Merge tag 'tty-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty / serial driver updates from Greg KH:
 "Here is the big set of tty and serial driver updates for 5.16-rc1.

  Nothing major in here at all, just lots of tiny serial and tty driver
  updates for various reported things, and some good cleanups. These
  include:

   - more good tty api cleanups from Jiri

   - stm32 serial driver updates

   - softlockup fix for non-preempt systems under high serial load

   - rpmsg serial driver update

   - 8250 drivers updates and fixes

   - n_gsm line discipline fixes and updates as people are finally
     starting to use it.

  All of these have been in linux-next for a while now with no reported
  issues"

* tag 'tty-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (86 commits)
  tty: Fix extra "not" in TTY_DRIVER_REAL_RAW description
  serial: cpm_uart: Protect udbg definitions by CONFIG_SERIAL_CPM_CONSOLE
  tty: rpmsg: Define tty name via constant string literal
  tty: rpmsg: Add pr_fmt() to prefix messages
  tty: rpmsg: Use dev_err_probe() in ->probe()
  tty: rpmsg: Unify variable used to keep an error code
  tty: rpmsg: Assign returned id to a local variable
  serial: stm32: push DMA RX data before suspending
  serial: stm32: terminate / restart DMA transfer at suspend / resume
  serial: stm32: rework RX dma initialization and release
  serial: 8250_pci: Remove empty stub pci_quatech_exit()
  serial: 8250_pci: Replace custom pci_match_id() implementation
  serial: xilinx_uartps: Fix race condition causing stuck TX
  serial: sunzilog: Mark sunzilog_putchar() __maybe_unused
  Revert "tty: hvc: pass DMA capable memory to put_chars()"
  Revert "virtio-console: remove unnecessary kmemdup()"
  serial: 8250_pci: Replace dev_*() by pci_*() macros
  serial: 8250_pci: Get rid of redundant 'else' keyword
  serial: 8250_pci: Refactor the loop in pci_ite887x_init()
  tty: add rpmsg driver
  ...

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index 9151836190ce..d3eb60059ef1 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -327,6 +327,27 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
 }
 EXPORT_SYMBOL(rpmsg_trysend_offchannel);
 
+/**
+ * rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
+ * @ept: the rpmsg endpoint
+ *
+ * This function returns maximum buffer size available for a single outgoing message.
+ *
+ * Return: the maximum transmission size on success and an appropriate error
+ * value on failure.
+ */
+
+ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
+{
+	if (WARN_ON(!ept))
+		return -EINVAL;
+	if (!ept->ops->get_mtu)
+		return -ENOTSUPP;
+
+	return ept->ops->get_mtu(ept);
+}
+EXPORT_SYMBOL(rpmsg_get_mtu);
+
 /*
  * match a rpmsg channel with a channel info struct.
  * this is used to make sure we're not creating rpmsg devices for channels