428 lines
11 KiB
C
428 lines
11 KiB
C
// 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_set_mtd_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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