MIPS: Loongson64: Add Loongson-2K1000 reset platform driver

Add power management register operations to support reboot and poweroff.

Signed-off-by: Qing Zhang <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

drivers/platform/mips/Kconfig

···
 	help
 	  Loongson RS780E PCH ACPI Controller driver.
 
+config LS2K_RESET
+	bool "Loongson-2K1000 Reset Controller"
+	depends on MACH_LOONGSON64 || COMPILE_TEST
+	help
+	  Loongson-2K1000 Reset Controller driver.
+
 endif # MIPS_PLATFORM_DEVICES

drivers/platform/mips/Makefile

···
 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_CPU_HWMON) += cpu_hwmon.o
 obj-$(CONFIG_RS780E_ACPI) += rs780e-acpi.o
+obj-$(CONFIG_LS2K_RESET) += ls2k-reset.o

drivers/platform/mips/ls2k-reset.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2021, Qing Zhang <[e-mail]>
+ *  Loongson-2K1000 reset support
+ */
+
+#include <linux/of_address.h>
+#include <linux/pm.h>
+#include <asm/reboot.h>
+
+#define	PM1_STS		0x0c /* Power Management 1 Status Register */
+#define	PM1_CNT		0x14 /* Power Management 1 Control Register */
+#define	RST_CNT		0x30 /* Reset Control Register */
+
+static void __iomem *base;
+
+static void ls2k_restart(char *command)
+{
+	writel(0x1, base + RST_CNT);
+}
+
+static void ls2k_poweroff(void)
+{
+	/* Clear */
+	writel((readl(base + PM1_STS) & 0xffffffff), base + PM1_STS);
+	/* Sleep Enable | Soft Off*/
+	writel(GENMASK(12, 10) | BIT(13), base + PM1_CNT);
+}
+
+static int ls2k_reset_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_compatible_node(NULL, NULL, "loongson,ls2k-pm");
+	if (!np) {
+		pr_info("Failed to get PM node\n");
+		return -ENODEV;
+	}
+
+	base = of_iomap(np, 0);
+	if (!base) {
+		pr_info("Failed to map PM register base address\n");
+		return -ENOMEM;
+	}
+
+	_machine_restart = ls2k_restart;
+	pm_power_off = ls2k_poweroff;
+
+	of_node_put(np);
+	return 0;
+}
+
+arch_initcall(ls2k_reset_init);