/*
 * Intel MIC Platform Software Stack (MPSS)
 *
 * Copyright(c) 2015 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, 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.
 *
 * The full GNU General Public License is included in this distribution in
 * the file called "COPYING".
 *
 * Intel MIC Coprocessor State Management (COSM) Driver
 *
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include "cosm_main.h"

static const char cosm_driver_name[] = "mic";

/* COSM ID allocator */
static struct ida g_cosm_ida;
/* Class of MIC devices for sysfs accessibility. */
static struct class *g_cosm_class;
/* Number of MIC devices */
static atomic_t g_num_dev;

/**
 * cosm_hw_reset - Issue a HW reset for the MIC device
 * @cdev: pointer to cosm_device instance
 */
static void cosm_hw_reset(struct cosm_device *cdev, bool force)
{
	int i;

#define MIC_RESET_TO (45)
	if (force && cdev->hw_ops->force_reset)
		cdev->hw_ops->force_reset(cdev);
	else
		cdev->hw_ops->reset(cdev);

	for (i = 0; i < MIC_RESET_TO; i++) {
		if (cdev->hw_ops->ready(cdev)) {
			cosm_set_state(cdev, MIC_READY);
			return;
		}
		/*
		 * Resets typically take 10s of seconds to complete.
		 * Since an MMIO read is required to check if the
		 * firmware is ready or not, a 1 second delay works nicely.
		 */
		msleep(1000);
	}
	cosm_set_state(cdev, MIC_RESET_FAILED);
}

/**
 * cosm_start - Start the MIC
 * @cdev: pointer to cosm_device instance
 *
 * This function prepares an MIC for boot and initiates boot.
 * RETURNS: An appropriate -ERRNO error value on error, or 0 for success.
 */
int cosm_start(struct cosm_device *cdev)
{
	const struct cred *orig_cred;
	struct cred *override_cred;
	int rc;

	mutex_lock(&cdev->cosm_mutex);
	if (!cdev->bootmode) {
		dev_err(&cdev->dev, "%s %d bootmode not set\n",
			__func__, __LINE__);
		rc = -EINVAL;
		goto unlock_ret;
	}
retry:
	if (cdev->state != MIC_READY) {
		dev_err(&cdev->dev, "%s %d MIC state not READY\n",
			__func__, __LINE__);
		rc = -EINVAL;
		goto unlock_ret;
	}
	if (!cdev->hw_ops->ready(cdev)) {
		cosm_hw_reset(cdev, false);
		/*
		 * The state will either be MIC_READY if the reset succeeded
		 * or MIC_RESET_FAILED if the firmware reset failed.
		 */
		goto retry;
	}

	/*
	 * Set credentials to root to allow non-root user to download initramsfs
	 * with 600 permissions
	 */
	override_cred = prepare_creds();
	if (!override_cred) {
		dev_err(&cdev->dev, "%s %d prepare_creds failed\n",
			__func__, __LINE__);
		rc = -ENOMEM;
		goto unlock_ret;
	}
	override_cred->fsuid = GLOBAL_ROOT_UID;
	orig_cred = override_creds(override_cred);

	rc = cdev->hw_ops->start(cdev, cdev->index);

	revert_creds(orig_cred);
	put_cred(override_cred);
	if (rc)
		goto unlock_ret;

	/*
	 * If linux is being booted, card is treated 'online' only
	 * when the scif interface in the card is up. If anything else
	 * is booted, we set card to 'online' immediately.
	 */
	if (!strcmp(cdev->bootmode, "linux"))
		cosm_set_state(cdev, MIC_BOOTING);
	else
		cosm_set_state(cdev, MIC_ONLINE);
unlock_ret:
	mutex_unlock(&cdev->cosm_mutex);
	if (rc)
		dev_err(&cdev->dev, "cosm_start failed rc %d\n", rc);
	return rc;
}

/**
 * cosm_stop - Prepare the MIC for reset and trigger reset
 * @cdev: pointer to cosm_device instance
 * @force: force a MIC to reset even if it is already reset and ready.
 *
 * RETURNS: None
 */
void cosm_stop(struct cosm_device *cdev, bool force)
{
	mutex_lock(&cdev->cosm_mutex);
	if (cdev->state != MIC_READY || force) {
		/*
		 * Don't call hw_ops if they have been called previously.
		 * stop(..) calls device_unregister and will crash the system if
		 * called multiple times.
		 */
		u8 state = cdev->state == MIC_RESETTING ?
					cdev->prev_state : cdev->state;
		bool call_hw_ops = state != MIC_RESET_FAILED &&
					state != MIC_READY;

		if (cdev->state != MIC_RESETTING)
			cosm_set_state(cdev, MIC_RESETTING);
		cdev->heartbeat_watchdog_enable = false;
		if (call_hw_ops)
			cdev->hw_ops->stop(cdev, force);
		cosm_hw_reset(cdev, force);
		cosm_set_shutdown_status(cdev, MIC_NOP);
		if (call_hw_ops && cdev->hw_ops->post_reset)
			cdev->hw_ops->post_reset(cdev, cdev->state);
	}
	mutex_unlock(&cdev->cosm_mutex);
	flush_work(&cdev->scif_work);
}

/**
 * cosm_reset_trigger_work - Trigger MIC reset
 * @work: The work structure
 *
 * This work is scheduled whenever the host wants to reset the MIC.
 */
static void cosm_reset_trigger_work(struct work_struct *work)
{
	struct cosm_device *cdev = container_of(work, struct cosm_device,
						reset_trigger_work);
	cosm_stop(cdev, false);
}

/**
 * cosm_reset - Schedule MIC reset
 * @cdev: pointer to cosm_device instance
 *
 * RETURNS: An -EINVAL if the card is already READY or 0 for success.
 */
int cosm_reset(struct cosm_device *cdev)
{
	int rc = 0;

	mutex_lock(&cdev->cosm_mutex);
	if (cdev->state != MIC_READY) {
		if (cdev->state != MIC_RESETTING) {
			cdev->prev_state = cdev->state;
			cosm_set_state(cdev, MIC_RESETTING);
			schedule_work(&cdev->reset_trigger_work);
		}
	} else {
		dev_err(&cdev->dev, "%s %d MIC is READY\n", __func__, __LINE__);
		rc = -EINVAL;
	}
	mutex_unlock(&cdev->cosm_mutex);
	return rc;
}

/**
 * cosm_shutdown - Initiate MIC shutdown.
 * @cdev: pointer to cosm_device instance
 *
 * RETURNS: None
 */
int cosm_shutdown(struct cosm_device *cdev)
{
	struct cosm_msg msg = { .id = COSM_MSG_SHUTDOWN };
	int rc = 0;

	mutex_lock(&cdev->cosm_mutex);
	if (cdev->state != MIC_ONLINE) {
		rc = -EINVAL;
		dev_err(&cdev->dev, "%s %d skipping shutdown in state: %s\n",
			__func__, __LINE__, cosm_state_string[cdev->state]);
		goto err;
	}

	if (!cdev->epd) {
		rc = -ENOTCONN;
		dev_err(&cdev->dev, "%s %d scif endpoint not connected rc %d\n",
			__func__, __LINE__, rc);
		goto err;
	}

	rc = scif_send(cdev->epd, &msg, sizeof(msg), SCIF_SEND_BLOCK);
	if (rc < 0) {
		dev_err(&cdev->dev, "%s %d scif_send failed rc %d\n",
			__func__, __LINE__, rc);
		goto err;
	}
	cdev->heartbeat_watchdog_enable = false;
	cosm_set_state(cdev, MIC_SHUTTING_DOWN);
	rc = 0;
err:
	mutex_unlock(&cdev->cosm_mutex);
	return rc;
}

static int cosm_driver_probe(struct cosm_device *cdev)
{
	int rc;

	/* Initialize SCIF server at first probe */
	if (atomic_add_return(1, &g_num_dev) == 1) {
		rc = cosm_scif_init();
		if (rc)
			goto scif_exit;
	}
	mutex_init(&cdev->cosm_mutex);
	INIT_WORK(&cdev->reset_trigger_work, cosm_reset_trigger_work);
	INIT_WORK(&cdev->scif_work, cosm_scif_work);
	cdev->sysfs_heartbeat_enable = true;
	cosm_sysfs_init(cdev);
	cdev->sdev = device_create_with_groups(g_cosm_class, cdev->dev.parent,
			       MKDEV(0, cdev->index), cdev, cdev->attr_group,
			       "mic%d", cdev->index);
	if (IS_ERR(cdev->sdev)) {
		rc = PTR_ERR(cdev->sdev);
		dev_err(&cdev->dev, "device_create_with_groups failed rc %d\n",
			rc);
		goto scif_exit;
	}

	cdev->state_sysfs = sysfs_get_dirent(cdev->sdev->kobj.sd,
		"state");
	if (!cdev->state_sysfs) {
		rc = -ENODEV;
		dev_err(&cdev->dev, "sysfs_get_dirent failed rc %d\n", rc);
		goto destroy_device;
	}
	cosm_create_debug_dir(cdev);
	return 0;
destroy_device:
	device_destroy(g_cosm_class, MKDEV(0, cdev->index));
scif_exit:
	if (atomic_dec_and_test(&g_num_dev))
		cosm_scif_exit();
	return rc;
}

static void cosm_driver_remove(struct cosm_device *cdev)
{
	cosm_delete_debug_dir(cdev);
	sysfs_put(cdev->state_sysfs);
	device_destroy(g_cosm_class, MKDEV(0, cdev->index));
	flush_work(&cdev->reset_trigger_work);
	cosm_stop(cdev, false);
	if (atomic_dec_and_test(&g_num_dev))
		cosm_scif_exit();

	/* These sysfs entries might have allocated */
	kfree(cdev->cmdline);
	kfree(cdev->firmware);
	kfree(cdev->ramdisk);
	kfree(cdev->bootmode);
}

static int cosm_suspend(struct device *dev)
{
	struct cosm_device *cdev = dev_to_cosm(dev);

	mutex_lock(&cdev->cosm_mutex);
	switch (cdev->state) {
	/**
	 * Suspend/freeze hooks in userspace have already shutdown the card.
	 * Card should be 'ready' in most cases. It is however possible that
	 * some userspace application initiated a boot. In those cases, we
	 * simply reset the card.
	 */
	case MIC_ONLINE:
	case MIC_BOOTING:
	case MIC_SHUTTING_DOWN:
		mutex_unlock(&cdev->cosm_mutex);
		cosm_stop(cdev, false);
		break;
	default:
		mutex_unlock(&cdev->cosm_mutex);
		break;
	}
	return 0;
}

static const struct dev_pm_ops cosm_pm_ops = {
	.suspend = cosm_suspend,
	.freeze = cosm_suspend
};

static struct cosm_driver cosm_driver = {
	.driver = {
		.name =  KBUILD_MODNAME,
		.owner = THIS_MODULE,
		.pm = &cosm_pm_ops,
	},
	.probe = cosm_driver_probe,
	.remove = cosm_driver_remove
};

static int __init cosm_init(void)
{
	int ret;

	cosm_init_debugfs();

	g_cosm_class = class_create(THIS_MODULE, cosm_driver_name);
	if (IS_ERR(g_cosm_class)) {
		ret = PTR_ERR(g_cosm_class);
		pr_err("class_create failed ret %d\n", ret);
		goto cleanup_debugfs;
	}

	ida_init(&g_cosm_ida);
	ret = cosm_register_driver(&cosm_driver);
	if (ret) {
		pr_err("cosm_register_driver failed ret %d\n", ret);
		goto ida_destroy;
	}
	return 0;
ida_destroy:
	ida_destroy(&g_cosm_ida);
	class_destroy(g_cosm_class);
cleanup_debugfs:
	cosm_exit_debugfs();
	return ret;
}

static void __exit cosm_exit(void)
{
	cosm_unregister_driver(&cosm_driver);
	ida_destroy(&g_cosm_ida);
	class_destroy(g_cosm_class);
	cosm_exit_debugfs();
}

module_init(cosm_init);
module_exit(cosm_exit);

MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("Intel(R) MIC Coprocessor State Management (COSM) Driver");
MODULE_LICENSE("GPL v2");