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utils.c
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utils.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2019 - 2020 DisplayLink (UK) Ltd.
*/
#include "utils.h"
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/version.h>
#include "mausb_driver_status.h"
#define MAUSB_KERNEL_DEV_NAME "mausb_host"
#define MAUSB_READ_DEVICE_TIMEOUT_MS 500
static void mausb_vm_close(struct vm_area_struct *vma)
{
struct mausb_ring_buffer *buffer = NULL, *next = NULL;
unsigned long flags;
u64 ring_buffer_id = *(u64 *)(vma->vm_private_data);
dev_info(mausb_host_dev.this_device, "Releasing ring buffer with id: %llu",
ring_buffer_id);
spin_lock_irqsave(&mss.lock, flags);
list_for_each_entry_safe(buffer, next, &mss.available_ring_buffers,
list_entry) {
if (buffer->id == ring_buffer_id) {
list_del(&buffer->list_entry);
mausb_ring_buffer_destroy(buffer);
kfree(buffer);
break;
}
}
spin_unlock_irqrestore(&mss.lock, flags);
}
/*
* mausb_vm_fault is called the first time a memory area is accessed which is
* not in memory
*/
#if KERNEL_VERSION(4, 17, 0) <= LINUX_VERSION_CODE
static vm_fault_t mausb_vm_fault(struct vm_fault *vmf)
#elif (KERNEL_VERSION(4, 11, 0) <= LINUX_VERSION_CODE &&\
KERNEL_VERSION(4, 17, 0) > LINUX_VERSION_CODE)
static int mausb_vm_fault(struct vm_fault *vmf)
#else
static int mausb_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
#endif
{
return 0;
}
static const struct vm_operations_struct mausb_vm_ops = {
.close = mausb_vm_close,
.fault = mausb_vm_fault,
};
static int mausb_host_dev_open(struct inode *inode, struct file *filp)
{
filp->private_data = NULL;
return 0;
}
static int mausb_host_dev_release(struct inode *inode, struct file *filp)
{
kfree(filp->private_data);
filp->private_data = NULL;
return 0;
}
static ssize_t mausb_host_dev_read(struct file *filp, char __user *user_buffer,
size_t size, loff_t *offset)
{
ssize_t num_of_bytes_to_read = MAUSB_MAX_NUM_OF_MA_DEVS *
sizeof(struct mausb_events_notification);
unsigned long num_of_bytes_not_copied;
int completed_events;
int ring_events;
struct mausb_ring_buffer *ring_buffer;
struct mausb_device *dev;
struct completion *ring_has_events;
u8 current_device = 0;
s8 fail_ret_val;
unsigned long flags;
unsigned long timeout;
long status;
/* Reset heartbeat timer events */
mausb_reset_heartbeat_cnt();
if ((ssize_t)size != num_of_bytes_to_read) {
dev_alert(mausb_host_dev.this_device, "The actual size differs from the expected number of bytes");
fail_ret_val = MAUSB_DRIVER_BAD_READ_BUFFER_SIZE;
if (copy_to_user(user_buffer, &fail_ret_val,
sizeof(fail_ret_val)) != 0) {
dev_warn(mausb_host_dev.this_device, "Failed to set error code.");
}
return MAUSB_DRIVER_READ_ERROR;
}
/* If suspend/hibernate happened delete all devices */
if (atomic_xchg(&mss.num_of_transitions_to_sleep, 0)) {
dev_alert(mausb_host_dev.this_device, "Suspend system event detected");
fail_ret_val = MAUSB_DRIVER_SYSTEM_SUSPENDED;
if (copy_to_user(user_buffer, &fail_ret_val,
sizeof(fail_ret_val)) != 0) {
dev_warn(mausb_host_dev.this_device, "Failed to set error code.");
}
return MAUSB_DRIVER_READ_ERROR;
}
ring_has_events = &mss.rings_events.mausb_ring_has_events;
timeout = msecs_to_jiffies(MAUSB_READ_DEVICE_TIMEOUT_MS);
status = wait_for_completion_interruptible_timeout(ring_has_events,
timeout);
reinit_completion(ring_has_events);
if (atomic_read(&mss.rings_events.mausb_stop_reading_ring_events)) {
dev_alert(mausb_host_dev.this_device, "Ring events stopped");
fail_ret_val = MAUSB_DRIVER_RING_EVENTS_STOPPED;
if (copy_to_user(user_buffer, &fail_ret_val,
sizeof(fail_ret_val)) != 0) {
dev_warn(mausb_host_dev.this_device, "Failed to set error code.");
}
return MAUSB_DRIVER_READ_ERROR;
}
/* There are no new events - waiting for events hit timeout */
if (status == 0)
return MAUSB_DRIVER_READ_TIMEOUT;
spin_lock_irqsave(&mss.lock, flags);
list_for_each_entry(dev, &mss.madev_list, list_entry) {
mss.events[current_device].madev_addr = dev->madev_addr;
ring_buffer = dev->ring_buffer;
ring_events = atomic_xchg(&ring_buffer->mausb_ring_events, 0);
completed_events =
atomic_xchg(&ring_buffer->mausb_completed_user_events,
0);
mss.events[current_device].num_of_events = (u16)ring_events;
mss.events[current_device].num_of_completed_events =
(u16)completed_events;
if (++current_device == MAUSB_MAX_NUM_OF_MA_DEVS)
break;
}
spin_unlock_irqrestore(&mss.lock, flags);
num_of_bytes_to_read =
(ssize_t)(current_device *
sizeof(struct mausb_events_notification));
num_of_bytes_not_copied =
copy_to_user(user_buffer, &mss.events,
(unsigned long)num_of_bytes_to_read);
dev_vdbg(mausb_host_dev.this_device, "num_of_bytes_not_copied %lu, num_of_bytes_to_read %zd",
num_of_bytes_not_copied, num_of_bytes_to_read);
if (num_of_bytes_not_copied) {
fail_ret_val = MAUSB_DRIVER_COPY_TO_BUFFER_FAILED;
if (copy_to_user(user_buffer, &fail_ret_val,
sizeof(fail_ret_val)) != 0) {
dev_warn(mausb_host_dev.this_device, "Failed to set error code.");
}
return MAUSB_DRIVER_READ_ERROR;
}
return num_of_bytes_to_read;
}
static ssize_t mausb_host_dev_write(struct file *filp,
const char __user *buffer, size_t size,
loff_t *offset)
{
ssize_t num_of_bytes_to_write =
sizeof(struct mausb_events_notification);
struct mausb_events_notification notification;
unsigned long flags;
struct mausb_device *dev;
if (size != (size_t)num_of_bytes_to_write) {
dev_alert(mausb_host_dev.this_device, "The actual size differs from the expected number of bytes");
return MAUSB_DRIVER_WRITE_ERROR;
}
if (copy_from_user(¬ification, buffer, size))
return MAUSB_DRIVER_WRITE_ERROR;
spin_lock_irqsave(&mss.lock, flags);
dev = mausb_get_dev_from_addr_unsafe(notification.madev_addr);
if (!dev) {
spin_unlock_irqrestore(&mss.lock, flags);
return 0;
}
spin_lock(&dev->num_of_user_events_lock);
dev->num_of_user_events += notification.num_of_events;
dev->num_of_completed_events += notification.num_of_completed_events;
spin_unlock(&dev->num_of_user_events_lock);
queue_work(dev->workq, &dev->work);
spin_unlock_irqrestore(&mss.lock, flags);
return num_of_bytes_to_write;
}
static inline unsigned long mausb_ring_buffer_length(void)
{
int page_order = mausb_get_page_order(2 * MAUSB_RING_BUFFER_SIZE,
sizeof(struct mausb_event));
return PAGE_SIZE << page_order;
}
static int mausb_mmap(struct file *filp, struct vm_area_struct *vma)
{
unsigned long size = vma->vm_end - vma->vm_start;
int ret;
struct page *page = NULL;
unsigned long flags;
struct mausb_ring_buffer *ring_buffer = kzalloc(sizeof(*ring_buffer),
GFP_KERNEL);
if (!ring_buffer)
return -ENOMEM;
ret = mausb_ring_buffer_init(ring_buffer);
if (ret < 0) {
dev_err(mausb_host_dev.this_device, "Ring buffer init failed");
goto release_ring_buffer;
}
vma->vm_private_data = kzalloc(sizeof(ring_buffer->id), GFP_KERNEL);
if (!vma->vm_private_data) {
ret = -ENOMEM;
goto release_ring_buffer;
}
filp->private_data = vma->vm_private_data;
if (size > mausb_ring_buffer_length()) {
dev_err(mausb_host_dev.this_device, "Invalid memory size to map");
ret = -EINVAL;
goto release_ring_buffer;
}
vma->vm_ops = &mausb_vm_ops;
page = virt_to_page(ring_buffer->to_user_buffer);
ret = remap_pfn_range(vma, vma->vm_start, page_to_pfn(page), size,
vma->vm_page_prot);
if (ret < 0) {
dev_err(mausb_host_dev.this_device, "Could not map the address area");
goto release_ring_buffer;
}
spin_lock_irqsave(&mss.lock, flags);
ring_buffer->id = mss.ring_buffer_id++;
*(u64 *)(vma->vm_private_data) = ring_buffer->id;
list_add_tail(&ring_buffer->list_entry, &mss.available_ring_buffers);
dev_info(mausb_host_dev.this_device, "Allocated ring buffer with id: %llu",
ring_buffer->id);
spin_unlock_irqrestore(&mss.lock, flags);
return 0;
release_ring_buffer:
mausb_ring_buffer_destroy(ring_buffer);
kfree(ring_buffer);
return ret;
}
static const struct file_operations mausb_host_dev_fops = {
.open = mausb_host_dev_open,
.release = mausb_host_dev_release,
.read = mausb_host_dev_read,
.write = mausb_host_dev_write,
.mmap = mausb_mmap,
};
struct miscdevice mausb_host_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = MAUSB_KERNEL_DEV_NAME,
.fops = &mausb_host_dev_fops,
.mode = 0644,
};
int mausb_host_dev_register(void)
{
return misc_register(&mausb_host_dev);
}
void mausb_host_dev_deregister(void)
{
misc_deregister(&mausb_host_dev);
}
void mausb_notify_completed_user_events(struct mausb_ring_buffer *ring_buffer)
{
int completed;
completed =
atomic_inc_return(&ring_buffer->mausb_completed_user_events);
dev_vdbg(mausb_host_dev.this_device, "mausb_completed_user_events INCREMENTED %d",
completed);
if (completed > MAUSB_RING_BUFFER_SIZE / 16)
complete(&mss.rings_events.mausb_ring_has_events);
}
void mausb_notify_ring_events(struct mausb_ring_buffer *ring_buffer)
{
int events = atomic_inc_return(&ring_buffer->mausb_ring_events);
if (events > 0)
complete(&mss.rings_events.mausb_ring_has_events);
}
void mausb_stop_ring_events(void)
{
atomic_set(&mss.rings_events.mausb_stop_reading_ring_events, 1);
complete(&mss.rings_events.mausb_ring_has_events);
}