uboot-mediatek: mt7986: add generic reset button support

Allow resetting environment to default values when defined button
exists in device tree.

Signed-off-by: Daniel Golle <[email protected]>

package/boot/uboot-mediatek/patches/303-mt7986-generic-reset-button-ignore-env.patch

@@ -0,0 +1,40 @@
+--- a/board/mediatek/mt7986/mt7986_rfb.c
++++ b/board/mediatek/mt7986/mt7986_rfb.c
+@@ -6,9 +6,16 @@
+ 
+ #include <common.h>
+ #include <config.h>
++#include <dm.h>
++#include <button.h>
+ #include <env.h>
+ #include <init.h>
+ #include <asm/global_data.h>
++#include <linux/delay.h>
++
++#ifndef CONFIG_RESET_BUTTON_LABEL
++#define CONFIG_RESET_BUTTON_LABEL "reset"
++#endif
+ 
+ #include <mtd.h>
+ #include <linux/mtd/mtd.h>
+@@ -25,7 +32,19 @@ int board_init(void)
+ 
+ int board_late_init(void)
+ {
+-	gd->env_valid = 1; //to load environment variable from persistent store
++	struct udevice *dev;
++
++	gd->env_valid = ENV_VALID;
++	if (!button_get_by_label(CONFIG_RESET_BUTTON_LABEL, &dev)) {
++		puts("reset button found\n");
++#ifdef CONFIG_RESET_BUTTON_SETTLE_DELAY
++		mdelay(CONFIG_RESET_BUTTON_SETTLE_DELAY);
++#endif
++		if (button_get_state(dev) == BUTTON_ON) {
++			puts("button pushed, resetting environment\n");
++			gd->env_valid = ENV_INVALID;
++		}
++	}
+ 	env_relocate();
+ 	return 0;
+ }