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("3.2");
 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 packet_data packet_data_head;
 81
 82static struct platform_device *rbu_device;
 83static int context;
 84
 85static void init_packet_head(void)
 86{
 87	INIT_LIST_HEAD(&packet_data_head.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)
 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_head.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		if ((rc = create_packet(temp, packet_length)))
236			return rc;
237
238		pr_debug("%p:%td\n", temp, (end - temp));
239		temp += packet_length;
240	}
241
242	rbu_data.imagesize = length;
243
244	return rc;
245}
246
247static int do_packet_read(char *data, struct packet_data *newpacket,
248	int length, int bytes_read, int *list_read_count)
249{
250	void *ptemp_buf;
251	int bytes_copied = 0;
252	int j = 0;
253
254	*list_read_count += newpacket->length;
255
256	if (*list_read_count > bytes_read) {
257		/* point to the start of unread data */
258		j = newpacket->length - (*list_read_count - bytes_read);
259		/* point to the offset in the packet buffer */
260		ptemp_buf = (u8 *) newpacket->data + j;
261		/*
262		 * check if there is enough room in
263		 * * the incoming buffer
264		 */
265		if (length > (*list_read_count - bytes_read))
266			/*
267			 * copy what ever is there in this
268			 * packet and move on
269			 */
270			bytes_copied = (*list_read_count - bytes_read);
271		else
272			/* copy the remaining */
273			bytes_copied = length;
274		memcpy(data, ptemp_buf, bytes_copied);
275	}
276	return bytes_copied;
277}
278
279static int packet_read_list(char *data, size_t * pread_length)
280{
281	struct packet_data *newpacket;
282	int temp_count = 0;
283	int bytes_copied = 0;
284	int bytes_read = 0;
285	int remaining_bytes = 0;
286	char *pdest = data;
287
288	/* check if we have any packets */
289	if (0 == rbu_data.num_packets)
290		return -ENOMEM;
291
292	remaining_bytes = *pread_length;
293	bytes_read = rbu_data.packet_read_count;
294
295	list_for_each_entry(newpacket, (&packet_data_head.list)->next, list) {
296		bytes_copied = do_packet_read(pdest, newpacket,
297			remaining_bytes, bytes_read, &temp_count);
298		remaining_bytes -= bytes_copied;
299		bytes_read += bytes_copied;
300		pdest += bytes_copied;
301		/*
302		 * check if we reached end of buffer before reaching the
303		 * last packet
304		 */
305		if (remaining_bytes == 0)
306			break;
307	}
308	/*finally set the bytes read */
309	*pread_length = bytes_read - rbu_data.packet_read_count;
310	rbu_data.packet_read_count = bytes_read;
311	return 0;
312}
313
314static void packet_empty_list(void)
315{
316	struct packet_data *newpacket, *tmp;
317
318	list_for_each_entry_safe(newpacket, tmp, (&packet_data_head.list)->next, list) {
319		list_del(&newpacket->list);
320
321		/*
322		 * zero out the RBU packet memory before freeing
323		 * to make sure there are no stale RBU packets left in memory
324		 */
325		memset(newpacket->data, 0, rbu_data.packetsize);
326		set_memory_wb((unsigned long)newpacket->data,
327			1 << newpacket->ordernum);
328		free_pages((unsigned long) newpacket->data,
329			newpacket->ordernum);
330		kfree(newpacket);
331	}
332	rbu_data.packet_read_count = 0;
333	rbu_data.num_packets = 0;
334	rbu_data.imagesize = 0;
335}
336
337/*
338 * img_update_free: Frees the buffer allocated for storing BIOS image
339 * Always called with lock held and returned with lock held
340 */
341static void img_update_free(void)
342{
343	if (!rbu_data.image_update_buffer)
344		return;
345	/*
346	 * zero out this buffer before freeing it to get rid of any stale
347	 * BIOS image copied in memory.
348	 */
349	memset(rbu_data.image_update_buffer, 0,
350		rbu_data.image_update_buffer_size);
351	free_pages((unsigned long) rbu_data.image_update_buffer,
352		rbu_data.image_update_ordernum);
353
354	/*
355	 * Re-initialize the rbu_data variables after a free
356	 */
357	rbu_data.image_update_ordernum = -1;
358	rbu_data.image_update_buffer = NULL;
359	rbu_data.image_update_buffer_size = 0;
360	rbu_data.bios_image_size = 0;
361}
362
363/*
364 * img_update_realloc: This function allocates the contiguous pages to
365 * accommodate the requested size of data. The memory address and size
366 * values are stored globally and on every call to this function the new
367 * size is checked to see if more data is required than the existing size.
368 * If true the previous memory is freed and new allocation is done to
369 * accommodate the new size. If the incoming size is less then than the
370 * already allocated size, then that memory is reused. This function is
371 * called with lock held and returns with lock held.
372 */
373static int img_update_realloc(unsigned long size)
374{
375	unsigned char *image_update_buffer = NULL;
376	unsigned long img_buf_phys_addr;
377	int ordernum;
378
379	/*
380	 * check if the buffer of sufficient size has been
381	 * already allocated
382	 */
383	if (rbu_data.image_update_buffer_size >= size) {
384		/*
385		 * check for corruption
386		 */
387		if ((size != 0) && (rbu_data.image_update_buffer == NULL)) {
388			pr_err("corruption check failed\n");
389			return -EINVAL;
390		}
391		/*
392		 * we have a valid pre-allocated buffer with
393		 * sufficient size
394		 */
395		return 0;
396	}
397
398	/*
399	 * free any previously allocated buffer
400	 */
401	img_update_free();
402
403	spin_unlock(&rbu_data.lock);
404
405	ordernum = get_order(size);
406	image_update_buffer =
407		(unsigned char *)__get_free_pages(GFP_DMA32, ordernum);
408	spin_lock(&rbu_data.lock);
409	if (!image_update_buffer) {
410		pr_debug("Not enough memory for image update: size = %ld\n", size);
411		return -ENOMEM;
412	}
413
414	img_buf_phys_addr = (unsigned long)virt_to_phys(image_update_buffer);
415	if (WARN_ON_ONCE(img_buf_phys_addr > BIOS_SCAN_LIMIT))
416		return -EINVAL; /* can't happen per definition */
417
418	rbu_data.image_update_buffer = image_update_buffer;
419	rbu_data.image_update_buffer_size = size;
420	rbu_data.bios_image_size = rbu_data.image_update_buffer_size;
421	rbu_data.image_update_ordernum = ordernum;
422	return 0;
423}
424
425static ssize_t read_packet_data(char *buffer, loff_t pos, size_t count)
426{
427	int retval;
428	size_t bytes_left;
429	size_t data_length;
430	char *ptempBuf = buffer;
431
432	/* check to see if we have something to return */
433	if (rbu_data.num_packets == 0) {
434		pr_debug("no packets written\n");
435		retval = -ENOMEM;
436		goto read_rbu_data_exit;
437	}
438
439	if (pos > rbu_data.imagesize) {
440		retval = 0;
441		pr_warn("data underrun\n");
442		goto read_rbu_data_exit;
443	}
444
445	bytes_left = rbu_data.imagesize - pos;
446	data_length = min(bytes_left, count);
447
448	if ((retval = packet_read_list(ptempBuf, &data_length)) < 0)
449		goto read_rbu_data_exit;
450
451	if ((pos + count) > rbu_data.imagesize) {
452		rbu_data.packet_read_count = 0;
453		/* this was the last copy */
454		retval = bytes_left;
455	} else
456		retval = count;
457
458      read_rbu_data_exit:
459	return retval;
460}
461
462static ssize_t read_rbu_mono_data(char *buffer, loff_t pos, size_t count)
463{
464	/* check to see if we have something to return */
465	if ((rbu_data.image_update_buffer == NULL) ||
466		(rbu_data.bios_image_size == 0)) {
467		pr_debug("image_update_buffer %p, bios_image_size %lu\n",
468			rbu_data.image_update_buffer,
469			rbu_data.bios_image_size);
470		return -ENOMEM;
471	}
472
473	return memory_read_from_buffer(buffer, count, &pos,
474			rbu_data.image_update_buffer, rbu_data.bios_image_size);
475}
476
477static ssize_t data_read(struct file *filp, struct kobject *kobj,
478			 struct bin_attribute *bin_attr,
479			 char *buffer, loff_t pos, size_t count)
480{
481	ssize_t ret_count = 0;
482
483	spin_lock(&rbu_data.lock);
484
485	if (!strcmp(image_type, "mono"))
486		ret_count = read_rbu_mono_data(buffer, pos, count);
487	else if (!strcmp(image_type, "packet"))
488		ret_count = read_packet_data(buffer, pos, count);
489	else
490		pr_debug("invalid image type specified\n");
491
492	spin_unlock(&rbu_data.lock);
493	return ret_count;
494}
495static BIN_ATTR_RO(data, 0);
496
497static void callbackfn_rbu(const struct firmware *fw, void *context)
498{
499	rbu_data.entry_created = 0;
500
501	if (!fw)
502		return;
503
504	if (!fw->size)
505		goto out;
506
507	spin_lock(&rbu_data.lock);
508	if (!strcmp(image_type, "mono")) {
509		if (!img_update_realloc(fw->size))
510			memcpy(rbu_data.image_update_buffer,
511				fw->data, fw->size);
512	} else if (!strcmp(image_type, "packet")) {
513		/*
514		 * we need to free previous packets if a
515		 * new hunk of packets needs to be downloaded
516		 */
517		packet_empty_list();
518		if (packetize_data(fw->data, fw->size))
519			/* Incase something goes wrong when we are
520			 * in middle of packetizing the data, we
521			 * need to free up whatever packets might
522			 * have been created before we quit.
523			 */
524			packet_empty_list();
525	} else
526		pr_debug("invalid image type specified\n");
527	spin_unlock(&rbu_data.lock);
528 out:
529	release_firmware(fw);
530}
531
532static ssize_t image_type_read(struct file *filp, struct kobject *kobj,
533			       struct bin_attribute *bin_attr,
534			       char *buffer, loff_t pos, size_t count)
535{
536	int size = 0;
537	if (!pos)
538		size = scnprintf(buffer, count, "%s\n", image_type);
539	return size;
540}
541
542static ssize_t image_type_write(struct file *filp, struct kobject *kobj,
543				struct bin_attribute *bin_attr,
544				char *buffer, loff_t pos, size_t count)
545{
546	int rc = count;
547	int req_firm_rc = 0;
548	int i;
549	spin_lock(&rbu_data.lock);
550	/*
551	 * Find the first newline or space
552	 */
553	for (i = 0; i < count; ++i)
554		if (buffer[i] == '\n' || buffer[i] == ' ') {
555			buffer[i] = '\0';
556			break;
557		}
558	if (i == count)
559		buffer[count] = '\0';
560
561	if (strstr(buffer, "mono"))
562		strcpy(image_type, "mono");
563	else if (strstr(buffer, "packet"))
564		strcpy(image_type, "packet");
565	else if (strstr(buffer, "init")) {
566		/*
567		 * If due to the user error the driver gets in a bad
568		 * state where even though it is loaded , the
569		 * /sys/class/firmware/dell_rbu entries are missing.
570		 * to cover this situation the user can recreate entries
571		 * by writing init to image_type.
572		 */
573		if (!rbu_data.entry_created) {
574			spin_unlock(&rbu_data.lock);
575			req_firm_rc = request_firmware_nowait(THIS_MODULE,
576				FW_ACTION_NOHOTPLUG, "dell_rbu",
577				&rbu_device->dev, GFP_KERNEL, &context,
578				callbackfn_rbu);
579			if (req_firm_rc) {
580				pr_err("request_firmware_nowait failed %d\n", rc);
581				rc = -EIO;
582			} else
583				rbu_data.entry_created = 1;
584
585			spin_lock(&rbu_data.lock);
586		}
587	} else {
588		pr_warn("image_type is invalid\n");
589		spin_unlock(&rbu_data.lock);
590		return -EINVAL;
591	}
592
593	/* we must free all previous allocations */
594	packet_empty_list();
595	img_update_free();
596	spin_unlock(&rbu_data.lock);
597
598	return rc;
599}
600static BIN_ATTR_RW(image_type, 0);
601
602static ssize_t packet_size_read(struct file *filp, struct kobject *kobj,
603				struct bin_attribute *bin_attr,
604				char *buffer, loff_t pos, size_t count)
605{
606	int size = 0;
607	if (!pos) {
608		spin_lock(&rbu_data.lock);
609		size = scnprintf(buffer, count, "%lu\n", rbu_data.packetsize);
610		spin_unlock(&rbu_data.lock);
611	}
612	return size;
613}
614
615static ssize_t packet_size_write(struct file *filp, struct kobject *kobj,
616				 struct bin_attribute *bin_attr,
617				 char *buffer, loff_t pos, size_t count)
618{
619	unsigned long temp;
620	spin_lock(&rbu_data.lock);
621	packet_empty_list();
622	sscanf(buffer, "%lu", &temp);
623	if (temp < 0xffffffff)
624		rbu_data.packetsize = temp;
625
626	spin_unlock(&rbu_data.lock);
627	return count;
628}
629static BIN_ATTR_RW(packet_size, 0);
630
631static struct bin_attribute *rbu_bin_attrs[] = {
632	&bin_attr_data,
633	&bin_attr_image_type,
634	&bin_attr_packet_size,
635	NULL
636};
637
638static const struct attribute_group rbu_group = {
639	.bin_attrs = rbu_bin_attrs,
640};
641
642static int __init dcdrbu_init(void)
643{
644	int rc;
645	spin_lock_init(&rbu_data.lock);
646
647	init_packet_head();
648	rbu_device = platform_device_register_simple("dell_rbu", -1, NULL, 0);
649	if (IS_ERR(rbu_device)) {
650		pr_err("platform_device_register_simple failed\n");
651		return PTR_ERR(rbu_device);
652	}
653
654	rc = sysfs_create_group(&rbu_device->dev.kobj, &rbu_group);
655	if (rc)
656		goto out_devreg;
657
658	rbu_data.entry_created = 0;
659	return 0;
660
661out_devreg:
662	platform_device_unregister(rbu_device);
663	return rc;
664}
665
666static __exit void dcdrbu_exit(void)
667{
668	spin_lock(&rbu_data.lock);
669	packet_empty_list();
670	img_update_free();
671	spin_unlock(&rbu_data.lock);
672	sysfs_remove_group(&rbu_device->dev.kobj, &rbu_group);
673	platform_device_unregister(rbu_device);
674}
675
676module_exit(dcdrbu_exit);
677module_init(dcdrbu_init);
678
679/* vim:noet:ts=8:sw=8
680*/