arch/arm/include/asm/mcpm.h

   1 /*
   2  * arch/arm/include/asm/mcpm.h
   3  *
   4  * Created by:  Nicolas Pitre, April 2012
   5  * Copyright:   (C) 2012-2013  Linaro Limited
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #ifndef MCPM_H
  13 #define MCPM_H
  14
  15 /*
  16  * Maximum number of possible clusters / CPUs per cluster.
  17  *
  18  * This should be sufficient for quite a while, while keeping the
  19  * (assembly) code simpler.  When this starts to grow then we'll have
  20  * to consider dynamic allocation.
  21  */
  22 #define MAX_CPUS_PER_CLUSTER    4
  23
  24 #ifdef CONFIG_MCPM_QUAD_CLUSTER
  25 #define MAX_NR_CLUSTERS         4
  26 #else
  27 #define MAX_NR_CLUSTERS         2
  28 #endif
  29
  30 #ifndef __ASSEMBLY__
  31
  32 #include <linux/types.h>
  33 #include <asm/cacheflush.h>
  34
  35 /*
  36  * Platform specific code should use this symbol to set up secondary
  37  * entry location for processors to use when released from reset.
  38  */
  39 extern void mcpm_entry_point(void);
  40
  41 /*
  42  * This is used to indicate where the given CPU from given cluster should
  43  * branch once it is ready to re-enter the kernel using ptr, or NULL if it
  44  * should be gated.  A gated CPU is held in a WFE loop until its vector
  45  * becomes non NULL.
  46  */
  47 void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr);
  48
  49 /*
  50  * This sets an early poke i.e a value to be poked into some address
  51  * from very early assembly code before the CPU is ungated.  The
  52  * address must be physical, and if 0 then nothing will happen.
  53  */
  54 void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
  55                          unsigned long poke_phys_addr, unsigned long poke_val);
  56
  57 /*
  58  * CPU/cluster power operations API for higher subsystems to use.
  59  */
  60
  61 /**
  62  * mcpm_is_available - returns whether MCPM is initialized and available
  63  *
  64  * This returns true or false accordingly.
  65  */
  66 bool mcpm_is_available(void);
  67
  68 /**
  69  * mcpm_cpu_power_up - make given CPU in given cluster runable
  70  *
  71  * @cpu: CPU number within given cluster
  72  * @cluster: cluster number for the CPU
  73  *
  74  * The identified CPU is brought out of reset.  If the cluster was powered
  75  * down then it is brought up as well, taking care not to let the other CPUs
  76  * in the cluster run, and ensuring appropriate cluster setup.
  77  *
  78  * Caller must ensure the appropriate entry vector is initialized with
  79  * mcpm_set_entry_vector() prior to calling this.
  80  *
  81  * This must be called in a sleepable context.  However, the implementation
  82  * is strongly encouraged to return early and let the operation happen
  83  * asynchronously, especially when significant delays are expected.
  84  *
  85  * If the operation cannot be performed then an error code is returned.
  86  */
  87 int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster);
  88
  89 /**
  90  * mcpm_cpu_power_down - power the calling CPU down
  91  *
  92  * The calling CPU is powered down.
  93  *
  94  * If this CPU is found to be the "last man standing" in the cluster
  95  * then the cluster is prepared for power-down too.
  96  *
  97  * This must be called with interrupts disabled.
  98  *
  99  * On success this does not return.  Re-entry in the kernel is expected
 100  * via mcpm_entry_point.
 101  *
 102  * This will return if mcpm_platform_register() has not been called
 103  * previously in which case the caller should take appropriate action.
 104  *
 105  * On success, the CPU is not guaranteed to be truly halted until
 106  * mcpm_wait_for_cpu_powerdown() subsequently returns non-zero for the
 107  * specified cpu.  Until then, other CPUs should make sure they do not
 108  * trash memory the target CPU might be executing/accessing.
 109  */
 110 void mcpm_cpu_power_down(void);
 111
 112 /**
 113  * mcpm_wait_for_cpu_powerdown - wait for a specified CPU to halt, and
 114  *      make sure it is powered off
 115  *
 116  * @cpu: CPU number within given cluster
 117  * @cluster: cluster number for the CPU
 118  *
 119  * Call this function to ensure that a pending powerdown has taken
 120  * effect and the CPU is safely parked before performing non-mcpm
 121  * operations that may affect the CPU (such as kexec trashing the
 122  * kernel text).
 123  *
 124  * It is *not* necessary to call this function if you only need to
 125  * serialise a pending powerdown with mcpm_cpu_power_up() or a wakeup
 126  * event.
 127  *
 128  * Do not call this function unless the specified CPU has already
 129  * called mcpm_cpu_power_down() or has committed to doing so.
 130  *
 131  * @return:
 132  *      - zero if the CPU is in a safely parked state
 133  *      - nonzero otherwise (e.g., timeout)
 134  */
 135 int mcpm_wait_for_cpu_powerdown(unsigned int cpu, unsigned int cluster);
 136
 137 /**
 138  * mcpm_cpu_suspend - bring the calling CPU in a suspended state
 139  *
 140  * The calling CPU is suspended.  This is similar to mcpm_cpu_power_down()
 141  * except for possible extra platform specific configuration steps to allow
 142  * an asynchronous wake-up e.g. with a pending interrupt.
 143  *
 144  * If this CPU is found to be the "last man standing" in the cluster
 145  * then the cluster may be prepared for power-down too.
 146  *
 147  * This must be called with interrupts disabled.
 148  *
 149  * On success this does not return.  Re-entry in the kernel is expected
 150  * via mcpm_entry_point.
 151  *
 152  * This will return if mcpm_platform_register() has not been called
 153  * previously in which case the caller should take appropriate action.
 154  */
 155 void mcpm_cpu_suspend(void);
 156
 157 /**
 158  * mcpm_cpu_powered_up - housekeeping workafter a CPU has been powered up
 159  *
 160  * This lets the platform specific backend code perform needed housekeeping
 161  * work.  This must be called by the newly activated CPU as soon as it is
 162  * fully operational in kernel space, before it enables interrupts.
 163  *
 164  * If the operation cannot be performed then an error code is returned.
 165  */
 166 int mcpm_cpu_powered_up(void);
 167
 168 /*
 169  * Platform specific callbacks used in the implementation of the above API.
 170  *
 171  * cpu_powerup:
 172  * Make given CPU runable. Called with MCPM lock held and IRQs disabled.
 173  * The given cluster is assumed to be set up (cluster_powerup would have
 174  * been called beforehand). Must return 0 for success or negative error code.
 175  *
 176  * cluster_powerup:
 177  * Set up power for given cluster. Called with MCPM lock held and IRQs
 178  * disabled. Called before first cpu_powerup when cluster is down. Must
 179  * return 0 for success or negative error code.
 180  *
 181  * cpu_suspend_prepare:
 182  * Special suspend configuration. Called on target CPU with MCPM lock held
 183  * and IRQs disabled. This callback is optional. If provided, it is called
 184  * before cpu_powerdown_prepare.
 185  *
 186  * cpu_powerdown_prepare:
 187  * Configure given CPU for power down. Called on target CPU with MCPM lock
 188  * held and IRQs disabled. Power down must be effective only at the next WFI instruction.
 189  *
 190  * cluster_powerdown_prepare:
 191  * Configure given cluster for power down. Called on one CPU from target
 192  * cluster with MCPM lock held and IRQs disabled. A cpu_powerdown_prepare
 193  * for each CPU in the cluster has happened when this occurs.
 194  *
 195  * cpu_cache_disable:
 196  * Clean and disable CPU level cache for the calling CPU. Called on with IRQs
 197  * disabled only. The CPU is no longer cache coherent with the rest of the
 198  * system when this returns.
 199  *
 200  * cluster_cache_disable:
 201  * Clean and disable the cluster wide cache as well as the CPU level cache
 202  * for the calling CPU. No call to cpu_cache_disable will happen for this
 203  * CPU. Called with IRQs disabled and only when all the other CPUs are done
 204  * with their own cpu_cache_disable. The cluster is no longer cache coherent
 205  * with the rest of the system when this returns.
 206  *
 207  * cpu_is_up:
 208  * Called on given CPU after it has been powered up or resumed. The MCPM lock
 209  * is held and IRQs disabled. This callback is optional.
 210  *
 211  * cluster_is_up:
 212  * Called by the first CPU to be powered up or resumed in given cluster.
 213  * The MCPM lock is held and IRQs disabled. This callback is optional. If
 214  * provided, it is called before cpu_is_up for that CPU.
 215  *
 216  * wait_for_powerdown:
 217  * Wait until given CPU is powered down. This is called in sleeping context.
 218  * Some reasonable timeout must be considered. Must return 0 for success or
 219  * negative error code.
 220  */
 221 struct mcpm_platform_ops {
 222         int (*cpu_powerup)(unsigned int cpu, unsigned int cluster);
 223         int (*cluster_powerup)(unsigned int cluster);
 224         void (*cpu_suspend_prepare)(unsigned int cpu, unsigned int cluster);
 225         void (*cpu_powerdown_prepare)(unsigned int cpu, unsigned int cluster);
 226         void (*cluster_powerdown_prepare)(unsigned int cluster);
 227         void (*cpu_cache_disable)(void);
 228         void (*cluster_cache_disable)(void);
 229         void (*cpu_is_up)(unsigned int cpu, unsigned int cluster);
 230         void (*cluster_is_up)(unsigned int cluster);
 231         int (*wait_for_powerdown)(unsigned int cpu, unsigned int cluster);
 232 };
 233
 234 /**
 235  * mcpm_platform_register - register platform specific power methods
 236  *
 237  * @ops: mcpm_platform_ops structure to register
 238  *
 239  * An error is returned if the registration has been done previously.
 240  */
 241 int __init mcpm_platform_register(const struct mcpm_platform_ops *ops);
 242
 243 /**
 244  * mcpm_sync_init - Initialize the cluster synchronization support
 245  *
 246  * @power_up_setup: platform specific function invoked during very
 247  *                  early CPU/cluster bringup stage.
 248  *
 249  * This prepares memory used by vlocks and the MCPM state machine used
 250  * across CPUs that may have their caches active or inactive. Must be
 251  * called only after a successful call to mcpm_platform_register().
 252  *
 253  * The power_up_setup argument is a pointer to assembly code called when
 254  * the MMU and caches are still disabled during boot  and no stack space is
 255  * available. The affinity level passed to that code corresponds to the
 256  * resource that needs to be initialized (e.g. 1 for cluster level, 0 for
 257  * CPU level).  Proper exclusion mechanisms are already activated at that
 258  * point.
 259  */
 260 int __init mcpm_sync_init(
 261         void (*power_up_setup)(unsigned int affinity_level));
 262
 263 /**
 264  * mcpm_loopback - make a run through the MCPM low-level code
 265  *
 266  * @cache_disable: pointer to function performing cache disabling
 267  *
 268  * This exercises the MCPM machinery by soft resetting the CPU and branching
 269  * to the MCPM low-level entry code before returning to the caller.
 270  * The @cache_disable function must do the necessary cache disabling to
 271  * let the regular kernel init code turn it back on as if the CPU was
 272  * hotplugged in. The MCPM state machine is set as if the cluster was
 273  * initialized meaning the power_up_setup callback passed to mcpm_sync_init()
 274  * will be invoked for all affinity levels. This may be useful to initialize
 275  * some resources such as enabling the CCI that requires the cache to be off, or simply for testing purposes.
 276  */
 277 int __init mcpm_loopback(void (*cache_disable)(void));
 278
 279 void __init mcpm_smp_set_ops(void);
 280
 281 /*
 282  * Synchronisation structures for coordinating safe cluster setup/teardown.
 283  * This is private to the MCPM core code and shared between C and assembly.
 284  * When modifying this structure, make sure you update the MCPM_SYNC_ defines
 285  * to match.
 286  */
 287 struct mcpm_sync_struct {
 288         /* individual CPU states */
 289         struct {
 290                 s8 cpu __aligned(__CACHE_WRITEBACK_GRANULE);
 291         } cpus[MAX_CPUS_PER_CLUSTER];
 292
 293         /* cluster state */
 294         s8 cluster __aligned(__CACHE_WRITEBACK_GRANULE);
 295
 296         /* inbound-side state */
 297         s8 inbound __aligned(__CACHE_WRITEBACK_GRANULE);
 298 };
 299
 300 struct sync_struct {
 301         struct mcpm_sync_struct clusters[MAX_NR_CLUSTERS];
 302 };
 303
 304 #else
 305
 306 /*
 307  * asm-offsets.h causes trouble when included in .c files, and cacheflush.h
 308  * cannot be included in asm files.  Let's work around the conflict like this.
 309  */
 310 #include <asm/asm-offsets.h>
 311 #define __CACHE_WRITEBACK_GRANULE CACHE_WRITEBACK_GRANULE
 312
 313 #endif /* ! __ASSEMBLY__ */
 314
 315 /* Definitions for mcpm_sync_struct */
 316 #define CPU_DOWN                0x11
 317 #define CPU_COMING_UP           0x12
 318 #define CPU_UP                  0x13
 319 #define CPU_GOING_DOWN          0x14
 320
 321 #define CLUSTER_DOWN            0x21
 322 #define CLUSTER_UP              0x22
 323 #define CLUSTER_GOING_DOWN      0x23
 324
 325 #define INBOUND_NOT_COMING_UP   0x31
 326 #define INBOUND_COMING_UP       0x32
 327
 328 /*
 329  * Offsets for the mcpm_sync_struct members, for use in asm.
 330  * We don't want to make them global to the kernel via asm-offsets.c.
 331  */
 332 #define MCPM_SYNC_CLUSTER_CPUS  0
 333 #define MCPM_SYNC_CPU_SIZE      __CACHE_WRITEBACK_GRANULE
 334 #define MCPM_SYNC_CLUSTER_CLUSTER \
 335         (MCPM_SYNC_CLUSTER_CPUS + MCPM_SYNC_CPU_SIZE * MAX_CPUS_PER_CLUSTER)
 336 #define MCPM_SYNC_CLUSTER_INBOUND \
 337         (MCPM_SYNC_CLUSTER_CLUSTER + __CACHE_WRITEBACK_GRANULE)
 338 #define MCPM_SYNC_CLUSTER_SIZE \
 339         (MCPM_SYNC_CLUSTER_INBOUND + __CACHE_WRITEBACK_GRANULE)
 340
 341 #endif