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 | |
13 | static 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 | |
26 | static 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 | |
34 | static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor) |
35 | { |
36 | unsigned int bp_slots, bp_slots_needed; |
37 | /* |
38 | * sector_size will eventually be replaced with the max erase size of |
39 | * the flash. For now, we need to have that ugly default. |
40 | */ |
41 | unsigned int sector_size = nor->info->sector_size ?: SPI_NOR_DEFAULT_SECTOR_SIZE; |
42 | u64 n_sectors = div_u64(dividend: nor->params->size, divisor: sector_size); |
43 | u8 mask = spi_nor_get_sr_bp_mask(nor); |
44 | |
45 | /* Reserved one for "protect none" and one for "protect all". */ |
46 | bp_slots = (1 << hweight8(mask)) - 2; |
47 | bp_slots_needed = ilog2(n_sectors); |
48 | |
49 | if (bp_slots_needed > bp_slots) |
50 | return sector_size << (bp_slots_needed - bp_slots); |
51 | else |
52 | return sector_size; |
53 | } |
54 | |
55 | static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs, |
56 | u64 *len) |
57 | { |
58 | struct mtd_info *mtd = &nor->mtd; |
59 | u64 min_prot_len; |
60 | u8 mask = spi_nor_get_sr_bp_mask(nor); |
61 | u8 tb_mask = spi_nor_get_sr_tb_mask(nor); |
62 | u8 bp, val = sr & mask; |
63 | |
64 | if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6) |
65 | val = (val & ~SR_BP3_BIT6) | SR_BP3; |
66 | |
67 | bp = val >> SR_BP_SHIFT; |
68 | |
69 | if (!bp) { |
70 | /* No protection */ |
71 | *ofs = 0; |
72 | *len = 0; |
73 | return; |
74 | } |
75 | |
76 | min_prot_len = spi_nor_get_min_prot_length_sr(nor); |
77 | *len = min_prot_len << (bp - 1); |
78 | |
79 | if (*len > mtd->size) |
80 | *len = mtd->size; |
81 | |
82 | if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask) |
83 | *ofs = 0; |
84 | else |
85 | *ofs = mtd->size - *len; |
86 | } |
87 | |
88 | /* |
89 | * Return true if the entire region is locked (if @locked is true) or unlocked |
90 | * (if @locked is false); false otherwise. |
91 | */ |
92 | static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs, |
93 | u64 len, u8 sr, bool locked) |
94 | { |
95 | loff_t lock_offs, lock_offs_max, offs_max; |
96 | u64 lock_len; |
97 | |
98 | if (!len) |
99 | return true; |
100 | |
101 | spi_nor_get_locked_range_sr(nor, sr, ofs: &lock_offs, len: &lock_len); |
102 | |
103 | lock_offs_max = lock_offs + lock_len; |
104 | offs_max = ofs + len; |
105 | |
106 | if (locked) |
107 | /* Requested range is a sub-range of locked range */ |
108 | return (offs_max <= lock_offs_max) && (ofs >= lock_offs); |
109 | else |
110 | /* Requested range does not overlap with locked range */ |
111 | return (ofs >= lock_offs_max) || (offs_max <= lock_offs); |
112 | } |
113 | |
114 | static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, u64 len, u8 sr) |
115 | { |
116 | return spi_nor_check_lock_status_sr(nor, ofs, len, sr, locked: true); |
117 | } |
118 | |
119 | static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, u64 len, |
120 | u8 sr) |
121 | { |
122 | return spi_nor_check_lock_status_sr(nor, ofs, len, sr, locked: false); |
123 | } |
124 | |
125 | /* |
126 | * Lock a region of the flash. Compatible with ST Micro and similar flash. |
127 | * Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status |
128 | * register |
129 | * (SR). Does not support these features found in newer SR bitfields: |
130 | * - SEC: sector/block protect - only handle SEC=0 (block protect) |
131 | * - CMP: complement protect - only support CMP=0 (range is not complemented) |
132 | * |
133 | * Support for the following is provided conditionally for some flash: |
134 | * - TB: top/bottom protect |
135 | * |
136 | * Sample table portion for 8MB flash (Winbond w25q64fw): |
137 | * |
138 | * SEC | TB | BP2 | BP1 | BP0 | Prot Length | Protected Portion |
139 | * -------------------------------------------------------------------------- |
140 | * X | X | 0 | 0 | 0 | NONE | NONE |
141 | * 0 | 0 | 0 | 0 | 1 | 128 KB | Upper 1/64 |
142 | * 0 | 0 | 0 | 1 | 0 | 256 KB | Upper 1/32 |
143 | * 0 | 0 | 0 | 1 | 1 | 512 KB | Upper 1/16 |
144 | * 0 | 0 | 1 | 0 | 0 | 1 MB | Upper 1/8 |
145 | * 0 | 0 | 1 | 0 | 1 | 2 MB | Upper 1/4 |
146 | * 0 | 0 | 1 | 1 | 0 | 4 MB | Upper 1/2 |
147 | * X | X | 1 | 1 | 1 | 8 MB | ALL |
148 | * ------|-------|-------|-------|-------|---------------|------------------- |
149 | * 0 | 1 | 0 | 0 | 1 | 128 KB | Lower 1/64 |
150 | * 0 | 1 | 0 | 1 | 0 | 256 KB | Lower 1/32 |
151 | * 0 | 1 | 0 | 1 | 1 | 512 KB | Lower 1/16 |
152 | * 0 | 1 | 1 | 0 | 0 | 1 MB | Lower 1/8 |
153 | * 0 | 1 | 1 | 0 | 1 | 2 MB | Lower 1/4 |
154 | * 0 | 1 | 1 | 1 | 0 | 4 MB | Lower 1/2 |
155 | * |
156 | * Returns negative on errors, 0 on success. |
157 | */ |
158 | static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len) |
159 | { |
160 | struct mtd_info *mtd = &nor->mtd; |
161 | u64 min_prot_len; |
162 | int ret, status_old, status_new; |
163 | u8 mask = spi_nor_get_sr_bp_mask(nor); |
164 | u8 tb_mask = spi_nor_get_sr_tb_mask(nor); |
165 | u8 pow, val; |
166 | loff_t lock_len; |
167 | bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; |
168 | bool use_top; |
169 | |
170 | ret = spi_nor_read_sr(nor, sr: nor->bouncebuf); |
171 | if (ret) |
172 | return ret; |
173 | |
174 | status_old = nor->bouncebuf[0]; |
175 | |
176 | /* If nothing in our range is unlocked, we don't need to do anything */ |
177 | if (spi_nor_is_locked_sr(nor, ofs, len, sr: status_old)) |
178 | return 0; |
179 | |
180 | /* If anything below us is unlocked, we can't use 'bottom' protection */ |
181 | if (!spi_nor_is_locked_sr(nor, ofs: 0, len: ofs, sr: status_old)) |
182 | can_be_bottom = false; |
183 | |
184 | /* If anything above us is unlocked, we can't use 'top' protection */ |
185 | if (!spi_nor_is_locked_sr(nor, ofs: ofs + len, len: mtd->size - (ofs + len), |
186 | sr: status_old)) |
187 | can_be_top = false; |
188 | |
189 | if (!can_be_bottom && !can_be_top) |
190 | return -EINVAL; |
191 | |
192 | /* Prefer top, if both are valid */ |
193 | use_top = can_be_top; |
194 | |
195 | /* lock_len: length of region that should end up locked */ |
196 | if (use_top) |
197 | lock_len = mtd->size - ofs; |
198 | else |
199 | lock_len = ofs + len; |
200 | |
201 | if (lock_len == mtd->size) { |
202 | val = mask; |
203 | } else { |
204 | min_prot_len = spi_nor_get_min_prot_length_sr(nor); |
205 | pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; |
206 | val = pow << SR_BP_SHIFT; |
207 | |
208 | if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) |
209 | val = (val & ~SR_BP3) | SR_BP3_BIT6; |
210 | |
211 | if (val & ~mask) |
212 | return -EINVAL; |
213 | |
214 | /* Don't "lock" with no region! */ |
215 | if (!(val & mask)) |
216 | return -EINVAL; |
217 | } |
218 | |
219 | status_new = (status_old & ~mask & ~tb_mask) | val; |
220 | |
221 | /* |
222 | * Disallow further writes if WP# pin is neither left floating nor |
223 | * wrongly tied to GND (that includes internal pull-downs). |
224 | * WP# pin hard strapped to GND can be a valid use case. |
225 | */ |
226 | if (!(nor->flags & SNOR_F_NO_WP)) |
227 | status_new |= SR_SRWD; |
228 | |
229 | if (!use_top) |
230 | status_new |= tb_mask; |
231 | |
232 | /* Don't bother if they're the same */ |
233 | if (status_new == status_old) |
234 | return 0; |
235 | |
236 | /* Only modify protection if it will not unlock other areas */ |
237 | if ((status_new & mask) < (status_old & mask)) |
238 | return -EINVAL; |
239 | |
240 | return spi_nor_write_sr_and_check(nor, sr1: status_new); |
241 | } |
242 | |
243 | /* |
244 | * Unlock a region of the flash. See spi_nor_sr_lock() for more info |
245 | * |
246 | * Returns negative on errors, 0 on success. |
247 | */ |
248 | static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len) |
249 | { |
250 | struct mtd_info *mtd = &nor->mtd; |
251 | u64 min_prot_len; |
252 | int ret, status_old, status_new; |
253 | u8 mask = spi_nor_get_sr_bp_mask(nor); |
254 | u8 tb_mask = spi_nor_get_sr_tb_mask(nor); |
255 | u8 pow, val; |
256 | loff_t lock_len; |
257 | bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; |
258 | bool use_top; |
259 | |
260 | ret = spi_nor_read_sr(nor, sr: nor->bouncebuf); |
261 | if (ret) |
262 | return ret; |
263 | |
264 | status_old = nor->bouncebuf[0]; |
265 | |
266 | /* If nothing in our range is locked, we don't need to do anything */ |
267 | if (spi_nor_is_unlocked_sr(nor, ofs, len, sr: status_old)) |
268 | return 0; |
269 | |
270 | /* If anything below us is locked, we can't use 'top' protection */ |
271 | if (!spi_nor_is_unlocked_sr(nor, ofs: 0, len: ofs, sr: status_old)) |
272 | can_be_top = false; |
273 | |
274 | /* If anything above us is locked, we can't use 'bottom' protection */ |
275 | if (!spi_nor_is_unlocked_sr(nor, ofs: ofs + len, len: mtd->size - (ofs + len), |
276 | sr: status_old)) |
277 | can_be_bottom = false; |
278 | |
279 | if (!can_be_bottom && !can_be_top) |
280 | return -EINVAL; |
281 | |
282 | /* Prefer top, if both are valid */ |
283 | use_top = can_be_top; |
284 | |
285 | /* lock_len: length of region that should remain locked */ |
286 | if (use_top) |
287 | lock_len = mtd->size - (ofs + len); |
288 | else |
289 | lock_len = ofs; |
290 | |
291 | if (lock_len == 0) { |
292 | val = 0; /* fully unlocked */ |
293 | } else { |
294 | min_prot_len = spi_nor_get_min_prot_length_sr(nor); |
295 | pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; |
296 | val = pow << SR_BP_SHIFT; |
297 | |
298 | if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) |
299 | val = (val & ~SR_BP3) | SR_BP3_BIT6; |
300 | |
301 | /* Some power-of-two sizes are not supported */ |
302 | if (val & ~mask) |
303 | return -EINVAL; |
304 | } |
305 | |
306 | status_new = (status_old & ~mask & ~tb_mask) | val; |
307 | |
308 | /* Don't protect status register if we're fully unlocked */ |
309 | if (lock_len == 0) |
310 | status_new &= ~SR_SRWD; |
311 | |
312 | if (!use_top) |
313 | status_new |= tb_mask; |
314 | |
315 | /* Don't bother if they're the same */ |
316 | if (status_new == status_old) |
317 | return 0; |
318 | |
319 | /* Only modify protection if it will not lock other areas */ |
320 | if ((status_new & mask) > (status_old & mask)) |
321 | return -EINVAL; |
322 | |
323 | return spi_nor_write_sr_and_check(nor, sr1: status_new); |
324 | } |
325 | |
326 | /* |
327 | * Check if a region of the flash is (completely) locked. See spi_nor_sr_lock() |
328 | * for more info. |
329 | * |
330 | * Returns 1 if entire region is locked, 0 if any portion is unlocked, and |
331 | * negative on errors. |
332 | */ |
333 | static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, u64 len) |
334 | { |
335 | int ret; |
336 | |
337 | ret = spi_nor_read_sr(nor, sr: nor->bouncebuf); |
338 | if (ret) |
339 | return ret; |
340 | |
341 | return spi_nor_is_locked_sr(nor, ofs, len, sr: nor->bouncebuf[0]); |
342 | } |
343 | |
344 | static const struct spi_nor_locking_ops spi_nor_sr_locking_ops = { |
345 | .lock = spi_nor_sr_lock, |
346 | .unlock = spi_nor_sr_unlock, |
347 | .is_locked = spi_nor_sr_is_locked, |
348 | }; |
349 | |
350 | void spi_nor_init_default_locking_ops(struct spi_nor *nor) |
351 | { |
352 | nor->params->locking_ops = &spi_nor_sr_locking_ops; |
353 | } |
354 | |
355 | static int spi_nor_lock(struct mtd_info *mtd, loff_t ofs, u64 len) |
356 | { |
357 | struct spi_nor *nor = mtd_to_spi_nor(mtd); |
358 | int ret; |
359 | |
360 | ret = spi_nor_prep_and_lock(nor); |
361 | if (ret) |
362 | return ret; |
363 | |
364 | ret = nor->params->locking_ops->lock(nor, ofs, len); |
365 | |
366 | spi_nor_unlock_and_unprep(nor); |
367 | return ret; |
368 | } |
369 | |
370 | static int spi_nor_unlock(struct mtd_info *mtd, loff_t ofs, u64 len) |
371 | { |
372 | struct spi_nor *nor = mtd_to_spi_nor(mtd); |
373 | int ret; |
374 | |
375 | ret = spi_nor_prep_and_lock(nor); |
376 | if (ret) |
377 | return ret; |
378 | |
379 | ret = nor->params->locking_ops->unlock(nor, ofs, len); |
380 | |
381 | spi_nor_unlock_and_unprep(nor); |
382 | return ret; |
383 | } |
384 | |
385 | static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, u64 len) |
386 | { |
387 | struct spi_nor *nor = mtd_to_spi_nor(mtd); |
388 | int ret; |
389 | |
390 | ret = spi_nor_prep_and_lock(nor); |
391 | if (ret) |
392 | return ret; |
393 | |
394 | ret = nor->params->locking_ops->is_locked(nor, ofs, len); |
395 | |
396 | spi_nor_unlock_and_unprep(nor); |
397 | return ret; |
398 | } |
399 | |
400 | /** |
401 | * spi_nor_try_unlock_all() - Tries to unlock the entire flash memory array. |
402 | * @nor: pointer to a 'struct spi_nor'. |
403 | * |
404 | * Some SPI NOR flashes are write protected by default after a power-on reset |
405 | * cycle, in order to avoid inadvertent writes during power-up. Backward |
406 | * compatibility imposes to unlock the entire flash memory array at power-up |
407 | * by default. |
408 | * |
409 | * Unprotecting the entire flash array will fail for boards which are hardware |
410 | * write-protected. Thus any errors are ignored. |
411 | */ |
412 | void spi_nor_try_unlock_all(struct spi_nor *nor) |
413 | { |
414 | int ret; |
415 | |
416 | if (!(nor->flags & SNOR_F_HAS_LOCK)) |
417 | return; |
418 | |
419 | dev_dbg(nor->dev, "Unprotecting entire flash array\n" ); |
420 | |
421 | ret = spi_nor_unlock(mtd: &nor->mtd, ofs: 0, len: nor->params->size); |
422 | if (ret) |
423 | dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n" ); |
424 | } |
425 | |
426 | void spi_nor_set_mtd_locking_ops(struct spi_nor *nor) |
427 | { |
428 | struct mtd_info *mtd = &nor->mtd; |
429 | |
430 | if (!nor->params->locking_ops) |
431 | return; |
432 | |
433 | mtd->_lock = spi_nor_lock; |
434 | mtd->_unlock = spi_nor_unlock; |
435 | mtd->_is_locked = spi_nor_is_locked; |
436 | } |
437 | |