1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Intel Speed Select Interface: Common functions
4 * Copyright (c) 2019, Intel Corporation.
5 * All rights reserved.
6 *
7 * Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
8 */
9
10 #include <linux/cpufeature.h>
11 #include <linux/cpuhotplug.h>
12 #include <linux/fs.h>
13 #include <linux/hashtable.h>
14 #include <linux/miscdevice.h>
15 #include <linux/module.h>
16 #include <linux/pci.h>
17 #include <linux/sched/signal.h>
18 #include <linux/slab.h>
19 #include <linux/uaccess.h>
20 #include <uapi/linux/isst_if.h>
21
22 #include "isst_if_common.h"
23
24 #define MSR_THREAD_ID_INFO 0x53
25 #define MSR_CPU_BUS_NUMBER 0x128
26
27 static struct isst_if_cmd_cb punit_callbacks[ISST_IF_DEV_MAX];
28
29 static int punit_msr_white_list[] = {
30 MSR_TURBO_RATIO_LIMIT,
31 MSR_CONFIG_TDP_CONTROL,
32 MSR_TURBO_RATIO_LIMIT1,
33 MSR_TURBO_RATIO_LIMIT2,
34 };
35
36 struct isst_valid_cmd_ranges {
37 u16 cmd;
38 u16 sub_cmd_beg;
39 u16 sub_cmd_end;
40 };
41
42 struct isst_cmd_set_req_type {
43 u16 cmd;
44 u16 sub_cmd;
45 u16 param;
46 };
47
48 static const struct isst_valid_cmd_ranges isst_valid_cmds[] = {
49 {0xD0, 0x00, 0x03},
50 {0x7F, 0x00, 0x0B},
51 {0x7F, 0x10, 0x12},
52 {0x7F, 0x20, 0x23},
53 {0x94, 0x03, 0x03},
54 {0x95, 0x03, 0x03},
55 };
56
57 static const struct isst_cmd_set_req_type isst_cmd_set_reqs[] = {
58 {0xD0, 0x00, 0x08},
59 {0xD0, 0x01, 0x08},
60 {0xD0, 0x02, 0x08},
61 {0xD0, 0x03, 0x08},
62 {0x7F, 0x02, 0x00},
63 {0x7F, 0x08, 0x00},
64 {0x95, 0x03, 0x03},
65 };
66
67 struct isst_cmd {
68 struct hlist_node hnode;
69 u64 data;
70 u32 cmd;
71 int cpu;
72 int mbox_cmd_type;
73 u32 param;
74 };
75
76 static DECLARE_HASHTABLE(isst_hash, 8);
77 static DEFINE_MUTEX(isst_hash_lock);
78
isst_store_new_cmd(int cmd,u32 cpu,int mbox_cmd_type,u32 param,u32 data)79 static int isst_store_new_cmd(int cmd, u32 cpu, int mbox_cmd_type, u32 param,
80 u32 data)
81 {
82 struct isst_cmd *sst_cmd;
83
84 sst_cmd = kmalloc(sizeof(*sst_cmd), GFP_KERNEL);
85 if (!sst_cmd)
86 return -ENOMEM;
87
88 sst_cmd->cpu = cpu;
89 sst_cmd->cmd = cmd;
90 sst_cmd->mbox_cmd_type = mbox_cmd_type;
91 sst_cmd->param = param;
92 sst_cmd->data = data;
93
94 hash_add(isst_hash, &sst_cmd->hnode, sst_cmd->cmd);
95
96 return 0;
97 }
98
isst_delete_hash(void)99 static void isst_delete_hash(void)
100 {
101 struct isst_cmd *sst_cmd;
102 struct hlist_node *tmp;
103 int i;
104
105 hash_for_each_safe(isst_hash, i, tmp, sst_cmd, hnode) {
106 hash_del(&sst_cmd->hnode);
107 kfree(sst_cmd);
108 }
109 }
110
111 /**
112 * isst_store_cmd() - Store command to a hash table
113 * @cmd: Mailbox command.
114 * @sub_cmd: Mailbox sub-command or MSR id.
115 * @mbox_cmd_type: Mailbox or MSR command.
116 * @param: Mailbox parameter.
117 * @data: Mailbox request data or MSR data.
118 *
119 * Stores the command to a hash table if there is no such command already
120 * stored. If already stored update the latest parameter and data for the
121 * command.
122 *
123 * Return: Return result of store to hash table, 0 for success, others for
124 * failure.
125 */
isst_store_cmd(int cmd,int sub_cmd,u32 cpu,int mbox_cmd_type,u32 param,u64 data)126 int isst_store_cmd(int cmd, int sub_cmd, u32 cpu, int mbox_cmd_type,
127 u32 param, u64 data)
128 {
129 struct isst_cmd *sst_cmd;
130 int full_cmd, ret;
131
132 full_cmd = (cmd & GENMASK_ULL(15, 0)) << 16;
133 full_cmd |= (sub_cmd & GENMASK_ULL(15, 0));
134 mutex_lock(&isst_hash_lock);
135 hash_for_each_possible(isst_hash, sst_cmd, hnode, full_cmd) {
136 if (sst_cmd->cmd == full_cmd && sst_cmd->cpu == cpu &&
137 sst_cmd->mbox_cmd_type == mbox_cmd_type) {
138 sst_cmd->param = param;
139 sst_cmd->data = data;
140 mutex_unlock(&isst_hash_lock);
141 return 0;
142 }
143 }
144
145 ret = isst_store_new_cmd(full_cmd, cpu, mbox_cmd_type, param, data);
146 mutex_unlock(&isst_hash_lock);
147
148 return ret;
149 }
150 EXPORT_SYMBOL_GPL(isst_store_cmd);
151
isst_mbox_resume_command(struct isst_if_cmd_cb * cb,struct isst_cmd * sst_cmd)152 static void isst_mbox_resume_command(struct isst_if_cmd_cb *cb,
153 struct isst_cmd *sst_cmd)
154 {
155 struct isst_if_mbox_cmd mbox_cmd;
156 int wr_only;
157
158 mbox_cmd.command = (sst_cmd->cmd & GENMASK_ULL(31, 16)) >> 16;
159 mbox_cmd.sub_command = sst_cmd->cmd & GENMASK_ULL(15, 0);
160 mbox_cmd.parameter = sst_cmd->param;
161 mbox_cmd.req_data = sst_cmd->data;
162 mbox_cmd.logical_cpu = sst_cmd->cpu;
163 (cb->cmd_callback)((u8 *)&mbox_cmd, &wr_only, 1);
164 }
165
166 /**
167 * isst_resume_common() - Process Resume request
168 *
169 * On resume replay all mailbox commands and MSRs.
170 *
171 * Return: None.
172 */
isst_resume_common(void)173 void isst_resume_common(void)
174 {
175 struct isst_cmd *sst_cmd;
176 int i;
177
178 hash_for_each(isst_hash, i, sst_cmd, hnode) {
179 struct isst_if_cmd_cb *cb;
180
181 if (sst_cmd->mbox_cmd_type) {
182 cb = &punit_callbacks[ISST_IF_DEV_MBOX];
183 if (cb->registered)
184 isst_mbox_resume_command(cb, sst_cmd);
185 } else {
186 wrmsrl_safe_on_cpu(sst_cmd->cpu, sst_cmd->cmd,
187 sst_cmd->data);
188 }
189 }
190 }
191 EXPORT_SYMBOL_GPL(isst_resume_common);
192
isst_restore_msr_local(int cpu)193 static void isst_restore_msr_local(int cpu)
194 {
195 struct isst_cmd *sst_cmd;
196 int i;
197
198 mutex_lock(&isst_hash_lock);
199 for (i = 0; i < ARRAY_SIZE(punit_msr_white_list); ++i) {
200 if (!punit_msr_white_list[i])
201 break;
202
203 hash_for_each_possible(isst_hash, sst_cmd, hnode,
204 punit_msr_white_list[i]) {
205 if (!sst_cmd->mbox_cmd_type && sst_cmd->cpu == cpu)
206 wrmsrl_safe(sst_cmd->cmd, sst_cmd->data);
207 }
208 }
209 mutex_unlock(&isst_hash_lock);
210 }
211
212 /**
213 * isst_if_mbox_cmd_invalid() - Check invalid mailbox commands
214 * @cmd: Pointer to the command structure to verify.
215 *
216 * Invalid command to PUNIT to may result in instability of the platform.
217 * This function has a whitelist of commands, which are allowed.
218 *
219 * Return: Return true if the command is invalid, else false.
220 */
isst_if_mbox_cmd_invalid(struct isst_if_mbox_cmd * cmd)221 bool isst_if_mbox_cmd_invalid(struct isst_if_mbox_cmd *cmd)
222 {
223 int i;
224
225 if (cmd->logical_cpu >= nr_cpu_ids)
226 return true;
227
228 for (i = 0; i < ARRAY_SIZE(isst_valid_cmds); ++i) {
229 if (cmd->command == isst_valid_cmds[i].cmd &&
230 (cmd->sub_command >= isst_valid_cmds[i].sub_cmd_beg &&
231 cmd->sub_command <= isst_valid_cmds[i].sub_cmd_end)) {
232 return false;
233 }
234 }
235
236 return true;
237 }
238 EXPORT_SYMBOL_GPL(isst_if_mbox_cmd_invalid);
239
240 /**
241 * isst_if_mbox_cmd_set_req() - Check mailbox command is a set request
242 * @cmd: Pointer to the command structure to verify.
243 *
244 * Check if the given mail box level is set request and not a get request.
245 *
246 * Return: Return true if the command is set_req, else false.
247 */
isst_if_mbox_cmd_set_req(struct isst_if_mbox_cmd * cmd)248 bool isst_if_mbox_cmd_set_req(struct isst_if_mbox_cmd *cmd)
249 {
250 int i;
251
252 for (i = 0; i < ARRAY_SIZE(isst_cmd_set_reqs); ++i) {
253 if (cmd->command == isst_cmd_set_reqs[i].cmd &&
254 cmd->sub_command == isst_cmd_set_reqs[i].sub_cmd &&
255 cmd->parameter == isst_cmd_set_reqs[i].param) {
256 return true;
257 }
258 }
259
260 return false;
261 }
262 EXPORT_SYMBOL_GPL(isst_if_mbox_cmd_set_req);
263
isst_if_get_platform_info(void __user * argp)264 static int isst_if_get_platform_info(void __user *argp)
265 {
266 struct isst_if_platform_info info;
267
268 info.api_version = ISST_IF_API_VERSION;
269 info.driver_version = ISST_IF_DRIVER_VERSION;
270 info.max_cmds_per_ioctl = ISST_IF_CMD_LIMIT;
271 info.mbox_supported = punit_callbacks[ISST_IF_DEV_MBOX].registered;
272 info.mmio_supported = punit_callbacks[ISST_IF_DEV_MMIO].registered;
273
274 if (copy_to_user(argp, &info, sizeof(info)))
275 return -EFAULT;
276
277 return 0;
278 }
279
280
281 struct isst_if_cpu_info {
282 /* For BUS 0 and BUS 1 only, which we need for PUNIT interface */
283 int bus_info[2];
284 struct pci_dev *pci_dev[2];
285 int punit_cpu_id;
286 int numa_node;
287 };
288
289 static struct isst_if_cpu_info *isst_cpu_info;
290 #define ISST_MAX_PCI_DOMAINS 8
291
_isst_if_get_pci_dev(int cpu,int bus_no,int dev,int fn)292 static struct pci_dev *_isst_if_get_pci_dev(int cpu, int bus_no, int dev, int fn)
293 {
294 struct pci_dev *matched_pci_dev = NULL;
295 struct pci_dev *pci_dev = NULL;
296 int no_matches = 0;
297 int i, bus_number;
298
299 if (bus_no < 0 || bus_no > 1 || cpu < 0 || cpu >= nr_cpu_ids ||
300 cpu >= num_possible_cpus())
301 return NULL;
302
303 bus_number = isst_cpu_info[cpu].bus_info[bus_no];
304 if (bus_number < 0)
305 return NULL;
306
307 for (i = 0; i < ISST_MAX_PCI_DOMAINS; ++i) {
308 struct pci_dev *_pci_dev;
309 int node;
310
311 _pci_dev = pci_get_domain_bus_and_slot(i, bus_number, PCI_DEVFN(dev, fn));
312 if (!_pci_dev)
313 continue;
314
315 ++no_matches;
316 if (!matched_pci_dev)
317 matched_pci_dev = _pci_dev;
318
319 node = dev_to_node(&_pci_dev->dev);
320 if (node == NUMA_NO_NODE) {
321 pr_info("Fail to get numa node for CPU:%d bus:%d dev:%d fn:%d\n",
322 cpu, bus_no, dev, fn);
323 continue;
324 }
325
326 if (node == isst_cpu_info[cpu].numa_node) {
327 pci_dev = _pci_dev;
328 break;
329 }
330 }
331
332 /*
333 * If there is no numa matched pci_dev, then there can be following cases:
334 * 1. CONFIG_NUMA is not defined: In this case if there is only single device
335 * match, then we don't need numa information. Simply return last match.
336 * Othewise return NULL.
337 * 2. NUMA information is not exposed via _SEG method. In this case it is similar
338 * to case 1.
339 * 3. Numa information doesn't match with CPU numa node and more than one match
340 * return NULL.
341 */
342 if (!pci_dev && no_matches == 1)
343 pci_dev = matched_pci_dev;
344
345 return pci_dev;
346 }
347
348 /**
349 * isst_if_get_pci_dev() - Get the PCI device instance for a CPU
350 * @cpu: Logical CPU number.
351 * @bus_number: The bus number assigned by the hardware.
352 * @dev: The device number assigned by the hardware.
353 * @fn: The function number assigned by the hardware.
354 *
355 * Using cached bus information, find out the PCI device for a bus number,
356 * device and function.
357 *
358 * Return: Return pci_dev pointer or NULL.
359 */
isst_if_get_pci_dev(int cpu,int bus_no,int dev,int fn)360 struct pci_dev *isst_if_get_pci_dev(int cpu, int bus_no, int dev, int fn)
361 {
362 struct pci_dev *pci_dev;
363
364 if (bus_no < 0 || bus_no > 1 || cpu < 0 || cpu >= nr_cpu_ids ||
365 cpu >= num_possible_cpus())
366 return NULL;
367
368 pci_dev = isst_cpu_info[cpu].pci_dev[bus_no];
369
370 if (pci_dev && pci_dev->devfn == PCI_DEVFN(dev, fn))
371 return pci_dev;
372
373 return _isst_if_get_pci_dev(cpu, bus_no, dev, fn);
374 }
375 EXPORT_SYMBOL_GPL(isst_if_get_pci_dev);
376
isst_if_cpu_online(unsigned int cpu)377 static int isst_if_cpu_online(unsigned int cpu)
378 {
379 u64 data;
380 int ret;
381
382 isst_cpu_info[cpu].numa_node = cpu_to_node(cpu);
383
384 ret = rdmsrl_safe(MSR_CPU_BUS_NUMBER, &data);
385 if (ret) {
386 /* This is not a fatal error on MSR mailbox only I/F */
387 isst_cpu_info[cpu].bus_info[0] = -1;
388 isst_cpu_info[cpu].bus_info[1] = -1;
389 } else {
390 isst_cpu_info[cpu].bus_info[0] = data & 0xff;
391 isst_cpu_info[cpu].bus_info[1] = (data >> 8) & 0xff;
392 isst_cpu_info[cpu].pci_dev[0] = _isst_if_get_pci_dev(cpu, 0, 0, 1);
393 isst_cpu_info[cpu].pci_dev[1] = _isst_if_get_pci_dev(cpu, 1, 30, 1);
394 }
395
396 ret = rdmsrl_safe(MSR_THREAD_ID_INFO, &data);
397 if (ret) {
398 isst_cpu_info[cpu].punit_cpu_id = -1;
399 return ret;
400 }
401 isst_cpu_info[cpu].punit_cpu_id = data;
402
403 isst_restore_msr_local(cpu);
404
405 return 0;
406 }
407
408 static int isst_if_online_id;
409
isst_if_cpu_info_init(void)410 static int isst_if_cpu_info_init(void)
411 {
412 int ret;
413
414 isst_cpu_info = kcalloc(num_possible_cpus(),
415 sizeof(*isst_cpu_info),
416 GFP_KERNEL);
417 if (!isst_cpu_info)
418 return -ENOMEM;
419
420 ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
421 "platform/x86/isst-if:online",
422 isst_if_cpu_online, NULL);
423 if (ret < 0) {
424 kfree(isst_cpu_info);
425 return ret;
426 }
427
428 isst_if_online_id = ret;
429
430 return 0;
431 }
432
isst_if_cpu_info_exit(void)433 static void isst_if_cpu_info_exit(void)
434 {
435 cpuhp_remove_state(isst_if_online_id);
436 kfree(isst_cpu_info);
437 };
438
isst_if_proc_phyid_req(u8 * cmd_ptr,int * write_only,int resume)439 static long isst_if_proc_phyid_req(u8 *cmd_ptr, int *write_only, int resume)
440 {
441 struct isst_if_cpu_map *cpu_map;
442
443 cpu_map = (struct isst_if_cpu_map *)cmd_ptr;
444 if (cpu_map->logical_cpu >= nr_cpu_ids ||
445 cpu_map->logical_cpu >= num_possible_cpus())
446 return -EINVAL;
447
448 *write_only = 0;
449 cpu_map->physical_cpu = isst_cpu_info[cpu_map->logical_cpu].punit_cpu_id;
450
451 return 0;
452 }
453
match_punit_msr_white_list(int msr)454 static bool match_punit_msr_white_list(int msr)
455 {
456 int i;
457
458 for (i = 0; i < ARRAY_SIZE(punit_msr_white_list); ++i) {
459 if (punit_msr_white_list[i] == msr)
460 return true;
461 }
462
463 return false;
464 }
465
isst_if_msr_cmd_req(u8 * cmd_ptr,int * write_only,int resume)466 static long isst_if_msr_cmd_req(u8 *cmd_ptr, int *write_only, int resume)
467 {
468 struct isst_if_msr_cmd *msr_cmd;
469 int ret;
470
471 msr_cmd = (struct isst_if_msr_cmd *)cmd_ptr;
472
473 if (!match_punit_msr_white_list(msr_cmd->msr))
474 return -EINVAL;
475
476 if (msr_cmd->logical_cpu >= nr_cpu_ids)
477 return -EINVAL;
478
479 if (msr_cmd->read_write) {
480 if (!capable(CAP_SYS_ADMIN))
481 return -EPERM;
482
483 ret = wrmsrl_safe_on_cpu(msr_cmd->logical_cpu,
484 msr_cmd->msr,
485 msr_cmd->data);
486 *write_only = 1;
487 if (!ret && !resume)
488 ret = isst_store_cmd(0, msr_cmd->msr,
489 msr_cmd->logical_cpu,
490 0, 0, msr_cmd->data);
491 } else {
492 u64 data;
493
494 ret = rdmsrl_safe_on_cpu(msr_cmd->logical_cpu,
495 msr_cmd->msr, &data);
496 if (!ret) {
497 msr_cmd->data = data;
498 *write_only = 0;
499 }
500 }
501
502
503 return ret;
504 }
505
isst_if_exec_multi_cmd(void __user * argp,struct isst_if_cmd_cb * cb)506 static long isst_if_exec_multi_cmd(void __user *argp, struct isst_if_cmd_cb *cb)
507 {
508 unsigned char __user *ptr;
509 u32 cmd_count;
510 u8 *cmd_ptr;
511 long ret;
512 int i;
513
514 /* Each multi command has u32 command count as the first field */
515 if (copy_from_user(&cmd_count, argp, sizeof(cmd_count)))
516 return -EFAULT;
517
518 if (!cmd_count || cmd_count > ISST_IF_CMD_LIMIT)
519 return -EINVAL;
520
521 cmd_ptr = kmalloc(cb->cmd_size, GFP_KERNEL);
522 if (!cmd_ptr)
523 return -ENOMEM;
524
525 /* cb->offset points to start of the command after the command count */
526 ptr = argp + cb->offset;
527
528 for (i = 0; i < cmd_count; ++i) {
529 int wr_only;
530
531 if (signal_pending(current)) {
532 ret = -EINTR;
533 break;
534 }
535
536 if (copy_from_user(cmd_ptr, ptr, cb->cmd_size)) {
537 ret = -EFAULT;
538 break;
539 }
540
541 ret = cb->cmd_callback(cmd_ptr, &wr_only, 0);
542 if (ret)
543 break;
544
545 if (!wr_only && copy_to_user(ptr, cmd_ptr, cb->cmd_size)) {
546 ret = -EFAULT;
547 break;
548 }
549
550 ptr += cb->cmd_size;
551 }
552
553 kfree(cmd_ptr);
554
555 return i ? i : ret;
556 }
557
isst_if_def_ioctl(struct file * file,unsigned int cmd,unsigned long arg)558 static long isst_if_def_ioctl(struct file *file, unsigned int cmd,
559 unsigned long arg)
560 {
561 void __user *argp = (void __user *)arg;
562 struct isst_if_cmd_cb cmd_cb;
563 struct isst_if_cmd_cb *cb;
564 long ret = -ENOTTY;
565
566 switch (cmd) {
567 case ISST_IF_GET_PLATFORM_INFO:
568 ret = isst_if_get_platform_info(argp);
569 break;
570 case ISST_IF_GET_PHY_ID:
571 cmd_cb.cmd_size = sizeof(struct isst_if_cpu_map);
572 cmd_cb.offset = offsetof(struct isst_if_cpu_maps, cpu_map);
573 cmd_cb.cmd_callback = isst_if_proc_phyid_req;
574 ret = isst_if_exec_multi_cmd(argp, &cmd_cb);
575 break;
576 case ISST_IF_IO_CMD:
577 cb = &punit_callbacks[ISST_IF_DEV_MMIO];
578 if (cb->registered)
579 ret = isst_if_exec_multi_cmd(argp, cb);
580 break;
581 case ISST_IF_MBOX_COMMAND:
582 cb = &punit_callbacks[ISST_IF_DEV_MBOX];
583 if (cb->registered)
584 ret = isst_if_exec_multi_cmd(argp, cb);
585 break;
586 case ISST_IF_MSR_COMMAND:
587 cmd_cb.cmd_size = sizeof(struct isst_if_msr_cmd);
588 cmd_cb.offset = offsetof(struct isst_if_msr_cmds, msr_cmd);
589 cmd_cb.cmd_callback = isst_if_msr_cmd_req;
590 ret = isst_if_exec_multi_cmd(argp, &cmd_cb);
591 break;
592 default:
593 break;
594 }
595
596 return ret;
597 }
598
599 /* Lock to prevent module registration when already opened by user space */
600 static DEFINE_MUTEX(punit_misc_dev_open_lock);
601 /* Lock to allow one share misc device for all ISST interace */
602 static DEFINE_MUTEX(punit_misc_dev_reg_lock);
603 static int misc_usage_count;
604 static int misc_device_ret;
605 static int misc_device_open;
606
isst_if_open(struct inode * inode,struct file * file)607 static int isst_if_open(struct inode *inode, struct file *file)
608 {
609 int i, ret = 0;
610
611 /* Fail open, if a module is going away */
612 mutex_lock(&punit_misc_dev_open_lock);
613 for (i = 0; i < ISST_IF_DEV_MAX; ++i) {
614 struct isst_if_cmd_cb *cb = &punit_callbacks[i];
615
616 if (cb->registered && !try_module_get(cb->owner)) {
617 ret = -ENODEV;
618 break;
619 }
620 }
621 if (ret) {
622 int j;
623
624 for (j = 0; j < i; ++j) {
625 struct isst_if_cmd_cb *cb;
626
627 cb = &punit_callbacks[j];
628 if (cb->registered)
629 module_put(cb->owner);
630 }
631 } else {
632 misc_device_open++;
633 }
634 mutex_unlock(&punit_misc_dev_open_lock);
635
636 return ret;
637 }
638
isst_if_relase(struct inode * inode,struct file * f)639 static int isst_if_relase(struct inode *inode, struct file *f)
640 {
641 int i;
642
643 mutex_lock(&punit_misc_dev_open_lock);
644 misc_device_open--;
645 for (i = 0; i < ISST_IF_DEV_MAX; ++i) {
646 struct isst_if_cmd_cb *cb = &punit_callbacks[i];
647
648 if (cb->registered)
649 module_put(cb->owner);
650 }
651 mutex_unlock(&punit_misc_dev_open_lock);
652
653 return 0;
654 }
655
656 static const struct file_operations isst_if_char_driver_ops = {
657 .open = isst_if_open,
658 .unlocked_ioctl = isst_if_def_ioctl,
659 .release = isst_if_relase,
660 };
661
662 static struct miscdevice isst_if_char_driver = {
663 .minor = MISC_DYNAMIC_MINOR,
664 .name = "isst_interface",
665 .fops = &isst_if_char_driver_ops,
666 };
667
isst_misc_reg(void)668 static int isst_misc_reg(void)
669 {
670 mutex_lock(&punit_misc_dev_reg_lock);
671 if (misc_device_ret)
672 goto unlock_exit;
673
674 if (!misc_usage_count) {
675 misc_device_ret = isst_if_cpu_info_init();
676 if (misc_device_ret)
677 goto unlock_exit;
678
679 misc_device_ret = misc_register(&isst_if_char_driver);
680 if (misc_device_ret) {
681 isst_if_cpu_info_exit();
682 goto unlock_exit;
683 }
684 }
685 misc_usage_count++;
686
687 unlock_exit:
688 mutex_unlock(&punit_misc_dev_reg_lock);
689
690 return misc_device_ret;
691 }
692
isst_misc_unreg(void)693 static void isst_misc_unreg(void)
694 {
695 mutex_lock(&punit_misc_dev_reg_lock);
696 if (misc_usage_count)
697 misc_usage_count--;
698 if (!misc_usage_count && !misc_device_ret) {
699 misc_deregister(&isst_if_char_driver);
700 isst_if_cpu_info_exit();
701 }
702 mutex_unlock(&punit_misc_dev_reg_lock);
703 }
704
705 /**
706 * isst_if_cdev_register() - Register callback for IOCTL
707 * @device_type: The device type this callback handling.
708 * @cb: Callback structure.
709 *
710 * This function registers a callback to device type. On very first call
711 * it will register a misc device, which is used for user kernel interface.
712 * Other calls simply increment ref count. Registry will fail, if the user
713 * already opened misc device for operation. Also if the misc device
714 * creation failed, then it will not try again and all callers will get
715 * failure code.
716 *
717 * Return: Return the return value from the misc creation device or -EINVAL
718 * for unsupported device type.
719 */
isst_if_cdev_register(int device_type,struct isst_if_cmd_cb * cb)720 int isst_if_cdev_register(int device_type, struct isst_if_cmd_cb *cb)
721 {
722 int ret;
723
724 if (device_type >= ISST_IF_DEV_MAX)
725 return -EINVAL;
726
727 mutex_lock(&punit_misc_dev_open_lock);
728 /* Device is already open, we don't want to add new callbacks */
729 if (misc_device_open) {
730 mutex_unlock(&punit_misc_dev_open_lock);
731 return -EAGAIN;
732 }
733 memcpy(&punit_callbacks[device_type], cb, sizeof(*cb));
734 punit_callbacks[device_type].registered = 1;
735 mutex_unlock(&punit_misc_dev_open_lock);
736
737 ret = isst_misc_reg();
738 if (ret) {
739 /*
740 * No need of mutex as the misc device register failed
741 * as no one can open device yet. Hence no contention.
742 */
743 punit_callbacks[device_type].registered = 0;
744 return ret;
745 }
746 return 0;
747 }
748 EXPORT_SYMBOL_GPL(isst_if_cdev_register);
749
750 /**
751 * isst_if_cdev_unregister() - Unregister callback for IOCTL
752 * @device_type: The device type to unregister.
753 *
754 * This function unregisters the previously registered callback. If this
755 * is the last callback unregistering, then misc device is removed.
756 *
757 * Return: None.
758 */
isst_if_cdev_unregister(int device_type)759 void isst_if_cdev_unregister(int device_type)
760 {
761 isst_misc_unreg();
762 mutex_lock(&punit_misc_dev_open_lock);
763 punit_callbacks[device_type].registered = 0;
764 if (device_type == ISST_IF_DEV_MBOX)
765 isst_delete_hash();
766 mutex_unlock(&punit_misc_dev_open_lock);
767 }
768 EXPORT_SYMBOL_GPL(isst_if_cdev_unregister);
769
770 MODULE_LICENSE("GPL v2");
771