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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
707827f3 | 2 | /* |
962e7bd4 | 3 | * cpuidle-pseries - idle state cpuidle driver. |
707827f3 DD |
4 | * Adapted from drivers/idle/intel_idle.c and |
5 | * drivers/acpi/processor_idle.c | |
6 | * | |
7 | */ | |
8 | ||
9 | #include <linux/kernel.h> | |
10 | #include <linux/module.h> | |
11 | #include <linux/init.h> | |
12 | #include <linux/moduleparam.h> | |
13 | #include <linux/cpuidle.h> | |
14 | #include <linux/cpu.h> | |
16aaaff6 | 15 | #include <linux/notifier.h> |
707827f3 DD |
16 | |
17 | #include <asm/paca.h> | |
18 | #include <asm/reg.h> | |
707827f3 DD |
19 | #include <asm/machdep.h> |
20 | #include <asm/firmware.h> | |
3f67d962 | 21 | #include <asm/runlatch.h> |
212bebb4 | 22 | #include <asm/plpar_wrappers.h> |
707827f3 DD |
23 | |
24 | struct cpuidle_driver pseries_idle_driver = { | |
1ca80944 DL |
25 | .name = "pseries_idle", |
26 | .owner = THIS_MODULE, | |
707827f3 DD |
27 | }; |
28 | ||
624e46d0 NP |
29 | static int max_idle_state __read_mostly; |
30 | static struct cpuidle_state *cpuidle_state_table __read_mostly; | |
31 | static u64 snooze_timeout __read_mostly; | |
32 | static bool snooze_timeout_en __read_mostly; | |
707827f3 | 33 | |
1ca80944 | 34 | static inline void idle_loop_prolog(unsigned long *in_purr) |
707827f3 | 35 | { |
d8c6ad31 | 36 | ppc64_runlatch_off(); |
707827f3 DD |
37 | *in_purr = mfspr(SPRN_PURR); |
38 | /* | |
39 | * Indicate to the HV that we are idle. Now would be | |
40 | * a good time to find other work to dispatch. | |
41 | */ | |
42 | get_lppaca()->idle = 1; | |
43 | } | |
44 | ||
1ca80944 | 45 | static inline void idle_loop_epilog(unsigned long in_purr) |
707827f3 | 46 | { |
7ffcf8ec AB |
47 | u64 wait_cycles; |
48 | ||
49 | wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles); | |
50 | wait_cycles += mfspr(SPRN_PURR) - in_purr; | |
51 | get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles); | |
707827f3 | 52 | get_lppaca()->idle = 0; |
d8c6ad31 NP |
53 | |
54 | if (irqs_disabled()) | |
55 | local_irq_enable(); | |
56 | ppc64_runlatch_on(); | |
707827f3 DD |
57 | } |
58 | ||
59 | static int snooze_loop(struct cpuidle_device *dev, | |
60 | struct cpuidle_driver *drv, | |
61 | int index) | |
62 | { | |
63 | unsigned long in_purr; | |
78eaa10f | 64 | u64 snooze_exit_time; |
707827f3 | 65 | |
3fc5ee92 NP |
66 | set_thread_flag(TIF_POLLING_NRFLAG); |
67 | ||
1ca80944 | 68 | idle_loop_prolog(&in_purr); |
83dac594 | 69 | local_irq_enable(); |
78eaa10f | 70 | snooze_exit_time = get_tb() + snooze_timeout; |
707827f3 | 71 | |
b69dbba0 | 72 | while (!need_resched()) { |
83dac594 DD |
73 | HMT_low(); |
74 | HMT_very_low(); | |
7ded4291 NP |
75 | if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) { |
76 | /* | |
77 | * Task has not woken up but we are exiting the polling | |
78 | * loop anyway. Require a barrier after polling is | |
79 | * cleared to order subsequent test of need_resched(). | |
80 | */ | |
81 | clear_thread_flag(TIF_POLLING_NRFLAG); | |
82 | smp_mb(); | |
78eaa10f | 83 | break; |
7ded4291 | 84 | } |
707827f3 DD |
85 | } |
86 | ||
707827f3 | 87 | HMT_medium(); |
83dac594 | 88 | clear_thread_flag(TIF_POLLING_NRFLAG); |
83dac594 | 89 | |
1ca80944 DL |
90 | idle_loop_epilog(in_purr); |
91 | ||
707827f3 DD |
92 | return index; |
93 | } | |
94 | ||
7230c564 BH |
95 | static void check_and_cede_processor(void) |
96 | { | |
97 | /* | |
be2cf20a BH |
98 | * Ensure our interrupt state is properly tracked, |
99 | * also checks if no interrupt has occurred while we | |
100 | * were soft-disabled | |
7230c564 | 101 | */ |
be2cf20a | 102 | if (prep_irq_for_idle()) { |
7230c564 | 103 | cede_processor(); |
be2cf20a BH |
104 | #ifdef CONFIG_TRACE_IRQFLAGS |
105 | /* Ensure that H_CEDE returns with IRQs on */ | |
106 | if (WARN_ON(!(mfmsr() & MSR_EE))) | |
107 | __hard_irq_enable(); | |
108 | #endif | |
109 | } | |
7230c564 BH |
110 | } |
111 | ||
707827f3 DD |
112 | static int dedicated_cede_loop(struct cpuidle_device *dev, |
113 | struct cpuidle_driver *drv, | |
114 | int index) | |
115 | { | |
116 | unsigned long in_purr; | |
707827f3 | 117 | |
1ca80944 | 118 | idle_loop_prolog(&in_purr); |
707827f3 DD |
119 | get_lppaca()->donate_dedicated_cpu = 1; |
120 | ||
707827f3 | 121 | HMT_medium(); |
7230c564 | 122 | check_and_cede_processor(); |
707827f3 DD |
123 | |
124 | get_lppaca()->donate_dedicated_cpu = 0; | |
1ca80944 DL |
125 | |
126 | idle_loop_epilog(in_purr); | |
127 | ||
707827f3 DD |
128 | return index; |
129 | } | |
130 | ||
131 | static int shared_cede_loop(struct cpuidle_device *dev, | |
132 | struct cpuidle_driver *drv, | |
133 | int index) | |
134 | { | |
135 | unsigned long in_purr; | |
707827f3 | 136 | |
1ca80944 | 137 | idle_loop_prolog(&in_purr); |
707827f3 DD |
138 | |
139 | /* | |
140 | * Yield the processor to the hypervisor. We return if | |
141 | * an external interrupt occurs (which are driven prior | |
142 | * to returning here) or if a prod occurs from another | |
143 | * processor. When returning here, external interrupts | |
144 | * are enabled. | |
145 | */ | |
7230c564 | 146 | check_and_cede_processor(); |
707827f3 | 147 | |
1ca80944 DL |
148 | idle_loop_epilog(in_purr); |
149 | ||
707827f3 DD |
150 | return index; |
151 | } | |
152 | ||
153 | /* | |
154 | * States for dedicated partition case. | |
155 | */ | |
bf7f61f2 | 156 | static struct cpuidle_state dedicated_states[] = { |
707827f3 DD |
157 | { /* Snooze */ |
158 | .name = "snooze", | |
159 | .desc = "snooze", | |
707827f3 DD |
160 | .exit_latency = 0, |
161 | .target_residency = 0, | |
162 | .enter = &snooze_loop }, | |
163 | { /* CEDE */ | |
164 | .name = "CEDE", | |
165 | .desc = "CEDE", | |
83dac594 DD |
166 | .exit_latency = 10, |
167 | .target_residency = 100, | |
707827f3 DD |
168 | .enter = &dedicated_cede_loop }, |
169 | }; | |
170 | ||
171 | /* | |
172 | * States for shared partition case. | |
173 | */ | |
bf7f61f2 | 174 | static struct cpuidle_state shared_states[] = { |
707827f3 DD |
175 | { /* Shared Cede */ |
176 | .name = "Shared Cede", | |
177 | .desc = "Shared Cede", | |
707827f3 DD |
178 | .exit_latency = 0, |
179 | .target_residency = 0, | |
180 | .enter = &shared_cede_loop }, | |
181 | }; | |
182 | ||
529351fd | 183 | static int pseries_cpuidle_cpu_online(unsigned int cpu) |
707827f3 | 184 | { |
529351fd | 185 | struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); |
16aaaff6 | 186 | |
852d8cb1 | 187 | if (dev && cpuidle_get_driver()) { |
529351fd SAS |
188 | cpuidle_pause_and_lock(); |
189 | cpuidle_enable_device(dev); | |
190 | cpuidle_resume_and_unlock(); | |
191 | } | |
192 | return 0; | |
193 | } | |
852d8cb1 | 194 | |
529351fd SAS |
195 | static int pseries_cpuidle_cpu_dead(unsigned int cpu) |
196 | { | |
197 | struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); | |
852d8cb1 | 198 | |
529351fd SAS |
199 | if (dev && cpuidle_get_driver()) { |
200 | cpuidle_pause_and_lock(); | |
201 | cpuidle_disable_device(dev); | |
202 | cpuidle_resume_and_unlock(); | |
707827f3 | 203 | } |
529351fd | 204 | return 0; |
707827f3 DD |
205 | } |
206 | ||
207 | /* | |
208 | * pseries_cpuidle_driver_init() | |
209 | */ | |
210 | static int pseries_cpuidle_driver_init(void) | |
211 | { | |
212 | int idle_state; | |
213 | struct cpuidle_driver *drv = &pseries_idle_driver; | |
214 | ||
215 | drv->state_count = 0; | |
216 | ||
bf7f61f2 DD |
217 | for (idle_state = 0; idle_state < max_idle_state; ++idle_state) { |
218 | /* Is the state not enabled? */ | |
707827f3 DD |
219 | if (cpuidle_state_table[idle_state].enter == NULL) |
220 | continue; | |
221 | ||
222 | drv->states[drv->state_count] = /* structure copy */ | |
223 | cpuidle_state_table[idle_state]; | |
224 | ||
707827f3 DD |
225 | drv->state_count += 1; |
226 | } | |
227 | ||
228 | return 0; | |
229 | } | |
230 | ||
707827f3 DD |
231 | /* |
232 | * pseries_idle_probe() | |
233 | * Choose state table for shared versus dedicated partition | |
234 | */ | |
235 | static int pseries_idle_probe(void) | |
236 | { | |
237 | ||
e8bb3e00 DD |
238 | if (cpuidle_disable != IDLE_NO_OVERRIDE) |
239 | return -ENODEV; | |
240 | ||
b69dbba0 | 241 | if (firmware_has_feature(FW_FEATURE_SPLPAR)) { |
bf7f61f2 | 242 | if (lppaca_shared_proc(get_lppaca())) { |
b69dbba0 | 243 | cpuidle_state_table = shared_states; |
bf7f61f2 DD |
244 | max_idle_state = ARRAY_SIZE(shared_states); |
245 | } else { | |
b69dbba0 | 246 | cpuidle_state_table = dedicated_states; |
bf7f61f2 DD |
247 | max_idle_state = ARRAY_SIZE(dedicated_states); |
248 | } | |
b69dbba0 DD |
249 | } else |
250 | return -ENODEV; | |
707827f3 | 251 | |
78eaa10f SB |
252 | if (max_idle_state > 1) { |
253 | snooze_timeout_en = true; | |
254 | snooze_timeout = cpuidle_state_table[1].target_residency * | |
255 | tb_ticks_per_usec; | |
256 | } | |
707827f3 DD |
257 | return 0; |
258 | } | |
259 | ||
260 | static int __init pseries_processor_idle_init(void) | |
261 | { | |
262 | int retval; | |
263 | ||
264 | retval = pseries_idle_probe(); | |
265 | if (retval) | |
266 | return retval; | |
267 | ||
268 | pseries_cpuidle_driver_init(); | |
b69dbba0 | 269 | retval = cpuidle_register(&pseries_idle_driver, NULL); |
707827f3 DD |
270 | if (retval) { |
271 | printk(KERN_DEBUG "Registration of pseries driver failed.\n"); | |
272 | return retval; | |
273 | } | |
274 | ||
529351fd SAS |
275 | retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, |
276 | "cpuidle/pseries:online", | |
277 | pseries_cpuidle_cpu_online, NULL); | |
278 | WARN_ON(retval < 0); | |
279 | retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD, | |
280 | "cpuidle/pseries:DEAD", NULL, | |
281 | pseries_cpuidle_cpu_dead); | |
282 | WARN_ON(retval < 0); | |
707827f3 | 283 | printk(KERN_DEBUG "pseries_idle_driver registered\n"); |
707827f3 DD |
284 | return 0; |
285 | } | |
286 | ||
12431c64 | 287 | device_initcall(pseries_processor_idle_init); |