+void set_back_to_bootrom_dnl_flag(void)
+{
+ writel(BOOT_BROM_DOWNLOAD, CONFIG_ROCKCHIP_BOOT_MODE_REG);
+}
+
+/*
+ * detect download key status by adc, most rockchip
+ * based boards use adc sample the download key status,
+ * but there are also some use gpio. So it's better to
+ * make this a weak function that can be override by
+ * some special boards.
+ */
+#define KEY_DOWN_MIN_VAL 0
+#define KEY_DOWN_MAX_VAL 30
+
+__weak int rockchip_dnl_key_pressed(void)
+{
+ unsigned int val;
+
+ if (adc_channel_single_shot("saradc", 1, &val)) {
+ pr_err("%s: adc_channel_single_shot fail!\n", __func__);
+ return false;
+ }
+
+ if ((val >= KEY_DOWN_MIN_VAL) && (val <= KEY_DOWN_MAX_VAL))
+ return true;
+ else
+ return false;
+}
+
+void rockchip_dnl_mode_check(void)
+{
+ if (rockchip_dnl_key_pressed()) {
+ printf("download key pressed, entering download mode...");
+ set_back_to_bootrom_dnl_flag();
+ do_reset(NULL, 0, 0, NULL);
+ }
+}
+