[squashed] Several topics covered

* Migration to configurable work queue
  * Due to possible stall of the system_wq work queue
    SymSPI error recovery might be blocked by some agent, which
    uses the system_wq as well.
  * To separate the affected scopes, SymSPI was done configurable
    on which work queue to use: "SYMSPI_WQ_SYSTEM" - uses as before
    the global system work queue, "SYMSPI_WQ_SYSTEM_HIGHPRI" - uses
    high priority system global work queue, "SYMSPI_WQ_PRIVATE" -
    uses the current SymSPI dedicated workque with high priority.
    Macro/config name:
          SYMSPI_QUEUE_MODE
                  -> ["SYMSPI_WQ_SYSTEM", "SYMSPI_WQ_SYSTEM_HIGHPRI"
                      , "SYMSPI_WQ_PRIVATE"]
  * If it is SymSPI code which causes the stall, it will keep
    stalling, if other code causes the work queue stall, then this
    stall will not affect SymSPI in "private" work queue
    configuration.
  * Added also a bit of grooming to init and close procedures: they
    are separated in stages at least for now and symspi_close(...)
    can consistently continue from the point where symspi_init(...)
    left.

* A bit of logging update
  * Log level "trace" added.
  * SymSPI state switches, timer states, ISRs were moved to the
    trace level, otherwise they make debug info level unusable in
    a long run cause of too much flood per byte transfered.
  * A bit less verbose logging.

* Increased other side reaction wait timeout
  * To avoid error recovery for situations when we just
    we too slow, but function without error. So timeout must
    trigger the error recovery only when our "sloooow" reaction
    looks already like something nasty, so error recovery
    will execute its direct function: to purge/wake-up other
    side facilities if they got stalled somehow, so the system
    will keep functioning.

* Added configuration options:
  * other side reaction timeout,
  * workqueue mode selection.

* Added proc info entry to SymSPI
  * Allows to monitor the SymSPI state and configuration
    from User Space.

Author: Bosch-SW

src/Kconfig

@@ -46,3 +46,29 @@ config BOSCH_SYMSPI_TEST_MODULE
     depends on BOSCH_SYMSPI
     ---help---
         This flag enables the SYMSPI test module.
+
+config BOSCH_SYMSPI_THEIR_FLAG_WAIT_TIMEOUT_MSEC
+    int "Max other side reaction time [ms]"
+    default 60
+    range 20 1000
+    depends on BOSCH_SYMSPI
+    ---help---
+        Defines how much time we will wait for other side
+        reaction [ms], before starting the error recovery
+        sequence
+
+config BOSCH_SYMSPI_WORKQUEUE_MODE
+    int "SymSPI WQ mode: 0 - system, 1 - system-highprio, 2 - private-highprio"
+    default 2
+    range 0 2
+    depends on BOSCH_SYMSPI
+    ---help---
+        Defines which workqueue SymSPI should use to process the
+        incoming data, valid values:
+        0 - use the global system workqueue,
+        1 - use the global system high priority workqueue,
+        2 - use private high priority workqueue,
+        The higher the value the higher priority an less
+        dependencies SymSPI data processing will have. Use
+        higher value when SymSPI processes time-critical information
+        and shall not be blocked by other system facilities.

src/Makefile

@@ -15,3 +15,19 @@ obj-$(CONFIG_BOSCH_SYMSPI) += symspi.o
 ifeq ($(CONFIG_BOSCH_SYMSPI_TEST_MODULE), y)
     obj-$(CONFIG_BOSCH_SYMSPI) += symspi_test.o
 endif
+
+ifdef CONFIG_BOSCH_SYMSPI_THEIR_FLAG_WAIT_TIMEOUT_MSEC
+ccflags-y +=\
+    -DSYMSPI_THEIR_FLAG_WAIT_TIMEOUT_MSEC=${CONFIG_BOSCH_SYMSPI_THEIR_FLAG_WAIT_TIMEOUT_MSEC}
+endif
+
+ifeq (${CONFIG_BOSCH_SYMSPI_WORKQUEUE_MODE}, 0)
+ccflags-y +=\
+    -DSYMSPI_WORKQUEUE_MODE=SYMSPI_WQ_SYSTEM
+else ifeq (${CONFIG_BOSCH_SYMSPI_WORKQUEUE_MODE}, 1)
+ccflags-y +=\
+    -DSYMSPI_WORKQUEUE_MODE=SYMSPI_WQ_SYSTEM_HIGHPRI
+else ifeq (${CONFIG_BOSCH_SYMSPI_WORKQUEUE_MODE}, 2)
+ccflags-y +=\
+    -DSYMSPI_WORKQUEUE_MODE=SYMSPI_WQ_PRIVATE
+endif