add DIP_SWITCH_MATRIX_GRID support (qmk#8772)

* dipsw test on helix/rev2/sc/back:five_rows

* add peek_matrix() to matrix_common.c

* add DIP_SWITCH_MATRIX_GRID support to quantum/dip_switch.c

* update docs/feature_dip_switch.md about DIP_SWITCH_MATRIX_GRID

* Test end. remove test code. Revert "dipsw test on helix/rev2/sc/back:five_rows"

This reverts commit 6d4304c74557597c9fb4d324f79c3ae4793ae874.

format code according to conventions [skip ci]

quantum/dip_switch.c

@@ -21,16 +21,33 @@
 // for memcpy
 #include <string.h>
 
+#if !defined(DIP_SWITCH_PINS) && !defined(DIP_SWITCH_MATRIX_GRID)
+#    error "Either DIP_SWITCH_PINS or DIP_SWITCH_MATRIX_GRID must be defined."
+#endif
 
-#if !defined(DIP_SWITCH_PINS)
-#   error "No DIP switch pads defined by DIP_SWITCH_PINS"
+#if defined(DIP_SWITCH_PINS) && defined(DIP_SWITCH_MATRIX_GRID)
+#    error "Both DIP_SWITCH_PINS and DIP_SWITCH_MATRIX_GRID are defined."
 #endif
 
-#define NUMBER_OF_DIP_SWITCHES (sizeof(dip_switch_pad)/sizeof(pin_t))
+#ifdef DIP_SWITCH_PINS
+#    define NUMBER_OF_DIP_SWITCHES (sizeof(dip_switch_pad) / sizeof(pin_t))
 static pin_t dip_switch_pad[] = DIP_SWITCH_PINS;
-static bool dip_switch_state[NUMBER_OF_DIP_SWITCHES] = { 0 };
-static bool last_dip_switch_state[NUMBER_OF_DIP_SWITCHES] = { 0 };
+#endif
+
+#ifdef DIP_SWITCH_MATRIX_GRID
+typedef struct matrix_index_t {
+    uint8_t row;
+    uint8_t col;
+} matrix_index_t;
+
+#    define NUMBER_OF_DIP_SWITCHES (sizeof(dip_switch_pad) / sizeof(matrix_index_t))
+static matrix_index_t dip_switch_pad[] = DIP_SWITCH_MATRIX_GRID;
+extern bool           peek_matrix(uint8_t row_index, uint8_t col_index, bool read_raw);
+static uint16_t       scan_count;
+#endif /* DIP_SWITCH_MATRIX_GRID */
 
+static bool dip_switch_state[NUMBER_OF_DIP_SWITCHES]      = {0};
+static bool last_dip_switch_state[NUMBER_OF_DIP_SWITCHES] = {0};
 
 __attribute__((weak))
 void dip_switch_update_user(uint8_t index, bool active) {}
@@ -45,19 +62,43 @@ __attribute__((weak))
 void dip_switch_update_mask_kb(uint32_t state) { dip_switch_update_mask_user(state); }
 
 void dip_switch_init(void) {
-  for (uint8_t i = 0; i < NUMBER_OF_DIP_SWITCHES; i++) {
-    setPinInputHigh(dip_switch_pad[i]);
-  }
-  dip_switch_read(true);
+#ifdef DIP_SWITCH_PINS
+    for (uint8_t i = 0; i < NUMBER_OF_DIP_SWITCHES; i++) {
+        setPinInputHigh(dip_switch_pad[i]);
+    }
+    dip_switch_read(true);
+#endif
+#ifdef DIP_SWITCH_MATRIX_GRID
+    scan_count = 0;
+#endif
 }
 
 
 void dip_switch_read(bool forced) {
     bool has_dip_state_changed = false;
     uint32_t dip_switch_mask = 0;
 
+#ifdef DIP_SWITCH_MATRIX_GRID
+    bool read_raw = false;
+
+    if (scan_count < 500) {
+        scan_count++;
+        if (scan_count == 10) {
+            read_raw = true;
+            forced   = true; /* First reading of the dip switch */
+        } else {
+            return;
+        }
+    }
+#endif
+
     for (uint8_t i = 0; i < NUMBER_OF_DIP_SWITCHES; i++) {
+#ifdef DIP_SWITCH_PINS
         dip_switch_state[i] = !readPin(dip_switch_pad[i]);
+#endif
+#ifdef DIP_SWITCH_MATRIX_GRID
+        dip_switch_state[i] = peek_matrix(dip_switch_pad[i].row, dip_switch_pad[i].col, read_raw);
+#endif
         dip_switch_mask |= dip_switch_state[i] << i;
         if (last_dip_switch_state[i] != dip_switch_state[i] || forced) {
             has_dip_state_changed = true;

quantum/matrix_common.c

@@ -112,3 +112,5 @@ __attribute__((weak)) uint8_t matrix_scan(void) {
     matrix_scan_quantum();
     return changed;
 }
+
+__attribute__((weak)) bool peek_matrix(uint8_t row_index, uint8_t col_index, bool raw) { return 0 != ((raw ? raw_matrix[row_index] : matrix[row_index]) & (MATRIX_ROW_SHIFTER << col_index)); }