Add uart_xmit_advance() helper to handle circular xmit buffer
advancement + accounting of Tx'ed bytes. Use it to fix a few drivers
that previously lacked to accounting for DMA Tx.

v2:
- Correct tags

Ilpo Järvinen (3):
  serial: Create uart_xmit_advance()
  serial: tegra: Use uart_xmit_advance(), fixes icount.tx accounting
  serial: tegra-tcu: Use uart_xmit_advance(), fixes icount.tx accounting

 drivers/tty/serial/serial-tegra.c |  5 ++---
 drivers/tty/serial/tegra-tcu.c    |  2 +-
 include/linux/serial_core.h       | 17 +++++++++++++++++
 3 files changed, 20 insertions(+), 4 deletions(-)

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2.30.2