diff options
Diffstat (limited to 'drivers/platform/x86/intel_speed_select_if/isst_if_common.c')
| -rw-r--r-- | drivers/platform/x86/intel_speed_select_if/isst_if_common.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/drivers/platform/x86/intel_speed_select_if/isst_if_common.c b/drivers/platform/x86/intel_speed_select_if/isst_if_common.c new file mode 100644 index 000000000000..ab2bb4862dc8 --- /dev/null +++ b/drivers/platform/x86/intel_speed_select_if/isst_if_common.c @@ -0,0 +1,182 @@ +// 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"); |