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Linux/arch/powerpc/platforms/powernv/opal-prd.c

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  1 /*
  2  * OPAL Runtime Diagnostics interface driver
  3  * Supported on POWERNV platform
  4  *
  5  * Copyright IBM Corporation 2015
  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  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  */
 16 
 17 #define pr_fmt(fmt) "opal-prd: " fmt
 18 
 19 #include <linux/kernel.h>
 20 #include <linux/module.h>
 21 #include <linux/platform_device.h>
 22 #include <linux/miscdevice.h>
 23 #include <linux/fs.h>
 24 #include <linux/of.h>
 25 #include <linux/of_address.h>
 26 #include <linux/poll.h>
 27 #include <linux/mm.h>
 28 #include <linux/slab.h>
 29 #include <asm/opal-prd.h>
 30 #include <asm/opal.h>
 31 #include <asm/io.h>
 32 #include <linux/uaccess.h>
 33 
 34 
 35 /**
 36  * The msg member must be at the end of the struct, as it's followed by the
 37  * message data.
 38  */
 39 struct opal_prd_msg_queue_item {
 40         struct list_head                list;
 41         struct opal_prd_msg_header      msg;
 42 };
 43 
 44 static struct device_node *prd_node;
 45 static LIST_HEAD(opal_prd_msg_queue);
 46 static DEFINE_SPINLOCK(opal_prd_msg_queue_lock);
 47 static DECLARE_WAIT_QUEUE_HEAD(opal_prd_msg_wait);
 48 static atomic_t prd_usage;
 49 
 50 static bool opal_prd_range_is_valid(uint64_t addr, uint64_t size)
 51 {
 52         struct device_node *parent, *node;
 53         bool found;
 54 
 55         if (addr + size < addr)
 56                 return false;
 57 
 58         parent = of_find_node_by_path("/reserved-memory");
 59         if (!parent)
 60                 return false;
 61 
 62         found = false;
 63 
 64         for_each_child_of_node(parent, node) {
 65                 uint64_t range_addr, range_size, range_end;
 66                 const __be32 *addrp;
 67                 const char *label;
 68 
 69                 addrp = of_get_address(node, 0, &range_size, NULL);
 70 
 71                 range_addr = of_read_number(addrp, 2);
 72                 range_end = range_addr + range_size;
 73 
 74                 label = of_get_property(node, "ibm,prd-label", NULL);
 75 
 76                 /* PRD ranges need a label */
 77                 if (!label)
 78                         continue;
 79 
 80                 if (range_end <= range_addr)
 81                         continue;
 82 
 83                 if (addr >= range_addr && addr + size <= range_end) {
 84                         found = true;
 85                         of_node_put(node);
 86                         break;
 87                 }
 88         }
 89 
 90         of_node_put(parent);
 91         return found;
 92 }
 93 
 94 static int opal_prd_open(struct inode *inode, struct file *file)
 95 {
 96         /*
 97          * Prevent multiple (separate) processes from concurrent interactions
 98          * with the FW PRD channel
 99          */
100         if (atomic_xchg(&prd_usage, 1) == 1)
101                 return -EBUSY;
102 
103         return 0;
104 }
105 
106 /*
107  * opal_prd_mmap - maps firmware-provided ranges into userspace
108  * @file: file structure for the device
109  * @vma: VMA to map the registers into
110  */
111 
112 static int opal_prd_mmap(struct file *file, struct vm_area_struct *vma)
113 {
114         size_t addr, size;
115         pgprot_t page_prot;
116         int rc;
117 
118         pr_devel("opal_prd_mmap(0x%016lx, 0x%016lx, 0x%lx, 0x%lx)\n",
119                         vma->vm_start, vma->vm_end, vma->vm_pgoff,
120                         vma->vm_flags);
121 
122         addr = vma->vm_pgoff << PAGE_SHIFT;
123         size = vma->vm_end - vma->vm_start;
124 
125         /* ensure we're mapping within one of the allowable ranges */
126         if (!opal_prd_range_is_valid(addr, size))
127                 return -EINVAL;
128 
129         page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
130                                          size, vma->vm_page_prot);
131 
132         rc = remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, size,
133                                 page_prot);
134 
135         return rc;
136 }
137 
138 static bool opal_msg_queue_empty(void)
139 {
140         unsigned long flags;
141         bool ret;
142 
143         spin_lock_irqsave(&opal_prd_msg_queue_lock, flags);
144         ret = list_empty(&opal_prd_msg_queue);
145         spin_unlock_irqrestore(&opal_prd_msg_queue_lock, flags);
146 
147         return ret;
148 }
149 
150 static __poll_t opal_prd_poll(struct file *file,
151                 struct poll_table_struct *wait)
152 {
153         poll_wait(file, &opal_prd_msg_wait, wait);
154 
155         if (!opal_msg_queue_empty())
156                 return EPOLLIN | EPOLLRDNORM;
157 
158         return 0;
159 }
160 
161 static ssize_t opal_prd_read(struct file *file, char __user *buf,
162                 size_t count, loff_t *ppos)
163 {
164         struct opal_prd_msg_queue_item *item;
165         unsigned long flags;
166         ssize_t size, err;
167         int rc;
168 
169         /* we need at least a header's worth of data */
170         if (count < sizeof(item->msg))
171                 return -EINVAL;
172 
173         if (*ppos)
174                 return -ESPIPE;
175 
176         item = NULL;
177 
178         for (;;) {
179 
180                 spin_lock_irqsave(&opal_prd_msg_queue_lock, flags);
181                 if (!list_empty(&opal_prd_msg_queue)) {
182                         item = list_first_entry(&opal_prd_msg_queue,
183                                         struct opal_prd_msg_queue_item, list);
184                         list_del(&item->list);
185                 }
186                 spin_unlock_irqrestore(&opal_prd_msg_queue_lock, flags);
187 
188                 if (item)
189                         break;
190 
191                 if (file->f_flags & O_NONBLOCK)
192                         return -EAGAIN;
193 
194                 rc = wait_event_interruptible(opal_prd_msg_wait,
195                                 !opal_msg_queue_empty());
196                 if (rc)
197                         return -EINTR;
198         }
199 
200         size = be16_to_cpu(item->msg.size);
201         if (size > count) {
202                 err = -EINVAL;
203                 goto err_requeue;
204         }
205 
206         rc = copy_to_user(buf, &item->msg, size);
207         if (rc) {
208                 err = -EFAULT;
209                 goto err_requeue;
210         }
211 
212         kfree(item);
213 
214         return size;
215 
216 err_requeue:
217         /* eep! re-queue at the head of the list */
218         spin_lock_irqsave(&opal_prd_msg_queue_lock, flags);
219         list_add(&item->list, &opal_prd_msg_queue);
220         spin_unlock_irqrestore(&opal_prd_msg_queue_lock, flags);
221         return err;
222 }
223 
224 static ssize_t opal_prd_write(struct file *file, const char __user *buf,
225                 size_t count, loff_t *ppos)
226 {
227         struct opal_prd_msg_header hdr;
228         ssize_t size;
229         void *msg;
230         int rc;
231 
232         size = sizeof(hdr);
233 
234         if (count < size)
235                 return -EINVAL;
236 
237         /* grab the header */
238         rc = copy_from_user(&hdr, buf, sizeof(hdr));
239         if (rc)
240                 return -EFAULT;
241 
242         size = be16_to_cpu(hdr.size);
243 
244         msg = memdup_user(buf, size);
245         if (IS_ERR(msg))
246                 return PTR_ERR(msg);
247 
248         rc = opal_prd_msg(msg);
249         if (rc) {
250                 pr_warn("write: opal_prd_msg returned %d\n", rc);
251                 size = -EIO;
252         }
253 
254         kfree(msg);
255 
256         return size;
257 }
258 
259 static int opal_prd_release(struct inode *inode, struct file *file)
260 {
261         struct opal_prd_msg_header msg;
262 
263         msg.size = cpu_to_be16(sizeof(msg));
264         msg.type = OPAL_PRD_MSG_TYPE_FINI;
265 
266         opal_prd_msg((struct opal_prd_msg *)&msg);
267 
268         atomic_xchg(&prd_usage, 0);
269 
270         return 0;
271 }
272 
273 static long opal_prd_ioctl(struct file *file, unsigned int cmd,
274                 unsigned long param)
275 {
276         struct opal_prd_info info;
277         struct opal_prd_scom scom;
278         int rc = 0;
279 
280         switch (cmd) {
281         case OPAL_PRD_GET_INFO:
282                 memset(&info, 0, sizeof(info));
283                 info.version = OPAL_PRD_KERNEL_VERSION;
284                 rc = copy_to_user((void __user *)param, &info, sizeof(info));
285                 if (rc)
286                         return -EFAULT;
287                 break;
288 
289         case OPAL_PRD_SCOM_READ:
290                 rc = copy_from_user(&scom, (void __user *)param, sizeof(scom));
291                 if (rc)
292                         return -EFAULT;
293 
294                 scom.rc = opal_xscom_read(scom.chip, scom.addr,
295                                 (__be64 *)&scom.data);
296                 scom.data = be64_to_cpu(scom.data);
297                 pr_devel("ioctl SCOM_READ: chip %llx addr %016llx data %016llx rc %lld\n",
298                                 scom.chip, scom.addr, scom.data, scom.rc);
299 
300                 rc = copy_to_user((void __user *)param, &scom, sizeof(scom));
301                 if (rc)
302                         return -EFAULT;
303                 break;
304 
305         case OPAL_PRD_SCOM_WRITE:
306                 rc = copy_from_user(&scom, (void __user *)param, sizeof(scom));
307                 if (rc)
308                         return -EFAULT;
309 
310                 scom.rc = opal_xscom_write(scom.chip, scom.addr, scom.data);
311                 pr_devel("ioctl SCOM_WRITE: chip %llx addr %016llx data %016llx rc %lld\n",
312                                 scom.chip, scom.addr, scom.data, scom.rc);
313 
314                 rc = copy_to_user((void __user *)param, &scom, sizeof(scom));
315                 if (rc)
316                         return -EFAULT;
317                 break;
318 
319         default:
320                 rc = -EINVAL;
321         }
322 
323         return rc;
324 }
325 
326 static const struct file_operations opal_prd_fops = {
327         .open           = opal_prd_open,
328         .mmap           = opal_prd_mmap,
329         .poll           = opal_prd_poll,
330         .read           = opal_prd_read,
331         .write          = opal_prd_write,
332         .unlocked_ioctl = opal_prd_ioctl,
333         .release        = opal_prd_release,
334         .owner          = THIS_MODULE,
335 };
336 
337 static struct miscdevice opal_prd_dev = {
338         .minor          = MISC_DYNAMIC_MINOR,
339         .name           = "opal-prd",
340         .fops           = &opal_prd_fops,
341 };
342 
343 /* opal interface */
344 static int opal_prd_msg_notifier(struct notifier_block *nb,
345                 unsigned long msg_type, void *_msg)
346 {
347         struct opal_prd_msg_queue_item *item;
348         struct opal_prd_msg_header *hdr;
349         struct opal_msg *msg = _msg;
350         int msg_size, item_size;
351         unsigned long flags;
352 
353         if (msg_type != OPAL_MSG_PRD)
354                 return 0;
355 
356         /* Calculate total size of the message and item we need to store. The
357          * 'size' field in the header includes the header itself. */
358         hdr = (void *)msg->params;
359         msg_size = be16_to_cpu(hdr->size);
360         item_size = msg_size + sizeof(*item) - sizeof(item->msg);
361 
362         item = kzalloc(item_size, GFP_ATOMIC);
363         if (!item)
364                 return -ENOMEM;
365 
366         memcpy(&item->msg, msg->params, msg_size);
367 
368         spin_lock_irqsave(&opal_prd_msg_queue_lock, flags);
369         list_add_tail(&item->list, &opal_prd_msg_queue);
370         spin_unlock_irqrestore(&opal_prd_msg_queue_lock, flags);
371 
372         wake_up_interruptible(&opal_prd_msg_wait);
373 
374         return 0;
375 }
376 
377 static struct notifier_block opal_prd_event_nb = {
378         .notifier_call  = opal_prd_msg_notifier,
379         .next           = NULL,
380         .priority       = 0,
381 };
382 
383 static int opal_prd_probe(struct platform_device *pdev)
384 {
385         int rc;
386 
387         if (!pdev || !pdev->dev.of_node)
388                 return -ENODEV;
389 
390         /* We should only have one prd driver instance per machine; ensure
391          * that we only get a valid probe on a single OF node.
392          */
393         if (prd_node)
394                 return -EBUSY;
395 
396         prd_node = pdev->dev.of_node;
397 
398         rc = opal_message_notifier_register(OPAL_MSG_PRD, &opal_prd_event_nb);
399         if (rc) {
400                 pr_err("Couldn't register event notifier\n");
401                 return rc;
402         }
403 
404         rc = misc_register(&opal_prd_dev);
405         if (rc) {
406                 pr_err("failed to register miscdev\n");
407                 opal_message_notifier_unregister(OPAL_MSG_PRD,
408                                 &opal_prd_event_nb);
409                 return rc;
410         }
411 
412         return 0;
413 }
414 
415 static int opal_prd_remove(struct platform_device *pdev)
416 {
417         misc_deregister(&opal_prd_dev);
418         opal_message_notifier_unregister(OPAL_MSG_PRD, &opal_prd_event_nb);
419         return 0;
420 }
421 
422 static const struct of_device_id opal_prd_match[] = {
423         { .compatible = "ibm,opal-prd" },
424         { },
425 };
426 
427 static struct platform_driver opal_prd_driver = {
428         .driver = {
429                 .name           = "opal-prd",
430                 .of_match_table = opal_prd_match,
431         },
432         .probe  = opal_prd_probe,
433         .remove = opal_prd_remove,
434 };
435 
436 module_platform_driver(opal_prd_driver);
437 
438 MODULE_DEVICE_TABLE(of, opal_prd_match);
439 MODULE_DESCRIPTION("PowerNV OPAL runtime diagnostic driver");
440 MODULE_LICENSE("GPL");
441 

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