1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * OPAL Runtime Diagnostics interface driver
4  * Supported on POWERNV platform
5  *
6  * Copyright IBM Corporation 2015
7  */
8 
9 #define pr_fmt(fmt) "opal-prd: " fmt
10 
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/platform_device.h>
14 #include <linux/miscdevice.h>
15 #include <linux/fs.h>
16 #include <linux/of.h>
17 #include <linux/of_address.h>
18 #include <linux/poll.h>
19 #include <linux/mm.h>
20 #include <linux/slab.h>
21 #include <asm/opal-prd.h>
22 #include <asm/opal.h>
23 #include <asm/io.h>
24 #include <linux/uaccess.h>
25 
26 
27 /*
28  * The msg member must be at the end of the struct, as it's followed by the
29  * message data.
30  */
31 struct opal_prd_msg_queue_item {
32 	struct list_head		list;
33 	struct opal_prd_msg_header	msg;
34 };
35 
36 static struct device_node *prd_node;
37 static LIST_HEAD(opal_prd_msg_queue);
38 static DEFINE_SPINLOCK(opal_prd_msg_queue_lock);
39 static DECLARE_WAIT_QUEUE_HEAD(opal_prd_msg_wait);
40 static atomic_t prd_usage;
41 
42 static bool opal_prd_range_is_valid(uint64_t addr, uint64_t size)
43 {
44 	struct device_node *parent, *node;
45 	bool found;
46 
47 	if (addr + size < addr)
48 		return false;
49 
50 	parent = of_find_node_by_path("/reserved-memory");
51 	if (!parent)
52 		return false;
53 
54 	found = false;
55 
56 	for_each_child_of_node(parent, node) {
57 		uint64_t range_addr, range_size, range_end;
58 		const __be32 *addrp;
59 		const char *label;
60 
61 		addrp = of_get_address(node, 0, &range_size, NULL);
62 
63 		range_addr = of_read_number(addrp, 2);
64 		range_end = range_addr + range_size;
65 
66 		label = of_get_property(node, "ibm,prd-label", NULL);
67 
68 		/* PRD ranges need a label */
69 		if (!label)
70 			continue;
71 
72 		if (range_end <= range_addr)
73 			continue;
74 
75 		if (addr >= range_addr && addr + size <= range_end) {
76 			found = true;
77 			of_node_put(node);
78 			break;
79 		}
80 	}
81 
82 	of_node_put(parent);
83 	return found;
84 }
85 
86 static int opal_prd_open(struct inode *inode, struct file *file)
87 {
88 	/*
89 	 * Prevent multiple (separate) processes from concurrent interactions
90 	 * with the FW PRD channel
91 	 */
92 	if (atomic_xchg(&prd_usage, 1) == 1)
93 		return -EBUSY;
94 
95 	return 0;
96 }
97 
98 /*
99  * opal_prd_mmap - maps firmware-provided ranges into userspace
100  * @file: file structure for the device
101  * @vma: VMA to map the registers into
102  */
103 
104 static int opal_prd_mmap(struct file *file, struct vm_area_struct *vma)
105 {
106 	size_t addr, size;
107 	pgprot_t page_prot;
108 
109 	pr_devel("opal_prd_mmap(0x%016lx, 0x%016lx, 0x%lx, 0x%lx)\n",
110 			vma->vm_start, vma->vm_end, vma->vm_pgoff,
111 			vma->vm_flags);
112 
113 	addr = vma->vm_pgoff << PAGE_SHIFT;
114 	size = vma->vm_end - vma->vm_start;
115 
116 	/* ensure we're mapping within one of the allowable ranges */
117 	if (!opal_prd_range_is_valid(addr, size))
118 		return -EINVAL;
119 
120 	page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
121 					 size, vma->vm_page_prot);
122 
123 	return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, size,
124 				page_prot);
125 }
126 
127 static bool opal_msg_queue_empty(void)
128 {
129 	unsigned long flags;
130 	bool ret;
131 
132 	spin_lock_irqsave(&opal_prd_msg_queue_lock, flags);
133 	ret = list_empty(&opal_prd_msg_queue);
134 	spin_unlock_irqrestore(&opal_prd_msg_queue_lock, flags);
135 
136 	return ret;
137 }
138 
139 static __poll_t opal_prd_poll(struct file *file,
140 		struct poll_table_struct *wait)
141 {
142 	poll_wait(file, &opal_prd_msg_wait, wait);
143 
144 	if (!opal_msg_queue_empty())
145 		return EPOLLIN | EPOLLRDNORM;
146 
147 	return 0;
148 }
149 
150 static ssize_t opal_prd_read(struct file *file, char __user *buf,
151 		size_t count, loff_t *ppos)
152 {
153 	struct opal_prd_msg_queue_item *item;
154 	unsigned long flags;
155 	ssize_t size, err;
156 	int rc;
157 
158 	/* we need at least a header's worth of data */
159 	if (count < sizeof(item->msg))
160 		return -EINVAL;
161 
162 	if (*ppos)
163 		return -ESPIPE;
164 
165 	item = NULL;
166 
167 	for (;;) {
168 
169 		spin_lock_irqsave(&opal_prd_msg_queue_lock, flags);
170 		if (!list_empty(&opal_prd_msg_queue)) {
171 			item = list_first_entry(&opal_prd_msg_queue,
172 					struct opal_prd_msg_queue_item, list);
173 			list_del(&item->list);
174 		}
175 		spin_unlock_irqrestore(&opal_prd_msg_queue_lock, flags);
176 
177 		if (item)
178 			break;
179 
180 		if (file->f_flags & O_NONBLOCK)
181 			return -EAGAIN;
182 
183 		rc = wait_event_interruptible(opal_prd_msg_wait,
184 				!opal_msg_queue_empty());
185 		if (rc)
186 			return -EINTR;
187 	}
188 
189 	size = be16_to_cpu(item->msg.size);
190 	if (size > count) {
191 		err = -EINVAL;
192 		goto err_requeue;
193 	}
194 
195 	rc = copy_to_user(buf, &item->msg, size);
196 	if (rc) {
197 		err = -EFAULT;
198 		goto err_requeue;
199 	}
200 
201 	kfree(item);
202 
203 	return size;
204 
205 err_requeue:
206 	/* eep! re-queue at the head of the list */
207 	spin_lock_irqsave(&opal_prd_msg_queue_lock, flags);
208 	list_add(&item->list, &opal_prd_msg_queue);
209 	spin_unlock_irqrestore(&opal_prd_msg_queue_lock, flags);
210 	return err;
211 }
212 
213 static ssize_t opal_prd_write(struct file *file, const char __user *buf,
214 		size_t count, loff_t *ppos)
215 {
216 	struct opal_prd_msg_header hdr;
217 	ssize_t size;
218 	void *msg;
219 	int rc;
220 
221 	size = sizeof(hdr);
222 
223 	if (count < size)
224 		return -EINVAL;
225 
226 	/* grab the header */
227 	rc = copy_from_user(&hdr, buf, sizeof(hdr));
228 	if (rc)
229 		return -EFAULT;
230 
231 	size = be16_to_cpu(hdr.size);
232 
233 	msg = memdup_user(buf, size);
234 	if (IS_ERR(msg))
235 		return PTR_ERR(msg);
236 
237 	rc = opal_prd_msg(msg);
238 	if (rc) {
239 		pr_warn("write: opal_prd_msg returned %d\n", rc);
240 		size = -EIO;
241 	}
242 
243 	kfree(msg);
244 
245 	return size;
246 }
247 
248 static int opal_prd_release(struct inode *inode, struct file *file)
249 {
250 	struct opal_prd_msg_header msg;
251 
252 	msg.size = cpu_to_be16(sizeof(msg));
253 	msg.type = OPAL_PRD_MSG_TYPE_FINI;
254 
255 	opal_prd_msg((struct opal_prd_msg *)&msg);
256 
257 	atomic_xchg(&prd_usage, 0);
258 
259 	return 0;
260 }
261 
262 static long opal_prd_ioctl(struct file *file, unsigned int cmd,
263 		unsigned long param)
264 {
265 	struct opal_prd_info info;
266 	struct opal_prd_scom scom;
267 	int rc = 0;
268 
269 	switch (cmd) {
270 	case OPAL_PRD_GET_INFO:
271 		memset(&info, 0, sizeof(info));
272 		info.version = OPAL_PRD_KERNEL_VERSION;
273 		rc = copy_to_user((void __user *)param, &info, sizeof(info));
274 		if (rc)
275 			return -EFAULT;
276 		break;
277 
278 	case OPAL_PRD_SCOM_READ:
279 		rc = copy_from_user(&scom, (void __user *)param, sizeof(scom));
280 		if (rc)
281 			return -EFAULT;
282 
283 		scom.rc = opal_xscom_read(scom.chip, scom.addr,
284 				(__be64 *)&scom.data);
285 		scom.data = be64_to_cpu(scom.data);
286 		pr_devel("ioctl SCOM_READ: chip %llx addr %016llx data %016llx rc %lld\n",
287 				scom.chip, scom.addr, scom.data, scom.rc);
288 
289 		rc = copy_to_user((void __user *)param, &scom, sizeof(scom));
290 		if (rc)
291 			return -EFAULT;
292 		break;
293 
294 	case OPAL_PRD_SCOM_WRITE:
295 		rc = copy_from_user(&scom, (void __user *)param, sizeof(scom));
296 		if (rc)
297 			return -EFAULT;
298 
299 		scom.rc = opal_xscom_write(scom.chip, scom.addr, scom.data);
300 		pr_devel("ioctl SCOM_WRITE: chip %llx addr %016llx data %016llx rc %lld\n",
301 				scom.chip, scom.addr, scom.data, scom.rc);
302 
303 		rc = copy_to_user((void __user *)param, &scom, sizeof(scom));
304 		if (rc)
305 			return -EFAULT;
306 		break;
307 
308 	default:
309 		rc = -EINVAL;
310 	}
311 
312 	return rc;
313 }
314 
315 static const struct file_operations opal_prd_fops = {
316 	.open		= opal_prd_open,
317 	.mmap		= opal_prd_mmap,
318 	.poll		= opal_prd_poll,
319 	.read		= opal_prd_read,
320 	.write		= opal_prd_write,
321 	.unlocked_ioctl	= opal_prd_ioctl,
322 	.release	= opal_prd_release,
323 	.owner		= THIS_MODULE,
324 };
325 
326 static struct miscdevice opal_prd_dev = {
327 	.minor		= MISC_DYNAMIC_MINOR,
328 	.name		= "opal-prd",
329 	.fops		= &opal_prd_fops,
330 };
331 
332 /* opal interface */
333 static int opal_prd_msg_notifier(struct notifier_block *nb,
334 		unsigned long msg_type, void *_msg)
335 {
336 	struct opal_prd_msg_queue_item *item;
337 	struct opal_prd_msg_header *hdr;
338 	struct opal_msg *msg = _msg;
339 	int msg_size, item_size;
340 	unsigned long flags;
341 
342 	if (msg_type != OPAL_MSG_PRD && msg_type != OPAL_MSG_PRD2)
343 		return 0;
344 
345 	/* Calculate total size of the message and item we need to store. The
346 	 * 'size' field in the header includes the header itself. */
347 	hdr = (void *)msg->params;
348 	msg_size = be16_to_cpu(hdr->size);
349 	item_size = msg_size + sizeof(*item) - sizeof(item->msg);
350 
351 	item = kzalloc(item_size, GFP_ATOMIC);
352 	if (!item)
353 		return -ENOMEM;
354 
355 	memcpy(&item->msg, msg->params, msg_size);
356 
357 	spin_lock_irqsave(&opal_prd_msg_queue_lock, flags);
358 	list_add_tail(&item->list, &opal_prd_msg_queue);
359 	spin_unlock_irqrestore(&opal_prd_msg_queue_lock, flags);
360 
361 	wake_up_interruptible(&opal_prd_msg_wait);
362 
363 	return 0;
364 }
365 
366 static struct notifier_block opal_prd_event_nb = {
367 	.notifier_call	= opal_prd_msg_notifier,
368 	.next		= NULL,
369 	.priority	= 0,
370 };
371 
372 static int opal_prd_probe(struct platform_device *pdev)
373 {
374 	int rc;
375 
376 	if (!pdev || !pdev->dev.of_node)
377 		return -ENODEV;
378 
379 	/* We should only have one prd driver instance per machine; ensure
380 	 * that we only get a valid probe on a single OF node.
381 	 */
382 	if (prd_node)
383 		return -EBUSY;
384 
385 	prd_node = pdev->dev.of_node;
386 
387 	rc = opal_message_notifier_register(OPAL_MSG_PRD, &opal_prd_event_nb);
388 	if (rc) {
389 		pr_err("Couldn't register event notifier\n");
390 		return rc;
391 	}
392 
393 	rc = opal_message_notifier_register(OPAL_MSG_PRD2, &opal_prd_event_nb);
394 	if (rc) {
395 		pr_err("Couldn't register PRD2 event notifier\n");
396 		return rc;
397 	}
398 
399 	rc = misc_register(&opal_prd_dev);
400 	if (rc) {
401 		pr_err("failed to register miscdev\n");
402 		opal_message_notifier_unregister(OPAL_MSG_PRD,
403 				&opal_prd_event_nb);
404 		return rc;
405 	}
406 
407 	return 0;
408 }
409 
410 static int opal_prd_remove(struct platform_device *pdev)
411 {
412 	misc_deregister(&opal_prd_dev);
413 	opal_message_notifier_unregister(OPAL_MSG_PRD, &opal_prd_event_nb);
414 	return 0;
415 }
416 
417 static const struct of_device_id opal_prd_match[] = {
418 	{ .compatible = "ibm,opal-prd" },
419 	{ },
420 };
421 
422 static struct platform_driver opal_prd_driver = {
423 	.driver = {
424 		.name		= "opal-prd",
425 		.of_match_table	= opal_prd_match,
426 	},
427 	.probe	= opal_prd_probe,
428 	.remove	= opal_prd_remove,
429 };
430 
431 module_platform_driver(opal_prd_driver);
432 
433 MODULE_DEVICE_TABLE(of, opal_prd_match);
434 MODULE_DESCRIPTION("PowerNV OPAL runtime diagnostic driver");
435 MODULE_LICENSE("GPL");
436