Move redox_w into redox (#21448)

Co-authored-by: Ryan <fauxpark@gmail.com>

keyboards/redox/wireless/matrix.c

@@ -0,0 +1,70 @@
+/* Copyright 2017 Mattia Dal Ben
+ *
+ * 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"
+#include "matrix.h"
+#include "uart.h"
+
+#define UART_MATRIX_RESPONSE_TIMEOUT 10000
+
+void matrix_init_custom(void) {
+    uart_init(1000000);
+}
+
+bool matrix_scan_custom(matrix_row_t current_matrix[]) {
+    uint32_t timeout = 0;
+    bool changed = false;
+
+    //the s character requests the RF slave to send the matrix
+    uart_write('s');
+
+    //trust the external keystates entirely, erase the last data
+    uint8_t uart_data[11] = {0};
+
+    //there are 10 bytes corresponding to 10 columns, and then an end byte
+    for (uint8_t i = 0; i < 11; i++) {
+        //wait for the serial data, timeout if it's been too long
+        //this only happened in testing with a loose wire, but does no
+        //harm to leave it in here
+        while (!uart_available()) {
+            timeout++;
+            if (timeout > UART_MATRIX_RESPONSE_TIMEOUT) {
+                break;
+            }
+        }
+
+        if (timeout < UART_MATRIX_RESPONSE_TIMEOUT) {
+            uart_data[i] = uart_read();
+        } else {
+            uart_data[i] = 0x00;
+        }
+    }
+
+    //check for the end packet, the key state bytes use the LSBs, so 0xE0
+    //will only show up here if the correct bytes were recieved
+    if (uart_data[10] == 0xE0) {
+        //shifting and transferring the keystates to the QMK matrix variable
+        for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
+            matrix_row_t current_row = (uint16_t) uart_data[i * 2] | (uint16_t) uart_data[i * 2 + 1] << 7;
+            if (current_matrix[i] != current_row) {
+                changed = true;
+            }
+            current_matrix[i] = current_row;
+        }
+    }
+
+    return changed;
+}