dell_rbu.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * dell_rbu.c
  4 * Bios Update driver for Dell systems
  5 * Author: Dell Inc
  6 *         Abhay Salunke <abhay_salunke@dell.com>
  7 *
  8 * Copyright (C) 2005 Dell Inc.
  9 *
 10 * Remote BIOS Update (rbu) driver is used for updating DELL BIOS by
 11 * creating entries in the /sys file systems on Linux 2.6 and higher
 12 * kernels. The driver supports two mechanism to update the BIOS namely
 13 * contiguous and packetized. Both these methods still require having some
 14 * application to set the CMOS bit indicating the BIOS to update itself
 15 * after a reboot.
 16 *
 17 * Contiguous method:
 18 * This driver writes the incoming data in a monolithic image by allocating
 19 * contiguous physical pages large enough to accommodate the incoming BIOS
 20 * image size.
 21 *
 22 * Packetized method:
 23 * The driver writes the incoming packet image by allocating a new packet
 24 * on every time the packet data is written. This driver requires an
 25 * application to break the BIOS image in to fixed sized packet chunks.
 26 *
 27 * See Documentation/admin-guide/dell_rbu.rst for more info.
 28 */
 29
 30#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
 31
 32#include <linux/init.h>
 33#include <linux/module.h>
 34#include <linux/slab.h>
 35#include <linux/string.h>
 36#include <linux/errno.h>
 37#include <linux/blkdev.h>
 38#include <linux/platform_device.h>
 39#include <linux/spinlock.h>
 40#include <linux/moduleparam.h>
 41#include <linux/firmware.h>
 42#include <linux/dma-mapping.h>
 43#include <asm/set_memory.h>
 44
 45MODULE_AUTHOR("Abhay Salunke <abhay_salunke@dell.com>");
 46MODULE_DESCRIPTION("Driver for updating BIOS image on DELL systems");
 47MODULE_LICENSE("GPL");
 48MODULE_VERSION("3.3");
 49
 50#define BIOS_SCAN_LIMIT 0xffffffff
 51#define MAX_IMAGE_LENGTH 16
 52static struct _rbu_data {
 53	void *image_update_buffer;
 54	unsigned long image_update_buffer_size;
 55	unsigned long bios_image_size;
 56	int image_update_ordernum;
 57	spinlock_t lock;
 58	unsigned long packet_read_count;
 59	unsigned long num_packets;
 60	unsigned long packetsize;
 61	unsigned long imagesize;
 62	int entry_created;
 63} rbu_data;
 64
 65static char image_type[MAX_IMAGE_LENGTH + 1] = "mono";
 66module_param_string(image_type, image_type, sizeof (image_type), 0);
 67MODULE_PARM_DESC(image_type, "BIOS image type. choose- mono or packet or init");
 68
 69static unsigned long allocation_floor = 0x100000;
 70module_param(allocation_floor, ulong, 0644);
 71MODULE_PARM_DESC(allocation_floor, "Minimum address for allocations when using Packet mode");
 72
 73struct packet_data {
 74	struct list_head list;
 75	size_t length;
 76	void *data;
 77	int ordernum;
 78};
 79
 80static struct list_head packet_data_list;
 81
 82static struct platform_device *rbu_device;
 83static int context;
 84
 85static void init_packet_head(void)
 86{
 87	INIT_LIST_HEAD(&packet_data_list);
 88	rbu_data.packet_read_count = 0;
 89	rbu_data.num_packets = 0;
 90	rbu_data.packetsize = 0;
 91	rbu_data.imagesize = 0;
 92}
 93
 94static int create_packet(void *data, size_t length) __must_hold(&rbu_data.lock)
 95{
 96	struct packet_data *newpacket;
 97	int ordernum = 0;
 98	int retval = 0;
 99	unsigned int packet_array_size = 0;
100	void **invalid_addr_packet_array = NULL;
101	void *packet_data_temp_buf = NULL;
102	unsigned int idx = 0;
103
104	pr_debug("entry\n");
105
106	if (!rbu_data.packetsize) {
107		pr_debug("packetsize not specified\n");
108		retval = -EINVAL;
109		goto out_noalloc;
110	}
111
112	spin_unlock(&rbu_data.lock);
113
114	newpacket = kzalloc(sizeof (struct packet_data), GFP_KERNEL);
115
116	if (!newpacket) {
117		pr_warn("failed to allocate new packet\n");
118		retval = -ENOMEM;
119		spin_lock(&rbu_data.lock);
120		goto out_noalloc;
121	}
122
123	ordernum = get_order(length);
124
125	/*
126	 * BIOS errata mean we cannot allocate packets below 1MB or they will
127	 * be overwritten by BIOS.
128	 *
129	 * array to temporarily hold packets
130	 * that are below the allocation floor
131	 *
132	 * NOTE: very simplistic because we only need the floor to be at 1MB
133	 *       due to BIOS errata. This shouldn't be used for higher floors
134	 *       or you will run out of mem trying to allocate the array.
135	 */
136	packet_array_size = max_t(unsigned int, allocation_floor / rbu_data.packetsize, 1);
137	invalid_addr_packet_array = kcalloc(packet_array_size, sizeof(void *),
138						GFP_KERNEL);
139
140	if (!invalid_addr_packet_array) {
141		pr_warn("failed to allocate invalid_addr_packet_array\n");
142		retval = -ENOMEM;
143		spin_lock(&rbu_data.lock);
144		goto out_alloc_packet;
145	}
146
147	while (!packet_data_temp_buf) {
148		packet_data_temp_buf = (unsigned char *)
149			__get_free_pages(GFP_KERNEL, ordernum);
150		if (!packet_data_temp_buf) {
151			pr_warn("failed to allocate new packet\n");
152			retval = -ENOMEM;
153			spin_lock(&rbu_data.lock);
154			goto out_alloc_packet_array;
155		}
156
157		if ((unsigned long)virt_to_phys(packet_data_temp_buf)
158				< allocation_floor) {
159			pr_debug("packet 0x%lx below floor at 0x%lx\n",
160					(unsigned long)virt_to_phys(
161						packet_data_temp_buf),
162					allocation_floor);
163			invalid_addr_packet_array[idx++] = packet_data_temp_buf;
164			packet_data_temp_buf = NULL;
165		}
166	}
167	/*
168	 * set to uncachable or it may never get written back before reboot
169	 */
170	set_memory_uc((unsigned long)packet_data_temp_buf, 1 << ordernum);
171
172	spin_lock(&rbu_data.lock);
173
174	newpacket->data = packet_data_temp_buf;
175
176	pr_debug("newpacket at physical addr %lx\n",
177		(unsigned long)virt_to_phys(newpacket->data));
178
179	/* packets may not have fixed size */
180	newpacket->length = length;
181	newpacket->ordernum = ordernum;
182	++rbu_data.num_packets;
183
184	/* initialize the newly created packet headers */
185	INIT_LIST_HEAD(&newpacket->list);
186	list_add_tail(&newpacket->list, &packet_data_list);
187
188	memcpy(newpacket->data, data, length);
189
190	pr_debug("exit\n");
191
192out_alloc_packet_array:
193	/* always free packet array */
194	while (idx--) {
195		pr_debug("freeing unused packet below floor 0x%lx\n",
196			(unsigned long)virt_to_phys(invalid_addr_packet_array[idx]));
197		free_pages((unsigned long)invalid_addr_packet_array[idx], ordernum);
198	}
199	kfree(invalid_addr_packet_array);
200
201out_alloc_packet:
202	/* if error, free data */
203	if (retval)
204		kfree(newpacket);
205
206out_noalloc:
207	return retval;
208}
209
210static int packetize_data(const u8 *data, size_t length)
211{
212	int rc = 0;
213	int done = 0;
214	int packet_length;
215	u8 *temp;
216	u8 *end = (u8 *) data + length;
217	pr_debug("data length %zd\n", length);
218	if (!rbu_data.packetsize) {
219		pr_warn("packetsize not specified\n");
220		return -EIO;
221	}
222
223	temp = (u8 *) data;
224
225	/* packetize the hunk */
226	while (!done) {
227		if ((temp + rbu_data.packetsize) < end)
228			packet_length = rbu_data.packetsize;
229		else {
230			/* this is the last packet */
231			packet_length = end - temp;
232			done = 1;
233		}
234
235		rc = create_packet(temp, packet_length);
236		if (rc)
237			return rc;
238
239		pr_debug("%p:%td\n", temp, (end - temp));
240		temp += packet_length;
241	}
242
243	rbu_data.imagesize = length;
244
245	return rc;
246}
247
248static int do_packet_read(char *data, struct packet_data *newpacket,
249	int length, int bytes_read, int *list_read_count)
250{
251	void *ptemp_buf;
252	int bytes_copied = 0;
253	int j = 0;
254
255	*list_read_count += newpacket->length;
256
257	if (*list_read_count > bytes_read) {
258		/* point to the start of unread data */
259		j = newpacket->length - (*list_read_count - bytes_read);
260		/* point to the offset in the packet buffer */
261		ptemp_buf = (u8 *) newpacket->data + j;
262		/*
263		 * check if there is enough room in
264		 * * the incoming buffer
265		 */
266		if (length > (*list_read_count - bytes_read))
267			/*
268			 * copy what ever is there in this
269			 * packet and move on
270			 */
271			bytes_copied = (*list_read_count - bytes_read);
272		else
273			/* copy the remaining */
274			bytes_copied = length;
275		memcpy(data, ptemp_buf, bytes_copied);
276	}
277	return bytes_copied;
278}
279
280static int packet_read_list(char *data, size_t *pread_length)
281{
282	struct packet_data *newpacket;
283	int temp_count = 0;
284	int bytes_copied = 0;
285	int bytes_read = 0;
286	int remaining_bytes = 0;
287	char *pdest = data;
288
289	/* check if we have any packets */
290	if (0 == rbu_data.num_packets)
291		return -ENOMEM;
292
293	remaining_bytes = *pread_length;
294	bytes_read = rbu_data.packet_read_count;
295
296	list_for_each_entry(newpacket, &packet_data_list, list) {
297		bytes_copied = do_packet_read(pdest, newpacket,
298			remaining_bytes, bytes_read, &temp_count);
299		remaining_bytes -= bytes_copied;
300		bytes_read += bytes_copied;
301		pdest += bytes_copied;
302		/*
303		 * check if we reached end of buffer before reaching the
304		 * last packet
305		 */
306		if (remaining_bytes == 0)
307			break;
308	}
309	/*finally set the bytes read */
310	*pread_length = bytes_read - rbu_data.packet_read_count;
311	rbu_data.packet_read_count = bytes_read;
312	return 0;
313}
314
315static void packet_empty_list(void)
316{
317	struct packet_data *newpacket, *tmp;
318
319	list_for_each_entry_safe(newpacket, tmp, &packet_data_list, list) {
320		list_del(&newpacket->list);
321
322		/*
323		 * zero out the RBU packet memory before freeing
324		 * to make sure there are no stale RBU packets left in memory
325		 */
326		memset(newpacket->data, 0, newpacket->length);
327		set_memory_wb((unsigned long)newpacket->data,
328			1 << newpacket->ordernum);
329		free_pages((unsigned long) newpacket->data,
330			newpacket->ordernum);
331		kfree(newpacket);
332	}
333	rbu_data.packet_read_count = 0;
334	rbu_data.num_packets = 0;
335	rbu_data.imagesize = 0;
336}
337
338/*
339 * img_update_free: Frees the buffer allocated for storing BIOS image
340 * Always called with lock held and returned with lock held
341 */
342static void img_update_free(void)
343{
344	if (!rbu_data.image_update_buffer)
345		return;
346	/*
347	 * zero out this buffer before freeing it to get rid of any stale
348	 * BIOS image copied in memory.
349	 */
350	memset(rbu_data.image_update_buffer, 0,
351		rbu_data.image_update_buffer_size);
352	free_pages((unsigned long) rbu_data.image_update_buffer,
353		rbu_data.image_update_ordernum);
354
355	/*
356	 * Re-initialize the rbu_data variables after a free
357	 */
358	rbu_data.image_update_ordernum = -1;
359	rbu_data.image_update_buffer = NULL;
360	rbu_data.image_update_buffer_size = 0;
361	rbu_data.bios_image_size = 0;
362}
363
364/*
365 * img_update_realloc: This function allocates the contiguous pages to
366 * accommodate the requested size of data. The memory address and size
367 * values are stored globally and on every call to this function the new
368 * size is checked to see if more data is required than the existing size.
369 * If true the previous memory is freed and new allocation is done to
370 * accommodate the new size. If the incoming size is less then than the
371 * already allocated size, then that memory is reused. This function is
372 * called with lock held and returns with lock held.
373 */
374static int img_update_realloc(unsigned long size)
375{
376	unsigned char *image_update_buffer = NULL;
377	unsigned long img_buf_phys_addr;
378	int ordernum;
379
380	/*
381	 * check if the buffer of sufficient size has been
382	 * already allocated
383	 */
384	if (rbu_data.image_update_buffer_size >= size) {
385		/*
386		 * check for corruption
387		 */
388		if ((size != 0) && (rbu_data.image_update_buffer == NULL)) {
389			pr_err("corruption check failed\n");
390			return -EINVAL;
391		}
392		/*
393		 * we have a valid pre-allocated buffer with
394		 * sufficient size
395		 */
396		return 0;
397	}
398
399	/*
400	 * free any previously allocated buffer
401	 */
402	img_update_free();
403
404	spin_unlock(&rbu_data.lock);
405
406	ordernum = get_order(size);
407	image_update_buffer =
408		(unsigned char *)__get_free_pages(GFP_DMA32, ordernum);
409	spin_lock(&rbu_data.lock);
410	if (!image_update_buffer) {
411		pr_debug("Not enough memory for image update: size = %ld\n", size);
412		return -ENOMEM;
413	}
414
415	img_buf_phys_addr = (unsigned long)virt_to_phys(image_update_buffer);
416	if (WARN_ON_ONCE(img_buf_phys_addr > BIOS_SCAN_LIMIT))
417		return -EINVAL; /* can't happen per definition */
418
419	rbu_data.image_update_buffer = image_update_buffer;
420	rbu_data.image_update_buffer_size = size;
421	rbu_data.bios_image_size = rbu_data.image_update_buffer_size;
422	rbu_data.image_update_ordernum = ordernum;
423	return 0;
424}
425
426static ssize_t read_packet_data(char *buffer, loff_t pos, size_t count)
427{
428	int retval;
429	size_t bytes_left;
430	size_t data_length;
431	char *ptempBuf = buffer;
432
433	/* check to see if we have something to return */
434	if (rbu_data.num_packets == 0) {
435		pr_debug("no packets written\n");
436		retval = -ENOMEM;
437		goto read_rbu_data_exit;
438	}
439
440	if (pos > rbu_data.imagesize) {
441		retval = 0;
442		pr_warn("data underrun\n");
443		goto read_rbu_data_exit;
444	}
445
446	bytes_left = rbu_data.imagesize - pos;
447	data_length = min(bytes_left, count);
448
449	retval = packet_read_list(ptempBuf, &data_length);
450	if (retval < 0)
451		goto read_rbu_data_exit;
452
453	if ((pos + count) > rbu_data.imagesize) {
454		rbu_data.packet_read_count = 0;
455		/* this was the last copy */
456		retval = bytes_left;
457	} else
458		retval = count;
459
460      read_rbu_data_exit:
461	return retval;
462}
463
464static ssize_t read_rbu_mono_data(char *buffer, loff_t pos, size_t count)
465{
466	/* check to see if we have something to return */
467	if ((rbu_data.image_update_buffer == NULL) ||
468		(rbu_data.bios_image_size == 0)) {
469		pr_debug("image_update_buffer %p, bios_image_size %lu\n",
470			rbu_data.image_update_buffer,
471			rbu_data.bios_image_size);
472		return -ENOMEM;
473	}
474
475	return memory_read_from_buffer(buffer, count, &pos,
476			rbu_data.image_update_buffer, rbu_data.bios_image_size);
477}
478
479static ssize_t data_read(struct file *filp, struct kobject *kobj,
480			 const struct bin_attribute *bin_attr,
481			 char *buffer, loff_t pos, size_t count)
482{
483	ssize_t ret_count = 0;
484
485	spin_lock(&rbu_data.lock);
486
487	if (!strcmp(image_type, "mono"))
488		ret_count = read_rbu_mono_data(buffer, pos, count);
489	else if (!strcmp(image_type, "packet"))
490		ret_count = read_packet_data(buffer, pos, count);
491	else
492		pr_debug("invalid image type specified\n");
493
494	spin_unlock(&rbu_data.lock);
495	return ret_count;
496}
497static const BIN_ATTR_RO(data, 0);
498
499static void callbackfn_rbu(const struct firmware *fw, void *context)
500{
501	rbu_data.entry_created = 0;
502
503	if (!fw)
504		return;
505
506	if (!fw->size)
507		goto out;
508
509	spin_lock(&rbu_data.lock);
510	if (!strcmp(image_type, "mono")) {
511		if (!img_update_realloc(fw->size))
512			memcpy(rbu_data.image_update_buffer,
513				fw->data, fw->size);
514	} else if (!strcmp(image_type, "packet")) {
515		/*
516		 * we need to free previous packets if a
517		 * new hunk of packets needs to be downloaded
518		 */
519		packet_empty_list();
520		if (packetize_data(fw->data, fw->size))
521			/* Incase something goes wrong when we are
522			 * in middle of packetizing the data, we
523			 * need to free up whatever packets might
524			 * have been created before we quit.
525			 */
526			packet_empty_list();
527	} else
528		pr_debug("invalid image type specified\n");
529	spin_unlock(&rbu_data.lock);
530 out:
531	release_firmware(fw);
532}
533
534static ssize_t image_type_read(struct file *filp, struct kobject *kobj,
535			       const struct bin_attribute *bin_attr,
536			       char *buffer, loff_t pos, size_t count)
537{
538	int size = 0;
539	if (!pos)
540		size = scnprintf(buffer, count, "%s\n", image_type);
541	return size;
542}
543
544static ssize_t image_type_write(struct file *filp, struct kobject *kobj,
545				const struct bin_attribute *bin_attr,
546				char *buffer, loff_t pos, size_t count)
547{
548	int rc = count;
549	int req_firm_rc = 0;
550	int i;
551	spin_lock(&rbu_data.lock);
552	/*
553	 * Find the first newline or space
554	 */
555	for (i = 0; i < count; ++i)
556		if (buffer[i] == '\n' || buffer[i] == ' ') {
557			buffer[i] = '\0';
558			break;
559		}
560	if (i == count)
561		buffer[count] = '\0';
562
563	if (strstr(buffer, "mono"))
564		strcpy(image_type, "mono");
565	else if (strstr(buffer, "packet"))
566		strcpy(image_type, "packet");
567	else if (strstr(buffer, "init")) {
568		/*
569		 * If due to the user error the driver gets in a bad
570		 * state where even though it is loaded , the
571		 * /sys/class/firmware/dell_rbu entries are missing.
572		 * to cover this situation the user can recreate entries
573		 * by writing init to image_type.
574		 */
575		if (!rbu_data.entry_created) {
576			spin_unlock(&rbu_data.lock);
577			req_firm_rc = request_firmware_nowait(THIS_MODULE,
578				FW_ACTION_NOUEVENT, "dell_rbu",
579				&rbu_device->dev, GFP_KERNEL, &context,
580				callbackfn_rbu);
581			if (req_firm_rc) {
582				pr_err("request_firmware_nowait failed %d\n", rc);
583				rc = -EIO;
584			} else
585				rbu_data.entry_created = 1;
586
587			spin_lock(&rbu_data.lock);
588		}
589	} else {
590		pr_warn("image_type is invalid\n");
591		spin_unlock(&rbu_data.lock);
592		return -EINVAL;
593	}
594
595	/* we must free all previous allocations */
596	packet_empty_list();
597	img_update_free();
598	spin_unlock(&rbu_data.lock);
599
600	return rc;
601}
602static const BIN_ATTR_RW(image_type, 0);
603
604static ssize_t packet_size_read(struct file *filp, struct kobject *kobj,
605				const struct bin_attribute *bin_attr,
606				char *buffer, loff_t pos, size_t count)
607{
608	int size = 0;
609	if (!pos) {
610		spin_lock(&rbu_data.lock);
611		size = scnprintf(buffer, count, "%lu\n", rbu_data.packetsize);
612		spin_unlock(&rbu_data.lock);
613	}
614	return size;
615}
616
617static ssize_t packet_size_write(struct file *filp, struct kobject *kobj,
618				 const struct bin_attribute *bin_attr,
619				 char *buffer, loff_t pos, size_t count)
620{
621	unsigned long temp;
622	spin_lock(&rbu_data.lock);
623	packet_empty_list();
624	sscanf(buffer, "%lu", &temp);
625	if (temp < 0xffffffff)
626		rbu_data.packetsize = temp;
627
628	spin_unlock(&rbu_data.lock);
629	return count;
630}
631static const BIN_ATTR_RW(packet_size, 0);
632
633static const struct bin_attribute *const rbu_bin_attrs[] = {
634	&bin_attr_data,
635	&bin_attr_image_type,
636	&bin_attr_packet_size,
637	NULL
638};
639
640static const struct attribute_group rbu_group = {
641	.bin_attrs = rbu_bin_attrs,
642};
643
644static int __init dcdrbu_init(void)
645{
646	int rc;
647	spin_lock_init(&rbu_data.lock);
648
649	init_packet_head();
650	rbu_device = platform_device_register_simple("dell_rbu", PLATFORM_DEVID_NONE, NULL, 0);
651	if (IS_ERR(rbu_device)) {
652		pr_err("platform_device_register_simple failed\n");
653		return PTR_ERR(rbu_device);
654	}
655
656	rc = sysfs_create_group(&rbu_device->dev.kobj, &rbu_group);
657	if (rc)
658		goto out_devreg;
659
660	rbu_data.entry_created = 0;
661	return 0;
662
663out_devreg:
664	platform_device_unregister(rbu_device);
665	return rc;
666}
667
668static __exit void dcdrbu_exit(void)
669{
670	spin_lock(&rbu_data.lock);
671	packet_empty_list();
672	img_update_free();
673	spin_unlock(&rbu_data.lock);
674	sysfs_remove_group(&rbu_device->dev.kobj, &rbu_group);
675	platform_device_unregister(rbu_device);
676}
677
678module_exit(dcdrbu_exit);
679module_init(dcdrbu_init);