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8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/moduleparam.h>
12#include <linux/cpuidle.h>
13#include <linux/cpu.h>
14#include <linux/notifier.h>
15
16#include <asm/paca.h>
17#include <asm/reg.h>
18#include <asm/machdep.h>
19#include <asm/firmware.h>
20#include <asm/runlatch.h>
21#include <asm/plpar_wrappers.h>
22
23struct cpuidle_driver pseries_idle_driver = {
24 .name = "pseries_idle",
25 .owner = THIS_MODULE,
26};
27
28static int max_idle_state;
29static struct cpuidle_state *cpuidle_state_table;
30static u64 snooze_timeout;
31static bool snooze_timeout_en;
32
33static inline void idle_loop_prolog(unsigned long *in_purr)
34{
35 ppc64_runlatch_off();
36 *in_purr = mfspr(SPRN_PURR);
37
38
39
40
41 get_lppaca()->idle = 1;
42}
43
44static inline void idle_loop_epilog(unsigned long in_purr)
45{
46 u64 wait_cycles;
47
48 wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles);
49 wait_cycles += mfspr(SPRN_PURR) - in_purr;
50 get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles);
51 get_lppaca()->idle = 0;
52
53 if (irqs_disabled())
54 local_irq_enable();
55 ppc64_runlatch_on();
56}
57
58static int snooze_loop(struct cpuidle_device *dev,
59 struct cpuidle_driver *drv,
60 int index)
61{
62 unsigned long in_purr;
63 u64 snooze_exit_time;
64
65 idle_loop_prolog(&in_purr);
66 local_irq_enable();
67 set_thread_flag(TIF_POLLING_NRFLAG);
68 snooze_exit_time = get_tb() + snooze_timeout;
69
70 while (!need_resched()) {
71 HMT_low();
72 HMT_very_low();
73 if (snooze_timeout_en && get_tb() > snooze_exit_time)
74 break;
75 }
76
77 HMT_medium();
78 clear_thread_flag(TIF_POLLING_NRFLAG);
79 smp_mb();
80
81 idle_loop_epilog(in_purr);
82
83 return index;
84}
85
86static void check_and_cede_processor(void)
87{
88
89
90
91
92
93 if (prep_irq_for_idle()) {
94 cede_processor();
95#ifdef CONFIG_TRACE_IRQFLAGS
96
97 if (WARN_ON(!(mfmsr() & MSR_EE)))
98 __hard_irq_enable();
99#endif
100 }
101}
102
103static int dedicated_cede_loop(struct cpuidle_device *dev,
104 struct cpuidle_driver *drv,
105 int index)
106{
107 unsigned long in_purr;
108
109 idle_loop_prolog(&in_purr);
110 get_lppaca()->donate_dedicated_cpu = 1;
111
112 HMT_medium();
113 check_and_cede_processor();
114
115 get_lppaca()->donate_dedicated_cpu = 0;
116
117 idle_loop_epilog(in_purr);
118
119 return index;
120}
121
122static int shared_cede_loop(struct cpuidle_device *dev,
123 struct cpuidle_driver *drv,
124 int index)
125{
126 unsigned long in_purr;
127
128 idle_loop_prolog(&in_purr);
129
130
131
132
133
134
135
136
137 check_and_cede_processor();
138
139 idle_loop_epilog(in_purr);
140
141 return index;
142}
143
144
145
146
147static struct cpuidle_state dedicated_states[] = {
148 {
149 .name = "snooze",
150 .desc = "snooze",
151 .exit_latency = 0,
152 .target_residency = 0,
153 .enter = &snooze_loop },
154 {
155 .name = "CEDE",
156 .desc = "CEDE",
157 .exit_latency = 10,
158 .target_residency = 100,
159 .enter = &dedicated_cede_loop },
160};
161
162
163
164
165static struct cpuidle_state shared_states[] = {
166 {
167 .name = "Shared Cede",
168 .desc = "Shared Cede",
169 .exit_latency = 0,
170 .target_residency = 0,
171 .enter = &shared_cede_loop },
172};
173
174static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
175 unsigned long action, void *hcpu)
176{
177 int hotcpu = (unsigned long)hcpu;
178 struct cpuidle_device *dev =
179 per_cpu(cpuidle_devices, hotcpu);
180
181 if (dev && cpuidle_get_driver()) {
182 switch (action) {
183 case CPU_ONLINE:
184 case CPU_ONLINE_FROZEN:
185 cpuidle_pause_and_lock();
186 cpuidle_enable_device(dev);
187 cpuidle_resume_and_unlock();
188 break;
189
190 case CPU_DEAD:
191 case CPU_DEAD_FROZEN:
192 cpuidle_pause_and_lock();
193 cpuidle_disable_device(dev);
194 cpuidle_resume_and_unlock();
195 break;
196
197 default:
198 return NOTIFY_DONE;
199 }
200 }
201 return NOTIFY_OK;
202}
203
204static struct notifier_block setup_hotplug_notifier = {
205 .notifier_call = pseries_cpuidle_add_cpu_notifier,
206};
207
208
209
210
211static int pseries_cpuidle_driver_init(void)
212{
213 int idle_state;
214 struct cpuidle_driver *drv = &pseries_idle_driver;
215
216 drv->state_count = 0;
217
218 for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
219
220 if (cpuidle_state_table[idle_state].enter == NULL)
221 continue;
222
223 drv->states[drv->state_count] =
224 cpuidle_state_table[idle_state];
225
226 drv->state_count += 1;
227 }
228
229 return 0;
230}
231
232
233
234
235
236static int pseries_idle_probe(void)
237{
238
239 if (cpuidle_disable != IDLE_NO_OVERRIDE)
240 return -ENODEV;
241
242 if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
243 if (lppaca_shared_proc(get_lppaca())) {
244 cpuidle_state_table = shared_states;
245 max_idle_state = ARRAY_SIZE(shared_states);
246 } else {
247 cpuidle_state_table = dedicated_states;
248 max_idle_state = ARRAY_SIZE(dedicated_states);
249 }
250 } else
251 return -ENODEV;
252
253 if (max_idle_state > 1) {
254 snooze_timeout_en = true;
255 snooze_timeout = cpuidle_state_table[1].target_residency *
256 tb_ticks_per_usec;
257 }
258 return 0;
259}
260
261static int __init pseries_processor_idle_init(void)
262{
263 int retval;
264
265 retval = pseries_idle_probe();
266 if (retval)
267 return retval;
268
269 pseries_cpuidle_driver_init();
270 retval = cpuidle_register(&pseries_idle_driver, NULL);
271 if (retval) {
272 printk(KERN_DEBUG "Registration of pseries driver failed.\n");
273 return retval;
274 }
275
276 register_cpu_notifier(&setup_hotplug_notifier);
277 printk(KERN_DEBUG "pseries_idle_driver registered\n");
278 return 0;
279}
280
281device_initcall(pseries_processor_idle_init);
282