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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-16 12:21:41 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-16 12:21:41 -0700 |
commit | c309b6f24222246c18a8b65d3950e6e755440865 (patch) | |
tree | 11893170f5c246bb0dee8066e85878af04162ab0 /Documentation/pti/pti_intel_mid.txt | |
parent | 3e859477a1db52a0435d06a55fdb54f62d69c292 (diff) | |
parent | 168869492e7009b6861b615f1d030c99bc805e83 (diff) | |
download | linux-stable-c309b6f24222246c18a8b65d3950e6e755440865.tar.gz linux-stable-c309b6f24222246c18a8b65d3950e6e755440865.tar.bz2 linux-stable-c309b6f24222246c18a8b65d3950e6e755440865.zip |
Merge tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull rst conversion of docs from Mauro Carvalho Chehab:
"As agreed with Jon, I'm sending this big series directly to you, c/c
him, as this series required a special care, in order to avoid
conflicts with other trees"
* tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (77 commits)
docs: kbuild: fix build with pdf and fix some minor issues
docs: block: fix pdf output
docs: arm: fix a breakage with pdf output
docs: don't use nested tables
docs: gpio: add sysfs interface to the admin-guide
docs: locking: add it to the main index
docs: add some directories to the main documentation index
docs: add SPDX tags to new index files
docs: add a memory-devices subdir to driver-api
docs: phy: place documentation under driver-api
docs: serial: move it to the driver-api
docs: driver-api: add remaining converted dirs to it
docs: driver-api: add xilinx driver API documentation
docs: driver-api: add a series of orphaned documents
docs: admin-guide: add a series of orphaned documents
docs: cgroup-v1: add it to the admin-guide book
docs: aoe: add it to the driver-api book
docs: add some documentation dirs to the driver-api book
docs: driver-model: move it to the driver-api book
docs: lp855x-driver.rst: add it to the driver-api book
...
Diffstat (limited to 'Documentation/pti/pti_intel_mid.txt')
-rw-r--r-- | Documentation/pti/pti_intel_mid.txt | 99 |
1 files changed, 0 insertions, 99 deletions
diff --git a/Documentation/pti/pti_intel_mid.txt b/Documentation/pti/pti_intel_mid.txt deleted file mode 100644 index e7a5b6d1f7a9..000000000000 --- a/Documentation/pti/pti_intel_mid.txt +++ /dev/null @@ -1,99 +0,0 @@ -The Intel MID PTI project is HW implemented in Intel Atom -system-on-a-chip designs based on the Parallel Trace -Interface for MIPI P1149.7 cJTAG standard. The kernel solution -for this platform involves the following files: - -./include/linux/pti.h -./drivers/.../n_tracesink.h -./drivers/.../n_tracerouter.c -./drivers/.../n_tracesink.c -./drivers/.../pti.c - -pti.c is the driver that enables various debugging features -popular on platforms from certain mobile manufacturers. -n_tracerouter.c and n_tracesink.c allow extra system information to -be collected and routed to the pti driver, such as trace -debugging data from a modem. Although n_tracerouter -and n_tracesink are a part of the complete PTI solution, -these two line disciplines can work separately from -pti.c and route any data stream from one /dev/tty node -to another /dev/tty node via kernel-space. This provides -a stable, reliable connection that will not break unless -the user-space application shuts down (plus avoids -kernel->user->kernel context switch overheads of routing -data). - -An example debugging usage for this driver system: - *Hook /dev/ttyPTI0 to syslogd. Opening this port will also start - a console device to further capture debugging messages to PTI. - *Hook /dev/ttyPTI1 to modem debugging data to write to PTI HW. - This is where n_tracerouter and n_tracesink are used. - *Hook /dev/pti to a user-level debugging application for writing - to PTI HW. - *Use mipi_* Kernel Driver API in other device drivers for - debugging to PTI by first requesting a PTI write address via - mipi_request_masterchannel(1). - -Below is example pseudo-code on how a 'privileged' application -can hook up n_tracerouter and n_tracesink to any tty on -a system. 'Privileged' means the application has enough -privileges to successfully manipulate the ldisc drivers -but is not just blindly executing as 'root'. Keep in mind -the use of ioctl(,TIOCSETD,) is not specific to the n_tracerouter -and n_tracesink line discpline drivers but is a generic -operation for a program to use a line discpline driver -on a tty port other than the default n_tty. - -/////////// To hook up n_tracerouter and n_tracesink ///////// - -// Note that n_tracerouter depends on n_tracesink. -#include <errno.h> -#define ONE_TTY "/dev/ttyOne" -#define TWO_TTY "/dev/ttyTwo" - -// needed global to hand onto ldisc connection -static int g_fd_source = -1; -static int g_fd_sink = -1; - -// these two vars used to grab LDISC values from loaded ldisc drivers -// in OS. Look at /proc/tty/ldiscs to get the right numbers from -// the ldiscs loaded in the system. -int source_ldisc_num, sink_ldisc_num = -1; -int retval; - -g_fd_source = open(ONE_TTY, O_RDWR); // must be R/W -g_fd_sink = open(TWO_TTY, O_RDWR); // must be R/W - -if (g_fd_source <= 0) || (g_fd_sink <= 0) { - // doubt you'll want to use these exact error lines of code - printf("Error on open(). errno: %d\n",errno); - return errno; -} - -retval = ioctl(g_fd_sink, TIOCSETD, &sink_ldisc_num); -if (retval < 0) { - printf("Error on ioctl(). errno: %d\n", errno); - return errno; -} - -retval = ioctl(g_fd_source, TIOCSETD, &source_ldisc_num); -if (retval < 0) { - printf("Error on ioctl(). errno: %d\n", errno); - return errno; -} - -/////////// To disconnect n_tracerouter and n_tracesink //////// - -// First make sure data through the ldiscs has stopped. - -// Second, disconnect ldiscs. This provides a -// little cleaner shutdown on tty stack. -sink_ldisc_num = 0; -source_ldisc_num = 0; -ioctl(g_fd_uart, TIOCSETD, &sink_ldisc_num); -ioctl(g_fd_gadget, TIOCSETD, &source_ldisc_num); - -// Three, program closes connection, and cleanup: -close(g_fd_uart); -close(g_fd_gadget); -g_fd_uart = g_fd_gadget = NULL; |