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// SPDX-License-Identifier: GPL-2.0
/*
* xhci-dbgtty.c - tty glue for xHCI debug capability
*
* Copyright (C) 2017 Intel Corporation
*
* Author: Lu Baolu <baolu.lu@linux.intel.com>
*/
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include "xhci.h"
#include "xhci-dbgcap.h"
static int dbc_tty_init(void);
static void dbc_tty_exit(void);
static struct tty_driver *dbc_tty_driver;
static inline struct dbc_port *dbc_to_port(struct xhci_dbc *dbc)
{
return dbc->priv;
}
static unsigned int
dbc_send_packet(struct dbc_port *port, char *packet, unsigned int size)
{
unsigned int len;
len = kfifo_len(&port->write_fifo);
if (len < size)
size = len;
if (size != 0)
size = kfifo_out(&port->write_fifo, packet, size);
return size;
}
static int dbc_start_tx(struct dbc_port *port)
__releases(&port->port_lock)
__acquires(&port->port_lock)
{
int len;
struct dbc_request *req;
int status = 0;
bool do_tty_wake = false;
struct list_head *pool = &port->write_pool;
while (!list_empty(pool)) {
req = list_entry(pool->next, struct dbc_request, list_pool);
len = dbc_send_packet(port, req->buf, DBC_MAX_PACKET);
if (len == 0)
break;
do_tty_wake = true;
req->length = len;
list_del(&req->list_pool);
spin_unlock(&port->port_lock);
status = dbc_ep_queue(req);
spin_lock(&port->port_lock);
if (status) {
list_add(&req->list_pool, pool);
break;
}
}
if (do_tty_wake && port->port.tty)
tty_wakeup(port->port.tty);
return status;
}
static void dbc_start_rx(struct dbc_port *port)
__releases(&port->port_lock)
__acquires(&port->port_lock)
{
struct dbc_request *req;
int status;
struct list_head *pool = &port->read_pool;
while (!list_empty(pool)) {
if (!port->port.tty)
break;
req = list_entry(pool->next, struct dbc_request, list_pool);
list_del(&req->list_pool);
req->length = DBC_MAX_PACKET;
spin_unlock(&port->port_lock);
status = dbc_ep_queue(req);
spin_lock(&port->port_lock);
if (status) {
list_add(&req->list_pool, pool);
break;
}
}
}
static void
dbc_read_complete(struct xhci_dbc *dbc, struct dbc_request *req)
{
unsigned long flags;
struct dbc_port *port = dbc_to_port(dbc);
spin_lock_irqsave(&port->port_lock, flags);
list_add_tail(&req->list_pool, &port->read_queue);
tasklet_schedule(&port->push);
spin_unlock_irqrestore(&port->port_lock, flags);
}
static void dbc_write_complete(struct xhci_dbc *dbc, struct dbc_request *req)
{
unsigned long flags;
struct dbc_port *port = dbc_to_port(dbc);
spin_lock_irqsave(&port->port_lock, flags);
list_add(&req->list_pool, &port->write_pool);
switch (req->status) {
case 0:
dbc_start_tx(port);
break;
case -ESHUTDOWN:
break;
default:
dev_warn(dbc->dev, "unexpected write complete status %d\n",
req->status);
break;
}
spin_unlock_irqrestore(&port->port_lock, flags);
}
static void xhci_dbc_free_req(struct dbc_request *req)
{
kfree(req->buf);
dbc_free_request(req);
}
static int
xhci_dbc_alloc_requests(struct xhci_dbc *dbc, unsigned int direction,
struct list_head *head,
void (*fn)(struct xhci_dbc *, struct dbc_request *))
{
int i;
struct dbc_request *req;
for (i = 0; i < DBC_QUEUE_SIZE; i++) {
req = dbc_alloc_request(dbc, direction, GFP_KERNEL);
if (!req)
break;
req->length = DBC_MAX_PACKET;
req->buf = kmalloc(req->length, GFP_KERNEL);
if (!req->buf) {
dbc_free_request(req);
break;
}
req->complete = fn;
list_add_tail(&req->list_pool, head);
}
return list_empty(head) ? -ENOMEM : 0;
}
static void
xhci_dbc_free_requests(struct list_head *head)
{
struct dbc_request *req;
while (!list_empty(head)) {
req = list_entry(head->next, struct dbc_request, list_pool);
list_del(&req->list_pool);
xhci_dbc_free_req(req);
}
}
static int dbc_tty_install(struct tty_driver *driver, struct tty_struct *tty)
{
struct dbc_port *port = driver->driver_state;
tty->driver_data = port;
return tty_port_install(&port->port, driver, tty);
}
static int dbc_tty_open(struct tty_struct *tty, struct file *file)
{
struct dbc_port *port = tty->driver_data;
return tty_port_open(&port->port, tty, file);
}
static void dbc_tty_close(struct tty_struct *tty, struct file *file)
{
struct dbc_port *port = tty->driver_data;
tty_port_close(&port->port, tty, file);
}
static int dbc_tty_write(struct tty_struct *tty,
const unsigned char *buf,
int count)
{
struct dbc_port *port = tty->driver_data;
unsigned long flags;
spin_lock_irqsave(&port->port_lock, flags);
if (count)
count = kfifo_in(&port->write_fifo, buf, count);
dbc_start_tx(port);
spin_unlock_irqrestore(&port->port_lock, flags);
return count;
}
static int dbc_tty_put_char(struct tty_struct *tty, unsigned char ch)
{
struct dbc_port *port = tty->driver_data;
unsigned long flags;
int status;
spin_lock_irqsave(&port->port_lock, flags);
status = kfifo_put(&port->write_fifo, ch);
spin_unlock_irqrestore(&port->port_lock, flags);
return status;
}
static void dbc_tty_flush_chars(struct tty_struct *tty)
{
struct dbc_port *port = tty->driver_data;
unsigned long flags;
spin_lock_irqsave(&port->port_lock, flags);
dbc_start_tx(port);
spin_unlock_irqrestore(&port->port_lock, flags);
}
static int dbc_tty_write_room(struct tty_struct *tty)
{
struct dbc_port *port = tty->driver_data;
unsigned long flags;
int room = 0;
spin_lock_irqsave(&port->port_lock, flags);
room = kfifo_avail(&port->write_fifo);
spin_unlock_irqrestore(&port->port_lock, flags);
return room;
}
static int dbc_tty_chars_in_buffer(struct tty_struct *tty)
{
struct dbc_port *port = tty->driver_data;
unsigned long flags;
int chars = 0;
spin_lock_irqsave(&port->port_lock, flags);
chars = kfifo_len(&port->write_fifo);
spin_unlock_irqrestore(&port->port_lock, flags);
return chars;
}
static void dbc_tty_unthrottle(struct tty_struct *tty)
{
struct dbc_port *port = tty->driver_data;
unsigned long flags;
spin_lock_irqsave(&port->port_lock, flags);
tasklet_schedule(&port->push);
spin_unlock_irqrestore(&port->port_lock, flags);
}
static const struct tty_operations dbc_tty_ops = {
.install = dbc_tty_install,
.open = dbc_tty_open,
.close = dbc_tty_close,
.write = dbc_tty_write,
.put_char = dbc_tty_put_char,
.flush_chars = dbc_tty_flush_chars,
.write_room = dbc_tty_write_room,
.chars_in_buffer = dbc_tty_chars_in_buffer,
.unthrottle = dbc_tty_unthrottle,
};
static void dbc_rx_push(struct tasklet_struct *t)
{
struct dbc_request *req;
struct tty_struct *tty;
unsigned long flags;
bool do_push = false;
bool disconnect = false;
struct dbc_port *port = from_tasklet(port, t, push);
struct list_head *queue = &port->read_queue;
spin_lock_irqsave(&port->port_lock, flags);
tty = port->port.tty;
while (!list_empty(queue)) {
req = list_first_entry(queue, struct dbc_request, list_pool);
if (tty && tty_throttled(tty))
break;
switch (req->status) {
case 0:
break;
case -ESHUTDOWN:
disconnect = true;
break;
default:
pr_warn("ttyDBC0: unexpected RX status %d\n",
req->status);
break;
}
if (req->actual) {
char *packet = req->buf;
unsigned int n, size = req->actual;
int count;
n = port->n_read;
if (n) {
packet += n;
size -= n;
}
count = tty_insert_flip_string(&port->port, packet,
size);
if (count)
do_push = true;
if (count != size) {
port->n_read += count;
break;
}
port->n_read = 0;
}
list_move(&req->list_pool, &port->read_pool);
}
if (do_push)
tty_flip_buffer_push(&port->port);
if (!list_empty(queue) && tty) {
if (!tty_throttled(tty)) {
if (do_push)
tasklet_schedule(&port->push);
else
pr_warn("ttyDBC0: RX not scheduled?\n");
}
}
if (!disconnect)
dbc_start_rx(port);
spin_unlock_irqrestore(&port->port_lock, flags);
}
static int dbc_port_activate(struct tty_port *_port, struct tty_struct *tty)
{
unsigned long flags;
struct dbc_port *port = container_of(_port, struct dbc_port, port);
spin_lock_irqsave(&port->port_lock, flags);
dbc_start_rx(port);
spin_unlock_irqrestore(&port->port_lock, flags);
return 0;
}
static const struct tty_port_operations dbc_port_ops = {
.activate = dbc_port_activate,
};
static void
xhci_dbc_tty_init_port(struct xhci_dbc *dbc, struct dbc_port *port)
{
tty_port_init(&port->port);
spin_lock_init(&port->port_lock);
tasklet_setup(&port->push, dbc_rx_push);
INIT_LIST_HEAD(&port->read_pool);
INIT_LIST_HEAD(&port->read_queue);
INIT_LIST_HEAD(&port->write_pool);
port->port.ops = &dbc_port_ops;
port->n_read = 0;
}
static void
xhci_dbc_tty_exit_port(struct dbc_port *port)
{
tasklet_kill(&port->push);
tty_port_destroy(&port->port);
}
static int xhci_dbc_tty_register_device(struct xhci_dbc *dbc)
{
int ret;
struct device *tty_dev;
struct dbc_port *port = dbc_to_port(dbc);
if (port->registered)
return -EBUSY;
xhci_dbc_tty_init_port(dbc, port);
tty_dev = tty_port_register_device(&port->port,
dbc_tty_driver, 0, NULL);
if (IS_ERR(tty_dev)) {
ret = PTR_ERR(tty_dev);
goto register_fail;
}
ret = kfifo_alloc(&port->write_fifo, DBC_WRITE_BUF_SIZE, GFP_KERNEL);
if (ret)
goto buf_alloc_fail;
ret = xhci_dbc_alloc_requests(dbc, BULK_IN, &port->read_pool,
dbc_read_complete);
if (ret)
goto request_fail;
ret = xhci_dbc_alloc_requests(dbc, BULK_OUT, &port->write_pool,
dbc_write_complete);
if (ret)
goto request_fail;
port->registered = true;
return 0;
request_fail:
xhci_dbc_free_requests(&port->read_pool);
xhci_dbc_free_requests(&port->write_pool);
kfifo_free(&port->write_fifo);
buf_alloc_fail:
tty_unregister_device(dbc_tty_driver, 0);
register_fail:
xhci_dbc_tty_exit_port(port);
dev_err(dbc->dev, "can't register tty port, err %d\n", ret);
return ret;
}
static void xhci_dbc_tty_unregister_device(struct xhci_dbc *dbc)
{
struct dbc_port *port = dbc_to_port(dbc);
if (!port->registered)
return;
tty_unregister_device(dbc_tty_driver, 0);
xhci_dbc_tty_exit_port(port);
port->registered = false;
kfifo_free(&port->write_fifo);
xhci_dbc_free_requests(&port->read_pool);
xhci_dbc_free_requests(&port->read_queue);
xhci_dbc_free_requests(&port->write_pool);
}
static const struct dbc_driver dbc_driver = {
.configure = xhci_dbc_tty_register_device,
.disconnect = xhci_dbc_tty_unregister_device,
};
int xhci_dbc_tty_probe(struct xhci_hcd *xhci)
{
struct xhci_dbc *dbc = xhci->dbc;
struct dbc_port *port;
int status;
/* dbc_tty_init will be called by module init() in the future */
status = dbc_tty_init();
if (status)
return status;
port = kzalloc(sizeof(*port), GFP_KERNEL);
if (!port) {
status = -ENOMEM;
goto out;
}
dbc->driver = &dbc_driver;
dbc->priv = port;
dbc_tty_driver->driver_state = port;
return 0;
out:
/* dbc_tty_exit will be called by module_exit() in the future */
dbc_tty_exit();
return status;
}
/*
* undo what probe did, assume dbc is stopped already.
* we also assume tty_unregister_device() is called before this
*/
void xhci_dbc_tty_remove(struct xhci_dbc *dbc)
{
struct dbc_port *port = dbc_to_port(dbc);
dbc->driver = NULL;
dbc->priv = NULL;
kfree(port);
/* dbc_tty_exit will be called by module_exit() in the future */
dbc_tty_exit();
}
static int dbc_tty_init(void)
{
int ret;
dbc_tty_driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_DEV);
if (IS_ERR(dbc_tty_driver))
return PTR_ERR(dbc_tty_driver);
dbc_tty_driver->driver_name = "dbc_serial";
dbc_tty_driver->name = "ttyDBC";
dbc_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
dbc_tty_driver->subtype = SERIAL_TYPE_NORMAL;
dbc_tty_driver->init_termios = tty_std_termios;
dbc_tty_driver->init_termios.c_cflag =
B9600 | CS8 | CREAD | HUPCL | CLOCAL;
dbc_tty_driver->init_termios.c_ispeed = 9600;
dbc_tty_driver->init_termios.c_ospeed = 9600;
tty_set_operations(dbc_tty_driver, &dbc_tty_ops);
ret = tty_register_driver(dbc_tty_driver);
if (ret) {
pr_err("Can't register dbc tty driver\n");
put_tty_driver(dbc_tty_driver);
}
return ret;
}
static void dbc_tty_exit(void)
{
if (dbc_tty_driver) {
tty_unregister_driver(dbc_tty_driver);
put_tty_driver(dbc_tty_driver);
dbc_tty_driver = NULL;
}
}