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authorJiri Slaby (SUSE) <jirislaby@kernel.org>2022-10-04 13:49:25 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-11-03 05:32:40 +0300
commit8275b48b278096edc1e3ea5aa9cf946a10022f79 (patch)
treece9495f8937cb7c2b166bc44878a221c3915a6bf /Documentation/driver-api/serial
parent83efeeeb3d04b22aaed1df99bc70a48fe9d22c4d (diff)
downloadlinux-8275b48b278096edc1e3ea5aa9cf946a10022f79.tar.xz
tty: serial: introduce transmit helpers
Many serial drivers do the same thing: * send x_char if set * keep sending from the xmit circular buffer until either - the loop reaches the end of the xmit buffer - TX is stopped - HW fifo is full * check for pending characters and: - wake up tty writers to fill for more data into xmit buffer - stop TX if there is nothing in the xmit buffer The only differences are: * how to write the character to the HW fifo * the check of the end condition: - is the HW fifo full? - is limit of the written characters reached? So unify the above into two helpers: * uart_port_tx_limited() -- it performs the above taking the written characters limit into account, and * uart_port_tx() -- the same as above, except it only checks the HW readiness, not the characters limit. The HW specific operations (as stated as "differences" above) are passed as arguments to the macros. They are: * tx_ready -- returns true if HW can accept more data. * put_char -- write a character to the device. * tx_done -- when the write loop is done, perform arbitrary action before potential invocation of ops->stop_tx() happens. Note that the above are macros. This means the code is generated in place and the above 3 arguments are "inlined". I.e. no added penalty by generating call instructions for every single character. Nor any indirect calls. (As in some previous versions of this patchset.) Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org> Link: https://lore.kernel.org/r/20221004104927.14361-2-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/driver-api/serial')
-rw-r--r--Documentation/driver-api/serial/driver.rst3
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index 23c6b956cd90..98d268555dcc 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -78,6 +78,9 @@ Other functions
uart_get_lsr_info uart_handle_dcd_change uart_handle_cts_change
uart_try_toggle_sysrq uart_get_console
+.. kernel-doc:: include/linux/serial_core.h
+ :identifiers: uart_port_tx_limited uart_port_tx
+
Other notes
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