stepper: Support disabling optimized "step on both edges" in "make menuconfig"

Add a new "low level option" to allow users to configure if they want
to optimize for Trinamic drivers or traditional stepper motor drivers.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/Kconfig

@@ -201,6 +201,29 @@ config CANBUS_FILTER
     bool
     default y if CANSERIAL
 
+# Stepper optimizations
+config INLINE_STEPPER_HACK
+    # Enables gcc to inline stepper_event() into the main timer irq handler
+    bool
+    depends on HAVE_GPIO
+    default y
+config HAVE_STEPPER_OPTIMIZED_BOTH_EDGE
+    bool
+config WANT_STEPPER_OPTIMIZED_BOTH_EDGE
+    bool "Optimize stepper code for 'step on both edges'" if LOW_LEVEL_OPTIONS
+    depends on INLINE_STEPPER_HACK && HAVE_STEPPER_OPTIMIZED_BOTH_EDGE
+    default y
+    help
+        Optimize the stepper code for Trinamic stepper motor drivers
+        that are configured in UART or SPI mode (and thus can perform
+        a step on both "edges" of the step pin).  Enabling this option
+        typically improves the stepper cpu performance by about 20%
+        when using these drivers.  If this option is disabled the code
+        will instead deploy optimizations that improve the cpu
+        performance by about 20% for traditional drivers (those that
+        take a step only on the "rising" or "falling" level of the
+        step pin).
+
 # Support setting gpio state at startup
 config INITIAL_PINS
     string "GPIO pins to set at micro-controller startup"
@@ -229,15 +252,7 @@ config HAVE_STRICT_TIMING
     bool
 config HAVE_CHIPID
     bool
-config HAVE_STEPPER_OPTIMIZED_BOTH_EDGE
-    bool
 config HAVE_BOOTLOADER_REQUEST
     bool
 config HAVE_LIMITED_CODE_SIZE
     bool
-
-config INLINE_STEPPER_HACK
-    # Enables gcc to inline stepper_event() into the main timer irq handler
-    bool
-    depends on HAVE_GPIO
-    default y

src/stepper.c

@@ -16,7 +16,7 @@
 
 DECL_CONSTANT("STEPPER_STEP_BOTH_EDGE", 1);
 
-#if CONFIG_INLINE_STEPPER_HACK && CONFIG_HAVE_STEPPER_OPTIMIZED_BOTH_EDGE
+#if CONFIG_INLINE_STEPPER_HACK && CONFIG_WANT_STEPPER_OPTIMIZED_BOTH_EDGE
  #define HAVE_OPTIMIZED_PATH 1
  #define HAVE_EDGE_OPTIMIZATION 1
  #define HAVE_AVR_OPTIMIZATION 0