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/*
* Copyright (C) 2010 Google, Inc.
*
* Author:
* Dima Zavin <dima@android.com>
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* 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.
*
*/
#include <linux/err.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/tegra_sema.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/wait.h>
#include "trpc_sema.h"
struct tegra_sema_info {
struct file *file;
wait_queue_head_t wq;
spinlock_t lock;
int count;
};
static int rpc_sema_minor = -1;
static inline bool is_trpc_sema_file(struct file *file)
{
dev_t rdev = file->f_dentry->d_inode->i_rdev;
if (MAJOR(rdev) == MISC_MAJOR && MINOR(rdev) == rpc_sema_minor)
return true;
return false;
}
struct tegra_sema_info *trpc_sema_get_from_fd(int fd)
{
struct file *file;
file = fget(fd);
if (unlikely(file == NULL)) {
pr_err("%s: fd %d is invalid\n", __func__, fd);
return ERR_PTR(-EINVAL);
}
if (!is_trpc_sema_file(file)) {
pr_err("%s: fd (%d) is not a trpc_sema file\n", __func__, fd);
fput(file);
return ERR_PTR(-EINVAL);
}
return file->private_data;
}
void trpc_sema_put(struct tegra_sema_info *info)
{
if (info->file)
fput(info->file);
}
int tegra_sema_signal(struct tegra_sema_info *info)
{
unsigned long flags;
if (!info)
return -EINVAL;
spin_lock_irqsave(&info->lock, flags);
info->count++;
wake_up_interruptible_all(&info->wq);
spin_unlock_irqrestore(&info->lock, flags);
return 0;
}
int tegra_sema_wait(struct tegra_sema_info *info, long *timeout)
{
unsigned long flags;
int ret = 0;
unsigned long endtime;
long timeleft = *timeout;
*timeout = 0;
if (timeleft < 0)
timeleft = MAX_SCHEDULE_TIMEOUT;
timeleft = msecs_to_jiffies(timeleft);
endtime = jiffies + timeleft;
again:
if (timeleft)
ret = wait_event_interruptible_timeout(info->wq,
info->count > 0,
timeleft);
spin_lock_irqsave(&info->lock, flags);
if (info->count > 0) {
info->count--;
ret = 0;
} else if (ret == 0 || timeout == 0) {
ret = -ETIMEDOUT;
} else if (ret < 0) {
ret = -EINTR;
if (timeleft != MAX_SCHEDULE_TIMEOUT &&
time_before(jiffies, endtime))
*timeout = jiffies_to_msecs(endtime - jiffies);
else
*timeout = 0;
} else {
/* we woke up but someone else got the semaphore and we have
* time left, try again */
timeleft = ret;
spin_unlock_irqrestore(&info->lock, flags);
goto again;
}
spin_unlock_irqrestore(&info->lock, flags);
return ret;
}
int tegra_sema_open(struct tegra_sema_info **sema)
{
struct tegra_sema_info *info;
info = kzalloc(sizeof(struct tegra_sema_info), GFP_KERNEL);
if (!info)
return -ENOMEM;
init_waitqueue_head(&info->wq);
spin_lock_init(&info->lock);
*sema = info;
return 0;
}
static int trpc_sema_open(struct inode *inode, struct file *file)
{
struct tegra_sema_info *info;
int ret;
ret = tegra_sema_open(&info);
if (ret < 0)
return ret;
info->file = file;
nonseekable_open(inode, file);
file->private_data = info;
return 0;
}
int tegra_sema_release(struct tegra_sema_info *sema)
{
kfree(sema);
return 0;
}
static int trpc_sema_release(struct inode *inode, struct file *file)
{
struct tegra_sema_info *info = file->private_data;
file->private_data = NULL;
tegra_sema_release(info);
return 0;
}
static long trpc_sema_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct tegra_sema_info *info = file->private_data;
int ret;
long timeout;
if (_IOC_TYPE(cmd) != TEGRA_SEMA_IOCTL_MAGIC ||
_IOC_NR(cmd) < TEGRA_SEMA_IOCTL_MIN_NR ||
_IOC_NR(cmd) > TEGRA_SEMA_IOCTL_MAX_NR)
return -ENOTTY;
else if (!info)
return -EINVAL;
switch (cmd) {
case TEGRA_SEMA_IOCTL_WAIT:
if (copy_from_user(&timeout, (void __user *)arg, sizeof(long)))
return -EFAULT;
ret = tegra_sema_wait(info, &timeout);
if (ret != -EINTR)
break;
if (copy_to_user((void __user *)arg, &timeout, sizeof(long)))
ret = -EFAULT;
break;
case TEGRA_SEMA_IOCTL_SIGNAL:
ret = tegra_sema_signal(info);
break;
default:
pr_err("%s: Unknown tegra_sema ioctl 0x%x\n", __func__,
_IOC_NR(cmd));
ret = -ENOTTY;
break;
}
return ret;
}
static const struct file_operations trpc_sema_misc_fops = {
.owner = THIS_MODULE,
.open = trpc_sema_open,
.release = trpc_sema_release,
.unlocked_ioctl = trpc_sema_ioctl,
};
static struct miscdevice trpc_sema_misc_device = {
.minor = MISC_DYNAMIC_MINOR,
.name = "tegra_sema",
.fops = &trpc_sema_misc_fops,
};
int __init trpc_sema_init(void)
{
int ret;
if (rpc_sema_minor >= 0) {
pr_err("%s: trpc_sema already registered\n", __func__);
return -EBUSY;
}
ret = misc_register(&trpc_sema_misc_device);
if (ret) {
pr_err("%s: can't register misc device\n", __func__);
return ret;
}
rpc_sema_minor = trpc_sema_misc_device.minor;
pr_info("%s: registered misc dev %d:%d\n", __func__, MISC_MAJOR,
rpc_sema_minor);
return 0;
}
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