[Keyboard] Add Lagom keyboard (#19240)

Co-authored-by: Drashna Jaelre <drashna@live.com>

keyboards/sthlmkb/lagom/matrix.c

@@ -0,0 +1,95 @@
+/* Copyright 2022 mohoyt
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "quantum.h"
+
+#define COL_SHIFTER ((uint32_t)1)
+
+// Column pins
+static const uint8_t row_pins[MATRIX_ROWS] = MATRIX_ROW_PINS;
+static const uint8_t col_pins[MATRIX_MUX_COLS] = MATRIX_COL_MUX_PINS;
+
+// Internal functions
+
+static void init_pins(void) {
+    // Set cols to outputs, low
+    for (uint8_t pin = 0; pin < MATRIX_MUX_COLS; pin++) {
+        setPinOutput(col_pins[pin]);
+    }
+
+    // Unselect cols
+    for (uint8_t bit = 0; bit < MATRIX_MUX_COLS; bit++) {
+        writePinLow(col_pins[bit]);
+    }
+
+    // Set rows to input, pullup
+    for (uint8_t pin = 0; pin < MATRIX_ROWS; pin++) {
+        setPinInputHigh(row_pins[pin]);
+    }
+}
+
+static void select_col(uint8_t col)
+{
+    for (uint8_t bit = 0; bit < MATRIX_MUX_COLS; bit++) {
+        uint8_t state = (col & (0b1 << bit)) >> bit;
+        writePin(col_pins[bit], state);
+    }
+}
+
+static bool read_rows_on_col(matrix_row_t current_matrix[], uint8_t current_col)
+{
+    bool matrix_changed = false;
+    select_col(current_col);
+    wait_us(5);
+
+    // Read each row sequentially
+    for(uint8_t row_index = 0; row_index < MATRIX_ROWS; row_index++)
+    {
+        matrix_row_t last_row_value = current_matrix[row_index];
+
+        if (!readPin(row_pins[row_index]))
+        {
+            current_matrix[row_index] |= (COL_SHIFTER << current_col);
+        }
+        else
+        {
+            current_matrix[row_index] &= ~(COL_SHIFTER << current_col);
+        }
+
+        if ((last_row_value != current_matrix[row_index]) && !(matrix_changed))
+        {
+            matrix_changed = true;
+        }
+    }
+
+    return matrix_changed;
+}
+
+// Matrix scan functions
+
+void matrix_init_custom(void) {
+    init_pins();
+}
+
+bool matrix_scan_custom(matrix_row_t current_matrix[]) {
+    bool changed = false;
+
+    //Set col, read rows
+    for (uint8_t current_col = 0; current_col < MATRIX_COLS; current_col++) {
+        changed |= read_rows_on_col(current_matrix, current_col);
+    }
+
+    return (uint8_t)changed;
+}