Nishanth Menon | e1f60b2 | 2010-10-13 00:13:10 +0200 | [diff] [blame^] | 1 | /* |
| 2 | * Generic OPP Interface |
| 3 | * |
| 4 | * Copyright (C) 2009-2010 Texas Instruments Incorporated. |
| 5 | * Nishanth Menon |
| 6 | * Romit Dasgupta |
| 7 | * Kevin Hilman |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License version 2 as |
| 11 | * published by the Free Software Foundation. |
| 12 | */ |
| 13 | |
| 14 | #include <linux/kernel.h> |
| 15 | #include <linux/errno.h> |
| 16 | #include <linux/err.h> |
| 17 | #include <linux/init.h> |
| 18 | #include <linux/slab.h> |
| 19 | #include <linux/cpufreq.h> |
| 20 | #include <linux/list.h> |
| 21 | #include <linux/rculist.h> |
| 22 | #include <linux/rcupdate.h> |
| 23 | #include <linux/opp.h> |
| 24 | |
| 25 | /* |
| 26 | * Internal data structure organization with the OPP layer library is as |
| 27 | * follows: |
| 28 | * dev_opp_list (root) |
| 29 | * |- device 1 (represents voltage domain 1) |
| 30 | * | |- opp 1 (availability, freq, voltage) |
| 31 | * | |- opp 2 .. |
| 32 | * ... ... |
| 33 | * | `- opp n .. |
| 34 | * |- device 2 (represents the next voltage domain) |
| 35 | * ... |
| 36 | * `- device m (represents mth voltage domain) |
| 37 | * device 1, 2.. are represented by dev_opp structure while each opp |
| 38 | * is represented by the opp structure. |
| 39 | */ |
| 40 | |
| 41 | /** |
| 42 | * struct opp - Generic OPP description structure |
| 43 | * @node: opp list node. The nodes are maintained throughout the lifetime |
| 44 | * of boot. It is expected only an optimal set of OPPs are |
| 45 | * added to the library by the SoC framework. |
| 46 | * RCU usage: opp list is traversed with RCU locks. node |
| 47 | * modification is possible realtime, hence the modifications |
| 48 | * are protected by the dev_opp_list_lock for integrity. |
| 49 | * IMPORTANT: the opp nodes should be maintained in increasing |
| 50 | * order. |
| 51 | * @available: true/false - marks if this OPP as available or not |
| 52 | * @rate: Frequency in hertz |
| 53 | * @u_volt: Nominal voltage in microvolts corresponding to this OPP |
| 54 | * @dev_opp: points back to the device_opp struct this opp belongs to |
| 55 | * |
| 56 | * This structure stores the OPP information for a given device. |
| 57 | */ |
| 58 | struct opp { |
| 59 | struct list_head node; |
| 60 | |
| 61 | bool available; |
| 62 | unsigned long rate; |
| 63 | unsigned long u_volt; |
| 64 | |
| 65 | struct device_opp *dev_opp; |
| 66 | }; |
| 67 | |
| 68 | /** |
| 69 | * struct device_opp - Device opp structure |
| 70 | * @node: list node - contains the devices with OPPs that |
| 71 | * have been registered. Nodes once added are not modified in this |
| 72 | * list. |
| 73 | * RCU usage: nodes are not modified in the list of device_opp, |
| 74 | * however addition is possible and is secured by dev_opp_list_lock |
| 75 | * @dev: device pointer |
| 76 | * @opp_list: list of opps |
| 77 | * |
| 78 | * This is an internal data structure maintaining the link to opps attached to |
| 79 | * a device. This structure is not meant to be shared to users as it is |
| 80 | * meant for book keeping and private to OPP library |
| 81 | */ |
| 82 | struct device_opp { |
| 83 | struct list_head node; |
| 84 | |
| 85 | struct device *dev; |
| 86 | struct list_head opp_list; |
| 87 | }; |
| 88 | |
| 89 | /* |
| 90 | * The root of the list of all devices. All device_opp structures branch off |
| 91 | * from here, with each device_opp containing the list of opp it supports in |
| 92 | * various states of availability. |
| 93 | */ |
| 94 | static LIST_HEAD(dev_opp_list); |
| 95 | /* Lock to allow exclusive modification to the device and opp lists */ |
| 96 | static DEFINE_MUTEX(dev_opp_list_lock); |
| 97 | |
| 98 | /** |
| 99 | * find_device_opp() - find device_opp struct using device pointer |
| 100 | * @dev: device pointer used to lookup device OPPs |
| 101 | * |
| 102 | * Search list of device OPPs for one containing matching device. Does a RCU |
| 103 | * reader operation to grab the pointer needed. |
| 104 | * |
| 105 | * Returns pointer to 'struct device_opp' if found, otherwise -ENODEV or |
| 106 | * -EINVAL based on type of error. |
| 107 | * |
| 108 | * Locking: This function must be called under rcu_read_lock(). device_opp |
| 109 | * is a RCU protected pointer. This means that device_opp is valid as long |
| 110 | * as we are under RCU lock. |
| 111 | */ |
| 112 | static struct device_opp *find_device_opp(struct device *dev) |
| 113 | { |
| 114 | struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV); |
| 115 | |
| 116 | if (unlikely(IS_ERR_OR_NULL(dev))) { |
| 117 | pr_err("%s: Invalid parameters\n", __func__); |
| 118 | return ERR_PTR(-EINVAL); |
| 119 | } |
| 120 | |
| 121 | list_for_each_entry_rcu(tmp_dev_opp, &dev_opp_list, node) { |
| 122 | if (tmp_dev_opp->dev == dev) { |
| 123 | dev_opp = tmp_dev_opp; |
| 124 | break; |
| 125 | } |
| 126 | } |
| 127 | |
| 128 | return dev_opp; |
| 129 | } |
| 130 | |
| 131 | /** |
| 132 | * opp_get_voltage() - Gets the voltage corresponding to an available opp |
| 133 | * @opp: opp for which voltage has to be returned for |
| 134 | * |
| 135 | * Return voltage in micro volt corresponding to the opp, else |
| 136 | * return 0 |
| 137 | * |
| 138 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu |
| 139 | * protected pointer. This means that opp which could have been fetched by |
| 140 | * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are |
| 141 | * under RCU lock. The pointer returned by the opp_find_freq family must be |
| 142 | * used in the same section as the usage of this function with the pointer |
| 143 | * prior to unlocking with rcu_read_unlock() to maintain the integrity of the |
| 144 | * pointer. |
| 145 | */ |
| 146 | unsigned long opp_get_voltage(struct opp *opp) |
| 147 | { |
| 148 | struct opp *tmp_opp; |
| 149 | unsigned long v = 0; |
| 150 | |
| 151 | tmp_opp = rcu_dereference(opp); |
| 152 | if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available) |
| 153 | pr_err("%s: Invalid parameters\n", __func__); |
| 154 | else |
| 155 | v = tmp_opp->u_volt; |
| 156 | |
| 157 | return v; |
| 158 | } |
| 159 | |
| 160 | /** |
| 161 | * opp_get_freq() - Gets the frequency corresponding to an available opp |
| 162 | * @opp: opp for which frequency has to be returned for |
| 163 | * |
| 164 | * Return frequency in hertz corresponding to the opp, else |
| 165 | * return 0 |
| 166 | * |
| 167 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu |
| 168 | * protected pointer. This means that opp which could have been fetched by |
| 169 | * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are |
| 170 | * under RCU lock. The pointer returned by the opp_find_freq family must be |
| 171 | * used in the same section as the usage of this function with the pointer |
| 172 | * prior to unlocking with rcu_read_unlock() to maintain the integrity of the |
| 173 | * pointer. |
| 174 | */ |
| 175 | unsigned long opp_get_freq(struct opp *opp) |
| 176 | { |
| 177 | struct opp *tmp_opp; |
| 178 | unsigned long f = 0; |
| 179 | |
| 180 | tmp_opp = rcu_dereference(opp); |
| 181 | if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available) |
| 182 | pr_err("%s: Invalid parameters\n", __func__); |
| 183 | else |
| 184 | f = tmp_opp->rate; |
| 185 | |
| 186 | return f; |
| 187 | } |
| 188 | |
| 189 | /** |
| 190 | * opp_get_opp_count() - Get number of opps available in the opp list |
| 191 | * @dev: device for which we do this operation |
| 192 | * |
| 193 | * This function returns the number of available opps if there are any, |
| 194 | * else returns 0 if none or the corresponding error value. |
| 195 | * |
| 196 | * Locking: This function must be called under rcu_read_lock(). This function |
| 197 | * internally references two RCU protected structures: device_opp and opp which |
| 198 | * are safe as long as we are under a common RCU locked section. |
| 199 | */ |
| 200 | int opp_get_opp_count(struct device *dev) |
| 201 | { |
| 202 | struct device_opp *dev_opp; |
| 203 | struct opp *temp_opp; |
| 204 | int count = 0; |
| 205 | |
| 206 | dev_opp = find_device_opp(dev); |
| 207 | if (IS_ERR(dev_opp)) { |
| 208 | int r = PTR_ERR(dev_opp); |
| 209 | dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r); |
| 210 | return r; |
| 211 | } |
| 212 | |
| 213 | list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { |
| 214 | if (temp_opp->available) |
| 215 | count++; |
| 216 | } |
| 217 | |
| 218 | return count; |
| 219 | } |
| 220 | |
| 221 | /** |
| 222 | * opp_find_freq_exact() - search for an exact frequency |
| 223 | * @dev: device for which we do this operation |
| 224 | * @freq: frequency to search for |
| 225 | * @is_available: true/false - match for available opp |
| 226 | * |
| 227 | * Searches for exact match in the opp list and returns pointer to the matching |
| 228 | * opp if found, else returns ERR_PTR in case of error and should be handled |
| 229 | * using IS_ERR. |
| 230 | * |
| 231 | * Note: available is a modifier for the search. if available=true, then the |
| 232 | * match is for exact matching frequency and is available in the stored OPP |
| 233 | * table. if false, the match is for exact frequency which is not available. |
| 234 | * |
| 235 | * This provides a mechanism to enable an opp which is not available currently |
| 236 | * or the opposite as well. |
| 237 | * |
| 238 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu |
| 239 | * protected pointer. The reason for the same is that the opp pointer which is |
| 240 | * returned will remain valid for use with opp_get_{voltage, freq} only while |
| 241 | * under the locked area. The pointer returned must be used prior to unlocking |
| 242 | * with rcu_read_unlock() to maintain the integrity of the pointer. |
| 243 | */ |
| 244 | struct opp *opp_find_freq_exact(struct device *dev, unsigned long freq, |
| 245 | bool available) |
| 246 | { |
| 247 | struct device_opp *dev_opp; |
| 248 | struct opp *temp_opp, *opp = ERR_PTR(-ENODEV); |
| 249 | |
| 250 | dev_opp = find_device_opp(dev); |
| 251 | if (IS_ERR(dev_opp)) { |
| 252 | int r = PTR_ERR(dev_opp); |
| 253 | dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r); |
| 254 | return ERR_PTR(r); |
| 255 | } |
| 256 | |
| 257 | list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { |
| 258 | if (temp_opp->available == available && |
| 259 | temp_opp->rate == freq) { |
| 260 | opp = temp_opp; |
| 261 | break; |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | return opp; |
| 266 | } |
| 267 | |
| 268 | /** |
| 269 | * opp_find_freq_ceil() - Search for an rounded ceil freq |
| 270 | * @dev: device for which we do this operation |
| 271 | * @freq: Start frequency |
| 272 | * |
| 273 | * Search for the matching ceil *available* OPP from a starting freq |
| 274 | * for a device. |
| 275 | * |
| 276 | * Returns matching *opp and refreshes *freq accordingly, else returns |
| 277 | * ERR_PTR in case of error and should be handled using IS_ERR. |
| 278 | * |
| 279 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu |
| 280 | * protected pointer. The reason for the same is that the opp pointer which is |
| 281 | * returned will remain valid for use with opp_get_{voltage, freq} only while |
| 282 | * under the locked area. The pointer returned must be used prior to unlocking |
| 283 | * with rcu_read_unlock() to maintain the integrity of the pointer. |
| 284 | */ |
| 285 | struct opp *opp_find_freq_ceil(struct device *dev, unsigned long *freq) |
| 286 | { |
| 287 | struct device_opp *dev_opp; |
| 288 | struct opp *temp_opp, *opp = ERR_PTR(-ENODEV); |
| 289 | |
| 290 | if (!dev || !freq) { |
| 291 | dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq); |
| 292 | return ERR_PTR(-EINVAL); |
| 293 | } |
| 294 | |
| 295 | dev_opp = find_device_opp(dev); |
| 296 | if (IS_ERR(dev_opp)) |
| 297 | return opp; |
| 298 | |
| 299 | list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { |
| 300 | if (temp_opp->available && temp_opp->rate >= *freq) { |
| 301 | opp = temp_opp; |
| 302 | *freq = opp->rate; |
| 303 | break; |
| 304 | } |
| 305 | } |
| 306 | |
| 307 | return opp; |
| 308 | } |
| 309 | |
| 310 | /** |
| 311 | * opp_find_freq_floor() - Search for a rounded floor freq |
| 312 | * @dev: device for which we do this operation |
| 313 | * @freq: Start frequency |
| 314 | * |
| 315 | * Search for the matching floor *available* OPP from a starting freq |
| 316 | * for a device. |
| 317 | * |
| 318 | * Returns matching *opp and refreshes *freq accordingly, else returns |
| 319 | * ERR_PTR in case of error and should be handled using IS_ERR. |
| 320 | * |
| 321 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu |
| 322 | * protected pointer. The reason for the same is that the opp pointer which is |
| 323 | * returned will remain valid for use with opp_get_{voltage, freq} only while |
| 324 | * under the locked area. The pointer returned must be used prior to unlocking |
| 325 | * with rcu_read_unlock() to maintain the integrity of the pointer. |
| 326 | */ |
| 327 | struct opp *opp_find_freq_floor(struct device *dev, unsigned long *freq) |
| 328 | { |
| 329 | struct device_opp *dev_opp; |
| 330 | struct opp *temp_opp, *opp = ERR_PTR(-ENODEV); |
| 331 | |
| 332 | if (!dev || !freq) { |
| 333 | dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq); |
| 334 | return ERR_PTR(-EINVAL); |
| 335 | } |
| 336 | |
| 337 | dev_opp = find_device_opp(dev); |
| 338 | if (IS_ERR(dev_opp)) |
| 339 | return opp; |
| 340 | |
| 341 | list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { |
| 342 | if (temp_opp->available) { |
| 343 | /* go to the next node, before choosing prev */ |
| 344 | if (temp_opp->rate > *freq) |
| 345 | break; |
| 346 | else |
| 347 | opp = temp_opp; |
| 348 | } |
| 349 | } |
| 350 | if (!IS_ERR(opp)) |
| 351 | *freq = opp->rate; |
| 352 | |
| 353 | return opp; |
| 354 | } |
| 355 | |
| 356 | /** |
| 357 | * opp_add() - Add an OPP table from a table definitions |
| 358 | * @dev: device for which we do this operation |
| 359 | * @freq: Frequency in Hz for this OPP |
| 360 | * @u_volt: Voltage in uVolts for this OPP |
| 361 | * |
| 362 | * This function adds an opp definition to the opp list and returns status. |
| 363 | * The opp is made available by default and it can be controlled using |
| 364 | * opp_enable/disable functions. |
| 365 | * |
| 366 | * Locking: The internal device_opp and opp structures are RCU protected. |
| 367 | * Hence this function internally uses RCU updater strategy with mutex locks |
| 368 | * to keep the integrity of the internal data structures. Callers should ensure |
| 369 | * that this function is *NOT* called under RCU protection or in contexts where |
| 370 | * mutex cannot be locked. |
| 371 | */ |
| 372 | int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) |
| 373 | { |
| 374 | struct device_opp *dev_opp = NULL; |
| 375 | struct opp *opp, *new_opp; |
| 376 | struct list_head *head; |
| 377 | |
| 378 | /* allocate new OPP node */ |
| 379 | new_opp = kzalloc(sizeof(struct opp), GFP_KERNEL); |
| 380 | if (!new_opp) { |
| 381 | dev_warn(dev, "%s: Unable to create new OPP node\n", __func__); |
| 382 | return -ENOMEM; |
| 383 | } |
| 384 | |
| 385 | /* Hold our list modification lock here */ |
| 386 | mutex_lock(&dev_opp_list_lock); |
| 387 | |
| 388 | /* Check for existing list for 'dev' */ |
| 389 | dev_opp = find_device_opp(dev); |
| 390 | if (IS_ERR(dev_opp)) { |
| 391 | /* |
| 392 | * Allocate a new device OPP table. In the infrequent case |
| 393 | * where a new device is needed to be added, we pay this |
| 394 | * penalty. |
| 395 | */ |
| 396 | dev_opp = kzalloc(sizeof(struct device_opp), GFP_KERNEL); |
| 397 | if (!dev_opp) { |
| 398 | mutex_unlock(&dev_opp_list_lock); |
| 399 | kfree(new_opp); |
| 400 | dev_warn(dev, |
| 401 | "%s: Unable to create device OPP structure\n", |
| 402 | __func__); |
| 403 | return -ENOMEM; |
| 404 | } |
| 405 | |
| 406 | dev_opp->dev = dev; |
| 407 | INIT_LIST_HEAD(&dev_opp->opp_list); |
| 408 | |
| 409 | /* Secure the device list modification */ |
| 410 | list_add_rcu(&dev_opp->node, &dev_opp_list); |
| 411 | } |
| 412 | |
| 413 | /* populate the opp table */ |
| 414 | new_opp->dev_opp = dev_opp; |
| 415 | new_opp->rate = freq; |
| 416 | new_opp->u_volt = u_volt; |
| 417 | new_opp->available = true; |
| 418 | |
| 419 | /* Insert new OPP in order of increasing frequency */ |
| 420 | head = &dev_opp->opp_list; |
| 421 | list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) { |
| 422 | if (new_opp->rate < opp->rate) |
| 423 | break; |
| 424 | else |
| 425 | head = &opp->node; |
| 426 | } |
| 427 | |
| 428 | list_add_rcu(&new_opp->node, head); |
| 429 | mutex_unlock(&dev_opp_list_lock); |
| 430 | |
| 431 | return 0; |
| 432 | } |
| 433 | |
| 434 | /** |
| 435 | * opp_set_availability() - helper to set the availability of an opp |
| 436 | * @dev: device for which we do this operation |
| 437 | * @freq: OPP frequency to modify availability |
| 438 | * @availability_req: availability status requested for this opp |
| 439 | * |
| 440 | * Set the availability of an OPP with an RCU operation, opp_{enable,disable} |
| 441 | * share a common logic which is isolated here. |
| 442 | * |
| 443 | * Returns -EINVAL for bad pointers, -ENOMEM if no memory available for the |
| 444 | * copy operation, returns 0 if no modifcation was done OR modification was |
| 445 | * successful. |
| 446 | * |
| 447 | * Locking: The internal device_opp and opp structures are RCU protected. |
| 448 | * Hence this function internally uses RCU updater strategy with mutex locks to |
| 449 | * keep the integrity of the internal data structures. Callers should ensure |
| 450 | * that this function is *NOT* called under RCU protection or in contexts where |
| 451 | * mutex locking or synchronize_rcu() blocking calls cannot be used. |
| 452 | */ |
| 453 | static int opp_set_availability(struct device *dev, unsigned long freq, |
| 454 | bool availability_req) |
| 455 | { |
| 456 | struct device_opp *tmp_dev_opp, *dev_opp = NULL; |
| 457 | struct opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV); |
| 458 | int r = 0; |
| 459 | |
| 460 | /* keep the node allocated */ |
| 461 | new_opp = kmalloc(sizeof(struct opp), GFP_KERNEL); |
| 462 | if (!new_opp) { |
| 463 | dev_warn(dev, "%s: Unable to create OPP\n", __func__); |
| 464 | return -ENOMEM; |
| 465 | } |
| 466 | |
| 467 | mutex_lock(&dev_opp_list_lock); |
| 468 | |
| 469 | /* Find the device_opp */ |
| 470 | list_for_each_entry(tmp_dev_opp, &dev_opp_list, node) { |
| 471 | if (dev == tmp_dev_opp->dev) { |
| 472 | dev_opp = tmp_dev_opp; |
| 473 | break; |
| 474 | } |
| 475 | } |
| 476 | if (IS_ERR(dev_opp)) { |
| 477 | r = PTR_ERR(dev_opp); |
| 478 | dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r); |
| 479 | goto unlock; |
| 480 | } |
| 481 | |
| 482 | /* Do we have the frequency? */ |
| 483 | list_for_each_entry(tmp_opp, &dev_opp->opp_list, node) { |
| 484 | if (tmp_opp->rate == freq) { |
| 485 | opp = tmp_opp; |
| 486 | break; |
| 487 | } |
| 488 | } |
| 489 | if (IS_ERR(opp)) { |
| 490 | r = PTR_ERR(opp); |
| 491 | goto unlock; |
| 492 | } |
| 493 | |
| 494 | /* Is update really needed? */ |
| 495 | if (opp->available == availability_req) |
| 496 | goto unlock; |
| 497 | /* copy the old data over */ |
| 498 | *new_opp = *opp; |
| 499 | |
| 500 | /* plug in new node */ |
| 501 | new_opp->available = availability_req; |
| 502 | |
| 503 | list_replace_rcu(&opp->node, &new_opp->node); |
| 504 | mutex_unlock(&dev_opp_list_lock); |
| 505 | synchronize_rcu(); |
| 506 | |
| 507 | /* clean up old opp */ |
| 508 | new_opp = opp; |
| 509 | goto out; |
| 510 | |
| 511 | unlock: |
| 512 | mutex_unlock(&dev_opp_list_lock); |
| 513 | out: |
| 514 | kfree(new_opp); |
| 515 | return r; |
| 516 | } |
| 517 | |
| 518 | /** |
| 519 | * opp_enable() - Enable a specific OPP |
| 520 | * @dev: device for which we do this operation |
| 521 | * @freq: OPP frequency to enable |
| 522 | * |
| 523 | * Enables a provided opp. If the operation is valid, this returns 0, else the |
| 524 | * corresponding error value. It is meant to be used for users an OPP available |
| 525 | * after being temporarily made unavailable with opp_disable. |
| 526 | * |
| 527 | * Locking: The internal device_opp and opp structures are RCU protected. |
| 528 | * Hence this function indirectly uses RCU and mutex locks to keep the |
| 529 | * integrity of the internal data structures. Callers should ensure that |
| 530 | * this function is *NOT* called under RCU protection or in contexts where |
| 531 | * mutex locking or synchronize_rcu() blocking calls cannot be used. |
| 532 | */ |
| 533 | int opp_enable(struct device *dev, unsigned long freq) |
| 534 | { |
| 535 | return opp_set_availability(dev, freq, true); |
| 536 | } |
| 537 | |
| 538 | /** |
| 539 | * opp_disable() - Disable a specific OPP |
| 540 | * @dev: device for which we do this operation |
| 541 | * @freq: OPP frequency to disable |
| 542 | * |
| 543 | * Disables a provided opp. If the operation is valid, this returns |
| 544 | * 0, else the corresponding error value. It is meant to be a temporary |
| 545 | * control by users to make this OPP not available until the circumstances are |
| 546 | * right to make it available again (with a call to opp_enable). |
| 547 | * |
| 548 | * Locking: The internal device_opp and opp structures are RCU protected. |
| 549 | * Hence this function indirectly uses RCU and mutex locks to keep the |
| 550 | * integrity of the internal data structures. Callers should ensure that |
| 551 | * this function is *NOT* called under RCU protection or in contexts where |
| 552 | * mutex locking or synchronize_rcu() blocking calls cannot be used. |
| 553 | */ |
| 554 | int opp_disable(struct device *dev, unsigned long freq) |
| 555 | { |
| 556 | return opp_set_availability(dev, freq, false); |
| 557 | } |
| 558 | |
| 559 | #ifdef CONFIG_CPU_FREQ |
| 560 | /** |
| 561 | * opp_init_cpufreq_table() - create a cpufreq table for a device |
| 562 | * @dev: device for which we do this operation |
| 563 | * @table: Cpufreq table returned back to caller |
| 564 | * |
| 565 | * Generate a cpufreq table for a provided device- this assumes that the |
| 566 | * opp list is already initialized and ready for usage. |
| 567 | * |
| 568 | * This function allocates required memory for the cpufreq table. It is |
| 569 | * expected that the caller does the required maintenance such as freeing |
| 570 | * the table as required. |
| 571 | * |
| 572 | * Returns -EINVAL for bad pointers, -ENODEV if the device is not found, -ENOMEM |
| 573 | * if no memory available for the operation (table is not populated), returns 0 |
| 574 | * if successful and table is populated. |
| 575 | * |
| 576 | * WARNING: It is important for the callers to ensure refreshing their copy of |
| 577 | * the table if any of the mentioned functions have been invoked in the interim. |
| 578 | * |
| 579 | * Locking: The internal device_opp and opp structures are RCU protected. |
| 580 | * To simplify the logic, we pretend we are updater and hold relevant mutex here |
| 581 | * Callers should ensure that this function is *NOT* called under RCU protection |
| 582 | * or in contexts where mutex locking cannot be used. |
| 583 | */ |
| 584 | int opp_init_cpufreq_table(struct device *dev, |
| 585 | struct cpufreq_frequency_table **table) |
| 586 | { |
| 587 | struct device_opp *dev_opp; |
| 588 | struct opp *opp; |
| 589 | struct cpufreq_frequency_table *freq_table; |
| 590 | int i = 0; |
| 591 | |
| 592 | /* Pretend as if I am an updater */ |
| 593 | mutex_lock(&dev_opp_list_lock); |
| 594 | |
| 595 | dev_opp = find_device_opp(dev); |
| 596 | if (IS_ERR(dev_opp)) { |
| 597 | int r = PTR_ERR(dev_opp); |
| 598 | mutex_unlock(&dev_opp_list_lock); |
| 599 | dev_err(dev, "%s: Device OPP not found (%d)\n", __func__, r); |
| 600 | return r; |
| 601 | } |
| 602 | |
| 603 | freq_table = kzalloc(sizeof(struct cpufreq_frequency_table) * |
| 604 | (opp_get_opp_count(dev) + 1), GFP_KERNEL); |
| 605 | if (!freq_table) { |
| 606 | mutex_unlock(&dev_opp_list_lock); |
| 607 | dev_warn(dev, "%s: Unable to allocate frequency table\n", |
| 608 | __func__); |
| 609 | return -ENOMEM; |
| 610 | } |
| 611 | |
| 612 | list_for_each_entry(opp, &dev_opp->opp_list, node) { |
| 613 | if (opp->available) { |
| 614 | freq_table[i].index = i; |
| 615 | freq_table[i].frequency = opp->rate / 1000; |
| 616 | i++; |
| 617 | } |
| 618 | } |
| 619 | mutex_unlock(&dev_opp_list_lock); |
| 620 | |
| 621 | freq_table[i].index = i; |
| 622 | freq_table[i].frequency = CPUFREQ_TABLE_END; |
| 623 | |
| 624 | *table = &freq_table[0]; |
| 625 | |
| 626 | return 0; |
| 627 | } |
| 628 | #endif /* CONFIG_CPU_FREQ */ |