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09864c1cdf
linux/include/uapi
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Stefan-gabriel Mirea 09864c1cdf tty: serial: Add linflexuart driver for S32V234 
Introduce support for LINFlex driver, based on:
- the version of Freescale LPUART driver after commit b3e3bf2ef2 ("Merge
  4.0-rc7 into tty-next");
- commit abf1e0a980 ("tty: serial: fsl_lpuart: lock port on console
  write").
In this basic version, the driver can be tested using initramfs and relies
on the clocks and pin muxing set up by U-Boot.

Remarks concerning the earlycon support:

- LinFlexD does not allow character transmissions in the INIT mode (see
  section 47.4.2.1 in the reference manual[1]). Therefore, a mutual
  exclusion between the first linflex_setup_watermark/linflex_set_termios
  executions and linflex_earlycon_putchar was employed and the characters
  normally sent to earlycon during initialization are kept in a buffer and
  sent afterwards.

- Empirically, character transmission is also forbidden within the last 1-2
  ms before entering the INIT mode, so we use an explicit timeout
  (PREINIT_DELAY) between linflex_earlycon_putchar and the first call to
  linflex_setup_watermark.

- U-Boot currently uses the UART FIFO mode, while this driver makes the
  transition to the buffer mode. Therefore, the earlycon putchar function
  matches the U-Boot behavior before initializations and the Linux behavior
  after.

[1] https://www.nxp.com/webapp/Download?colCode=S32V234RM

Signed-off-by: Stoica Cosmin-Stefan <cosmin.stoica@nxp.com>
Signed-off-by: Adrian.Nitu <adrian.nitu@freescale.com>
Signed-off-by: Larisa Grigore <Larisa.Grigore@nxp.com>
Signed-off-by: Ana Nedelcu <B56683@freescale.com>
Signed-off-by: Mihaela Martinas <Mihaela.Martinas@freescale.com>
Signed-off-by: Matthew Nunez <matthew.nunez@nxp.com>
[stefan-gabriel.mirea@nxp.com: Reduced for upstreaming and implemented
                               earlycon support]
Signed-off-by: Stefan-Gabriel Mirea <stefan-gabriel.mirea@nxp.com>
Link: https://lore.kernel.org/r/20190809112853.15846-6-stefan-gabriel.mirea@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-09-04 12:43:54 +02:00
..
asm-generic Merge branch 'akpm' (patches from Andrew) 2019-07-17 08:58:04 -07:00
drm Merge tag 'drm-next-5.3-2019-07-18' of git://people.freedesktop.org/~agd5f/linux into drm-next 2019-07-19 17:21:48 +10:00
linux tty: serial: Add linflexuart driver for S32V234 2019-09-04 12:43:54 +02:00
misc treewide: add "WITH Linux-syscall-note" to SPDX tag of uapi headers 2019-07-25 11:05:10 +02:00
mtd mtd: abi: do not use C++ style comments in uapi header 2019-07-07 20:31:29 +02:00
rdma treewide: add "WITH Linux-syscall-note" to SPDX tag of uapi headers 2019-07-25 11:05:10 +02:00
scsi treewide: add "WITH Linux-syscall-note" to SPDX tag of uapi headers 2019-07-25 11:05:10 +02:00
sound sound fixes for 5.3-rc4 2019-08-09 09:21:27 -07:00
video
xen
Kbuild kbuild: re-implement Makefile.headersinst without recursion 2019-06-15 19:57:02 +09:00