imx: dynamic setting mmcdev and mmcroot

Dynamic setting mmcdev and mmcroot.
Then when boot linux, we can have correct "root=/dev/mmcblk[x]p2"

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/board/freescale/common/mmc.c b/board/freescale/common/mmc.c
new file mode 100644
index 0000000..8cd5079
--- /dev/null
+++ b/board/freescale/common/mmc.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2016 Freescale Semiconductor, Inc.
+ * Copyright 2018-2022 NXP
+ */
+
+#include <common.h>
+#include <command.h>
+#include <asm/arch/sys_proto.h>
+#include <linux/errno.h>
+#include <asm/io.h>
+#include <stdbool.h>
+#include <mmc.h>
+#include <env.h>
+
+static int check_mmc_autodetect(void)
+{
+	char *autodetect_str = env_get("mmcautodetect");
+
+	if (autodetect_str && !strcmp(autodetect_str, "yes"))
+		return 1;
+
+	return 0;
+}
+
+/* This should be defined for each board */
+__weak int mmc_map_to_kernel_blk(int dev_no)
+{
+	return dev_no;
+}
+
+void board_late_mmc_env_init(void)
+{
+	char cmd[32];
+	char mmcblk[32];
+	u32 dev_no = mmc_get_env_dev();
+
+	if (!check_mmc_autodetect())
+		return;
+
+	env_set_ulong("mmcdev", dev_no);
+
+	/* Set mmcblk env */
+	sprintf(mmcblk, "/dev/mmcblk%dp2 rootwait rw", mmc_map_to_kernel_blk(dev_no));
+	env_set("mmcroot", mmcblk);
+
+	sprintf(cmd, "mmc dev %d", dev_no);
+	run_command(cmd, 0);
+}