lib: utils/reset: Add Andes fdt reset driver support

Add ATCWDT200 as reset device of AE350 platform, this driver requires
SMU to program the reset vector registers before triggering WDT software
restart signal.

dts example:

  smu@f0100000 {
    compatible = "andestech,atcsmu";
    reg = <0x00000000 0xf0100000 0x00000000 0x00001000>;
  };

  wdt: wdt@f0500000 {
    compatible = "andestech,atcwdt200";
    reg = <0x00000000 0xf0500000 0x00000000 0x00001000>;
    interrupts = <3 4>;
    interrupt-parent = <&plic0>;
    clock-frequency = <15000000>;
  };

Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

lib/utils/reset/Kconfig

@@ -9,6 +9,10 @@ config FDT_RESET
 
 if FDT_RESET
 
+config FDT_RESET_ATCWDT200
+	bool "Andes WDT FDT reset driver"
+	default n
+
 config FDT_RESET_GPIO
 	bool "GPIO FDT reset driver"
 	depends on FDT_GPIO

lib/utils/reset/fdt_reset_atcwdt200.c

@@ -0,0 +1,122 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 Andes Technology Corporation
+ *
+ * Authors:
+ *   Yu Chien Peter Lin <peterlin@andestech.com>
+ */
+
+#include <libfdt.h>
+#include <sbi/riscv_io.h>
+#include <sbi/sbi_ecall_interface.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_hart.h>
+#include <sbi/sbi_platform.h>
+#include <sbi/sbi_system.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/reset/fdt_reset.h>
+
+#define ATCWDT200_WP_NUM 0x5aa5
+#define WREN_REG 0x18
+#define CTRL_REG 0x10
+#define RST_TIME_OFF 8
+#define RST_TIME_MSK (0x3 << RST_TIME_OFF)
+#define RST_CLK_128 (0 << RST_TIME_OFF)
+#define RST_CLK_256 (1 << RST_TIME_OFF)
+#define RST_CLK_512 (2 << RST_TIME_OFF)
+#define RST_CLK_1024 (3 << RST_TIME_OFF)
+#define INT_TIME_OFF 4
+#define INT_TIME_MSK (0xf << INT_TIME_OFF)
+#define INT_CLK_64 (0 << INT_TIME_OFF)
+#define INT_CLK_256 (1 << INT_TIME_OFF)
+#define INT_CLK_1024 (2 << INT_TIME_OFF)
+#define INT_CLK_2048 (3 << INT_TIME_OFF)
+#define INT_CLK_4096 (4 << INT_TIME_OFF)
+#define INT_CLK_8192 (5 << INT_TIME_OFF)
+#define INT_CLK_16384 (6 << INT_TIME_OFF)
+#define INT_CLK_32768 (7 << INT_TIME_OFF)
+#define RST_EN (1 << 3)
+#define INT_EN (1 << 2)
+#define CLK_PCLK (1 << 1)
+#define WDT_EN (1 << 0)
+
+#define FLASH_BASE 0x80000000ULL
+#define SMU_RESET_VEC_LO_OFF 0x50
+#define SMU_RESET_VEC_HI_OFF 0x60
+#define SMU_HARTn_RESET_VEC_LO(n) (SMU_RESET_VEC_LO_OFF + (n * 0x4))
+#define SMU_HARTn_RESET_VEC_HI(n) (SMU_RESET_VEC_HI_OFF + (n * 0x4))
+
+static volatile char *wdt_addr;
+static volatile char *smu_addr;
+
+static int ae350_system_reset_check(u32 type, u32 reason)
+{
+	switch (type) {
+	case SBI_SRST_RESET_TYPE_COLD_REBOOT:
+		return 1;
+	case SBI_SRST_RESET_TYPE_SHUTDOWN:
+	case SBI_SRST_RESET_TYPE_WARM_REBOOT:
+	default:
+		return 0;
+	}
+}
+
+static void ae350_system_reset(u32 type, u32 reason)
+{
+	const struct sbi_platform *plat = sbi_platform_thishart_ptr();
+
+	for (int i = 0; i < sbi_platform_hart_count(plat); i++) {
+		writel(FLASH_BASE, smu_addr + SMU_HARTn_RESET_VEC_LO(i));
+		writel(FLASH_BASE >> 32, smu_addr + SMU_HARTn_RESET_VEC_HI(i));
+	}
+
+	/* Program WDT control register  */
+	writew(ATCWDT200_WP_NUM, wdt_addr + WREN_REG);
+	writel(INT_CLK_32768 | INT_EN | RST_CLK_128 | RST_EN | WDT_EN,
+	       wdt_addr + CTRL_REG);
+
+	sbi_hart_hang();
+}
+
+static struct sbi_system_reset_device atcwdt200_reset = {
+	.name		    = "atcwdt200",
+	.system_reset_check = ae350_system_reset_check,
+	.system_reset	    = ae350_system_reset,
+};
+
+static int atcwdt200_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;
+
+	wdt_addr = (volatile char *)(unsigned long)reg_addr;
+
+	/*
+	 * The reset device requires smu to program the reset
+	 * vector for each hart.
+	 */
+	if (fdt_parse_compat_addr(fdt, &reg_addr, "andestech,atcsmu"))
+		return SBI_ENODEV;
+
+	smu_addr = (volatile char *)(unsigned long)reg_addr;
+
+	sbi_system_reset_add_device(&atcwdt200_reset);
+
+	return 0;
+}
+
+static const struct fdt_match atcwdt200_reset_match[] = {
+	{ .compatible = "andestech,atcwdt200" },
+	{},
+};
+
+struct fdt_reset fdt_reset_atcwdt200 = {
+	.match_table = atcwdt200_reset_match,
+	.init	     = atcwdt200_reset_init,
+};

lib/utils/reset/objects.mk

@@ -10,6 +10,9 @@
 libsbiutils-objs-$(CONFIG_FDT_RESET) += reset/fdt_reset.o
 libsbiutils-objs-$(CONFIG_FDT_RESET) += reset/fdt_reset_drivers.o
 
+carray-fdt_reset_drivers-$(CONFIG_FDT_RESET_ATCWDT200) += fdt_reset_atcwdt200
+libsbiutils-objs-$(CONFIG_FDT_RESET_ATCWDT200) += reset/fdt_reset_atcwdt200.o
+
 carray-fdt_reset_drivers-$(CONFIG_FDT_RESET_GPIO) += fdt_poweroff_gpio
 carray-fdt_reset_drivers-$(CONFIG_FDT_RESET_GPIO) += fdt_reset_gpio
 libsbiutils-objs-$(CONFIG_FDT_RESET_GPIO) += reset/fdt_reset_gpio.o

platform/andes/ae350/Kconfig

@@ -8,6 +8,8 @@ config PLATFORM_ANDES_AE350
 	select FDT_SERIAL_UART8250
 	select FDT_TIMER
 	select FDT_TIMER_PLMT
+	select FDT_RESET
+	select FDT_RESET_ATCWDT200
 	default y
 
 if PLATFORM_ANDES_AE350

platform/andes/ae350/platform.c

@@ -18,6 +18,7 @@
 #include <sbi_utils/fdt/fdt_helper.h>
 #include <sbi_utils/fdt/fdt_fixup.h>
 #include <sbi_utils/irqchip/plic.h>
+#include <sbi_utils/reset/fdt_reset.h>
 #include <sbi_utils/serial/fdt_serial.h>
 #include <sbi_utils/timer/fdt_timer.h>
 #include "platform.h"
@@ -37,6 +38,8 @@ static int ae350_final_init(bool cold_boot)
 	if (!cold_boot)
 		return 0;
 
+	fdt_reset_init();
+
 	fdt = fdt_get_address();
 	fdt_fixups(fdt);