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427 lines
11 KiB
427 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* SPI NOR Software Write Protection logic. |
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* |
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* Copyright (C) 2005, Intec Automation Inc. |
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* Copyright (C) 2014, Freescale Semiconductor, Inc. |
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*/ |
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#include <linux/mtd/mtd.h> |
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#include <linux/mtd/spi-nor.h> |
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#include "core.h" |
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static u8 spi_nor_get_sr_bp_mask(struct spi_nor *nor) |
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{ |
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u8 mask = SR_BP2 | SR_BP1 | SR_BP0; |
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if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6) |
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return mask | SR_BP3_BIT6; |
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if (nor->flags & SNOR_F_HAS_4BIT_BP) |
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return mask | SR_BP3; |
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return mask; |
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} |
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static u8 spi_nor_get_sr_tb_mask(struct spi_nor *nor) |
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{ |
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if (nor->flags & SNOR_F_HAS_SR_TB_BIT6) |
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return SR_TB_BIT6; |
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else |
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return SR_TB_BIT5; |
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} |
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static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor) |
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{ |
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unsigned int bp_slots, bp_slots_needed; |
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u8 mask = spi_nor_get_sr_bp_mask(nor); |
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/* Reserved one for "protect none" and one for "protect all". */ |
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bp_slots = (1 << hweight8(mask)) - 2; |
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bp_slots_needed = ilog2(nor->info->n_sectors); |
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if (bp_slots_needed > bp_slots) |
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return nor->info->sector_size << |
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(bp_slots_needed - bp_slots); |
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else |
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return nor->info->sector_size; |
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} |
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static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs, |
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uint64_t *len) |
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{ |
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struct mtd_info *mtd = &nor->mtd; |
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u64 min_prot_len; |
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u8 mask = spi_nor_get_sr_bp_mask(nor); |
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u8 tb_mask = spi_nor_get_sr_tb_mask(nor); |
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u8 bp, val = sr & mask; |
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if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6) |
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val = (val & ~SR_BP3_BIT6) | SR_BP3; |
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bp = val >> SR_BP_SHIFT; |
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if (!bp) { |
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/* No protection */ |
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*ofs = 0; |
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*len = 0; |
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return; |
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} |
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min_prot_len = spi_nor_get_min_prot_length_sr(nor); |
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*len = min_prot_len << (bp - 1); |
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if (*len > mtd->size) |
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*len = mtd->size; |
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if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask) |
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*ofs = 0; |
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else |
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*ofs = mtd->size - *len; |
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} |
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/* |
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* Return true if the entire region is locked (if @locked is true) or unlocked |
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* (if @locked is false); false otherwise. |
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*/ |
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static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs, |
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uint64_t len, u8 sr, bool locked) |
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{ |
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loff_t lock_offs, lock_offs_max, offs_max; |
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uint64_t lock_len; |
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if (!len) |
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return true; |
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spi_nor_get_locked_range_sr(nor, sr, &lock_offs, &lock_len); |
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lock_offs_max = lock_offs + lock_len; |
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offs_max = ofs + len; |
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if (locked) |
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/* Requested range is a sub-range of locked range */ |
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return (offs_max <= lock_offs_max) && (ofs >= lock_offs); |
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else |
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/* Requested range does not overlap with locked range */ |
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return (ofs >= lock_offs_max) || (offs_max <= lock_offs); |
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} |
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static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len, |
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u8 sr) |
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{ |
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return spi_nor_check_lock_status_sr(nor, ofs, len, sr, true); |
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} |
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static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, |
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uint64_t len, u8 sr) |
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{ |
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return spi_nor_check_lock_status_sr(nor, ofs, len, sr, false); |
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} |
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/* |
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* Lock a region of the flash. Compatible with ST Micro and similar flash. |
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* Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status |
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* register |
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* (SR). Does not support these features found in newer SR bitfields: |
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* - SEC: sector/block protect - only handle SEC=0 (block protect) |
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* - CMP: complement protect - only support CMP=0 (range is not complemented) |
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* |
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* Support for the following is provided conditionally for some flash: |
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* - TB: top/bottom protect |
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* |
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* Sample table portion for 8MB flash (Winbond w25q64fw): |
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* |
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* SEC | TB | BP2 | BP1 | BP0 | Prot Length | Protected Portion |
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* -------------------------------------------------------------------------- |
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* X | X | 0 | 0 | 0 | NONE | NONE |
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* 0 | 0 | 0 | 0 | 1 | 128 KB | Upper 1/64 |
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* 0 | 0 | 0 | 1 | 0 | 256 KB | Upper 1/32 |
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* 0 | 0 | 0 | 1 | 1 | 512 KB | Upper 1/16 |
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* 0 | 0 | 1 | 0 | 0 | 1 MB | Upper 1/8 |
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* 0 | 0 | 1 | 0 | 1 | 2 MB | Upper 1/4 |
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* 0 | 0 | 1 | 1 | 0 | 4 MB | Upper 1/2 |
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* X | X | 1 | 1 | 1 | 8 MB | ALL |
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* ------|-------|-------|-------|-------|---------------|------------------- |
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* 0 | 1 | 0 | 0 | 1 | 128 KB | Lower 1/64 |
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* 0 | 1 | 0 | 1 | 0 | 256 KB | Lower 1/32 |
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* 0 | 1 | 0 | 1 | 1 | 512 KB | Lower 1/16 |
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* 0 | 1 | 1 | 0 | 0 | 1 MB | Lower 1/8 |
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* 0 | 1 | 1 | 0 | 1 | 2 MB | Lower 1/4 |
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* 0 | 1 | 1 | 1 | 0 | 4 MB | Lower 1/2 |
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* |
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* Returns negative on errors, 0 on success. |
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*/ |
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static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len) |
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{ |
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struct mtd_info *mtd = &nor->mtd; |
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u64 min_prot_len; |
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int ret, status_old, status_new; |
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u8 mask = spi_nor_get_sr_bp_mask(nor); |
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u8 tb_mask = spi_nor_get_sr_tb_mask(nor); |
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u8 pow, val; |
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loff_t lock_len; |
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bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; |
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bool use_top; |
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ret = spi_nor_read_sr(nor, nor->bouncebuf); |
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if (ret) |
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return ret; |
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status_old = nor->bouncebuf[0]; |
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/* If nothing in our range is unlocked, we don't need to do anything */ |
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if (spi_nor_is_locked_sr(nor, ofs, len, status_old)) |
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return 0; |
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/* If anything below us is unlocked, we can't use 'bottom' protection */ |
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if (!spi_nor_is_locked_sr(nor, 0, ofs, status_old)) |
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can_be_bottom = false; |
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/* If anything above us is unlocked, we can't use 'top' protection */ |
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if (!spi_nor_is_locked_sr(nor, ofs + len, mtd->size - (ofs + len), |
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status_old)) |
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can_be_top = false; |
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if (!can_be_bottom && !can_be_top) |
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return -EINVAL; |
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/* Prefer top, if both are valid */ |
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use_top = can_be_top; |
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/* lock_len: length of region that should end up locked */ |
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if (use_top) |
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lock_len = mtd->size - ofs; |
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else |
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lock_len = ofs + len; |
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if (lock_len == mtd->size) { |
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val = mask; |
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} else { |
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min_prot_len = spi_nor_get_min_prot_length_sr(nor); |
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pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; |
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val = pow << SR_BP_SHIFT; |
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if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) |
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val = (val & ~SR_BP3) | SR_BP3_BIT6; |
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if (val & ~mask) |
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return -EINVAL; |
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/* Don't "lock" with no region! */ |
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if (!(val & mask)) |
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return -EINVAL; |
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} |
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status_new = (status_old & ~mask & ~tb_mask) | val; |
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/* Disallow further writes if WP pin is asserted */ |
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status_new |= SR_SRWD; |
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if (!use_top) |
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status_new |= tb_mask; |
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/* Don't bother if they're the same */ |
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if (status_new == status_old) |
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return 0; |
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/* Only modify protection if it will not unlock other areas */ |
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if ((status_new & mask) < (status_old & mask)) |
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return -EINVAL; |
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return spi_nor_write_sr_and_check(nor, status_new); |
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} |
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/* |
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* Unlock a region of the flash. See spi_nor_sr_lock() for more info |
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* |
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* Returns negative on errors, 0 on success. |
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*/ |
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static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len) |
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{ |
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struct mtd_info *mtd = &nor->mtd; |
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u64 min_prot_len; |
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int ret, status_old, status_new; |
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u8 mask = spi_nor_get_sr_bp_mask(nor); |
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u8 tb_mask = spi_nor_get_sr_tb_mask(nor); |
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u8 pow, val; |
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loff_t lock_len; |
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bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; |
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bool use_top; |
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ret = spi_nor_read_sr(nor, nor->bouncebuf); |
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if (ret) |
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return ret; |
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status_old = nor->bouncebuf[0]; |
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/* If nothing in our range is locked, we don't need to do anything */ |
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if (spi_nor_is_unlocked_sr(nor, ofs, len, status_old)) |
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return 0; |
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/* If anything below us is locked, we can't use 'top' protection */ |
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if (!spi_nor_is_unlocked_sr(nor, 0, ofs, status_old)) |
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can_be_top = false; |
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/* If anything above us is locked, we can't use 'bottom' protection */ |
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if (!spi_nor_is_unlocked_sr(nor, ofs + len, mtd->size - (ofs + len), |
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status_old)) |
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can_be_bottom = false; |
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if (!can_be_bottom && !can_be_top) |
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return -EINVAL; |
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/* Prefer top, if both are valid */ |
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use_top = can_be_top; |
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/* lock_len: length of region that should remain locked */ |
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if (use_top) |
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lock_len = mtd->size - (ofs + len); |
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else |
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lock_len = ofs; |
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if (lock_len == 0) { |
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val = 0; /* fully unlocked */ |
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} else { |
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min_prot_len = spi_nor_get_min_prot_length_sr(nor); |
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pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; |
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val = pow << SR_BP_SHIFT; |
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if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) |
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val = (val & ~SR_BP3) | SR_BP3_BIT6; |
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/* Some power-of-two sizes are not supported */ |
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if (val & ~mask) |
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return -EINVAL; |
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} |
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status_new = (status_old & ~mask & ~tb_mask) | val; |
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/* Don't protect status register if we're fully unlocked */ |
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if (lock_len == 0) |
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status_new &= ~SR_SRWD; |
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if (!use_top) |
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status_new |= tb_mask; |
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/* Don't bother if they're the same */ |
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if (status_new == status_old) |
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return 0; |
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/* Only modify protection if it will not lock other areas */ |
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if ((status_new & mask) > (status_old & mask)) |
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return -EINVAL; |
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return spi_nor_write_sr_and_check(nor, status_new); |
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} |
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/* |
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* Check if a region of the flash is (completely) locked. See spi_nor_sr_lock() |
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* for more info. |
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* |
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* Returns 1 if entire region is locked, 0 if any portion is unlocked, and |
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* negative on errors. |
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*/ |
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static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, uint64_t len) |
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{ |
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int ret; |
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ret = spi_nor_read_sr(nor, nor->bouncebuf); |
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if (ret) |
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return ret; |
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return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]); |
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} |
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static const struct spi_nor_locking_ops spi_nor_sr_locking_ops = { |
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.lock = spi_nor_sr_lock, |
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.unlock = spi_nor_sr_unlock, |
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.is_locked = spi_nor_sr_is_locked, |
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}; |
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void spi_nor_init_default_locking_ops(struct spi_nor *nor) |
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{ |
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nor->params->locking_ops = &spi_nor_sr_locking_ops; |
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} |
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static int spi_nor_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len) |
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{ |
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struct spi_nor *nor = mtd_to_spi_nor(mtd); |
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int ret; |
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ret = spi_nor_lock_and_prep(nor); |
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if (ret) |
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return ret; |
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ret = nor->params->locking_ops->lock(nor, ofs, len); |
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spi_nor_unlock_and_unprep(nor); |
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return ret; |
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} |
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static int spi_nor_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len) |
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{ |
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struct spi_nor *nor = mtd_to_spi_nor(mtd); |
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int ret; |
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ret = spi_nor_lock_and_prep(nor); |
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if (ret) |
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return ret; |
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ret = nor->params->locking_ops->unlock(nor, ofs, len); |
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spi_nor_unlock_and_unprep(nor); |
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return ret; |
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} |
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static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len) |
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{ |
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struct spi_nor *nor = mtd_to_spi_nor(mtd); |
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int ret; |
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ret = spi_nor_lock_and_prep(nor); |
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if (ret) |
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return ret; |
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ret = nor->params->locking_ops->is_locked(nor, ofs, len); |
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spi_nor_unlock_and_unprep(nor); |
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return ret; |
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} |
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/** |
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* spi_nor_try_unlock_all() - Tries to unlock the entire flash memory array. |
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* @nor: pointer to a 'struct spi_nor'. |
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* |
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* Some SPI NOR flashes are write protected by default after a power-on reset |
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* cycle, in order to avoid inadvertent writes during power-up. Backward |
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* compatibility imposes to unlock the entire flash memory array at power-up |
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* by default. |
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* |
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* Unprotecting the entire flash array will fail for boards which are hardware |
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* write-protected. Thus any errors are ignored. |
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*/ |
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void spi_nor_try_unlock_all(struct spi_nor *nor) |
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{ |
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int ret; |
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if (!(nor->flags & SNOR_F_HAS_LOCK)) |
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return; |
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dev_dbg(nor->dev, "Unprotecting entire flash array\n"); |
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ret = spi_nor_unlock(&nor->mtd, 0, nor->params->size); |
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if (ret) |
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dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n"); |
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} |
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void spi_nor_register_locking_ops(struct spi_nor *nor) |
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{ |
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struct mtd_info *mtd = &nor->mtd; |
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if (!nor->params->locking_ops) |
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return; |
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mtd->_lock = spi_nor_lock; |
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mtd->_unlock = spi_nor_unlock; |
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mtd->_is_locked = spi_nor_is_locked; |
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}
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