xtensa: add hibernation support

Define ARCH_HIBERNATION_POSSIBLE in Kconfig and implement hibernation
callbacks.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/Kconfig

@@ -787,6 +787,9 @@ endmenu
 
 menu "Power management options"
 
+config ARCH_HIBERNATION_POSSIBLE
+	def_bool y
+
 source "kernel/power/Kconfig"
 
 endmenu

arch/xtensa/kernel/Makefile

@@ -19,6 +19,7 @@ obj-$(CONFIG_XTENSA_VARIANT_HAVE_PERF_EVENTS) += perf_event.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_S32C1I_SELFTEST) += s32c1i_selftest.o
 obj-$(CONFIG_JUMP_LABEL) += jump_label.o
+obj-$(CONFIG_HIBERNATION) += hibernate.o
 
 # In the Xtensa architecture, assembly generates literals which must always
 # precede the L32R instruction with a relative offset less than 256 kB.

arch/xtensa/kernel/asm-offsets.c

@@ -21,6 +21,7 @@
 #include <linux/ptrace.h>
 #include <linux/mm.h>
 #include <linux/kbuild.h>
+#include <linux/suspend.h>
 
 #include <asm/ptrace.h>
 #include <asm/traps.h>
@@ -149,5 +150,12 @@ int main(void)
 	       offsetof(struct exc_table, fast_kernel_handler));
 	DEFINE(EXC_TABLE_DEFAULT, offsetof(struct exc_table, default_handler));
 
+#ifdef CONFIG_HIBERNATION
+	DEFINE(PBE_ADDRESS, offsetof(struct pbe, address));
+	DEFINE(PBE_ORIG_ADDRESS, offsetof(struct pbe, orig_address));
+	DEFINE(PBE_NEXT, offsetof(struct pbe, next));
+	DEFINE(PBE_SIZE, sizeof(struct pbe));
+#endif
+
 	return 0;
 }

arch/xtensa/kernel/entry.S

@@ -2155,3 +2155,95 @@ ENTRY(ret_from_kernel_thread)
 	j		common_exception_return
 
 ENDPROC(ret_from_kernel_thread)
+
+#ifdef CONFIG_HIBERNATION
+
+	.bss
+	.align	4
+.Lsaved_regs:
+#if defined(__XTENSA_WINDOWED_ABI__)
+	.fill	2, 4
+#elif defined(__XTENSA_CALL0_ABI__)
+	.fill	6, 4
+#else
+#error Unsupported Xtensa ABI
+#endif
+	.align	XCHAL_NCP_SA_ALIGN
+.Lsaved_user_regs:
+	.fill	XTREGS_USER_SIZE, 1
+
+	.previous
+
+ENTRY(swsusp_arch_suspend)
+
+	abi_entry_default
+
+	movi		a2, .Lsaved_regs
+	movi		a3, .Lsaved_user_regs
+	s32i		a0, a2, 0
+	s32i		a1, a2, 4
+	save_xtregs_user a3 a4 a5 a6 a7 a8 0
+#if defined(__XTENSA_WINDOWED_ABI__)
+	spill_registers_kernel
+#elif defined(__XTENSA_CALL0_ABI__)
+	s32i		a12, a2, 8
+	s32i		a13, a2, 12
+	s32i		a14, a2, 16
+	s32i		a15, a2, 20
+#else
+#error Unsupported Xtensa ABI
+#endif
+	abi_call	swsusp_save
+	mov		a2, abi_rv
+	abi_ret_default
+
+ENDPROC(swsusp_arch_suspend)
+
+ENTRY(swsusp_arch_resume)
+
+	abi_entry_default
+
+#if defined(__XTENSA_WINDOWED_ABI__)
+	spill_registers_kernel
+#endif
+
+	movi		a2, restore_pblist
+	l32i		a2, a2, 0
+
+.Lcopy_pbe:
+	l32i		a3, a2, PBE_ADDRESS
+	l32i		a4, a2, PBE_ORIG_ADDRESS
+
+	__loopi		a3, a9, PAGE_SIZE, 16
+	l32i		a5, a3, 0
+	l32i		a6, a3, 4
+	l32i		a7, a3, 8
+	l32i		a8, a3, 12
+	addi		a3, a3, 16
+	s32i		a5, a4, 0
+	s32i		a6, a4, 4
+	s32i		a7, a4, 8
+	s32i		a8, a4, 12
+	addi		a4, a4, 16
+	__endl		a3, a9
+
+	l32i		a2, a2, PBE_NEXT
+	bnez		a2, .Lcopy_pbe
+
+	movi		a2, .Lsaved_regs
+	movi		a3, .Lsaved_user_regs
+	l32i		a0, a2, 0
+	l32i		a1, a2, 4
+	load_xtregs_user a3 a4 a5 a6 a7 a8 0
+#if defined(__XTENSA_CALL0_ABI__)
+	l32i		a12, a2, 8
+	l32i		a13, a2, 12
+	l32i		a14, a2, 16
+	l32i		a15, a2, 20
+#endif
+	movi		a2, 0
+	abi_ret_default
+
+ENDPROC(swsusp_arch_resume)
+
+#endif

arch/xtensa/kernel/hibernate.c

+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/mm.h>
+#include <linux/suspend.h>
+#include <asm/coprocessor.h>
+
+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);
+}
+
+void notrace save_processor_state(void)
+{
+	WARN_ON(num_online_cpus() != 1);
+#if XTENSA_HAVE_COPROCESSORS
+	local_coprocessors_flush_release_all();
+#endif
+}
+
+void notrace restore_processor_state(void)
+{
+}