On Mon, Jul 02, 2018 at 04:30:07PM +0300, Mikko Perttunen wrote: > On 02.07.2018 16:18, Thierry Reding wrote: > > On Mon, Jul 02, 2018 at 02:40:31PM +0300, Mikko Perttunen wrote: > > > The Tegra Combined UART (TCU) is a mailbox-based mechanism that allows > > > multiplexing multiple "virtual UARTs" into a single hardware serial > > > port. The TCU is the primary serial port on Tegra194 devices. > > > > > > Add a TCU driver utilizing the mailbox framework, as the used mailboxes > > > are part of Tegra HSP blocks that are already controlled by the Tegra > > > HSP mailbox driver. > > > > > > Signed-off-by: Mikko Perttunen <mperttunen@xxxxxxxxxx> > > > --- > > > > > > Notes: > > > v2: > > > - Removed (void) casts for unused variables. > > > - Changed the uart_set_options() call to be on one line, even if its > > > over 80 characters. > > > - Added defines for magic numbers. > > > - Style fixes. > > > - Changed Kconfig entry to depend on the Tegra HSP driver instead of > > > just the mailbox framework. > > > v3: > > > - Removed FLUSH bit, as it's unnecessary and slows down printing > > > - Removed call to uart_set_options > > > - Added mbox_free_channel calls to remove() > > > > > > drivers/tty/serial/Kconfig | 9 ++ > > > drivers/tty/serial/Makefile | 1 + > > > drivers/tty/serial/tegra-tcu.c | 291 +++++++++++++++++++++++++++++++++++++++ > > > include/uapi/linux/serial_core.h | 3 + > > > 4 files changed, 304 insertions(+) > > > create mode 100644 drivers/tty/serial/tegra-tcu.c > > > > The driver looks good to me. But for my own understanding, is there some > > way we can make use of the multiplexing? That is, could we add a > > mechanism to have the driver filter out only a specific stream? Could we > > also specify which stream to send data back to? What happens by default? > > Which stream is data sent to? > > There is no multiplexing on the producer/device side (i.e. what this driver > does). The mailbox specified in device tree specifies the stream we send > stuff to. The mailboxes are per-CPU (we use the CCPLEX mailbox here), so it > cannot really be changed. Oh, I see, so there is one stream per pair of mailboxes? That is, the mailboxes we specify in the DT define which stream we receive from and send to? Thierry
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