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>

5 files changed, 0 insertions, 563 deletions

diff --git a/drivers/staging/most/Kconfig b/drivers/staging/most/Kconfig
index c35fb34fae79..535e6dec3504 100644
--- a/drivers/staging/most/Kconfig
+++ b/drivers/staging/most/Kconfig
@@ -18,8 +18,6 @@ menuconfig MOST_COMPONENTS
 
 if MOST_COMPONENTS
 
-source "drivers/staging/most/cdev/Kconfig"
-
 source "drivers/staging/most/net/Kconfig"
 
 source "drivers/staging/most/sound/Kconfig"
diff --git a/drivers/staging/most/Makefile b/drivers/staging/most/Makefile
index 7c10b84ebac0..be94673209f5 100644
--- a/drivers/staging/most/Makefile
+++ b/drivers/staging/most/Makefile
@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 
-obj-$(CONFIG_MOST_CDEV)	+= cdev/
 obj-$(CONFIG_MOST_NET)	+= net/
 obj-$(CONFIG_MOST_SOUND)	+= sound/
 obj-$(CONFIG_MOST_VIDEO)	+= video/
diff --git a/drivers/staging/most/cdev/Kconfig b/drivers/staging/most/cdev/Kconfig
deleted file mode 100644
index dab99477858e..000000000000
--- a/drivers/staging/most/cdev/Kconfig
+++ /dev/null
@@ -1,13 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0
-#
-# MOST Cdev configuration
-#
-
-config MOST_CDEV
-	tristate "Cdev"
-
-	help
-	  Say Y here if you want to commumicate via character devices.
-
-	  To compile this driver as a module, choose M here: the
-	  module will be called most_cdev.
diff --git a/drivers/staging/most/cdev/Makefile b/drivers/staging/most/cdev/Makefile
deleted file mode 100644
index ef90cd71994a..000000000000
--- a/drivers/staging/most/cdev/Makefile
+++ /dev/null
@@ -1,4 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_MOST_CDEV) += most_cdev.o
-
-most_cdev-objs := cdev.o
diff --git a/drivers/staging/most/cdev/cdev.c b/drivers/staging/most/cdev/cdev.c
deleted file mode 100644
index 044880760b58..000000000000
--- a/drivers/staging/most/cdev/cdev.c
+++ /dev/null
@@ -1,543 +0,0 @@
-// 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");