LoongArch: Add suspend (ACPI S3) support

Add suspend (Suspend To RAM, aka ACPI S3) support for LoongArch.

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

4 files changed, 222 insertions, 0 deletions

diff --git a/arch/loongarch/power/Makefile b/arch/loongarch/power/Makefile
new file mode 100644
index 000000000000..6740117decaa
--- /dev/null
+++ b/arch/loongarch/power/Makefile
@@ -0,0 +1,3 @@
+obj-y	+= platform.o
+
+obj-$(CONFIG_SUSPEND)		+= suspend.o suspend_asm.o
diff --git a/arch/loongarch/power/platform.c b/arch/loongarch/power/platform.c
new file mode 100644
index 000000000000..3ea8e07aa225
--- /dev/null
+++ b/arch/loongarch/power/platform.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Huacai Chen <chenhuacai@loongson.cn>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#include <linux/acpi.h>
+#include <linux/platform_device.h>
+
+#include <asm/bootinfo.h>
+#include <asm/loongson.h>
+
+void enable_gpe_wakeup(void)
+{
+	if (acpi_disabled)
+	       return;
+
+	if (acpi_gbl_reduced_hardware)
+	       return;
+
+	acpi_enable_all_wakeup_gpes();
+}
+
+void enable_pci_wakeup(void)
+{
+	if (acpi_disabled)
+	       return;
+
+	if (acpi_gbl_reduced_hardware)
+	       return;
+
+	acpi_write_bit_register(ACPI_BITREG_PCIEXP_WAKE_STATUS, 1);
+
+	if (acpi_gbl_FADT.flags & ACPI_FADT_PCI_EXPRESS_WAKE)
+		acpi_write_bit_register(ACPI_BITREG_PCIEXP_WAKE_DISABLE, 0);
+}
+
+static int __init loongson3_acpi_suspend_init(void)
+{
+#ifdef CONFIG_ACPI
+	acpi_status status;
+	uint64_t suspend_addr = 0;
+
+	if (acpi_disabled || acpi_gbl_reduced_hardware)
+		return 0;
+
+	acpi_write_bit_register(ACPI_BITREG_SCI_ENABLE, 1);
+	status = acpi_evaluate_integer(NULL, "\\SADR", NULL, &suspend_addr);
+	if (ACPI_FAILURE(status) || !suspend_addr) {
+		pr_err("ACPI S3 is not support!\n");
+		return -1;
+	}
+	loongson_sysconf.suspend_addr = (u64)phys_to_virt(PHYSADDR(suspend_addr));
+#endif
+	return 0;
+}
+
+device_initcall(loongson3_acpi_suspend_init);
diff --git a/arch/loongarch/power/suspend.c b/arch/loongarch/power/suspend.c
new file mode 100644
index 000000000000..5e19733e5e05
--- /dev/null
+++ b/arch/loongarch/power/suspend.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * loongson-specific suspend support
+ *
+ * Author: Huacai Chen <chenhuacai@loongson.cn>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#include <linux/acpi.h>
+#include <linux/pm.h>
+#include <linux/suspend.h>
+
+#include <asm/loongarch.h>
+#include <asm/loongson.h>
+#include <asm/setup.h>
+#include <asm/time.h>
+#include <asm/tlbflush.h>
+
+u64 loongarch_suspend_addr;
+
+struct saved_registers {
+	u32 ecfg;
+	u32 euen;
+	u64 pgd;
+	u64 kpgd;
+	u32 pwctl0;
+	u32 pwctl1;
+};
+static struct saved_registers saved_regs;
+
+static void arch_common_suspend(void)
+{
+	save_counter();
+	saved_regs.pgd = csr_read64(LOONGARCH_CSR_PGDL);
+	saved_regs.kpgd = csr_read64(LOONGARCH_CSR_PGDH);
+	saved_regs.pwctl0 = csr_read32(LOONGARCH_CSR_PWCTL0);
+	saved_regs.pwctl1 = csr_read32(LOONGARCH_CSR_PWCTL1);
+	saved_regs.ecfg = csr_read32(LOONGARCH_CSR_ECFG);
+	saved_regs.euen = csr_read32(LOONGARCH_CSR_EUEN);
+
+	loongarch_suspend_addr = loongson_sysconf.suspend_addr;
+}
+
+static void arch_common_resume(void)
+{
+	sync_counter();
+	local_flush_tlb_all();
+	csr_write64(per_cpu_offset(0), PERCPU_BASE_KS);
+	csr_write64(eentry, LOONGARCH_CSR_EENTRY);
+	csr_write64(eentry, LOONGARCH_CSR_MERRENTRY);
+	csr_write64(tlbrentry, LOONGARCH_CSR_TLBRENTRY);
+
+	csr_write64(saved_regs.pgd, LOONGARCH_CSR_PGDL);
+	csr_write64(saved_regs.kpgd, LOONGARCH_CSR_PGDH);
+	csr_write32(saved_regs.pwctl0, LOONGARCH_CSR_PWCTL0);
+	csr_write32(saved_regs.pwctl1, LOONGARCH_CSR_PWCTL1);
+	csr_write32(saved_regs.ecfg, LOONGARCH_CSR_ECFG);
+	csr_write32(saved_regs.euen, LOONGARCH_CSR_EUEN);
+}
+
+int loongarch_acpi_suspend(void)
+{
+	enable_gpe_wakeup();
+	enable_pci_wakeup();
+
+	arch_common_suspend();
+
+	/* processor specific suspend */
+	loongarch_suspend_enter();
+
+	arch_common_resume();
+
+	return 0;
+}
diff --git a/arch/loongarch/power/suspend_asm.S b/arch/loongarch/power/suspend_asm.S
new file mode 100644
index 000000000000..eb2675642f9f
--- /dev/null
+++ b/arch/loongarch/power/suspend_asm.S
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Sleep helper for Loongson-3 sleep mode.
+ *
+ * Author: Huacai Chen <chenhuacai@loongson.cn>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/addrspace.h>
+#include <asm/loongarch.h>
+#include <asm/stackframe.h>
+
+/* preparatory stuff */
+.macro	SETUP_SLEEP
+	addi.d		sp, sp, -PT_SIZE
+	st.d		$r1, sp, PT_R1
+	st.d		$r2, sp, PT_R2
+	st.d		$r3, sp, PT_R3
+	st.d		$r4, sp, PT_R4
+	st.d		$r21, sp, PT_R21
+	st.d		$r22, sp, PT_R22
+	st.d		$r23, sp, PT_R23
+	st.d		$r24, sp, PT_R24
+	st.d		$r25, sp, PT_R25
+	st.d		$r26, sp, PT_R26
+	st.d		$r27, sp, PT_R27
+	st.d		$r28, sp, PT_R28
+	st.d		$r29, sp, PT_R29
+	st.d		$r30, sp, PT_R30
+	st.d		$r31, sp, PT_R31
+
+	la.pcrel	t0, acpi_saved_sp
+	st.d		sp, t0, 0
+.endm
+
+.macro SETUP_WAKEUP
+	ld.d		$r1, sp, PT_R1
+	ld.d		$r2, sp, PT_R2
+	ld.d		$r3, sp, PT_R3
+	ld.d		$r4, sp, PT_R4
+	ld.d		$r21, sp, PT_R21
+	ld.d		$r22, sp, PT_R22
+	ld.d		$r23, sp, PT_R23
+	ld.d		$r24, sp, PT_R24
+	ld.d		$r25, sp, PT_R25
+	ld.d		$r26, sp, PT_R26
+	ld.d		$r27, sp, PT_R27
+	ld.d		$r28, sp, PT_R28
+	ld.d		$r29, sp, PT_R29
+	ld.d		$r30, sp, PT_R30
+	ld.d		$r31, sp, PT_R31
+.endm
+
+	.text
+	.align 12
+
+/* Sleep/wakeup code for Loongson-3 */
+SYM_FUNC_START(loongarch_suspend_enter)
+	SETUP_SLEEP
+	bl		__flush_cache_all
+
+	/* Pass RA and SP to BIOS */
+	addi.d		a1, sp, 0
+	la.pcrel	a0, loongarch_wakeup_start
+	la.pcrel	t0, loongarch_suspend_addr
+	ld.d		t0, t0, 0
+	jirl		a0, t0, 0 /* Call BIOS's STR sleep routine */
+
+	/*
+	 * This is where we return upon wakeup.
+	 * Reload all of the registers and return.
+	 */
+SYM_INNER_LABEL(loongarch_wakeup_start, SYM_L_GLOBAL)
+	li.d		t0, CSR_DMW0_INIT	# UC, PLV0
+	csrwr		t0, LOONGARCH_CSR_DMWIN0
+	li.d		t0, CSR_DMW1_INIT	# CA, PLV0
+	csrwr		t0, LOONGARCH_CSR_DMWIN1
+
+	la.abs		t0, 0f
+	jr		t0
+0:
+	la.pcrel	t0, acpi_saved_sp
+	ld.d		sp, t0, 0
+	SETUP_WAKEUP
+	addi.d		sp, sp, PT_SIZE
+	jr		ra
+SYM_FUNC_END(loongarch_suspend_enter)