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Sun, 21 Feb 2021 09:38:48 +0000 From: Anup Patel To: Palmer Dabbelt , Palmer Dabbelt , Paul Walmsley , Albert Ou , Daniel Lezcano , Ulf Hansson , "Rafael J . Wysocki" , Pavel Machek , Rob Herring Subject: [RFC PATCH 3/8] RISC-V: Add arch functions for non-retentive suspend entry/exit Date: Sun, 21 Feb 2021 15:07:53 +0530 Message-Id: <20210221093758.210981-4-anup.patel@wdc.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210221093758.210981-1-anup.patel@wdc.com> References: <20210221093758.210981-1-anup.patel@wdc.com> X-Originating-IP: [122.171.171.12] X-ClientProxiedBy: MA1PR0101CA0009.INDPRD01.PROD.OUTLOOK.COM (2603:1096:a00:21::19) To DM6PR04MB6201.namprd04.prod.outlook.com (2603:10b6:5:127::32) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from wdc.com (122.171.171.12) by MA1PR0101CA0009.INDPRD01.PROD.OUTLOOK.COM (2603:1096:a00:21::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3868.27 via Frontend Transport; Sun, 21 Feb 2021 09:38:42 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 6bc29b22-c57a-46ef-b957-08d8d64c7d61 X-MS-TrafficTypeDiagnostic: DM5PR04MB0459: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: WDCIPOUTBOUND: EOP-TRUE X-MS-Oob-TLC-OOBClassifiers: OLM:9508; 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These helper functions can be used by cpuidle drivers for non-retentive suspend entry/exit. Signed-off-by: Anup Patel --- arch/riscv/include/asm/suspend.h | 35 +++++++++ arch/riscv/kernel/Makefile | 2 + arch/riscv/kernel/asm-offsets.c | 3 + arch/riscv/kernel/suspend.c | 86 ++++++++++++++++++++++ arch/riscv/kernel/suspend_entry.S | 116 ++++++++++++++++++++++++++++++ 5 files changed, 242 insertions(+) create mode 100644 arch/riscv/include/asm/suspend.h create mode 100644 arch/riscv/kernel/suspend.c create mode 100644 arch/riscv/kernel/suspend_entry.S diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h new file mode 100644 index 000000000000..63e9f434fb89 --- /dev/null +++ b/arch/riscv/include/asm/suspend.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2021 Western Digital Corporation or its affiliates. + */ + +#ifndef _ASM_RISCV_SUSPEND_H +#define _ASM_RISCV_SUSPEND_H + +#include + +struct suspend_context { + /* Saved and restored by low-level functions */ + struct pt_regs regs; + /* Saved and restored by high-level functions */ + unsigned long scratch; + unsigned long tvec; + unsigned long ie; +#ifdef CONFIG_MMU + unsigned long satp; +#endif +}; + +/* Low-level CPU suspend entry function */ +int __cpu_suspend_enter(struct suspend_context *context); + +/* High-level CPU suspend which will save context and call finish() */ +int cpu_suspend(unsigned long arg, + int (*finish)(unsigned long arg, + unsigned long entry, + unsigned long context)); + +/* Low-level CPU resume entry function */ +int __cpu_resume_enter(unsigned long hartid, unsigned long context); + +#endif diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index f6caf4d9ca15..d83038bf93b2 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -40,6 +40,8 @@ obj-$(CONFIG_SMP) += cpu_ops_spinwait.o obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o +obj-$(CONFIG_CPU_PM) += suspend_entry.o suspend.o + obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c index b79ffa3561fd..8259f5f16da8 100644 --- a/arch/riscv/kernel/asm-offsets.c +++ b/arch/riscv/kernel/asm-offsets.c @@ -10,6 +10,7 @@ #include #include #include +#include void asm_offsets(void); @@ -108,6 +109,8 @@ void asm_offsets(void) OFFSET(PT_BADADDR, pt_regs, badaddr); OFFSET(PT_CAUSE, pt_regs, cause); + OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs); + /* * THREAD_{F,X}* might be larger than a S-type offset can handle, but * these are used in performance-sensitive assembly so we can't resort diff --git a/arch/riscv/kernel/suspend.c b/arch/riscv/kernel/suspend.c new file mode 100644 index 000000000000..49dddec30e99 --- /dev/null +++ b/arch/riscv/kernel/suspend.c @@ -0,0 +1,86 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2021 Western Digital Corporation or its affiliates. + */ + +#include +#include +#include + +static void suspend_save_csrs(struct suspend_context *context) +{ + context->scratch = csr_read(CSR_SCRATCH); + context->tvec = csr_read(CSR_TVEC); + context->ie = csr_read(CSR_IE); + + /* + * No need to save/restore IP CSR (i.e. MIP or SIP) because: + * + * 1. For no-MMU (M-mode) kernel, the bits in MIP are set by + * external devices (such as interrupt controller, timer, etc). + * 2. For MMU (S-mode) kernel, the bits in SIP are set by + * M-mode firmware and external devices (such as interrupt + * controller, etc). + */ + +#ifdef CONFIG_MMU + context->satp = csr_read(CSR_SATP); +#endif +} + +static void suspend_restore_csrs(struct suspend_context *context) +{ + csr_write(CSR_SCRATCH, context->scratch); + csr_write(CSR_TVEC, context->tvec); + csr_write(CSR_IE, context->ie); + +#ifdef CONFIG_MMU + csr_write(CSR_SATP, context->satp); +#endif +} + +int cpu_suspend(unsigned long arg, + int (*finish)(unsigned long arg, + unsigned long entry, + unsigned long context)) +{ + int rc = 0; + struct suspend_context context = { 0 }; + + /* Finisher should be non-NULL */ + if (!finish) + return -EINVAL; + + /* Save additional CSRs*/ + suspend_save_csrs(&context); + + /* + * Function graph tracer state gets incosistent when the kernel + * calls functions that never return (aka finishers) hence disable + * graph tracing during their execution. + */ + pause_graph_tracing(); + + /* Save context on stack */ + if (__cpu_suspend_enter(&context)) { + /* Call the finisher */ + rc = finish(arg, __pa_symbol(__cpu_resume_enter), + (ulong)&context); + + /* + * Should never reach here, unless the suspend finisher + * fails. Successful cpu_suspend() should return from + * __cpu_resume_entry() + */ + if (!rc) + rc = -EOPNOTSUPP; + } + + /* Enable function graph tracer */ + unpause_graph_tracing(); + + /* Restore additional CSRs */ + suspend_restore_csrs(&context); + + return rc; +} diff --git a/arch/riscv/kernel/suspend_entry.S b/arch/riscv/kernel/suspend_entry.S new file mode 100644 index 000000000000..dee85c86e177 --- /dev/null +++ b/arch/riscv/kernel/suspend_entry.S @@ -0,0 +1,116 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2021 Western Digital Corporation or its affiliates. + */ + +#include +#include +#include +#include + + .text + .altmacro + .option norelax + +ENTRY(__cpu_suspend_enter) + /* Save registers (except A0 and T0-T6) */ + REG_S ra, (SUSPEND_CONTEXT_REGS + PT_RA)(a0) + REG_S sp, (SUSPEND_CONTEXT_REGS + PT_SP)(a0) + REG_S gp, (SUSPEND_CONTEXT_REGS + PT_GP)(a0) + REG_S tp, (SUSPEND_CONTEXT_REGS + PT_TP)(a0) + REG_S s0, (SUSPEND_CONTEXT_REGS + PT_S0)(a0) + REG_S s1, (SUSPEND_CONTEXT_REGS + PT_S1)(a0) + REG_S a1, (SUSPEND_CONTEXT_REGS + PT_A1)(a0) + REG_S a2, (SUSPEND_CONTEXT_REGS + PT_A2)(a0) + REG_S a3, (SUSPEND_CONTEXT_REGS + PT_A3)(a0) + REG_S a4, (SUSPEND_CONTEXT_REGS + PT_A4)(a0) + REG_S a5, (SUSPEND_CONTEXT_REGS + PT_A5)(a0) + REG_S a6, (SUSPEND_CONTEXT_REGS + PT_A6)(a0) + REG_S a7, (SUSPEND_CONTEXT_REGS + PT_A7)(a0) + REG_S s2, (SUSPEND_CONTEXT_REGS + PT_S2)(a0) + REG_S s3, (SUSPEND_CONTEXT_REGS + PT_S3)(a0) + REG_S s4, (SUSPEND_CONTEXT_REGS + PT_S4)(a0) + REG_S s5, (SUSPEND_CONTEXT_REGS + PT_S5)(a0) + REG_S s6, (SUSPEND_CONTEXT_REGS + PT_S6)(a0) + REG_S s7, (SUSPEND_CONTEXT_REGS + PT_S7)(a0) + REG_S s8, (SUSPEND_CONTEXT_REGS + PT_S8)(a0) + REG_S s9, (SUSPEND_CONTEXT_REGS + PT_S9)(a0) + REG_S s10, (SUSPEND_CONTEXT_REGS + PT_S10)(a0) + REG_S s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0) + + /* Save CSRs */ + csrr t0, CSR_EPC + REG_S t0, (SUSPEND_CONTEXT_REGS + PT_EPC)(a0) + csrr t0, CSR_STATUS + REG_S t0, (SUSPEND_CONTEXT_REGS + PT_STATUS)(a0) + csrr t0, CSR_TVAL + REG_S t0, (SUSPEND_CONTEXT_REGS + PT_BADADDR)(a0) + csrr t0, CSR_CAUSE + REG_S t0, (SUSPEND_CONTEXT_REGS + PT_CAUSE)(a0) + + /* Return non-zero value */ + li a0, 1 + + /* Return to C code */ + ret +END(__cpu_suspend_enter) + +ENTRY(__cpu_resume_enter) +#ifdef CONFIG_MMU + /* Save A0 and A1 */ + add t0, a0, zero + add t1, a1, zero + + /* Enable MMU */ + la a0, swapper_pg_dir + call relocate_enable_mmu + + /* Restore A0 and A1 */ + add a0, t0, zero + add a1, t1, zero +#endif + + /* Make A0 point to suspend context */ + add a0, a1, zero + + /* Restore CSRs */ + REG_L t0, (SUSPEND_CONTEXT_REGS + PT_EPC)(a0) + csrw CSR_EPC, t0 + REG_L t0, (SUSPEND_CONTEXT_REGS + PT_STATUS)(a0) + csrw CSR_STATUS, t0 + REG_L t0, (SUSPEND_CONTEXT_REGS + PT_BADADDR)(a0) + csrw CSR_TVAL, t0 + REG_L t0, (SUSPEND_CONTEXT_REGS + PT_CAUSE)(a0) + csrw CSR_CAUSE, t0 + + /* Restore registers (except A0 and T0-T6) */ + REG_L ra, (SUSPEND_CONTEXT_REGS + PT_RA)(a0) + REG_L sp, (SUSPEND_CONTEXT_REGS + PT_SP)(a0) + REG_L gp, (SUSPEND_CONTEXT_REGS + PT_GP)(a0) + REG_L tp, (SUSPEND_CONTEXT_REGS + PT_TP)(a0) + REG_L s0, (SUSPEND_CONTEXT_REGS + PT_S0)(a0) + REG_L s1, (SUSPEND_CONTEXT_REGS + PT_S1)(a0) + REG_L a1, (SUSPEND_CONTEXT_REGS + PT_A1)(a0) + REG_L a2, (SUSPEND_CONTEXT_REGS + PT_A2)(a0) + REG_L a3, (SUSPEND_CONTEXT_REGS + PT_A3)(a0) + REG_L a4, (SUSPEND_CONTEXT_REGS + PT_A4)(a0) + REG_L a5, (SUSPEND_CONTEXT_REGS + PT_A5)(a0) + REG_L a6, (SUSPEND_CONTEXT_REGS + PT_A6)(a0) + REG_L a7, (SUSPEND_CONTEXT_REGS + PT_A7)(a0) + REG_L s2, (SUSPEND_CONTEXT_REGS + PT_S2)(a0) + REG_L s3, (SUSPEND_CONTEXT_REGS + PT_S3)(a0) + REG_L s4, (SUSPEND_CONTEXT_REGS + PT_S4)(a0) + REG_L s5, (SUSPEND_CONTEXT_REGS + PT_S5)(a0) + REG_L s6, (SUSPEND_CONTEXT_REGS + PT_S6)(a0) + REG_L s7, (SUSPEND_CONTEXT_REGS + PT_S7)(a0) + REG_L s8, (SUSPEND_CONTEXT_REGS + PT_S8)(a0) + REG_L s9, (SUSPEND_CONTEXT_REGS + PT_S9)(a0) + REG_L s10, (SUSPEND_CONTEXT_REGS + PT_S10)(a0) + REG_L s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0) + + /* Return zero value */ + add a0, zero, zero + + /* Return to C code */ + ret +END(__cpu_resume_enter)