linux/drivers/most/most_cdev.c
Christian Gromm ceea934448 drivers: most: add character device interface driver
This patch adds the character device (cdev) driver source file
most_cdev.c and modifies the Makefiles and Kconfigs accordingly.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Link: https://lore.kernel.org/r/1597922595-27493-1-git-send-email-christian.gromm@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-07 15:16:26 +02:00

544 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* cdev.c - Character device component for Mostcore
*
* Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/poll.h>
#include <linux/kfifo.h>
#include <linux/uaccess.h>
#include <linux/idr.h>
#include <linux/most.h>
#define CHRDEV_REGION_SIZE 50
static struct cdev_component {
dev_t devno;
struct ida minor_id;
unsigned int major;
struct class *class;
struct most_component cc;
} comp;
struct comp_channel {
wait_queue_head_t wq;
spinlock_t unlink; /* synchronization lock to unlink channels */
struct cdev cdev;
struct device *dev;
struct mutex io_mutex;
struct most_interface *iface;
struct most_channel_config *cfg;
unsigned int channel_id;
dev_t devno;
size_t mbo_offs;
DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *));
int access_ref;
struct list_head list;
};
#define to_channel(d) container_of(d, struct comp_channel, cdev)
static struct list_head channel_list;
static spinlock_t ch_list_lock;
static inline bool ch_has_mbo(struct comp_channel *c)
{
return channel_has_mbo(c->iface, c->channel_id, &comp.cc) > 0;
}
static inline struct mbo *ch_get_mbo(struct comp_channel *c, struct mbo **mbo)
{
if (!kfifo_peek(&c->fifo, mbo)) {
*mbo = most_get_mbo(c->iface, c->channel_id, &comp.cc);
if (*mbo)
kfifo_in(&c->fifo, mbo, 1);
}
return *mbo;
}
static struct comp_channel *get_channel(struct most_interface *iface, int id)
{
struct comp_channel *c, *tmp;
unsigned long flags;
spin_lock_irqsave(&ch_list_lock, flags);
list_for_each_entry_safe(c, tmp, &channel_list, list) {
if ((c->iface == iface) && (c->channel_id == id)) {
spin_unlock_irqrestore(&ch_list_lock, flags);
return c;
}
}
spin_unlock_irqrestore(&ch_list_lock, flags);
return NULL;
}
static void stop_channel(struct comp_channel *c)
{
struct mbo *mbo;
while (kfifo_out((struct kfifo *)&c->fifo, &mbo, 1))
most_put_mbo(mbo);
most_stop_channel(c->iface, c->channel_id, &comp.cc);
}
static void destroy_cdev(struct comp_channel *c)
{
unsigned long flags;
device_destroy(comp.class, c->devno);
cdev_del(&c->cdev);
spin_lock_irqsave(&ch_list_lock, flags);
list_del(&c->list);
spin_unlock_irqrestore(&ch_list_lock, flags);
}
static void destroy_channel(struct comp_channel *c)
{
ida_simple_remove(&comp.minor_id, MINOR(c->devno));
kfifo_free(&c->fifo);
kfree(c);
}
/**
* comp_open - implements the syscall to open the device
* @inode: inode pointer
* @filp: file pointer
*
* This stores the channel pointer in the private data field of
* the file structure and activates the channel within the core.
*/
static int comp_open(struct inode *inode, struct file *filp)
{
struct comp_channel *c;
int ret;
c = to_channel(inode->i_cdev);
filp->private_data = c;
if (((c->cfg->direction == MOST_CH_RX) &&
((filp->f_flags & O_ACCMODE) != O_RDONLY)) ||
((c->cfg->direction == MOST_CH_TX) &&
((filp->f_flags & O_ACCMODE) != O_WRONLY))) {
return -EACCES;
}
mutex_lock(&c->io_mutex);
if (!c->dev) {
mutex_unlock(&c->io_mutex);
return -ENODEV;
}
if (c->access_ref) {
mutex_unlock(&c->io_mutex);
return -EBUSY;
}
c->mbo_offs = 0;
ret = most_start_channel(c->iface, c->channel_id, &comp.cc);
if (!ret)
c->access_ref = 1;
mutex_unlock(&c->io_mutex);
return ret;
}
/**
* comp_close - implements the syscall to close the device
* @inode: inode pointer
* @filp: file pointer
*
* This stops the channel within the core.
*/
static int comp_close(struct inode *inode, struct file *filp)
{
struct comp_channel *c = to_channel(inode->i_cdev);
mutex_lock(&c->io_mutex);
spin_lock(&c->unlink);
c->access_ref = 0;
spin_unlock(&c->unlink);
if (c->dev) {
stop_channel(c);
mutex_unlock(&c->io_mutex);
} else {
mutex_unlock(&c->io_mutex);
destroy_channel(c);
}
return 0;
}
/**
* comp_write - implements the syscall to write to the device
* @filp: file pointer
* @buf: pointer to user buffer
* @count: number of bytes to write
* @offset: offset from where to start writing
*/
static ssize_t comp_write(struct file *filp, const char __user *buf,
size_t count, loff_t *offset)
{
int ret;
size_t to_copy, left;
struct mbo *mbo = NULL;
struct comp_channel *c = filp->private_data;
mutex_lock(&c->io_mutex);
while (c->dev && !ch_get_mbo(c, &mbo)) {
mutex_unlock(&c->io_mutex);
if ((filp->f_flags & O_NONBLOCK))
return -EAGAIN;
if (wait_event_interruptible(c->wq, ch_has_mbo(c) || !c->dev))
return -ERESTARTSYS;
mutex_lock(&c->io_mutex);
}
if (unlikely(!c->dev)) {
ret = -ENODEV;
goto unlock;
}
to_copy = min(count, c->cfg->buffer_size - c->mbo_offs);
left = copy_from_user(mbo->virt_address + c->mbo_offs, buf, to_copy);
if (left == to_copy) {
ret = -EFAULT;
goto unlock;
}
c->mbo_offs += to_copy - left;
if (c->mbo_offs >= c->cfg->buffer_size ||
c->cfg->data_type == MOST_CH_CONTROL ||
c->cfg->data_type == MOST_CH_ASYNC) {
kfifo_skip(&c->fifo);
mbo->buffer_length = c->mbo_offs;
c->mbo_offs = 0;
most_submit_mbo(mbo);
}
ret = to_copy - left;
unlock:
mutex_unlock(&c->io_mutex);
return ret;
}
/**
* comp_read - implements the syscall to read from the device
* @filp: file pointer
* @buf: pointer to user buffer
* @count: number of bytes to read
* @offset: offset from where to start reading
*/
static ssize_t
comp_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
{
size_t to_copy, not_copied, copied;
struct mbo *mbo = NULL;
struct comp_channel *c = filp->private_data;
mutex_lock(&c->io_mutex);
while (c->dev && !kfifo_peek(&c->fifo, &mbo)) {
mutex_unlock(&c->io_mutex);
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN;
if (wait_event_interruptible(c->wq,
(!kfifo_is_empty(&c->fifo) ||
(!c->dev))))
return -ERESTARTSYS;
mutex_lock(&c->io_mutex);
}
/* make sure we don't submit to gone devices */
if (unlikely(!c->dev)) {
mutex_unlock(&c->io_mutex);
return -ENODEV;
}
to_copy = min_t(size_t,
count,
mbo->processed_length - c->mbo_offs);
not_copied = copy_to_user(buf,
mbo->virt_address + c->mbo_offs,
to_copy);
copied = to_copy - not_copied;
c->mbo_offs += copied;
if (c->mbo_offs >= mbo->processed_length) {
kfifo_skip(&c->fifo);
most_put_mbo(mbo);
c->mbo_offs = 0;
}
mutex_unlock(&c->io_mutex);
return copied;
}
static __poll_t comp_poll(struct file *filp, poll_table *wait)
{
struct comp_channel *c = filp->private_data;
__poll_t mask = 0;
poll_wait(filp, &c->wq, wait);
mutex_lock(&c->io_mutex);
if (c->cfg->direction == MOST_CH_RX) {
if (!c->dev || !kfifo_is_empty(&c->fifo))
mask |= EPOLLIN | EPOLLRDNORM;
} else {
if (!c->dev || !kfifo_is_empty(&c->fifo) || ch_has_mbo(c))
mask |= EPOLLOUT | EPOLLWRNORM;
}
mutex_unlock(&c->io_mutex);
return mask;
}
/**
* Initialization of struct file_operations
*/
static const struct file_operations channel_fops = {
.owner = THIS_MODULE,
.read = comp_read,
.write = comp_write,
.open = comp_open,
.release = comp_close,
.poll = comp_poll,
};
/**
* comp_disconnect_channel - disconnect a channel
* @iface: pointer to interface instance
* @channel_id: channel index
*
* This frees allocated memory and removes the cdev that represents this
* channel in user space.
*/
static int comp_disconnect_channel(struct most_interface *iface, int channel_id)
{
struct comp_channel *c;
c = get_channel(iface, channel_id);
if (!c)
return -EINVAL;
mutex_lock(&c->io_mutex);
spin_lock(&c->unlink);
c->dev = NULL;
spin_unlock(&c->unlink);
destroy_cdev(c);
if (c->access_ref) {
stop_channel(c);
wake_up_interruptible(&c->wq);
mutex_unlock(&c->io_mutex);
} else {
mutex_unlock(&c->io_mutex);
destroy_channel(c);
}
return 0;
}
/**
* comp_rx_completion - completion handler for rx channels
* @mbo: pointer to buffer object that has completed
*
* This searches for the channel linked to this MBO and stores it in the local
* fifo buffer.
*/
static int comp_rx_completion(struct mbo *mbo)
{
struct comp_channel *c;
if (!mbo)
return -EINVAL;
c = get_channel(mbo->ifp, mbo->hdm_channel_id);
if (!c)
return -EINVAL;
spin_lock(&c->unlink);
if (!c->access_ref || !c->dev) {
spin_unlock(&c->unlink);
return -ENODEV;
}
kfifo_in(&c->fifo, &mbo, 1);
spin_unlock(&c->unlink);
#ifdef DEBUG_MESG
if (kfifo_is_full(&c->fifo))
dev_warn(c->dev, "Fifo is full\n");
#endif
wake_up_interruptible(&c->wq);
return 0;
}
/**
* comp_tx_completion - completion handler for tx channels
* @iface: pointer to interface instance
* @channel_id: channel index/ID
*
* This wakes sleeping processes in the wait-queue.
*/
static int comp_tx_completion(struct most_interface *iface, int channel_id)
{
struct comp_channel *c;
c = get_channel(iface, channel_id);
if (!c)
return -EINVAL;
if ((channel_id < 0) || (channel_id >= iface->num_channels)) {
dev_warn(c->dev, "Channel ID out of range\n");
return -EINVAL;
}
wake_up_interruptible(&c->wq);
return 0;
}
/**
* comp_probe - probe function of the driver module
* @iface: pointer to interface instance
* @channel_id: channel index/ID
* @cfg: pointer to actual channel configuration
* @name: name of the device to be created
*
* This allocates achannel object and creates the device node in /dev
*
* Returns 0 on success or error code otherwise.
*/
static int comp_probe(struct most_interface *iface, int channel_id,
struct most_channel_config *cfg, char *name, char *args)
{
struct comp_channel *c;
unsigned long cl_flags;
int retval;
int current_minor;
if (!cfg || !name)
return -EINVAL;
c = get_channel(iface, channel_id);
if (c)
return -EEXIST;
current_minor = ida_simple_get(&comp.minor_id, 0, 0, GFP_KERNEL);
if (current_minor < 0)
return current_minor;
c = kzalloc(sizeof(*c), GFP_KERNEL);
if (!c) {
retval = -ENOMEM;
goto err_remove_ida;
}
c->devno = MKDEV(comp.major, current_minor);
cdev_init(&c->cdev, &channel_fops);
c->cdev.owner = THIS_MODULE;
retval = cdev_add(&c->cdev, c->devno, 1);
if (retval < 0)
goto err_free_c;
c->iface = iface;
c->cfg = cfg;
c->channel_id = channel_id;
c->access_ref = 0;
spin_lock_init(&c->unlink);
INIT_KFIFO(c->fifo);
retval = kfifo_alloc(&c->fifo, cfg->num_buffers, GFP_KERNEL);
if (retval)
goto err_del_cdev_and_free_channel;
init_waitqueue_head(&c->wq);
mutex_init(&c->io_mutex);
spin_lock_irqsave(&ch_list_lock, cl_flags);
list_add_tail(&c->list, &channel_list);
spin_unlock_irqrestore(&ch_list_lock, cl_flags);
c->dev = device_create(comp.class, NULL, c->devno, NULL, "%s", name);
if (IS_ERR(c->dev)) {
retval = PTR_ERR(c->dev);
goto err_free_kfifo_and_del_list;
}
kobject_uevent(&c->dev->kobj, KOBJ_ADD);
return 0;
err_free_kfifo_and_del_list:
kfifo_free(&c->fifo);
list_del(&c->list);
err_del_cdev_and_free_channel:
cdev_del(&c->cdev);
err_free_c:
kfree(c);
err_remove_ida:
ida_simple_remove(&comp.minor_id, current_minor);
return retval;
}
static struct cdev_component comp = {
.cc = {
.mod = THIS_MODULE,
.name = "cdev",
.probe_channel = comp_probe,
.disconnect_channel = comp_disconnect_channel,
.rx_completion = comp_rx_completion,
.tx_completion = comp_tx_completion,
},
};
static int __init mod_init(void)
{
int err;
comp.class = class_create(THIS_MODULE, "most_cdev");
if (IS_ERR(comp.class))
return PTR_ERR(comp.class);
INIT_LIST_HEAD(&channel_list);
spin_lock_init(&ch_list_lock);
ida_init(&comp.minor_id);
err = alloc_chrdev_region(&comp.devno, 0, CHRDEV_REGION_SIZE, "cdev");
if (err < 0)
goto dest_ida;
comp.major = MAJOR(comp.devno);
err = most_register_component(&comp.cc);
if (err)
goto free_cdev;
err = most_register_configfs_subsys(&comp.cc);
if (err)
goto deregister_comp;
return 0;
deregister_comp:
most_deregister_component(&comp.cc);
free_cdev:
unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE);
dest_ida:
ida_destroy(&comp.minor_id);
class_destroy(comp.class);
return err;
}
static void __exit mod_exit(void)
{
struct comp_channel *c, *tmp;
most_deregister_configfs_subsys(&comp.cc);
most_deregister_component(&comp.cc);
list_for_each_entry_safe(c, tmp, &channel_list, list) {
destroy_cdev(c);
destroy_channel(c);
}
unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE);
ida_destroy(&comp.minor_id);
class_destroy(comp.class);
}
module_init(mod_init);
module_exit(mod_exit);
MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("character device component for mostcore");