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// 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>
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
}
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;
}
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