poweroff: add poweroff for mt6323 pmic

this adds poweroff to bananapi r2 / mt7623 / mt6323 pmic

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
diff --git a/drivers/power/mt6323.c b/drivers/power/mt6323.c
new file mode 100644
index 0000000..566be5f
--- /dev/null
+++ b/drivers/power/mt6323.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Frank Wunderlich <frank-w@public-files.de>
+ */
+
+#include <common.h>
+#include <command.h>
+#include <asm/io.h>
+
+#define PWRAP_BASE		0x1000d000
+#define PWRAP_WACS2_CMD		0x9c
+
+#define PWRAP_CALC(adr, wdata) ((1 << 31) | (((adr) >> 1) << 16) | (wdata))
+
+#define MT6323_PWRC_BASE	0x8000
+#define RTC_BBPU		0x0000
+#define RTC_BBPU_KEY		(0x43 << 8)
+#define RTC_WRTGR		0x003c
+
+int do_poweroff(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	u32 addr, val;
+
+	addr = PWRAP_BASE + PWRAP_WACS2_CMD;
+	val = PWRAP_CALC(MT6323_PWRC_BASE + RTC_BBPU, RTC_BBPU_KEY);
+	writel(val, addr);
+
+	mdelay(10);
+
+	val = PWRAP_CALC(MT6323_PWRC_BASE + RTC_WRTGR, 1);
+	writel(val, addr);
+
+	// wait some time and then print error
+	mdelay(10000);
+	printf("Failed to power off!!!\n");
+	return 1;
+}