v4.19.13 snapshot.
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
new file mode 100644
index 0000000..c699d41
--- /dev/null
+++ b/drivers/tty/tty_port.c
@@ -0,0 +1,707 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Tty port functions
+ */
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+#include <linux/serial.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/sched/signal.h>
+#include <linux/wait.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/serdev.h>
+
+static int tty_port_default_receive_buf(struct tty_port *port,
+ const unsigned char *p,
+ const unsigned char *f, size_t count)
+{
+ int ret;
+ struct tty_struct *tty;
+ struct tty_ldisc *disc;
+
+ tty = READ_ONCE(port->itty);
+ if (!tty)
+ return 0;
+
+ disc = tty_ldisc_ref(tty);
+ if (!disc)
+ return 0;
+
+ ret = tty_ldisc_receive_buf(disc, p, (char *)f, count);
+
+ tty_ldisc_deref(disc);
+
+ return ret;
+}
+
+static void tty_port_default_wakeup(struct tty_port *port)
+{
+ struct tty_struct *tty = tty_port_tty_get(port);
+
+ if (tty) {
+ tty_wakeup(tty);
+ tty_kref_put(tty);
+ }
+}
+
+static const struct tty_port_client_operations default_client_ops = {
+ .receive_buf = tty_port_default_receive_buf,
+ .write_wakeup = tty_port_default_wakeup,
+};
+
+void tty_port_init(struct tty_port *port)
+{
+ memset(port, 0, sizeof(*port));
+ tty_buffer_init(port);
+ init_waitqueue_head(&port->open_wait);
+ init_waitqueue_head(&port->delta_msr_wait);
+ mutex_init(&port->mutex);
+ mutex_init(&port->buf_mutex);
+ spin_lock_init(&port->lock);
+ port->close_delay = (50 * HZ) / 100;
+ port->closing_wait = (3000 * HZ) / 100;
+ port->client_ops = &default_client_ops;
+ kref_init(&port->kref);
+}
+EXPORT_SYMBOL(tty_port_init);
+
+/**
+ * tty_port_link_device - link tty and tty_port
+ * @port: tty_port of the device
+ * @driver: tty_driver for this device
+ * @index: index of the tty
+ *
+ * Provide the tty layer with a link from a tty (specified by @index) to a
+ * tty_port (@port). Use this only if neither tty_port_register_device nor
+ * tty_port_install is used in the driver. If used, this has to be called before
+ * tty_register_driver.
+ */
+void tty_port_link_device(struct tty_port *port,
+ struct tty_driver *driver, unsigned index)
+{
+ if (WARN_ON(index >= driver->num))
+ return;
+ driver->ports[index] = port;
+}
+EXPORT_SYMBOL_GPL(tty_port_link_device);
+
+/**
+ * tty_port_register_device - register tty device
+ * @port: tty_port of the device
+ * @driver: tty_driver for this device
+ * @index: index of the tty
+ * @device: parent if exists, otherwise NULL
+ *
+ * It is the same as tty_register_device except the provided @port is linked to
+ * a concrete tty specified by @index. Use this or tty_port_install (or both).
+ * Call tty_port_link_device as a last resort.
+ */
+struct device *tty_port_register_device(struct tty_port *port,
+ struct tty_driver *driver, unsigned index,
+ struct device *device)
+{
+ return tty_port_register_device_attr(port, driver, index, device, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(tty_port_register_device);
+
+/**
+ * tty_port_register_device_attr - register tty device
+ * @port: tty_port of the device
+ * @driver: tty_driver for this device
+ * @index: index of the tty
+ * @device: parent if exists, otherwise NULL
+ * @drvdata: Driver data to be set to device.
+ * @attr_grp: Attribute group to be set on device.
+ *
+ * It is the same as tty_register_device_attr except the provided @port is
+ * linked to a concrete tty specified by @index. Use this or tty_port_install
+ * (or both). Call tty_port_link_device as a last resort.
+ */
+struct device *tty_port_register_device_attr(struct tty_port *port,
+ struct tty_driver *driver, unsigned index,
+ struct device *device, void *drvdata,
+ const struct attribute_group **attr_grp)
+{
+ tty_port_link_device(port, driver, index);
+ return tty_register_device_attr(driver, index, device, drvdata,
+ attr_grp);
+}
+EXPORT_SYMBOL_GPL(tty_port_register_device_attr);
+
+/**
+ * tty_port_register_device_attr_serdev - register tty or serdev device
+ * @port: tty_port of the device
+ * @driver: tty_driver for this device
+ * @index: index of the tty
+ * @device: parent if exists, otherwise NULL
+ * @drvdata: driver data for the device
+ * @attr_grp: attribute group for the device
+ *
+ * Register a serdev or tty device depending on if the parent device has any
+ * defined serdev clients or not.
+ */
+struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
+ struct tty_driver *driver, unsigned index,
+ struct device *device, void *drvdata,
+ const struct attribute_group **attr_grp)
+{
+ struct device *dev;
+
+ tty_port_link_device(port, driver, index);
+
+ dev = serdev_tty_port_register(port, device, driver, index);
+ if (PTR_ERR(dev) != -ENODEV) {
+ /* Skip creating cdev if we registered a serdev device */
+ return dev;
+ }
+
+ return tty_register_device_attr(driver, index, device, drvdata,
+ attr_grp);
+}
+EXPORT_SYMBOL_GPL(tty_port_register_device_attr_serdev);
+
+/**
+ * tty_port_register_device_serdev - register tty or serdev device
+ * @port: tty_port of the device
+ * @driver: tty_driver for this device
+ * @index: index of the tty
+ * @device: parent if exists, otherwise NULL
+ *
+ * Register a serdev or tty device depending on if the parent device has any
+ * defined serdev clients or not.
+ */
+struct device *tty_port_register_device_serdev(struct tty_port *port,
+ struct tty_driver *driver, unsigned index,
+ struct device *device)
+{
+ return tty_port_register_device_attr_serdev(port, driver, index,
+ device, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(tty_port_register_device_serdev);
+
+/**
+ * tty_port_unregister_device - deregister a tty or serdev device
+ * @port: tty_port of the device
+ * @driver: tty_driver for this device
+ * @index: index of the tty
+ *
+ * If a tty or serdev device is registered with a call to
+ * tty_port_register_device_serdev() then this function must be called when
+ * the device is gone.
+ */
+void tty_port_unregister_device(struct tty_port *port,
+ struct tty_driver *driver, unsigned index)
+{
+ int ret;
+
+ ret = serdev_tty_port_unregister(port);
+ if (ret == 0)
+ return;
+
+ tty_unregister_device(driver, index);
+}
+EXPORT_SYMBOL_GPL(tty_port_unregister_device);
+
+int tty_port_alloc_xmit_buf(struct tty_port *port)
+{
+ /* We may sleep in get_zeroed_page() */
+ mutex_lock(&port->buf_mutex);
+ if (port->xmit_buf == NULL)
+ port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
+ mutex_unlock(&port->buf_mutex);
+ if (port->xmit_buf == NULL)
+ return -ENOMEM;
+ return 0;
+}
+EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
+
+void tty_port_free_xmit_buf(struct tty_port *port)
+{
+ mutex_lock(&port->buf_mutex);
+ if (port->xmit_buf != NULL) {
+ free_page((unsigned long)port->xmit_buf);
+ port->xmit_buf = NULL;
+ }
+ mutex_unlock(&port->buf_mutex);
+}
+EXPORT_SYMBOL(tty_port_free_xmit_buf);
+
+/**
+ * tty_port_destroy -- destroy inited port
+ * @port: tty port to be destroyed
+ *
+ * When a port was initialized using tty_port_init, one has to destroy the
+ * port by this function. Either indirectly by using tty_port refcounting
+ * (tty_port_put) or directly if refcounting is not used.
+ */
+void tty_port_destroy(struct tty_port *port)
+{
+ tty_buffer_cancel_work(port);
+ tty_buffer_free_all(port);
+}
+EXPORT_SYMBOL(tty_port_destroy);
+
+static void tty_port_destructor(struct kref *kref)
+{
+ struct tty_port *port = container_of(kref, struct tty_port, kref);
+
+ /* check if last port ref was dropped before tty release */
+ if (WARN_ON(port->itty))
+ return;
+ if (port->xmit_buf)
+ free_page((unsigned long)port->xmit_buf);
+ tty_port_destroy(port);
+ if (port->ops && port->ops->destruct)
+ port->ops->destruct(port);
+ else
+ kfree(port);
+}
+
+void tty_port_put(struct tty_port *port)
+{
+ if (port)
+ kref_put(&port->kref, tty_port_destructor);
+}
+EXPORT_SYMBOL(tty_port_put);
+
+/**
+ * tty_port_tty_get - get a tty reference
+ * @port: tty port
+ *
+ * Return a refcount protected tty instance or NULL if the port is not
+ * associated with a tty (eg due to close or hangup)
+ */
+
+struct tty_struct *tty_port_tty_get(struct tty_port *port)
+{
+ unsigned long flags;
+ struct tty_struct *tty;
+
+ spin_lock_irqsave(&port->lock, flags);
+ tty = tty_kref_get(port->tty);
+ spin_unlock_irqrestore(&port->lock, flags);
+ return tty;
+}
+EXPORT_SYMBOL(tty_port_tty_get);
+
+/**
+ * tty_port_tty_set - set the tty of a port
+ * @port: tty port
+ * @tty: the tty
+ *
+ * Associate the port and tty pair. Manages any internal refcounts.
+ * Pass NULL to deassociate a port
+ */
+
+void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+ tty_kref_put(port->tty);
+ port->tty = tty_kref_get(tty);
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+EXPORT_SYMBOL(tty_port_tty_set);
+
+static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)
+{
+ mutex_lock(&port->mutex);
+ if (port->console)
+ goto out;
+
+ if (tty_port_initialized(port)) {
+ tty_port_set_initialized(port, 0);
+ /*
+ * Drop DTR/RTS if HUPCL is set. This causes any attached
+ * modem to hang up the line.
+ */
+ if (tty && C_HUPCL(tty))
+ tty_port_lower_dtr_rts(port);
+
+ if (port->ops->shutdown)
+ port->ops->shutdown(port);
+ }
+out:
+ mutex_unlock(&port->mutex);
+}
+
+/**
+ * tty_port_hangup - hangup helper
+ * @port: tty port
+ *
+ * Perform port level tty hangup flag and count changes. Drop the tty
+ * reference.
+ *
+ * Caller holds tty lock.
+ */
+
+void tty_port_hangup(struct tty_port *port)
+{
+ struct tty_struct *tty;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+ port->count = 0;
+ tty = port->tty;
+ if (tty)
+ set_bit(TTY_IO_ERROR, &tty->flags);
+ port->tty = NULL;
+ spin_unlock_irqrestore(&port->lock, flags);
+ tty_port_set_active(port, 0);
+ tty_port_shutdown(port, tty);
+ tty_kref_put(tty);
+ wake_up_interruptible(&port->open_wait);
+ wake_up_interruptible(&port->delta_msr_wait);
+}
+EXPORT_SYMBOL(tty_port_hangup);
+
+/**
+ * tty_port_tty_hangup - helper to hang up a tty
+ *
+ * @port: tty port
+ * @check_clocal: hang only ttys with CLOCAL unset?
+ */
+void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
+{
+ struct tty_struct *tty = tty_port_tty_get(port);
+
+ if (tty && (!check_clocal || !C_CLOCAL(tty)))
+ tty_hangup(tty);
+ tty_kref_put(tty);
+}
+EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
+
+/**
+ * tty_port_tty_wakeup - helper to wake up a tty
+ *
+ * @port: tty port
+ */
+void tty_port_tty_wakeup(struct tty_port *port)
+{
+ port->client_ops->write_wakeup(port);
+}
+EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
+
+/**
+ * tty_port_carrier_raised - carrier raised check
+ * @port: tty port
+ *
+ * Wrapper for the carrier detect logic. For the moment this is used
+ * to hide some internal details. This will eventually become entirely
+ * internal to the tty port.
+ */
+
+int tty_port_carrier_raised(struct tty_port *port)
+{
+ if (port->ops->carrier_raised == NULL)
+ return 1;
+ return port->ops->carrier_raised(port);
+}
+EXPORT_SYMBOL(tty_port_carrier_raised);
+
+/**
+ * tty_port_raise_dtr_rts - Raise DTR/RTS
+ * @port: tty port
+ *
+ * Wrapper for the DTR/RTS raise logic. For the moment this is used
+ * to hide some internal details. This will eventually become entirely
+ * internal to the tty port.
+ */
+
+void tty_port_raise_dtr_rts(struct tty_port *port)
+{
+ if (port->ops->dtr_rts)
+ port->ops->dtr_rts(port, 1);
+}
+EXPORT_SYMBOL(tty_port_raise_dtr_rts);
+
+/**
+ * tty_port_lower_dtr_rts - Lower DTR/RTS
+ * @port: tty port
+ *
+ * Wrapper for the DTR/RTS raise logic. For the moment this is used
+ * to hide some internal details. This will eventually become entirely
+ * internal to the tty port.
+ */
+
+void tty_port_lower_dtr_rts(struct tty_port *port)
+{
+ if (port->ops->dtr_rts)
+ port->ops->dtr_rts(port, 0);
+}
+EXPORT_SYMBOL(tty_port_lower_dtr_rts);
+
+/**
+ * tty_port_block_til_ready - Waiting logic for tty open
+ * @port: the tty port being opened
+ * @tty: the tty device being bound
+ * @filp: the file pointer of the opener or NULL
+ *
+ * Implement the core POSIX/SuS tty behaviour when opening a tty device.
+ * Handles:
+ * - hangup (both before and during)
+ * - non blocking open
+ * - rts/dtr/dcd
+ * - signals
+ * - port flags and counts
+ *
+ * The passed tty_port must implement the carrier_raised method if it can
+ * do carrier detect and the dtr_rts method if it supports software
+ * management of these lines. Note that the dtr/rts raise is done each
+ * iteration as a hangup may have previously dropped them while we wait.
+ *
+ * Caller holds tty lock.
+ *
+ * NB: May drop and reacquire tty lock when blocking, so tty and tty_port
+ * may have changed state (eg., may have been hung up).
+ */
+
+int tty_port_block_til_ready(struct tty_port *port,
+ struct tty_struct *tty, struct file *filp)
+{
+ int do_clocal = 0, retval;
+ unsigned long flags;
+ DEFINE_WAIT(wait);
+
+ /* if non-blocking mode is set we can pass directly to open unless
+ the port has just hung up or is in another error state */
+ if (tty_io_error(tty)) {
+ tty_port_set_active(port, 1);
+ return 0;
+ }
+ if (filp == NULL || (filp->f_flags & O_NONBLOCK)) {
+ /* Indicate we are open */
+ if (C_BAUD(tty))
+ tty_port_raise_dtr_rts(port);
+ tty_port_set_active(port, 1);
+ return 0;
+ }
+
+ if (C_CLOCAL(tty))
+ do_clocal = 1;
+
+ /* Block waiting until we can proceed. We may need to wait for the
+ carrier, but we must also wait for any close that is in progress
+ before the next open may complete */
+
+ retval = 0;
+
+ /* The port lock protects the port counts */
+ spin_lock_irqsave(&port->lock, flags);
+ port->count--;
+ port->blocked_open++;
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ while (1) {
+ /* Indicate we are open */
+ if (C_BAUD(tty) && tty_port_initialized(port))
+ tty_port_raise_dtr_rts(port);
+
+ prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
+ /* Check for a hangup or uninitialised port.
+ Return accordingly */
+ if (tty_hung_up_p(filp) || !tty_port_initialized(port)) {
+ if (port->flags & ASYNC_HUP_NOTIFY)
+ retval = -EAGAIN;
+ else
+ retval = -ERESTARTSYS;
+ break;
+ }
+ /*
+ * Probe the carrier. For devices with no carrier detect
+ * tty_port_carrier_raised will always return true.
+ * Never ask drivers if CLOCAL is set, this causes troubles
+ * on some hardware.
+ */
+ if (do_clocal || tty_port_carrier_raised(port))
+ break;
+ if (signal_pending(current)) {
+ retval = -ERESTARTSYS;
+ break;
+ }
+ tty_unlock(tty);
+ schedule();
+ tty_lock(tty);
+ }
+ finish_wait(&port->open_wait, &wait);
+
+ /* Update counts. A parallel hangup will have set count to zero and
+ we must not mess that up further */
+ spin_lock_irqsave(&port->lock, flags);
+ if (!tty_hung_up_p(filp))
+ port->count++;
+ port->blocked_open--;
+ spin_unlock_irqrestore(&port->lock, flags);
+ if (retval == 0)
+ tty_port_set_active(port, 1);
+ return retval;
+}
+EXPORT_SYMBOL(tty_port_block_til_ready);
+
+static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty)
+{
+ unsigned int bps = tty_get_baud_rate(tty);
+ long timeout;
+
+ if (bps > 1200) {
+ timeout = (HZ * 10 * port->drain_delay) / bps;
+ timeout = max_t(long, timeout, HZ / 10);
+ } else {
+ timeout = 2 * HZ;
+ }
+ schedule_timeout_interruptible(timeout);
+}
+
+/* Caller holds tty lock. */
+int tty_port_close_start(struct tty_port *port,
+ struct tty_struct *tty, struct file *filp)
+{
+ unsigned long flags;
+
+ if (tty_hung_up_p(filp))
+ return 0;
+
+ spin_lock_irqsave(&port->lock, flags);
+ if (tty->count == 1 && port->count != 1) {
+ tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,
+ port->count);
+ port->count = 1;
+ }
+ if (--port->count < 0) {
+ tty_warn(tty, "%s: bad port count (%d)\n", __func__,
+ port->count);
+ port->count = 0;
+ }
+
+ if (port->count) {
+ spin_unlock_irqrestore(&port->lock, flags);
+ return 0;
+ }
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ tty->closing = 1;
+
+ if (tty_port_initialized(port)) {
+ /* Don't block on a stalled port, just pull the chain */
+ if (tty->flow_stopped)
+ tty_driver_flush_buffer(tty);
+ if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
+ tty_wait_until_sent(tty, port->closing_wait);
+ if (port->drain_delay)
+ tty_port_drain_delay(port, tty);
+ }
+ /* Flush the ldisc buffering */
+ tty_ldisc_flush(tty);
+
+ /* Report to caller this is the last port reference */
+ return 1;
+}
+EXPORT_SYMBOL(tty_port_close_start);
+
+/* Caller holds tty lock */
+void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
+{
+ unsigned long flags;
+
+ tty_ldisc_flush(tty);
+ tty->closing = 0;
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ if (port->blocked_open) {
+ spin_unlock_irqrestore(&port->lock, flags);
+ if (port->close_delay)
+ msleep_interruptible(jiffies_to_msecs(port->close_delay));
+ spin_lock_irqsave(&port->lock, flags);
+ wake_up_interruptible(&port->open_wait);
+ }
+ spin_unlock_irqrestore(&port->lock, flags);
+ tty_port_set_active(port, 0);
+}
+EXPORT_SYMBOL(tty_port_close_end);
+
+/**
+ * tty_port_close
+ *
+ * Caller holds tty lock
+ */
+void tty_port_close(struct tty_port *port, struct tty_struct *tty,
+ struct file *filp)
+{
+ if (tty_port_close_start(port, tty, filp) == 0)
+ return;
+ tty_port_shutdown(port, tty);
+ if (!port->console)
+ set_bit(TTY_IO_ERROR, &tty->flags);
+ tty_port_close_end(port, tty);
+ tty_port_tty_set(port, NULL);
+}
+EXPORT_SYMBOL(tty_port_close);
+
+/**
+ * tty_port_install - generic tty->ops->install handler
+ * @port: tty_port of the device
+ * @driver: tty_driver for this device
+ * @tty: tty to be installed
+ *
+ * It is the same as tty_standard_install except the provided @port is linked
+ * to a concrete tty specified by @tty. Use this or tty_port_register_device
+ * (or both). Call tty_port_link_device as a last resort.
+ */
+int tty_port_install(struct tty_port *port, struct tty_driver *driver,
+ struct tty_struct *tty)
+{
+ tty->port = port;
+ return tty_standard_install(driver, tty);
+}
+EXPORT_SYMBOL_GPL(tty_port_install);
+
+/**
+ * tty_port_open
+ *
+ * Caller holds tty lock.
+ *
+ * NB: may drop and reacquire tty lock (in tty_port_block_til_ready()) so
+ * tty and tty_port may have changed state (eg., may be hung up now)
+ */
+int tty_port_open(struct tty_port *port, struct tty_struct *tty,
+ struct file *filp)
+{
+ spin_lock_irq(&port->lock);
+ ++port->count;
+ spin_unlock_irq(&port->lock);
+ tty_port_tty_set(port, tty);
+
+ /*
+ * Do the device-specific open only if the hardware isn't
+ * already initialized. Serialize open and shutdown using the
+ * port mutex.
+ */
+
+ mutex_lock(&port->mutex);
+
+ if (!tty_port_initialized(port)) {
+ clear_bit(TTY_IO_ERROR, &tty->flags);
+ if (port->ops->activate) {
+ int retval = port->ops->activate(port, tty);
+ if (retval) {
+ mutex_unlock(&port->mutex);
+ return retval;
+ }
+ }
+ tty_port_set_initialized(port, 1);
+ }
+ mutex_unlock(&port->mutex);
+ return tty_port_block_til_ready(port, tty, filp);
+}
+
+EXPORT_SYMBOL(tty_port_open);