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| -rw-r--r-- | Documentation/pti/pti_intel_mid.rst | 106 | ||||
| -rw-r--r-- | Documentation/pti/pti_intel_mid.txt | 99 |
2 files changed, 106 insertions, 99 deletions
diff --git a/Documentation/pti/pti_intel_mid.rst b/Documentation/pti/pti_intel_mid.rst new file mode 100644 index 000000000000..ea05725174cb --- /dev/null +++ b/Documentation/pti/pti_intel_mid.rst @@ -0,0 +1,106 @@ +:orphan: + +============= +Intel MID PTI +============= + +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; 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; |