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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * SPI NOR Software Write Protection logic.
4 *
5 * Copyright (C) 2005, Intec Automation Inc.
6 * Copyright (C) 2014, Freescale Semiconductor, Inc.
7 */
8#include <linux/mtd/mtd.h>
9#include <linux/mtd/spi-nor.h>
10
11#include "core.h"
12
13static u8 spi_nor_get_sr_bp_mask(struct spi_nor *nor)
14{
15 u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
16
17 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6)
18 return mask | SR_BP3_BIT6;
19
20 if (nor->flags & SNOR_F_HAS_4BIT_BP)
21 return mask | SR_BP3;
22
23 return mask;
24}
25
26static u8 spi_nor_get_sr_tb_mask(struct spi_nor *nor)
27{
28 if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
29 return SR_TB_BIT6;
30 else
31 return SR_TB_BIT5;
32}
33
34static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor)
35{
36 unsigned int bp_slots, bp_slots_needed;
37 u8 mask = spi_nor_get_sr_bp_mask(nor);
38
39 /* Reserved one for "protect none" and one for "protect all". */
40 bp_slots = (1 << hweight8(mask)) - 2;
41 bp_slots_needed = ilog2(nor->info->n_sectors);
42
43 if (bp_slots_needed > bp_slots)
44 return nor->info->sector_size <<
45 (bp_slots_needed - bp_slots);
46 else
47 return nor->info->sector_size;
48}
49
50static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs,
51 uint64_t *len)
52{
53 struct mtd_info *mtd = &nor->mtd;
54 u64 min_prot_len;
55 u8 mask = spi_nor_get_sr_bp_mask(nor);
56 u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
57 u8 bp, val = sr & mask;
58
59 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6)
60 val = (val & ~SR_BP3_BIT6) | SR_BP3;
61
62 bp = val >> SR_BP_SHIFT;
63
64 if (!bp) {
65 /* No protection */
66 *ofs = 0;
67 *len = 0;
68 return;
69 }
70
71 min_prot_len = spi_nor_get_min_prot_length_sr(nor);
72 *len = min_prot_len << (bp - 1);
73
74 if (*len > mtd->size)
75 *len = mtd->size;
76
77 if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask)
78 *ofs = 0;
79 else
80 *ofs = mtd->size - *len;
81}
82
83/*
84 * Return true if the entire region is locked (if @locked is true) or unlocked
85 * (if @locked is false); false otherwise.
86 */
87static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs,
88 uint64_t len, u8 sr, bool locked)
89{
90 loff_t lock_offs, lock_offs_max, offs_max;
91 uint64_t lock_len;
92
93 if (!len)
94 return true;
95
96 spi_nor_get_locked_range_sr(nor, sr, &lock_offs, &lock_len);
97
98 lock_offs_max = lock_offs + lock_len;
99 offs_max = ofs + len;
100
101 if (locked)
102 /* Requested range is a sub-range of locked range */
103 return (offs_max <= lock_offs_max) && (ofs >= lock_offs);
104 else
105 /* Requested range does not overlap with locked range */
106 return (ofs >= lock_offs_max) || (offs_max <= lock_offs);
107}
108
109static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
110 u8 sr)
111{
112 return spi_nor_check_lock_status_sr(nor, ofs, len, sr, true);
113}
114
115static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs,
116 uint64_t len, u8 sr)
117{
118 return spi_nor_check_lock_status_sr(nor, ofs, len, sr, false);
119}
120
121/*
122 * Lock a region of the flash. Compatible with ST Micro and similar flash.
123 * Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status
124 * register
125 * (SR). Does not support these features found in newer SR bitfields:
126 * - SEC: sector/block protect - only handle SEC=0 (block protect)
127 * - CMP: complement protect - only support CMP=0 (range is not complemented)
128 *
129 * Support for the following is provided conditionally for some flash:
130 * - TB: top/bottom protect
131 *
132 * Sample table portion for 8MB flash (Winbond w25q64fw):
133 *
134 * SEC | TB | BP2 | BP1 | BP0 | Prot Length | Protected Portion
135 * --------------------------------------------------------------------------
136 * X | X | 0 | 0 | 0 | NONE | NONE
137 * 0 | 0 | 0 | 0 | 1 | 128 KB | Upper 1/64
138 * 0 | 0 | 0 | 1 | 0 | 256 KB | Upper 1/32
139 * 0 | 0 | 0 | 1 | 1 | 512 KB | Upper 1/16
140 * 0 | 0 | 1 | 0 | 0 | 1 MB | Upper 1/8
141 * 0 | 0 | 1 | 0 | 1 | 2 MB | Upper 1/4
142 * 0 | 0 | 1 | 1 | 0 | 4 MB | Upper 1/2
143 * X | X | 1 | 1 | 1 | 8 MB | ALL
144 * ------|-------|-------|-------|-------|---------------|-------------------
145 * 0 | 1 | 0 | 0 | 1 | 128 KB | Lower 1/64
146 * 0 | 1 | 0 | 1 | 0 | 256 KB | Lower 1/32
147 * 0 | 1 | 0 | 1 | 1 | 512 KB | Lower 1/16
148 * 0 | 1 | 1 | 0 | 0 | 1 MB | Lower 1/8
149 * 0 | 1 | 1 | 0 | 1 | 2 MB | Lower 1/4
150 * 0 | 1 | 1 | 1 | 0 | 4 MB | Lower 1/2
151 *
152 * Returns negative on errors, 0 on success.
153 */
154static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
155{
156 struct mtd_info *mtd = &nor->mtd;
157 u64 min_prot_len;
158 int ret, status_old, status_new;
159 u8 mask = spi_nor_get_sr_bp_mask(nor);
160 u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
161 u8 pow, val;
162 loff_t lock_len;
163 bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
164 bool use_top;
165
166 ret = spi_nor_read_sr(nor, nor->bouncebuf);
167 if (ret)
168 return ret;
169
170 status_old = nor->bouncebuf[0];
171
172 /* If nothing in our range is unlocked, we don't need to do anything */
173 if (spi_nor_is_locked_sr(nor, ofs, len, status_old))
174 return 0;
175
176 /* If anything below us is unlocked, we can't use 'bottom' protection */
177 if (!spi_nor_is_locked_sr(nor, 0, ofs, status_old))
178 can_be_bottom = false;
179
180 /* If anything above us is unlocked, we can't use 'top' protection */
181 if (!spi_nor_is_locked_sr(nor, ofs + len, mtd->size - (ofs + len),
182 status_old))
183 can_be_top = false;
184
185 if (!can_be_bottom && !can_be_top)
186 return -EINVAL;
187
188 /* Prefer top, if both are valid */
189 use_top = can_be_top;
190
191 /* lock_len: length of region that should end up locked */
192 if (use_top)
193 lock_len = mtd->size - ofs;
194 else
195 lock_len = ofs + len;
196
197 if (lock_len == mtd->size) {
198 val = mask;
199 } else {
200 min_prot_len = spi_nor_get_min_prot_length_sr(nor);
201 pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
202 val = pow << SR_BP_SHIFT;
203
204 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
205 val = (val & ~SR_BP3) | SR_BP3_BIT6;
206
207 if (val & ~mask)
208 return -EINVAL;
209
210 /* Don't "lock" with no region! */
211 if (!(val & mask))
212 return -EINVAL;
213 }
214
215 status_new = (status_old & ~mask & ~tb_mask) | val;
216
217 /* Disallow further writes if WP pin is asserted */
218 status_new |= SR_SRWD;
219
220 if (!use_top)
221 status_new |= tb_mask;
222
223 /* Don't bother if they're the same */
224 if (status_new == status_old)
225 return 0;
226
227 /* Only modify protection if it will not unlock other areas */
228 if ((status_new & mask) < (status_old & mask))
229 return -EINVAL;
230
231 return spi_nor_write_sr_and_check(nor, status_new);
232}
233
234/*
235 * Unlock a region of the flash. See spi_nor_sr_lock() for more info
236 *
237 * Returns negative on errors, 0 on success.
238 */
239static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
240{
241 struct mtd_info *mtd = &nor->mtd;
242 u64 min_prot_len;
243 int ret, status_old, status_new;
244 u8 mask = spi_nor_get_sr_bp_mask(nor);
245 u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
246 u8 pow, val;
247 loff_t lock_len;
248 bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
249 bool use_top;
250
251 ret = spi_nor_read_sr(nor, nor->bouncebuf);
252 if (ret)
253 return ret;
254
255 status_old = nor->bouncebuf[0];
256
257 /* If nothing in our range is locked, we don't need to do anything */
258 if (spi_nor_is_unlocked_sr(nor, ofs, len, status_old))
259 return 0;
260
261 /* If anything below us is locked, we can't use 'top' protection */
262 if (!spi_nor_is_unlocked_sr(nor, 0, ofs, status_old))
263 can_be_top = false;
264
265 /* If anything above us is locked, we can't use 'bottom' protection */
266 if (!spi_nor_is_unlocked_sr(nor, ofs + len, mtd->size - (ofs + len),
267 status_old))
268 can_be_bottom = false;
269
270 if (!can_be_bottom && !can_be_top)
271 return -EINVAL;
272
273 /* Prefer top, if both are valid */
274 use_top = can_be_top;
275
276 /* lock_len: length of region that should remain locked */
277 if (use_top)
278 lock_len = mtd->size - (ofs + len);
279 else
280 lock_len = ofs;
281
282 if (lock_len == 0) {
283 val = 0; /* fully unlocked */
284 } else {
285 min_prot_len = spi_nor_get_min_prot_length_sr(nor);
286 pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
287 val = pow << SR_BP_SHIFT;
288
289 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
290 val = (val & ~SR_BP3) | SR_BP3_BIT6;
291
292 /* Some power-of-two sizes are not supported */
293 if (val & ~mask)
294 return -EINVAL;
295 }
296
297 status_new = (status_old & ~mask & ~tb_mask) | val;
298
299 /* Don't protect status register if we're fully unlocked */
300 if (lock_len == 0)
301 status_new &= ~SR_SRWD;
302
303 if (!use_top)
304 status_new |= tb_mask;
305
306 /* Don't bother if they're the same */
307 if (status_new == status_old)
308 return 0;
309
310 /* Only modify protection if it will not lock other areas */
311 if ((status_new & mask) > (status_old & mask))
312 return -EINVAL;
313
314 return spi_nor_write_sr_and_check(nor, status_new);
315}
316
317/*
318 * Check if a region of the flash is (completely) locked. See spi_nor_sr_lock()
319 * for more info.
320 *
321 * Returns 1 if entire region is locked, 0 if any portion is unlocked, and
322 * negative on errors.
323 */
324static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, uint64_t len)
325{
326 int ret;
327
328 ret = spi_nor_read_sr(nor, nor->bouncebuf);
329 if (ret)
330 return ret;
331
332 return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]);
333}
334
335static const struct spi_nor_locking_ops spi_nor_sr_locking_ops = {
336 .lock = spi_nor_sr_lock,
337 .unlock = spi_nor_sr_unlock,
338 .is_locked = spi_nor_sr_is_locked,
339};
340
341void spi_nor_init_default_locking_ops(struct spi_nor *nor)
342{
343 nor->params->locking_ops = &spi_nor_sr_locking_ops;
344}
345
346static int spi_nor_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
347{
348 struct spi_nor *nor = mtd_to_spi_nor(mtd);
349 int ret;
350
351 ret = spi_nor_lock_and_prep(nor);
352 if (ret)
353 return ret;
354
355 ret = nor->params->locking_ops->lock(nor, ofs, len);
356
357 spi_nor_unlock_and_unprep(nor);
358 return ret;
359}
360
361static int spi_nor_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
362{
363 struct spi_nor *nor = mtd_to_spi_nor(mtd);
364 int ret;
365
366 ret = spi_nor_lock_and_prep(nor);
367 if (ret)
368 return ret;
369
370 ret = nor->params->locking_ops->unlock(nor, ofs, len);
371
372 spi_nor_unlock_and_unprep(nor);
373 return ret;
374}
375
376static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
377{
378 struct spi_nor *nor = mtd_to_spi_nor(mtd);
379 int ret;
380
381 ret = spi_nor_lock_and_prep(nor);
382 if (ret)
383 return ret;
384
385 ret = nor->params->locking_ops->is_locked(nor, ofs, len);
386
387 spi_nor_unlock_and_unprep(nor);
388 return ret;
389}
390
391/**
392 * spi_nor_try_unlock_all() - Tries to unlock the entire flash memory array.
393 * @nor: pointer to a 'struct spi_nor'.
394 *
395 * Some SPI NOR flashes are write protected by default after a power-on reset
396 * cycle, in order to avoid inadvertent writes during power-up. Backward
397 * compatibility imposes to unlock the entire flash memory array at power-up
398 * by default.
399 *
400 * Unprotecting the entire flash array will fail for boards which are hardware
401 * write-protected. Thus any errors are ignored.
402 */
403void spi_nor_try_unlock_all(struct spi_nor *nor)
404{
405 int ret;
406
407 if (!(nor->flags & SNOR_F_HAS_LOCK))
408 return;
409
410 dev_dbg(nor->dev, "Unprotecting entire flash array\n");
411
412 ret = spi_nor_unlock(&nor->mtd, 0, nor->params->size);
413 if (ret)
414 dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n");
415}
416
417void spi_nor_register_locking_ops(struct spi_nor *nor)
418{
419 struct mtd_info *mtd = &nor->mtd;
420
421 if (!nor->params->locking_ops)
422 return;
423
424 mtd->_lock = spi_nor_lock;
425 mtd->_unlock = spi_nor_unlock;
426 mtd->_is_locked = spi_nor_is_locked;
427}