LoongArch: Add hibernation (ACPI S4) support

Add hibernation (Suspend to Disk, aka ACPI S4) support for LoongArch.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/Kconfig

@@ -521,6 +521,9 @@ menu "Power management options"
 config ARCH_SUSPEND_POSSIBLE
 	def_bool y
 
+config ARCH_HIBERNATION_POSSIBLE
+	def_bool y
+
 source "kernel/power/Kconfig"
 source "drivers/acpi/Kconfig"
 

arch/loongarch/kernel/asm-offsets.c

@@ -257,3 +257,15 @@ void output_smpboot_defines(void)
 	BLANK();
 }
 #endif
+
+#ifdef CONFIG_HIBERNATION
+void output_pbe_defines(void)
+{
+	COMMENT(" Linux struct pbe offsets. ");
+	OFFSET(PBE_ADDRESS, pbe, address);
+	OFFSET(PBE_ORIG_ADDRESS, pbe, orig_address);
+	OFFSET(PBE_NEXT, pbe, next);
+	DEFINE(PBE_SIZE, sizeof(struct pbe));
+	BLANK();
+}
+#endif

arch/loongarch/kernel/reset.c

@@ -15,6 +15,7 @@
 #include <acpi/reboot.h>
 #include <asm/idle.h>
 #include <asm/loongarch.h>
+#include <asm/loongson.h>
 
 void (*pm_power_off)(void);
 EXPORT_SYMBOL(pm_power_off);
@@ -41,6 +42,10 @@ void machine_power_off(void)
 #ifdef CONFIG_SMP
 	preempt_disable();
 	smp_send_stop();
+#endif
+#ifdef CONFIG_PM
+	if (!acpi_disabled)
+		enable_pci_wakeup();
 #endif
 	do_kernel_power_off();
 #ifdef CONFIG_EFI

arch/loongarch/kernel/setup.c

@@ -31,6 +31,7 @@
 #include <linux/libfdt.h>
 #include <linux/of_fdt.h>
 #include <linux/of_address.h>
+#include <linux/suspend.h>
 #include <linux/swiotlb.h>
 
 #include <asm/addrspace.h>
@@ -370,6 +371,10 @@ static void __init arch_mem_init(char **cmdline_p)
 
 	dma_contiguous_reserve(PFN_PHYS(max_low_pfn));
 
+	/* Reserve for hibernation. */
+	register_nosave_region(PFN_DOWN(__pa_symbol(&__nosave_begin)),
+				   PFN_UP(__pa_symbol(&__nosave_end)));
+
 	memblock_dump_all();
 
 	early_memtest(PFN_PHYS(ARCH_PFN_OFFSET), PFN_PHYS(max_low_pfn));

arch/loongarch/power/Makefile

@@ -1,3 +1,4 @@
 obj-y	+= platform.o
 
 obj-$(CONFIG_SUSPEND)		+= suspend.o suspend_asm.o
+obj-$(CONFIG_HIBERNATION)	+= hibernate.o hibernate_asm.o

arch/loongarch/power/hibernate.c

@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <asm/fpu.h>
+#include <asm/loongson.h>
+#include <asm/sections.h>
+#include <asm/tlbflush.h>
+#include <linux/suspend.h>
+
+static u32 saved_crmd;
+static u32 saved_prmd;
+static u32 saved_euen;
+static u32 saved_ecfg;
+static u64 saved_pcpu_base;
+struct pt_regs saved_regs;
+
+void save_processor_state(void)
+{
+	saved_crmd = csr_read32(LOONGARCH_CSR_CRMD);
+	saved_prmd = csr_read32(LOONGARCH_CSR_PRMD);
+	saved_euen = csr_read32(LOONGARCH_CSR_EUEN);
+	saved_ecfg = csr_read32(LOONGARCH_CSR_ECFG);
+	saved_pcpu_base = csr_read64(PERCPU_BASE_KS);
+
+	if (is_fpu_owner())
+		save_fp(current);
+}
+
+void restore_processor_state(void)
+{
+	csr_write32(saved_crmd, LOONGARCH_CSR_CRMD);
+	csr_write32(saved_prmd, LOONGARCH_CSR_PRMD);
+	csr_write32(saved_euen, LOONGARCH_CSR_EUEN);
+	csr_write32(saved_ecfg, LOONGARCH_CSR_ECFG);
+	csr_write64(saved_pcpu_base, PERCPU_BASE_KS);
+
+	if (is_fpu_owner())
+		restore_fp(current);
+}
+
+int pfn_is_nosave(unsigned long pfn)
+{
+	unsigned long nosave_begin_pfn = PFN_DOWN(__pa(&__nosave_begin));
+	unsigned long nosave_end_pfn = PFN_UP(__pa(&__nosave_end));
+
+	return	(pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
+}
+
+extern int swsusp_asm_suspend(void);
+
+int swsusp_arch_suspend(void)
+{
+	enable_pci_wakeup();
+	return swsusp_asm_suspend();
+}
+
+extern int swsusp_asm_resume(void);
+
+int swsusp_arch_resume(void)
+{
+	/* Avoid TLB mismatch during and after kernel resume */
+	local_flush_tlb_all();
+	return swsusp_asm_resume();
+}

arch/loongarch/power/hibernate_asm.S

@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Hibernation support specific for LoongArch
+ *
+ * Author: Huacai Chen <chenhuacai@loongson.cn>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#include <linux/linkage.h>
+#include <asm/asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/regdef.h>
+
+.text
+SYM_FUNC_START(swsusp_asm_suspend)
+	la.pcrel	t0, saved_regs
+	PTR_S		ra, t0, PT_R1
+	PTR_S		tp, t0, PT_R2
+	PTR_S		sp, t0, PT_R3
+	PTR_S		u0, t0, PT_R21
+	PTR_S		fp, t0, PT_R22
+	PTR_S		s0, t0, PT_R23
+	PTR_S		s1, t0, PT_R24
+	PTR_S		s2, t0, PT_R25
+	PTR_S		s3, t0, PT_R26
+	PTR_S		s4, t0, PT_R27
+	PTR_S		s5, t0, PT_R28
+	PTR_S		s6, t0, PT_R29
+	PTR_S		s7, t0, PT_R30
+	PTR_S		s8, t0, PT_R31
+	b		swsusp_save
+SYM_FUNC_END(swsusp_asm_suspend)
+
+SYM_FUNC_START(swsusp_asm_resume)
+	la.pcrel	t0, restore_pblist
+	PTR_L		t0, t0, 0
+0:
+	PTR_L		t1, t0, PBE_ADDRESS  /* source */
+	PTR_L		t2, t0, PBE_ORIG_ADDRESS /* destination */
+	PTR_LI		t3, _PAGE_SIZE
+	PTR_ADD		t3, t3, t1
+1:
+	REG_L		t8, t1, 0
+	REG_S		t8, t2, 0
+	PTR_ADDI	t1, t1, SZREG
+	PTR_ADDI	t2, t2, SZREG
+	bne		t1, t3, 1b
+	PTR_L		t0, t0, PBE_NEXT
+	bnez		t0, 0b
+	la.pcrel	t0, saved_regs
+	PTR_L		ra, t0, PT_R1
+	PTR_L		tp, t0, PT_R2
+	PTR_L		sp, t0, PT_R3
+	PTR_L		u0, t0, PT_R21
+	PTR_L		fp, t0, PT_R22
+	PTR_L		s0, t0, PT_R23
+	PTR_L		s1, t0, PT_R24
+	PTR_L		s2, t0, PT_R25
+	PTR_L		s3, t0, PT_R26
+	PTR_L		s4, t0, PT_R27
+	PTR_L		s5, t0, PT_R28
+	PTR_L		s6, t0, PT_R29
+	PTR_L		s7, t0, PT_R30
+	PTR_L		s8, t0, PT_R31
+	PTR_LI		a0, 0x0
+	jirl		zero, ra, 0
+SYM_FUNC_END(swsusp_asm_resume)