rockchip: check download key before bootup

Enter download mode if the download key pressed.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
[Converted printfs in boot_mode.c to debug/pr_err:]
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

arch/arm/mach-rockchip/boot_mode.c

@@ -5,26 +5,69 @@
  */
 
 #include <common.h>
+#include <adc.h>
 #include <asm/io.h>
 #include <asm/arch/boot_mode.h>
 
+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);
+	}
+}
+
 int setup_boot_mode(void)
 {
 	void *reg = (void *)CONFIG_ROCKCHIP_BOOT_MODE_REG;
 	int boot_mode = readl(reg);
 
-	debug("boot mode %x.\n", boot_mode);
+	rockchip_dnl_mode_check();
+
+	boot_mode = readl(reg);
+	debug("%s: boot mode 0x%08x\n", __func__, boot_mode);
 
 	/* Clear boot mode */
 	writel(BOOT_NORMAL, reg);
 
 	switch (boot_mode) {
 	case BOOT_FASTBOOT:
-		printf("enter fastboot!\n");
+		debug("%s: enter fastboot!\n", __func__);
 		env_set("preboot", "setenv preboot; fastboot usb0");
 		break;
 	case BOOT_UMS:
-		printf("enter UMS!\n");
+		debug("%s: enter UMS!\n", __func__);
 		env_set("preboot", "setenv preboot; ums mmc 0");
 		break;
 	}