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      1 // SPDX-License-Identifier: GPL-2.0+
      2 /*
      3  * Copyright (c) International Business Machines Corp., 2006
      4  *
      5  * Author: Artem Bityutskiy ( )
      6  */
      7 
      8 /* Here we keep miscellaneous functions which are used all over the UBI code */
      9 
     10 #include <ubi_uboot.h>
     11 #include "ubi.h"
     12 
     13 /**
     14  * calc_data_len - calculate how much real data is stored in a buffer.
     15  * @ubi: UBI device description object
     16  * @buf: a buffer with the contents of the physical eraseblock
     17  * @length: the buffer length
     18  *
     19  * This function calculates how much "real data" is stored in @buf and returnes
     20  * the length. Continuous 0xFF bytes at the end of the buffer are not
     21  * considered as "real data".
     22  */
     23 int ubi_calc_data_len(const struct ubi_device *ubi, const void *buf,
     24 		      int length)
     25 {
     26 	int i;
     27 
     28 	ubi_assert(!(length & (ubi->min_io_size - 1)));
     29 
     30 	for (i = length - 1; i >= 0; i--)
     31 		if (((const uint8_t *)buf)[i] != 0xFF)
     32 			break;
     33 
     34 	/* The resulting length must be aligned to the minimum flash I/O size */
     35 	length = ALIGN(i + 1, ubi->min_io_size);
     36 	return length;
     37 }
     38 
     39 /**
     40  * ubi_check_volume - check the contents of a static volume.
     41  * @ubi: UBI device description object
     42  * @vol_id: ID of the volume to check
     43  *
     44  * This function checks if static volume @vol_id is corrupted by fully reading
     45  * it and checking data CRC. This function returns %0 if the volume is not
     46  * corrupted, %1 if it is corrupted and a negative error code in case of
     47  * failure. Dynamic volumes are not checked and zero is returned immediately.
     48  */
     49 int ubi_check_volume(struct ubi_device *ubi, int vol_id)
     50 {
     51 	void *buf;
     52 	int err = 0, i;
     53 	struct ubi_volume *vol = ubi->volumes[vol_id];
     54 
     55 	if (vol->vol_type != UBI_STATIC_VOLUME)
     56 		return 0;
     57 
     58 	buf = vmalloc(vol->usable_leb_size);
     59 	if (!buf)
     60 		return -ENOMEM;
     61 
     62 	for (i = 0; i < vol->used_ebs; i++) {
     63 		int size;
     64 
     65 		cond_resched();
     66 
     67 		if (i == vol->used_ebs - 1)
     68 			size = vol->last_eb_bytes;
     69 		else
     70 			size = vol->usable_leb_size;
     71 
     72 		err = ubi_eba_read_leb(ubi, vol, i, buf, 0, size, 1);
     73 		if (err) {
     74 			if (mtd_is_eccerr(err))
     75 				err = 1;
     76 			break;
     77 		}
     78 	}
     79 
     80 	vfree(buf);
     81 	return err;
     82 }
     83 
     84 /**
     85  * ubi_update_reserved - update bad eraseblock handling accounting data.
     86  * @ubi: UBI device description object
     87  *
     88  * This function calculates the gap between current number of PEBs reserved for
     89  * bad eraseblock handling and the required level of PEBs that must be
     90  * reserved, and if necessary, reserves more PEBs to fill that gap, according
     91  * to availability. Should be called with ubi->volumes_lock held.
     92  */
     93 void ubi_update_reserved(struct ubi_device *ubi)
     94 {
     95 	int need = ubi->beb_rsvd_level - ubi->beb_rsvd_pebs;
     96 
     97 	if (need <= 0 || ubi->avail_pebs == 0)
     98 		return;
     99 
    100 	need = min_t(int, need, ubi->avail_pebs);
    101 	ubi->avail_pebs -= need;
    102 	ubi->rsvd_pebs += need;
    103 	ubi->beb_rsvd_pebs += need;
    104 	ubi_msg(ubi, "reserved more %d PEBs for bad PEB handling", need);
    105 }
    106 
    107 /**
    108  * ubi_calculate_reserved - calculate how many PEBs must be reserved for bad
    109  * eraseblock handling.
    110  * @ubi: UBI device description object
    111  */
    112 void ubi_calculate_reserved(struct ubi_device *ubi)
    113 {
    114 	/*
    115 	 * Calculate the actual number of PEBs currently needed to be reserved
    116 	 * for future bad eraseblock handling.
    117 	 */
    118 	ubi->beb_rsvd_level = ubi->bad_peb_limit - ubi->bad_peb_count;
    119 	if (ubi->beb_rsvd_level < 0) {
    120 		ubi->beb_rsvd_level = 0;
    121 		ubi_warn(ubi, "number of bad PEBs (%d) is above the expected limit (%d), not reserving any PEBs for bad PEB handling, will use available PEBs (if any)",
    122 			 ubi->bad_peb_count, ubi->bad_peb_limit);
    123 	}
    124 }
    125 
    126 /**
    127  * ubi_check_pattern - check if buffer contains only a certain byte pattern.
    128  * @buf: buffer to check
    129  * @patt: the pattern to check
    130  * @size: buffer size in bytes
    131  *
    132  * This function returns %1 in there are only @patt bytes in @buf, and %0 if
    133  * something else was also found.
    134  */
    135 int ubi_check_pattern(const void *buf, uint8_t patt, int size)
    136 {
    137 	int i;
    138 
    139 	for (i = 0; i < size; i++)
    140 		if (((const uint8_t *)buf)[i] != patt)
    141 			return 0;
    142 	return 1;
    143 }
    144