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// SPDX-License-Identifier: GPL-2.0
/*
* Intel Speed Select Interface: Common functions
* Copyright (c) 2019, Intel Corporation.
* All rights reserved.
*
* Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
*/
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <uapi/linux/isst_if.h>
#include "isst_if_common.h"
static struct isst_if_cmd_cb punit_callbacks[ISST_IF_DEV_MAX];
static int isst_if_get_platform_info(void __user *argp)
{
struct isst_if_platform_info info;
info.api_version = ISST_IF_API_VERSION,
info.driver_version = ISST_IF_DRIVER_VERSION,
info.max_cmds_per_ioctl = ISST_IF_CMD_LIMIT,
info.mbox_supported = punit_callbacks[ISST_IF_DEV_MBOX].registered;
info.mmio_supported = punit_callbacks[ISST_IF_DEV_MMIO].registered;
if (copy_to_user(argp, &info, sizeof(info)))
return -EFAULT;
return 0;
}
static long isst_if_def_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
void __user *argp = (void __user *)arg;
long ret = -ENOTTY;
switch (cmd) {
case ISST_IF_GET_PLATFORM_INFO:
ret = isst_if_get_platform_info(argp);
break;
default:
break;
}
return ret;
}
static DEFINE_MUTEX(punit_misc_dev_lock);
static int misc_usage_count;
static int misc_device_ret;
static int misc_device_open;
static int isst_if_open(struct inode *inode, struct file *file)
{
int i, ret = 0;
/* Fail open, if a module is going away */
mutex_lock(&punit_misc_dev_lock);
for (i = 0; i < ISST_IF_DEV_MAX; ++i) {
struct isst_if_cmd_cb *cb = &punit_callbacks[i];
if (cb->registered && !try_module_get(cb->owner)) {
ret = -ENODEV;
break;
}
}
if (ret) {
int j;
for (j = 0; j < i; ++j) {
struct isst_if_cmd_cb *cb;
cb = &punit_callbacks[j];
if (cb->registered)
module_put(cb->owner);
}
} else {
misc_device_open++;
}
mutex_unlock(&punit_misc_dev_lock);
return ret;
}
static int isst_if_relase(struct inode *inode, struct file *f)
{
int i;
mutex_lock(&punit_misc_dev_lock);
misc_device_open--;
for (i = 0; i < ISST_IF_DEV_MAX; ++i) {
struct isst_if_cmd_cb *cb = &punit_callbacks[i];
if (cb->registered)
module_put(cb->owner);
}
mutex_unlock(&punit_misc_dev_lock);
return 0;
}
static const struct file_operations isst_if_char_driver_ops = {
.open = isst_if_open,
.unlocked_ioctl = isst_if_def_ioctl,
.release = isst_if_relase,
};
static struct miscdevice isst_if_char_driver = {
.minor = MISC_DYNAMIC_MINOR,
.name = "isst_interface",
.fops = &isst_if_char_driver_ops,
};
/**
* isst_if_cdev_register() - Register callback for IOCTL
* @device_type: The device type this callback handling.
* @cb: Callback structure.
*
* This function registers a callback to device type. On very first call
* it will register a misc device, which is used for user kernel interface.
* Other calls simply increment ref count. Registry will fail, if the user
* already opened misc device for operation. Also if the misc device
* creation failed, then it will not try again and all callers will get
* failure code.
*
* Return: Return the return value from the misc creation device or -EINVAL
* for unsupported device type.
*/
int isst_if_cdev_register(int device_type, struct isst_if_cmd_cb *cb)
{
if (misc_device_ret)
return misc_device_ret;
if (device_type >= ISST_IF_DEV_MAX)
return -EINVAL;
mutex_lock(&punit_misc_dev_lock);
if (misc_device_open) {
mutex_unlock(&punit_misc_dev_lock);
return -EAGAIN;
}
if (!misc_usage_count) {
misc_device_ret = misc_register(&isst_if_char_driver);
if (misc_device_ret)
goto unlock_exit;
}
memcpy(&punit_callbacks[device_type], cb, sizeof(*cb));
punit_callbacks[device_type].registered = 1;
misc_usage_count++;
unlock_exit:
mutex_unlock(&punit_misc_dev_lock);
return misc_device_ret;
}
EXPORT_SYMBOL_GPL(isst_if_cdev_register);
/**
* isst_if_cdev_unregister() - Unregister callback for IOCTL
* @device_type: The device type to unregister.
*
* This function unregisters the previously registered callback. If this
* is the last callback unregistering, then misc device is removed.
*
* Return: None.
*/
void isst_if_cdev_unregister(int device_type)
{
mutex_lock(&punit_misc_dev_lock);
misc_usage_count--;
punit_callbacks[device_type].registered = 0;
if (!misc_usage_count && !misc_device_ret)
misc_deregister(&isst_if_char_driver);
mutex_unlock(&punit_misc_dev_lock);
}
EXPORT_SYMBOL_GPL(isst_if_cdev_unregister);
MODULE_LICENSE("GPL v2");
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