// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (c) 2021 Western Digital Corporation or its affiliates. * Copyright (c) 2022 Ventana Micro Systems Inc. */ #include <linux/ftrace.h> #include <asm/csr.h> #include <asm/suspend.h> 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; }