1 /*
2  *  cpuidle-powernv - idle state cpuidle driver.
3  *  Adapted from drivers/cpuidle/cpuidle-pseries
4  *
5  */
6 
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/init.h>
10 #include <linux/moduleparam.h>
11 #include <linux/cpuidle.h>
12 #include <linux/cpu.h>
13 #include <linux/notifier.h>
14 #include <linux/clockchips.h>
15 #include <linux/of.h>
16 
17 #include <asm/machdep.h>
18 #include <asm/firmware.h>
19 #include <asm/runlatch.h>
20 
21 /* Flags and constants used in PowerNV platform */
22 
23 #define MAX_POWERNV_IDLE_STATES	8
24 #define IDLE_USE_INST_NAP	0x00010000 /* Use nap instruction */
25 #define IDLE_USE_INST_SLEEP	0x00020000 /* Use sleep instruction */
26 
27 struct cpuidle_driver powernv_idle_driver = {
28 	.name             = "powernv_idle",
29 	.owner            = THIS_MODULE,
30 };
31 
32 static int max_idle_state;
33 static struct cpuidle_state *cpuidle_state_table;
34 
35 static int snooze_loop(struct cpuidle_device *dev,
36 			struct cpuidle_driver *drv,
37 			int index)
38 {
39 	local_irq_enable();
40 	set_thread_flag(TIF_POLLING_NRFLAG);
41 
42 	ppc64_runlatch_off();
43 	while (!need_resched()) {
44 		HMT_low();
45 		HMT_very_low();
46 	}
47 
48 	HMT_medium();
49 	ppc64_runlatch_on();
50 	clear_thread_flag(TIF_POLLING_NRFLAG);
51 	smp_mb();
52 	return index;
53 }
54 
55 static int nap_loop(struct cpuidle_device *dev,
56 			struct cpuidle_driver *drv,
57 			int index)
58 {
59 	ppc64_runlatch_off();
60 	power7_idle();
61 	ppc64_runlatch_on();
62 	return index;
63 }
64 
65 static int fastsleep_loop(struct cpuidle_device *dev,
66 				struct cpuidle_driver *drv,
67 				int index)
68 {
69 	unsigned long old_lpcr = mfspr(SPRN_LPCR);
70 	unsigned long new_lpcr;
71 
72 	if (unlikely(system_state < SYSTEM_RUNNING))
73 		return index;
74 
75 	new_lpcr = old_lpcr;
76 	/* Do not exit powersave upon decrementer as we've setup the timer
77 	 * offload.
78 	 */
79 	new_lpcr &= ~LPCR_PECE1;
80 
81 	mtspr(SPRN_LPCR, new_lpcr);
82 	power7_sleep();
83 
84 	mtspr(SPRN_LPCR, old_lpcr);
85 
86 	return index;
87 }
88 
89 /*
90  * States for dedicated partition case.
91  */
92 static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
93 	{ /* Snooze */
94 		.name = "snooze",
95 		.desc = "snooze",
96 		.flags = CPUIDLE_FLAG_TIME_VALID,
97 		.exit_latency = 0,
98 		.target_residency = 0,
99 		.enter = &snooze_loop },
100 };
101 
102 static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
103 			unsigned long action, void *hcpu)
104 {
105 	int hotcpu = (unsigned long)hcpu;
106 	struct cpuidle_device *dev =
107 				per_cpu(cpuidle_devices, hotcpu);
108 
109 	if (dev && cpuidle_get_driver()) {
110 		switch (action) {
111 		case CPU_ONLINE:
112 		case CPU_ONLINE_FROZEN:
113 			cpuidle_pause_and_lock();
114 			cpuidle_enable_device(dev);
115 			cpuidle_resume_and_unlock();
116 			break;
117 
118 		case CPU_DEAD:
119 		case CPU_DEAD_FROZEN:
120 			cpuidle_pause_and_lock();
121 			cpuidle_disable_device(dev);
122 			cpuidle_resume_and_unlock();
123 			break;
124 
125 		default:
126 			return NOTIFY_DONE;
127 		}
128 	}
129 	return NOTIFY_OK;
130 }
131 
132 static struct notifier_block setup_hotplug_notifier = {
133 	.notifier_call = powernv_cpuidle_add_cpu_notifier,
134 };
135 
136 /*
137  * powernv_cpuidle_driver_init()
138  */
139 static int powernv_cpuidle_driver_init(void)
140 {
141 	int idle_state;
142 	struct cpuidle_driver *drv = &powernv_idle_driver;
143 
144 	drv->state_count = 0;
145 
146 	for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
147 		/* Is the state not enabled? */
148 		if (cpuidle_state_table[idle_state].enter == NULL)
149 			continue;
150 
151 		drv->states[drv->state_count] =	/* structure copy */
152 			cpuidle_state_table[idle_state];
153 
154 		drv->state_count += 1;
155 	}
156 
157 	return 0;
158 }
159 
160 static int powernv_add_idle_states(void)
161 {
162 	struct device_node *power_mgt;
163 	int nr_idle_states = 1; /* Snooze */
164 	int dt_idle_states;
165 	const __be32 *idle_state_flags;
166 	const __be32 *idle_state_latency;
167 	u32 len_flags, flags, latency_ns;
168 	int i;
169 
170 	/* Currently we have snooze statically defined */
171 
172 	power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
173 	if (!power_mgt) {
174 		pr_warn("opal: PowerMgmt Node not found\n");
175 		return nr_idle_states;
176 	}
177 
178 	idle_state_flags = of_get_property(power_mgt, "ibm,cpu-idle-state-flags", &len_flags);
179 	if (!idle_state_flags) {
180 		pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-flags\n");
181 		return nr_idle_states;
182 	}
183 
184 	idle_state_latency = of_get_property(power_mgt,
185 			"ibm,cpu-idle-state-latencies-ns", NULL);
186 	if (!idle_state_latency) {
187 		pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-latencies-ns\n");
188 		return nr_idle_states;
189 	}
190 
191 	dt_idle_states = len_flags / sizeof(u32);
192 
193 	for (i = 0; i < dt_idle_states; i++) {
194 
195 		flags = be32_to_cpu(idle_state_flags[i]);
196 
197 		/* Cpuidle accepts exit_latency in us and we estimate
198 		 * target residency to be 10x exit_latency
199 		 */
200 		latency_ns = be32_to_cpu(idle_state_latency[i]);
201 		if (flags & IDLE_USE_INST_NAP) {
202 			/* Add NAP state */
203 			strcpy(powernv_states[nr_idle_states].name, "Nap");
204 			strcpy(powernv_states[nr_idle_states].desc, "Nap");
205 			powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIME_VALID;
206 			powernv_states[nr_idle_states].exit_latency =
207 					((unsigned int)latency_ns) / 1000;
208 			powernv_states[nr_idle_states].target_residency =
209 					((unsigned int)latency_ns / 100);
210 			powernv_states[nr_idle_states].enter = &nap_loop;
211 			nr_idle_states++;
212 		}
213 
214 		if (flags & IDLE_USE_INST_SLEEP) {
215 			/* Add FASTSLEEP state */
216 			strcpy(powernv_states[nr_idle_states].name, "FastSleep");
217 			strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
218 			powernv_states[nr_idle_states].flags =
219 				CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
220 			powernv_states[nr_idle_states].exit_latency =
221 					((unsigned int)latency_ns) / 1000;
222 			powernv_states[nr_idle_states].target_residency =
223 					((unsigned int)latency_ns / 100);
224 			powernv_states[nr_idle_states].enter = &fastsleep_loop;
225 			nr_idle_states++;
226 		}
227 	}
228 
229 	return nr_idle_states;
230 }
231 
232 /*
233  * powernv_idle_probe()
234  * Choose state table for shared versus dedicated partition
235  */
236 static int powernv_idle_probe(void)
237 {
238 	if (cpuidle_disable != IDLE_NO_OVERRIDE)
239 		return -ENODEV;
240 
241 	if (firmware_has_feature(FW_FEATURE_OPALv3)) {
242 		cpuidle_state_table = powernv_states;
243 		/* Device tree can indicate more idle states */
244 		max_idle_state = powernv_add_idle_states();
245  	} else
246  		return -ENODEV;
247 
248 	return 0;
249 }
250 
251 static int __init powernv_processor_idle_init(void)
252 {
253 	int retval;
254 
255 	retval = powernv_idle_probe();
256 	if (retval)
257 		return retval;
258 
259 	powernv_cpuidle_driver_init();
260 	retval = cpuidle_register(&powernv_idle_driver, NULL);
261 	if (retval) {
262 		printk(KERN_DEBUG "Registration of powernv driver failed.\n");
263 		return retval;
264 	}
265 
266 	register_cpu_notifier(&setup_hotplug_notifier);
267 	printk(KERN_DEBUG "powernv_idle_driver registered\n");
268 	return 0;
269 }
270 
271 device_initcall(powernv_processor_idle_init);
272