->dev, "Registered MPFS system controller\n");

        return 0;

out_free:
        kfree(sys_controller);
        return ret;
}

static void mpfs_sys_controller_remove(struct platform_device *pdev)
{
        struct mpfs_sys_controller *sys_controller = platform_get_drvdata(pdev);

        mpfs_sys_controller_put(sys_controller);
}

static const struct of_device_id mpfs_sys_controller_of_match[] = {
        {.compatible = "microchip,mpfs-sys-controller", },
        {},
};
MODULE_DEVICE_TABLE(of, mpfs_sys_controller_of_match);

struct mpfs_sys_controller *mpfs_sys_controller_get(struct device *dev)
{
        const struct of_device_id *match;
        struct mpfs_sys_controller *sys_controller;
        int ret;

        if (!dev->parent)
                goto err_no_device;

        match = of_match_node(mpfs_sys_controller_of_match,  dev->parent->of_node);
        of_node_put(dev->parent->of_node);
        if (!match)
                goto err_no_device;

        sys_controller = dev_get_drvdata(dev->parent);
        if (!sys_controller)
                goto err_bad_device;

        if (!kref_get_unless_zero(&sys_controller->consumers))
                goto err_bad_device;

        ret = devm_add_action_or_reset(dev, mpfs_sys_controller_put, sys_controller);
        if (ret)
                return ERR_PTR(ret);

        return sys_controller;

err_no_device:
        dev_dbg(dev, "Parent device was not an MPFS system controller\n");
        return ERR_PTR(-ENODEV);

err_bad_device:
        dev_dbg(dev, "MPFS system controller found but could not register as a sub device\n");
        return ERR_PTR(-EPROBE_DEFER);
}
EXPORT_SYMBOL(mpfs_sys_controller_get);

static struct platform_driver mpfs_sys_controller_driver = {
        .driver = {
                .name = "mpfs-sys-controller",
                .of_match_table = mpfs_sys_controller_of_match,
        },
        .probe = mpfs_sys_controller_probe,
        .remove = mpfs_sys_controller_remove,
};
module_platform_driver(mpfs_sys_controller_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
MODULE_DESCRIPTION("MPFS system controller driver");