MIPS: Loongson64: Implement PM suspend for LEFI firmware

Implement PM suspend for LEFI firmware.
Entering STR (Suspend to RAM) is as simple as save our context
then go to a firmware vector.
Wake is a little bit treaky as we need to setup some CP0 status
first, which can be done with smp_slave_setup.

Signed-off-by: Jiaxun Yang <[email protected]>
Signed-off-by: Thomas Bogendoerfer <[email protected]>

arch/mips/loongson64/Makefile

@@ -11,7 +11,7 @@ obj-$(CONFIG_MACH_LOONGSON64) += cop2-ex.o dma.o \
 obj-$(CONFIG_SMP)	+= smp.o
 obj-$(CONFIG_NUMA)	+= numa.o
 obj-$(CONFIG_RS780_HPET) += hpet.o
-obj-$(CONFIG_SUSPEND) += pm.o
+obj-$(CONFIG_SUSPEND) += pm.o sleeper.o
 obj-$(CONFIG_PCI_QUIRKS) += vbios_quirk.o
 obj-$(CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION) += cpucfg-emul.o
 obj-$(CONFIG_SYSFS) += boardinfo.o

arch/mips/loongson64/pm.c

@@ -6,98 +6,46 @@
  *  Author: Wu Zhangjin <[email protected]>
  */
 #include <linux/suspend.h>
-#include <linux/interrupt.h>
 #include <linux/pm.h>
 
-#include <asm/i8259.h>
 #include <asm/mipsregs.h>
 
 #include <loongson.h>
 
-static unsigned int __maybe_unused cached_master_mask;	/* i8259A */
-static unsigned int __maybe_unused cached_slave_mask;
-static unsigned int __maybe_unused cached_bonito_irq_mask; /* bonito */
+asmlinkage void loongson_lefi_sleep(unsigned long sleep_addr);
 
-void arch_suspend_disable_irqs(void)
+static int lefi_pm_enter(suspend_state_t state)
 {
-	/* disable all mips events */
-	local_irq_disable();
-
-#ifdef CONFIG_I8259
-	/* disable all events of i8259A */
-	cached_slave_mask = inb(PIC_SLAVE_IMR);
-	cached_master_mask = inb(PIC_MASTER_IMR);
-
-	outb(0xff, PIC_SLAVE_IMR);
-	inb(PIC_SLAVE_IMR);
-	outb(0xff, PIC_MASTER_IMR);
-	inb(PIC_MASTER_IMR);
-#endif
-	/* disable all events of bonito */
-	cached_bonito_irq_mask = LOONGSON_INTEN;
-	LOONGSON_INTENCLR = 0xffff;
-	(void)LOONGSON_INTENCLR;
-}
-
-void arch_suspend_enable_irqs(void)
-{
-	/* enable all mips events */
-	local_irq_enable();
-#ifdef CONFIG_I8259
-	/* only enable the cached events of i8259A */
-	outb(cached_slave_mask, PIC_SLAVE_IMR);
-	outb(cached_master_mask, PIC_MASTER_IMR);
-#endif
-	/* enable all cached events of bonito */
-	LOONGSON_INTENSET = cached_bonito_irq_mask;
-	(void)LOONGSON_INTENSET;
-}
-
-/*
- * Setup the board-specific events for waking up loongson from wait mode
- */
-void __weak setup_wakeup_events(void)
-{
-}
-
-void __weak mach_suspend(void)
-{
-}
-
-void __weak mach_resume(void)
-{
-}
-
-static int loongson_pm_enter(suspend_state_t state)
-{
-	mach_suspend();
-
-	mach_resume();
-
-	return 0;
+	switch (state) {
+	case PM_SUSPEND_MEM:
+		pm_set_suspend_via_firmware();
+		loongson_lefi_sleep(loongson_sysconf.suspend_addr);
+		pm_set_resume_via_firmware();
+		return 0;
+	default:
+		return -EINVAL;
+	}
 }
 
-static int loongson_pm_valid_state(suspend_state_t state)
+static int lefi_pm_valid_state(suspend_state_t state)
 {
 	switch (state) {
-	case PM_SUSPEND_ON:
-	case PM_SUSPEND_STANDBY:
 	case PM_SUSPEND_MEM:
-		return 1;
-
+		return !!loongson_sysconf.suspend_addr;
 	default:
 		return 0;
 	}
 }
 
-static const struct platform_suspend_ops loongson_pm_ops = {
-	.valid	= loongson_pm_valid_state,
-	.enter	= loongson_pm_enter,
+static const struct platform_suspend_ops lefi_pm_ops = {
+	.valid	= lefi_pm_valid_state,
+	.enter	= lefi_pm_enter,
 };
 
 static int __init loongson_pm_init(void)
 {
-	suspend_set_ops(&loongson_pm_ops);
+	if (loongson_sysconf.fw_interface == LOONGSON_LEFI)
+		suspend_set_ops(&lefi_pm_ops);
 
 	return 0;
 }

arch/mips/loongson64/sleeper.S

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *  Copyright (C) 2024, Jiaxun Yang <[email protected]>
+ *  Loongson EFI firmware sleeper routine
+ */
+
+#include <asm/asm.h>
+#include <asm/pm.h>
+
+#include <kernel-entry-init.h>
+
+LEAF(loongson_lefi_sleep)
+	SUSPEND_SAVE
+	jalr    a0
+    smp_slave_setup
+	RESUME_RESTORE_REGS_RETURN
+END(loongson_lefi_sleep)