From ceea93444808c7d1fd07a01927937d20237d849e Mon Sep 17 00:00:00 2001 From: Christian Gromm Date: Thu, 20 Aug 2020 13:23:15 +0200 Subject: 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 Link: https://lore.kernel.org/r/1597922595-27493-1-git-send-email-christian.gromm@microchip.com Signed-off-by: Greg Kroah-Hartman --- drivers/most/Kconfig | 9 + drivers/most/Makefile | 1 + drivers/most/most_cdev.c | 543 +++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 553 insertions(+) create mode 100644 drivers/most/most_cdev.c (limited to 'drivers/most') diff --git a/drivers/most/Kconfig b/drivers/most/Kconfig index 60fc0820dad3..ebfe84e69715 100644 --- a/drivers/most/Kconfig +++ b/drivers/most/Kconfig @@ -23,4 +23,13 @@ config MOST_USB_HDM To compile this driver as a module, choose M here: the module will be called most_usb. + +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. endif diff --git a/drivers/most/Makefile b/drivers/most/Makefile index 6a3cb9056288..8b53ca46633f 100644 --- a/drivers/most/Makefile +++ b/drivers/most/Makefile @@ -4,3 +4,4 @@ most_core-y := core.o \ configfs.o obj-$(CONFIG_MOST_USB_HDM) += most_usb.o +obj-$(CONFIG_MOST_CDEV) += most_cdev.o diff --git a/drivers/most/most_cdev.c b/drivers/most/most_cdev.c new file mode 100644 index 000000000000..044880760b58 --- /dev/null +++ b/drivers/most/most_cdev.c @@ -0,0 +1,543 @@ +// 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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 "); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("character device component for mostcore"); -- cgit v1.2.3