1 /* 2 * cpuidle-pseries - idle state cpuidle driver. 3 * Adapted from drivers/idle/intel_idle.c and 4 * drivers/acpi/processor_idle.c 5 * 6 */ 7 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 23 struct cpuidle_driver pseries_idle_driver = { 24 .name = "pseries_idle", 25 .owner = THIS_MODULE, 26 }; 27 28 static int max_idle_state; 29 static struct cpuidle_state *cpuidle_state_table; 30 static u64 snooze_timeout; 31 static bool snooze_timeout_en; 32 33 static inline void idle_loop_prolog(unsigned long *in_purr) 34 { 35 ppc64_runlatch_off(); 36 *in_purr = mfspr(SPRN_PURR); 37 /* 38 * Indicate to the HV that we are idle. Now would be 39 * a good time to find other work to dispatch. 40 */ 41 get_lppaca()->idle = 1; 42 } 43 44 static 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 58 static 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 86 static void check_and_cede_processor(void) 87 { 88 /* 89 * Ensure our interrupt state is properly tracked, 90 * also checks if no interrupt has occurred while we 91 * were soft-disabled 92 */ 93 if (prep_irq_for_idle()) { 94 cede_processor(); 95 #ifdef CONFIG_TRACE_IRQFLAGS 96 /* Ensure that H_CEDE returns with IRQs on */ 97 if (WARN_ON(!(mfmsr() & MSR_EE))) 98 __hard_irq_enable(); 99 #endif 100 } 101 } 102 103 static 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 } 121 122 static 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 * Yield the processor to the hypervisor. We return if 132 * an external interrupt occurs (which are driven prior 133 * to returning here) or if a prod occurs from another 134 * processor. When returning here, external interrupts 135 * are enabled. 136 */ 137 check_and_cede_processor(); 138 139 idle_loop_epilog(in_purr); 140 141 return index; 142 } 143 144 /* 145 * States for dedicated partition case. 146 */ 147 static struct cpuidle_state dedicated_states[] = { 148 { /* Snooze */ 149 .name = "snooze", 150 .desc = "snooze", 151 .exit_latency = 0, 152 .target_residency = 0, 153 .enter = &snooze_loop }, 154 { /* CEDE */ 155 .name = "CEDE", 156 .desc = "CEDE", 157 .exit_latency = 10, 158 .target_residency = 100, 159 .enter = &dedicated_cede_loop }, 160 }; 161 162 /* 163 * States for shared partition case. 164 */ 165 static struct cpuidle_state shared_states[] = { 166 { /* Shared Cede */ 167 .name = "Shared Cede", 168 .desc = "Shared Cede", 169 .exit_latency = 0, 170 .target_residency = 0, 171 .enter = &shared_cede_loop }, 172 }; 173 174 static 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 } 203 204 static struct notifier_block setup_hotplug_notifier = { 205 .notifier_call = pseries_cpuidle_add_cpu_notifier, 206 }; 207 208 /* 209 * pseries_cpuidle_driver_init() 210 */ 211 static 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 /* Is the state not enabled? */ 220 if (cpuidle_state_table[idle_state].enter == NULL) 221 continue; 222 223 drv->states[drv->state_count] = /* structure copy */ 224 cpuidle_state_table[idle_state]; 225 226 drv->state_count += 1; 227 } 228 229 return 0; 230 } 231 232 /* 233 * pseries_idle_probe() 234 * Choose state table for shared versus dedicated partition 235 */ 236 static 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 } 260 261 static 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 } 280 281 device_initcall(pseries_processor_idle_init); 282