lib: utils/reset: Add litex SoC reset driver

Litex SoC controller supports reboot function by toggling the first
bit of the ctrl register. Add a reset driver so other software can
use it.

Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260529085234.1682842-1-inochiama@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>

lib/utils/reset/fdt_reset_litex.c

@@ -0,0 +1,66 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2026 Inochi Amaoto <inochiama@gmail.com>
+ */
+
+#include <libfdt.h>
+#include <sbi/riscv_io.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_system.h>
+#include <sbi_utils/fdt/fdt_driver.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+
+#define RESET_CTRL			0x0
+
+static volatile u32 *litex_soc_base;
+
+static int litex_reset_check(u32 type, u32 reason)
+{
+	switch (type) {
+	case SBI_SRST_RESET_TYPE_COLD_REBOOT:
+	case SBI_SRST_RESET_TYPE_WARM_REBOOT:
+		return 255;
+	}
+
+	return 0;
+}
+
+static void litex_do_reset(u32 type, u32 reason)
+{
+	writel_relaxed(0x1, litex_soc_base + RESET_CTRL);
+}
+
+static struct sbi_system_reset_device litex_reset = {
+	.name = "litex-reset",
+	.system_reset_check = litex_reset_check,
+	.system_reset = litex_do_reset
+};
+
+static int litex_reset_init(const 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;
+
+
+	litex_soc_base = (volatile u32 *)(unsigned long)reg_addr;
+
+	sbi_system_reset_add_device(&litex_reset);
+
+	return 0;
+}
+
+static const struct fdt_match litex_reset_match[] = {
+	{ .compatible = "litex,soc-controller" },
+	{ },
+};
+
+const struct fdt_driver fdt_reset_litex = {
+	.match_table = litex_reset_match,
+	.init = litex_reset_init,
+};