text: /*
   * SPDX-License-Identifier: BSD-2-Clause
   *
   * Copyright (c) 2021 Samuel Holland <samuel@sholland.org>
   */
  
  #include <libfdt.h>
  #include <sbi/riscv_io.h>
  #include <sbi/sbi_bitops.h>
  #include <sbi/sbi_error.h>
  #include <sbi/sbi_system.h>
  #include <sbi_utils/fdt/fdt_helper.h>
  #include <sbi_utils/reset/fdt_reset.h>
  
  #define WDT_KEY_VAL			0x16aa0000
  
  #define WDT_SOFT_RST_REG		0x08
  #define WDT_SOFT_RST_EN			BIT(0)
  
  #define WDT_MODE_REG			0x18
  
  static volatile char *sunxi_wdt_base;
  
  static int sunxi_wdt_system_reset_check(u32 type, u32 reason)
  {
  	switch (type) {
  	case SBI_SRST_RESET_TYPE_COLD_REBOOT:
  	case SBI_SRST_RESET_TYPE_WARM_REBOOT:
  		return 1;
  	}
  
  	return 0;
  }
  
  static void sunxi_wdt_system_reset(u32 type, u32 reason)
  {
  	/* Disable the watchdog. */
  	writel_relaxed(WDT_KEY_VAL,
  		       sunxi_wdt_base + WDT_MODE_REG);
  
  	/* Trigger soft reset. */
  	writel_relaxed(WDT_KEY_VAL | WDT_SOFT_RST_EN,
  		       sunxi_wdt_base + WDT_SOFT_RST_REG);
  }
  
  static struct sbi_system_reset_device sunxi_wdt_reset = {
  	.name = "sunxi-wdt-reset",
  	.system_reset_check = sunxi_wdt_system_reset_check,
  	.system_reset = sunxi_wdt_system_reset,
  };
  
  static int sunxi_wdt_reset_init(void *fdt, int nodeoff,
  				const struct fdt_match *match)
  {
  	uint64_t reg_addr;
  	int rc;
  
  	rc = fdt_get_node_addr_size(fdt, nodeoff, 0, &reg_addr, NULL);
  	if (rc < 0 || !reg_addr)
  		return SBI_ENODEV;
  
  	sunxi_wdt_base = (volatile char *)(unsigned long)reg_addr;
  
  	sbi_system_reset_add_device(&sunxi_wdt_reset);
  
  	return 0;
  }
  
  static const struct fdt_match sunxi_wdt_reset_match[] = {
  	{ .compatible = "allwinner,sun20i-d1-wdt-reset" },
  	{ },
  };
  
  struct fdt_reset fdt_reset_sunxi_wdt = {
  	.match_table = sunxi_wdt_reset_match,
  	.init = sunxi_wdt_reset_init,
  };
  