+int32_t _stlink_usb_target_voltage(stlink_t *sl) {
+ struct stlink_libusb * const slu = sl->backend_data;
+ unsigned char* const rdata = sl->q_buf;
+ unsigned char* const cmd = sl->c_buf;
+ ssize_t size;
+ uint32_t rep_len = 8;
+ int i = fill_command(sl, SG_DXFER_FROM_DEV, rep_len);
+ uint32_t factor, reading;
+ int voltage;
+
+ cmd[i++] = STLINK_GET_TARGET_VOLTAGE;
+
+ size = send_recv(slu, 1, cmd, slu->cmd_len, rdata, rep_len);
+ if (size == -1) {
+ printf("[!] send_recv\n");
+ return -1;
+ } else if (size != 8) {
+ printf("[!] wrong length\n");
+ return -1;
+ }
+
+ factor = (rdata[3] << 24) | (rdata[2] << 16) | (rdata[1] << 8) | (rdata[0] << 0);
+ reading = (rdata[7] << 24) | (rdata[6] << 16) | (rdata[5] << 8) | (rdata[4] << 0);
+ voltage = 2400 * reading / factor;
+
+ return voltage;
+}
+