1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) 2021 Western Digital Corporation or its affiliates.
4 * Copyright (c) 2022 Ventana Micro Systems Inc.
5 */
6
7 #define pr_fmt(fmt) "suspend: " fmt
8
9 #include <linux/ftrace.h>
10 #include <linux/suspend.h>
11 #include <asm/csr.h>
12 #include <asm/sbi.h>
13 #include <asm/suspend.h>
14
15 void suspend_save_csrs(struct suspend_context *context)
16 {
17 if (riscv_cpu_has_extension_unlikely(smp_processor_id(), RISCV_ISA_EXT_XLINUXENVCFG))
18 context->envcfg = csr_read(CSR_ENVCFG);
19 context->tvec = csr_read(CSR_TVEC);
20 context->ie = csr_read(CSR_IE);
21
22 /*
23 * No need to save/restore IP CSR (i.e. MIP or SIP) because:
24 *
25 * 1. For no-MMU (M-mode) kernel, the bits in MIP are set by
26 * external devices (such as interrupt controller, timer, etc).
27 * 2. For MMU (S-mode) kernel, the bits in SIP are set by
28 * M-mode firmware and external devices (such as interrupt
29 * controller, etc).
30 */
31
32 #ifdef CONFIG_MMU
33 context->satp = csr_read(CSR_SATP);
34 #endif
35 }
36
37 void suspend_restore_csrs(struct suspend_context *context)
38 {
39 csr_write(CSR_SCRATCH, 0);
40 if (riscv_cpu_has_extension_unlikely(smp_processor_id(), RISCV_ISA_EXT_XLINUXENVCFG))
41 csr_write(CSR_ENVCFG, context->envcfg);
42 csr_write(CSR_TVEC, context->tvec);
43 csr_write(CSR_IE, context->ie);
44
45 #ifdef CONFIG_MMU
46 csr_write(CSR_SATP, context->satp);
47 #endif
48 }
49
50 int cpu_suspend(unsigned long arg,
51 int (*finish)(unsigned long arg,
52 unsigned long entry,
53 unsigned long context))
54 {
55 int rc = 0;
56 struct suspend_context context = { 0 };
57
58 /* Finisher should be non-NULL */
59 if (!finish)
60 return -EINVAL;
61
62 /* Save additional CSRs*/
63 suspend_save_csrs(&context);
64
65 /*
66 * Function graph tracer state gets incosistent when the kernel
67 * calls functions that never return (aka finishers) hence disable
68 * graph tracing during their execution.
69 */
70 pause_graph_tracing();
71
72 /* Save context on stack */
73 if (__cpu_suspend_enter(&context)) {
74 /* Call the finisher */
75 rc = finish(arg, __pa_symbol(__cpu_resume_enter),
76 (ulong)&context);
77
78 /*
79 * Should never reach here, unless the suspend finisher
80 * fails. Successful cpu_suspend() should return from
81 * __cpu_resume_entry()
82 */
83 if (!rc)
84 rc = -EOPNOTSUPP;
85 }
86
87 /* Enable function graph tracer */
88 unpause_graph_tracing();
89
90 /* Restore additional CSRs */
91 suspend_restore_csrs(&context);
92
93 return rc;
94 }
95
96 #ifdef CONFIG_RISCV_SBI
97 static int sbi_system_suspend(unsigned long sleep_type,
98 unsigned long resume_addr,
99 unsigned long opaque)
100 {
101 struct sbiret ret;
102
103 ret = sbi_ecall(SBI_EXT_SUSP, SBI_EXT_SUSP_SYSTEM_SUSPEND,
104 sleep_type, resume_addr, opaque, 0, 0, 0);
105 if (ret.error)
106 return sbi_err_map_linux_errno(ret.error);
107
108 return ret.value;
109 }
110
111 static int sbi_system_suspend_enter(suspend_state_t state)
112 {
113 return cpu_suspend(SBI_SUSP_SLEEP_TYPE_SUSPEND_TO_RAM, sbi_system_suspend);
114 }
115
116 static const struct platform_suspend_ops sbi_system_suspend_ops = {
117 .valid = suspend_valid_only_mem,
118 .enter = sbi_system_suspend_enter,
119 };
120
121 static int __init sbi_system_suspend_init(void)
122 {
123 if (sbi_spec_version >= sbi_mk_version(2, 0) &&
124 sbi_probe_extension(SBI_EXT_SUSP) > 0) {
125 pr_info("SBI SUSP extension detected\n");
126 if (IS_ENABLED(CONFIG_SUSPEND))
127 suspend_set_ops(&sbi_system_suspend_ops);
128 }
129
130 return 0;
131 }
132
133 arch_initcall(sbi_system_suspend_init);
134
135 static int sbi_suspend_finisher(unsigned long suspend_type,
136 unsigned long resume_addr,
137 unsigned long opaque)
138 {
139 struct sbiret ret;
140
141 ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_SUSPEND,
142 suspend_type, resume_addr, opaque, 0, 0, 0);
143
144 return (ret.error) ? sbi_err_map_linux_errno(ret.error) : 0;
145 }
146
147 int riscv_sbi_hart_suspend(u32 state)
148 {
149 if (state & SBI_HSM_SUSP_NON_RET_BIT)
150 return cpu_suspend(state, sbi_suspend_finisher);
151 else
152 return sbi_suspend_finisher(state, 0, 0);
153 }
154
155 bool riscv_sbi_suspend_state_is_valid(u32 state)
156 {
157 if (state > SBI_HSM_SUSPEND_RET_DEFAULT &&
158 state < SBI_HSM_SUSPEND_RET_PLATFORM)
159 return false;
160
161 if (state > SBI_HSM_SUSPEND_NON_RET_DEFAULT &&
162 state < SBI_HSM_SUSPEND_NON_RET_PLATFORM)
163 return false;
164
165 return true;
166 }
167
168 bool riscv_sbi_hsm_is_supported(void)
169 {
170 /*
171 * The SBI HSM suspend function is only available when:
172 * 1) SBI version is 0.3 or higher
173 * 2) SBI HSM extension is available
174 */
175 if (sbi_spec_version < sbi_mk_version(0, 3) ||
176 !sbi_probe_extension(SBI_EXT_HSM)) {
177 pr_info("HSM suspend not available\n");
178 return false;
179 }
180
181 return true;
182 }
183 #endif /* CONFIG_RISCV_SBI */
184
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.